ManualGESTAR2014 English

GESTAR 2014.- User’s Manual

1

DRAFT #1 UNDER REVIEW

GESTAR 2014 USER’S MANUAL

Application for Hydraulic and Energy Engineering of Pressurised Irrigation Networks

Escuela Politécnica Superior de Huesca University of Zaragoza

Carretera Zaragoza s/n. 22071-Huesca

Email: [email protected] Website: www.gestarcad.com

Translation Lauren Lyon

October 12th 2014

http://www.gestarcad.com/�


2

CONTENTS

1 INTRODUCTION _____________________________________________________ 3

2 INSTALLATION _____________________________________________________ 7

3 REVIEW OF FUNCTIONS ____________________________________________ 17

4 OPERATIONAL PROTOCOL _________________________________________ 43

5 TOOLBARS _________________________________________________________ 46

6 PROGRAMME MENUS _____________________________________________ 124

7 EDITING THE MODEL _____________________________________________ 179

8 SIZING COLLECTIVE BRANCHED NETWORKS ______________________ 225

9 HYDRAULIC ANALYSIS ____________________________________________ 265

10 EVALUATION OF POWER COSTS AND OPTIMIZATION OF REGULATIONS IN PUMPING STATIONS ___________________________________ 302

11 IN-PLOT DESIGN __________________________________________________ 324

12 OPTIMISING IRRIGATION SCHEDULES _____________________________ 413

13 HANDLING DATABASES ___________________________________________ 427


3

1 INTRODUCTION

GESTAR offers the most complete software package for engineering pressurised irrigation systems (collective distribution networks and systems for use in irrigation on plots). Its tools and modules, specifically designed for pressurised irrigation and tested over the long term, enable optimum design, execution and management,

♦

integrating a wide range of resources, many of them available exclusively in this programme, and a long history of innovations and application to large and small systems. Some of its principal features are summarised below.

Integration of modules for optimisation, hydraulic analysis and analysis of energy in the same environment

♦

, making these tasks easier and more convenient, while more importantly, enabling much more economic and reliable solutions to be found than those obtained in processes simply based on optimisation routines.

High optimisation levels for branching networks

♦

with a set layout, with multiple options, protocols and handy tools for finding solutions with substantial reductions in system costs.

Hydraulic analysis module, unique in its robustness, flexibility and efficiency, developed specifically and with exclusive capabilities

♦

, such as Inverse Analysis, effective treatment of low resistance Elements and regulating valves, general modelling of individual and lateral emitters with pressure-dependent flow emitted, pump performance curves with inflection points, modelling of direct pumping stations, etc.

♦ Interoperable environment using the ACCESS standard as an intermediary for communicating with all types of CAD/GIS systems or third party programmes, as well as utilities for

All modules and tools, while making intensive internal use of advanced numerical procedures, are transparent to the user, in an intuitive graphic interface.

bidirectional communication with

♦

AutoCAD.

Integration of many innovative tools

♦

(generating scenarios, alarms, filters, evolution over time, configuration of pipes with en route consumption, emitters, etc) conceived and developed thanks to extensive experience in network design and modelling.

Availability of databases

for pipes, valves, singular losses, sprinklers, drip branches, fluids, electricity prices, pumps, etc.


4

FIGURE 1.1 GESTAR Architecture

FIGURE 1.1 shows a synoptic diagram of the main modules schematising the architecture of the application.

The Flow Rate and Tools Control module supports the front end visualisation and user interface, links the various operating modules and launches and controls the auxiliary tools which handle the practical configuration and analysis resources, such as: outputting and consultation of data and results, generators of random and/or deterministic scenarios, automatic results analysts, risk programmers, configuration of alarms, formulation of Design Flow Rates, head loss options and many others.

The Size Optimisation module carries out the economic optimisation of branching networks with a given layout, both on demand and rotational, finding the combination of diameters, material and pressure rating to satisfy at minimum cost the supplied flow rate and minimum pressures of hydrants and emitters. This optimisation accepts both gravity feed with set total head, and direct pumping stations, in which case the optimisation process not only finds the pump head which minimises total annual costs (abbreviated method with simplified calculation of power costs), but also the most favourable composition and regulation of the pumping station, using iterative procedures and a detailed calculation of power consumption, incorporating the variability of flow demand during the campaign and the hydraulic power response of the pumping station.

The Hydraulic and Power Simulation module, designed to reproduce the behaviour of projected or built networks, in normal or exceptional conditions, is applied to the designs obtained from the module above, incorporating all constructive and operational details, or to existing systems. On one hand it validates the behaviour of the system realistically and generally, making it possible to identify, diagnose and resolve possible malfunctions. On the other, it enables the definition and verification of later necessary changes and adjustments, optimising the management and planning of the


5

system throughout its service life. The hydraulic and power results provided by these simulations enable a detailed analysis of the system’s behaviour. Some recent applications of these resources, carried out with the optimum sizing tools, are the selection of network operation alternatives (pumping direct or to a reservoir, irrigation on demand or in turns), the study of possible sectorisation or turns with different pressure scales, or the selection of the most suitable irrigation periods and electricity rates for a given exploitation policy.

The module for Regulating Pumping Stations provides innovative and specialised resources for the correct design and exploitation of the pumping stations feeding irrigation networks, their regulation, and the minimisation of power costs. The many application examples of these resources include the rational selection in the design phase of the best number, type and adjustment of pump units; the best adjustment to suit the operational characteristics of a system already in use; the diagnosis of the origins of possible malfunctions and the definition of modifications needed in operational networks with inefficient or obsolete pumping stations.

The Plot Design module (in Beta, not documented in this manual) combines adaptations of the above modules and specific extensions for optimum sizing and analysis of sprinkler and localised networks.

The satellite modules, dedicated to supplying the Databases (pipes, singular head losses, valve head losses, according to type and degree of opening, pumps, electricity rates, sprinklers, emitters, fluids) and the I/O communication of data and results (shares data with AutoCAD and ACCESS, exports to MS Office), offer additional support for the productivity and interoperability of the application.

Finally, the TELEGESTAR tools form a DLL library environment independent of GESTAR, making it possible to migrate and integrate the hydraulic and power simulation functions provided by GESTAR, and specific resources for optimising the management of pumping stations, in any remote control and remote management system.

GESTAR began development in 1993, in the Faculty of Fluid Mechanics at the University of Zaragoza, linked to the Escuela Politécnica Superior (Polytechnic) of Huesca, in the Agricultural Engineering degree programme, and was given a considerable boost by the agreement of 1995 between the Aragonese Government’s Agriculture Department and the University of Zaragoza: “Advanced Hydraulic Modelling and Evaluation of Irrigation Networks”. Since then, new agreements, various sources of funding for R&D projects, and funds from technical assistance and licensing contracts have enabled us continuously to update, expand and refine its features in a permanent feedback cycle: development of innovations => intensive application => identification of needs/improvements => new development of innovations


7

2 INSTALLATION

2.1 MINIMUM REQUIREMENTS

GESTAR2014 is a 32-bit single-user application for use in operating systems in the Windows family.

To run GESTAR2014 and use all its functions your PC will need the following resources:

♦ Windows XP-SP2 or later, Windows 7, Windows 8, 32-bit or 64-bit versions. Windows VISTA IS NOT RECOMMENDED (a)

♦ Minimum 512 Mb RAM (2Gb recommended)

♦ Minimum free hard drive space: 105 Mb

♦ Virtual PDF printer (b)

♦ MS Access, MS Excel, MS Word version 97 or later (c)

♦ For communication with AutoCAD, if used, the version of AutoCAD must be from 2002-2010 (d).

♦ OS updated to .NET Framework 4 (e)

(a) Although we do not recommend installing GESTAR 2014 with Windows Vista, if using this OS, remember to turn on the compatibility options of GESTAR.exe (in C:/Program files/GESTAR2014/GESTAR2014.exe): Run in Administrator Mode and Compatible with XP.

(b) A freeware virtual PDF printer (CutePDF Writer) is bundled with the GESTAR installer, in case this type of utility is not available, for producing the documents generated in the optimum network sizing process. C/Program files/Gestar2014/CuteWriter.exe. Run the installer CuteWriter.exe and follow the instructions. (Internet connection required during installation).

(c) If using GESTAR’s I/O communications tools with ACCESS databases, the databases created by GESTAR (export processes) are in MS Office 97 format (compatible with all later versions), and user-generated databases to be read by GESTAR (e.g., import process) must be saved as MS Office 97 files.

(d) If using the GESTAR network I/O communications tools with AutoCAD, the version of AutoCAD must be from 2002 to 2014, inclusive. Due to the limitations on


8

application dialogues in Windows Vista, GESTAR’s tools for communicating with AutoCAD are not currently operational or reliable in Windows Vista, but they are accessible in Windows 7 and Windows 8. Therefore, if communication is needed with AutoCAD, Windows Vista is not recommended at present.

(e) GESTAR 2014 uses modern Microsoft technology which requires a specific OS update. This update (.NET Framework 4) is usually already installed in the latest versions of Windows 8, but not in XP, Vista (not recommended) and Windows 7. Microsoft .NET Framework 4 will be installed automatically if you have an Internet connection when you begin installing an application using this technology, such as GESTAR 2014, but it requires a fast connection and takes time. Your PC may already have this update installed if it was previously needed by other programmes.

.

2.2 OPERATIONAL MODES

GESTAR and its modes of operation are structured as A SINGLE APPLICATION with a SHARED INSTALLER (Gestar20XXSetup.exe) enabling different levels of access to the implemented resources, according to the available privileges and the option chosen in the start-up screen of the programme (FIGURE 2.1) after installation. The installers have an expiry date to ensure that the application is constantly updated.

The three available versions (or operational modes) are Educational, Professional and Premium.


9

FIGURE 2.1 GESTAR start-up screen

The installer and other resources such as developed examples, additional documentation, or auxiliary tools available now or in the future, can be accessed by registering on the new website www.gestarcad.com. Registration is free and requires only an email address. The website automatically generates a password which will be sent to that email address (the password can be changed after logging in at the website). The registration data is stored according to data protection law. Incorrect information will lead to removal from the system.

Public domain mode. Internet connection not required to run. Simply download the installer and run it for access to this version. This mode includes working versions of all tools in the application, but limited to a certain number of components and small sized systems (

GESTAR Educational

Table 2. 1). The application has no expiry date in Educational mode, although we recommend registering at the website in order to be notified of updates and access available documentation.

Educational Professional Premium*

25 Junction Nodes 100 3000 20 Known Consumption 100 3000 7 Regulating Hydrants 7 3000 2 Dams 10 300 2 Reservoirs 10 300 2 Known Pressure 10 300

20 Emitters 20 3000 5 Free Nodes 5 300 5 Double Condition Nodes 5 300

30 Pipes 125 3000



10

5 Emitter Lines 5 3000 7 Valves 7 300

Pumps 5/3 (analysis/regulation)

5/3 300

5 Free Elements 5 300 300 Polyline Vertices 300 300

*Set points. If users need higher values (unlimited) special versions can be supplied at no additional cost.

Table 2. 1 Maximum values of components according to operational modes. Changes may appear in the Educational and Professional modes without previous notice. See www.gestarcad.com.

Public domain mode. Requires registration at the website and internet connection with log-in (user’s email address and password) each time the application starts. The username and current version will be checked on start-up, as it is regularly updated. The Professional version can handle a greater maximum number of components than the Educational version although some resources are restricted or disabled. These conditions, like those of

GESTAR Professional

Table 2. 1, can be modified without previous notice.

Access to GESTAR Premium mode is reserved for public or private bodies or professionals who have participated to some degree in sponsoring the development and maintenance of the GESTAR application. Types of sponsorship (agreement, technical assistance, licensing) are described online at http://www.acquanalyst.com/contenido.php?modulo=faq. The respective contract models can be downloaded from the website. Please contact the User Help Service by email at

GESTAR Premium

[email protected] for any further questions.

To use GESTAR in Premium mode you will need a licence file, associated exclusively with the computer where the application is installed, available only to Premium users, and have previously paid to register the license as described in section 2.3, p. 11.

Using GESTAR in Premium mode does not require an Internet connection and it is compatible with later use in either of the other two modes, Educational and Professional. However, users should remember that networks generated with tools for importing from AutoCAD in the Premium version, of any size, cannot be opened with the Professional version, which does not have this function.

Premium Licences include a series of technical assistance and support services (User Help Service) for 12 months from the date of activation of the GESTAR Premium licence: ♦ Free updates.

♦ Free access to the support service, by telephone and online, in aspects relating to the use of the application only ([email protected]).

♦ Free remote migration service (see conditions) of the Premium licence.


mailto:[email protected]�



11

♦ Each Licence to use GESTAR Premium may include in some countries free enrolment in one of the 7-hour training seminars which the authors organise on a regular basis, at locations and dates announced as they arise.

Starting from the end of the 12 month period users can opt to subscribe to an extension of the User Help Service with an additional contract, which includes updating, support and migration services.

Sponsors with multi-year contracts may provide access through temporary licences to Premium versions for companies or bodies to which they delegate activities in their area of responsibility, whether legal or territorial, during their period of use. During the period of validity these temporary licences will include the user Help Service.

2.3 GENERAL INSTALLATION PROCESS. PREMIUM REGISTRATION

After registering as a user at the website www.gestarcad.com, go to DOWNLOADS/download Software. When the option Download the Installer is selected, the user can run or save the latest installer of the application.

IMPORTANT:

If you do not have a fast internet connection, BEFORE INSTALLING GESTAR 2014 check whether the OS has been updated with .NET Framework 4. Your PC may already have this update installed if it was previously needed by other programmes. If not, install this update before installing GESTAR 2014.

To check whether this resource is available, look in the Windows folder, usually in C: (e.g. C:\WINDOWS\Microsoft.NET\Framework) and check whether there is a folder called v4.xxx (xxx can be any number). If you do not have the updated .NET Framework 4, it will be installed automatically if you have a fast Internet connection when you begin installing an application using this technology, such as GESTAR 2014. Alternatively, you can install .NET Framework 4 manually. To do this, search on the Microsoft website for “installer .NET Framework 4” and download the file “dotNetFx40_Full_x86_x64.exe”, which you should run BEFORE starting to install GESTAR2014. If your OS already has this update (because it is a recent Windows 8 version or the update was previously installed for another application) the OS will alert you, and may cancel the process. If not, let the process finish.

Before installing GESTAR, install all the programmes which communicate with GESTAR: MS Office, AutoCAD, virtual pdf printer.

You can install GESTAR and register the Premium licence directly if your User account is an Administrator account for the equipment, and the OS is XP or later (except Windows VISTA, which is not recommended).



12

However, in order to explain all possible cases and circumstances, we recommend reviewing the points given below and consulting the diagram in Appendix XIII.

If the programme will be used by more than one User we recommend creating a new shared User account just for using with GESTAR, as if GESTAR is installed in an existing User account it may not be accessible from another one.

PRIVILEGES AND CHECKS BEFORE INSTALLING GESTAR (AND REGISTERING AND UPDATING A PREMIUM LICENCE IF APPLICABLE)

Installing GESTAR requires Administrator privileges, at least during the Installation process (and Registration of the PREMIUM licence, if applicable).

If the User installing GESTAR is NOT an Administrator (not in the administrators group), go to the User account management tools via the Control Panel and follow this protocol:

Give the User temporary Administrator privileges so they can install GESTAR.

Install GESTAR (and Register the Licence if you have a PREMIUM mode licence, see below).

Withdraw the Administrator privileges from the User account and assign Standard privileges.

If you have a PREMIUM licence, regardless of the Operating System used, to enable the User to update the programme later without the need for Administrator intervention, assign the User Administrator privileges (Total Control) exclusively for the folder containing the programme, C:/Program files/GESTAR2014. To do this, locate the folder, open its properties (right-click on the folder) and assign “Full Control” Security properties to the User in question.

To run, the programme requires a number format where decimals are separated by “,” and thousands are separated by “.”. To confirm this setting or reconfigure it if necessary, go to the Control Panel and then to the Windows Regional Configuration tools.

GESTAR 2014 is a native 32-bit application. If you have a 64-bit OS, the application will be installed by default in the hard disc C: in the folder Program files (x86). All the applications which need to communicate with GESTAR (AutoCAD, Ms Office) in principle should be 32-bit. If they are 64-bit, you must check they are 32-bit compatible. (C: Program files (x86)).


13

If you have a PREMIUM licence, identify and save the installer file you will use to activate it to facilitate future reinstalls and registrations if they should be necessary.

After launching the installer Gestar20XXSetup.exe (running from Download or double-clicking the saved .exe file) the installation assistant will open (FIGURE 2.2).

FIGURE 2.2 Installation decisions. Left (Language), Right (Accept conditions)

Running the installer requires choosing a language (FIGURE 2.2 Left: there are four options: Spanish, English, French and Portuguese, but more options can be offered; see www.gestaracad.com ) and accepting the terms and conditions of use (FIGURE 2.2 Right). At the end of installation, users who do not have the option to print to PDF are recommended to install the virtual PDF printer included at C/Program Files/Gestar20XX/CuteWriter.exe. To do this, run CuteWriter.exe and follow its instructions.

When GESTAR 2014 finishes installing a desktop shortcut will appear, linking to the folder “Gestar data files” which contains the databases, manuals and examples associated with the application. Access these files through the folder.

If working with the Professional version, you will need an Internet connection via FTP (port 21) each time the application is launched, and to provide the username and password you were given when registering online.

If your OS is Windows VISTA, you will have to configure the Compatibility properties of the GESTAR2014 executable file (default location C:/Program files/GESTAR2014/GESTAR2014.exe). To do this, right-click on the file GESTAR2014.exe and select Properties. Enable the option “Run in compatibility mode Windows XP Service Pack 2” and “Privilege level: Run this program as an administrator”.


14

Installation of GESTAR Premium requires Administrator privileges.

PRIVILEGES FOR INSTALLING A PREMIUM LICENCE

If the user installing GESTAR is not an Administrator (not part of the administrators group) the procedure is as follows:

♦ Give user permissions to be able to install GESTAR (temporarily only).

♦ Install and register.

♦ Withdraw permissions.

For users to be able to update the application later, without needing the Administrator’s help, we recommend applying administrator privileges to the user in question, for the folder containing the application only.

If the application will be used by more than one user, we recommend the creation of a new shared user account specifically for using GESTAR.

When first launching GESTAR and choosing the Premium option, the programme will show the Registration Form in

REGISTRATION OF A PREMIUM LICENCE

FIGURE 2.3.

FIGURE 2.3 Premium License Registration Form

In the Registration Form, FIGURE 2.3, a sequence of numbers will appear in the top field. This is the “Licence Code”. This code must be sent by email to the User Help Service ([email protected]). The fields Company and Project are blank at this stage.

It will be confirmed that the person who will be the Reference User (at the beginning, the same person as indicated in the corresponding Licensing contract), their company or body (and in the case of temporarily granted licences, the name of the specific project the application will be used for) and a contact telephone number and email address.


15

At the end of this procedure, until the Licence File is received, click Exit and continue working with the Educational and Professional versions.

After checking the data received, the User Help Service will immediately send the Reference User an email with the Licence File (*.ges) associated with the Licence Code, which should be saved to a folder on the same computer as the programme. After saving the Licence File, you can activate the Premium Licence by restarting the application in Premium mode. The same Registration Form window will appear as in .FIGURE 2.3. Click the button Load Licence to open a file browsing window, where you can locate and open the Licence File. After opening the Licence File the fields Company and Project will be automatically filled in, FIGURE 2.4.

FIGURE 2.4 Premium License Registration Form

We recommend checking that the Company and Project information in the licence registration window are correct, as this information will appear on all the documents generated by GESTAR. Next, click the button Register and wait for the application to finish launching.

IMPORTANT: Do not cancel or restart GESTAR until this first launch has completed.

If the process has completed correctly, after a few seconds the GESTAR welcome screen will appear. You may now use GESTAR in Premium mode.

Once the version is registered, no further information or internet connection will be required when launching the Premium version.

Subsequent launches of GESTAR in Premium mode do not require further registration or internet access. The version will also not expire during the validity period of the licence, although updating is recommended. This does not require reinstalling or re-registering. To update, run the update application ActualizacionGestar.exe, which you will find at the download area of the website www.gestarcad.com

UPDATES


16

Versions can be updated for 12 months from the date of registration of the Premium Licence.

IMPORTANT, PLEASE READ CAREFULLY:

If a Premium Licence has been registered on your computer, UNDER NO CIRCUMSTANCES should you uninstall it or install a new version of GESTAR without specific instructions by the authors, as you could lose your licence.

UNINSTALLING AND MIGRATING PREMIUM LICENCES

If you want to migrate your licence from one computer to another, you must use the GESTAR licence migration protocol which the development group will give you when notified. For migration to be effective, it is essential that the original GESTAR application registered with a Premium Licence is operational and accessible (without uninstalling or reinstalling the operating system or formatting the drive where it is installed) on the computer for which the Premium Licence was originally issued, at the time of applying the protocol.

The protocol consists of four steps:

1) Uninstall the GESTAR application from the computer where the licence is stored. Make a note of the uninstall code which appears at the end of the process.

2) Install the application (with the installer for the latest version to which you have access, according to the update contract*) on the new computer (or reformatted disc or new OS, after reconfiguration) and make a note of the new licence condition code which appears in the Licence Registration window (Figure 2).

3) Email [email protected] with both codes: the uninstall code and the new licence condition code.

4) You will receive an email with the new licence file which you must register immediately following the process described above: REGISTRATION OF A PREMIUM LICENCE



17

3 REVIEW OF FUNCTIONS

In this chapter we give an overview of the characteristics, features and applications of the different models and tools of GESTAR shown in Chapter 1. Detailed operating instructions will be given in the rest of the manual.

As some of these resources are innovative and exclusive, and users may not have previous experience or training with them, we recommend reading this chapter carefully in order to understand the basic concepts for using the latest tools included in GESTAR.

This chapter cites publications and references (listed in under REFERENCES, at

the end of the Appendices of the manual), most of which are available for download at www.gestarcad.com, for users who would like more in-depth understanding of the theoretical basis, calculation methods and computational techniques used in the various modules of the application.

While the GESTAR interface is intuitive and easy to use, like all modern

engineering tools, GESTAR is a valuable platform which facilitates work and enhances skills, but does not replace them or remove the need for professional qualifications, training and experience in hydraulic engineering applied to irrigation systems to make the most of the resources it offers.

The use of the best calculation tools requires users who are sufficiently prepared

to understand the processes involved and interpret the results. If not, problems may arise in operation, concepts and projects.

3.1 GRAPHIC INTERFACE

Networks are loaded, boundary conditions specified, parameters modified, results presented and analysed in a completely interactive graphic interface.

All operations and options are handled by using icons, toolbars, dialogue windows and drop-down menus, making the full use of its capabilities easy and intuitive. Its use does not require lengthy study beforehand, enabling all types of users, from designers to irrigators, to learn quickly how to use the tools needed for each purpose. For this reason we emphasise the graphic user interface, intuitive handling, consistent algorithms when faced with extreme situations, integrated resolution of auxiliary tasks using utilities, checking consistency of in/out data, automatic checking of boundary conditions, user-configurable assistants and set points, error handling, etc. In particular, we highlight the following resources:

Interactive configuration: Graphic and interactive “click & drop” configuration of networks, “point and click” input/output in intuitive, user-friendly windows, scale



18

reproduction of the network layout, diagrams, dialogue windows, help menus, tables, graphs, error management, etc.

Working with UTM co-ordinates: Origin and scale (proportional to the screen resolution or set by the user) configurable for adjusting maps and orthophotos used as background.

Inserting images: As auxiliary cartographic backgrounds for layouts or in bmp, jpg, or gif format.

Consultation and documentation of data and results: Editing windows, colour codes, map of numerical values, pop-up window with data on the selected component, tables of results, export of ACCESS and EXCEL database text files. Graphs of evolution over time.

Configurable graphic parameters: Default values, prefix of identifiers, colour coding and visualization format in the map of numerical values, appearance of map background, Nodes and Elements, visualisation/hiding symbols of Nodes and Elements, direction arrows, number of digits in displayed data.

Rectangular and irregular polygonal section: For cutting, copying, pasting, moving, deleting, calculating cost and assigning parameters to all selected components.

Dividing a pipe into two stretches: At the point selected by the cursor on an existing Pipe, enabling the introduction of an intermediate Node, interpolating its elevation and the lengths of the two resulting stretches.

Joining networks: Merging two independent *.network files into a single output file in order to join partial networks in a larger system, with optional assignation of different prefixes to the components of each network and overlapping shared connection Nodes (co-ordinate and ID).

Zoom In/out: Zoom in to enlarge and zoom to half size, selection of initial zoom level set in Scale options.

Scrolling: Navigation around the network map using horizontal and vertical scroll bars.

Searching for nodes/elements: Directly locating Nodes and Elements by ID and by comments field, with markings on the map or automatic pop-up windows for editing their data.

Inserting images: Informative text added to the network map with configurable format.

3.2 OPTIMUM SIZING OF BRANCHING NETWORKS

In the case of networks configured as strictly branching (see APPENDIX I, p. 441) with predetermined design flow rates and layout, GESTAR provides the sizing tool which includes economic optimisation criteria; this can find the combination of Pipes to meet the set pressure requirements for Design flow rates, with a minimum overall cost, or very close to the overall minimum.


19

A network is called strictly branching if it has a branching topology in which there is a single total head point set, which normally corresponds to the inflow point, while the remaining Nodes in the network are assimilated to known consumption points, i.e., bifurcation Nodes, with null consumption, or regulated hydrants with flow equal to maximum flow rate. It is well known (UPV, 1993) that networks where the topology and boundary conditions are implemented configuring a strictly branching network offer particular advantages in design, as line flow rates can be determined in advance, separately from hydraulic equations, making it possible on one hand to establish optimum economical sizing methods for the diameters and Material of the network, and on the other, to then calculate the pressure of each point of the system, once the diameters have been set, for each demand configuration formulated.

Occasionally, the topology and configuration of boundary conditions diverge slightly from the strictly branching structure, and through a series of simplifications or suppositions the paradigm can be recovered, enabling the application of optimization modules to be extended. In these cases it is even more necessary, if possible, to apply the unrestricted simulation tools at a later stage to the branching configuration, reproducing the real topology of the system, in all its detail, in order to check the validity and scope of the approximations and hypotheses introduced in the sizing module.

It should also be noted that, incorporating optimization techniques in sizing, the results must always be treated with caution, for several reasons:

The statistical flow rates used in the case of on-demand networks, and the conditions of adjusting the pressure to the set levels, can cause excessive kinks in certain branches, and these areas can become extremely vulnerable to concentration of demand in the immediate area and at the ends, leading to sharp pressure drops in combinations of demand, often causing anomalous situations which the “optimum sizing” not only cannot predict, but can actively cause.

The sensitivity of the mathematical solution to pressure restrictions, layout hypotheses or conditions set in the use of the network (type of demand, turn rotations, equivalent irrigation periods, etc.) can lead to significant cost reductions through the right adjustments.

In contrast, the network may run better in terms of flexibility and safety, sometimes notably so, thanks to tweaking the sizing, which while marginally increasing the cost of the solution classified as “optimal”, gives much greater flexibility and safety, compensating for this increased cost.

Meanwhile, some of the results given as a mathematically optimal combination of Pipes may be constructively unviable (diameters which do not decrease downstream, multiple diameters, different materials interspersed, etc) or make execution more expensive in practice (special pieces, stocks, logistics, labour costs, etc).

All these aspects, which can be resolved only through the meticulous hydraulic analysis of the system, conclude in some cases with savings which are often greater than the differences found in the application of different optimization algorithms, and which in any case improve the quality and rationality of the design.


20

Despite these reservations, it is essential to incorporate optimization techniques in the sizing phase, in terms of facilitating the search for economy and viability of the initial design, which before the other phases, can be considered “rational pre-sizing”.

Among the optimum sizing algorithms for strictly branching networks incorporating the Economic Series Model, which supposes that a continuous potential function exists describing the cost of conduits according to their diameter, we find DIOPCAL (UPV, 1999) which originated in the Hydraulic Model Research and Development group (IDMH) of the Polytechnic University of Valencia. Thanks to the co-ordinated research project HID-98-0341-C03-02 by the Ministry of Science and Technology, these types of routines were integrated into the GESTAR programme. Since then, together with an intensive refining process for the sizing models, many improvements and refinements have been incorporated in the sizing modules, as well as a new optimisation procedure which combines a notably improved Economic Series Model (González and Aliod, 2003) with Labye type discontinuous optimization algorithms (Labye et al., 1988). Both methods (standard and improved) can optionally be used in the sizing modules, having been extended to accept an arbitrary number of Nodes and accept alphanumerical identifiers of up to fifteen characters.

It should be noted that if a hydraulic simulation phase is carried out on the sizing obtained in any optimisation process, and suitable measures are taken based on the observed results, systems can sometimes be found which with a valid functional behaviour are even more economical. The formulation and verification by simulation of the behaviour of turns postulated in certain critical branches of the network, taken together with the functioning on demand of the other hydrants, also provides designs with economies representing savings in the initial cost of the system.

We present below the main features and resources of the optimisation module.

Calculation of Design Flow Rates: through accumulation of open intakes in turn-based irrigation or by the Clement formulation for on-demand irrigation, with different levels of guaranteed supply, gradable according to the number of intakes. Design flow rates can be adjusted by the user in the module itself or by editing the Pipes.

Sizing Pipes for on-demand networks: For branching networks with a known total head (with direct feed or through interposed pumping) with given layouts, Design flow rates and pressure set points, through economic optimization techniques.

Sizing Pipes for rotational networks, with specified turns, using economic optimization criteria, for branching networks with a known total head (with direct feed or through an intermediate pump) with a given layout and pressure set points.

Inclusion of single and distributed losses: The effect of single losses can be studied through their equivalent length, distributed uniformly throughout as a percentage of the length of each conduit, either specifically or stretch by stretch.

Set pipelines: Stretches of pipelines can also be defined whose properties are set and are not altered during optimisation.

Optimum nominal discharge height: In the case of networks with direct pumping, for design flow rates in the network, giving the weighted efficiency of the pump, the annual


21

volumes served, the unit costs of the contracted power supply, and the applicable surcharges or discount rates, if any, it also gives the height which will optimise power and amortisation costs.

Adjustment of parameters: Various adjustments and optimisation options which enable sizing to be refined and additional costs to be assessed are now user-configurable and accessible.

Express resizing: Starting from a binary file or text file generated in a previous sizing procedure, containing the complete description of the network to be optimised and the established restrictions, individual values can be easily adjusted or systematic tests carried out with the help of the sizing assistant.

Guide to refining sizes. Options about the most critical Nodes, whose pressure requirements raise the costs of conduits the most, so that pressure requirements on them can be reduced in a rational and orderly manner, in order to lower system costs.

Identifying overpressure due to transients by sections, enabling pipe costs to be adjusted by reusing the results of the analysis of transients to judge the correct pressure rating for each section, adjusted for calculated overpressure rather than a single overall value.

Identifying maximum acceptable speeds by sections, in order to adjust costs by reusing the results of the analysis of transients to judge the maximum acceptable speed suited to each section, adjusted for local conditions rather than a single overall value.

3.3 HYDRAULIC/POWER ANALYSIS

The hydraulic and power analysis of a pressurized distribution system consists of prediction and detailed verification, using computational simulation techniques, simulating network behaviour in such a way that all hydraulic parameters (flow rate, pressure, speed, etc) can be assessed for each component of the network, and the relevant power parameters (power rating, efficiency, costs, etc.) in pumping equipment (individual pumps and stations), for each significant configuration of momentary demand. The topology of the network and its components (hydrants, conduits, pumps, regulating devices, etc.) will be defined either by previous sizing or by pre-existing information on construction in the case of already designed and/or executed networks.

Network analysis will go beyond the pure design phase in the technical office, being essential during construction, as the diverse and complex problems which can arise during conversion to a pressurised network, from first assessment to final delivery, mean many constant changes to the initial project, many of which are improvised during construction. These should be studied for possible malfunctions or knock-on effects which might not be noticed by the draughtsman or builder.

These simulation techniques, originally applied to supply systems, have shown themselves to be ideally suited and even more precise and reliable (Aliod et al, 1997) in irrigation networks, as:


22

♦ We can be sure of layouts and construction details, as this infrastructure is usually newer and better documented.

♦ It is not necessary to simplify or synthesise the network of pipes and outlets; even if extensive, they can be loaded in the model.

♦ A low level of uncertainty is introduced in the forecast consumption at the point of demand, thanks to the presence of regulating and measuring devices in the hydrants, making it possible to find out deterministically the consumption status of outlets, with irrigation notification protocols transmitted to farm managers or by automatic procedures based on flow rate sensors installed in the hydrants.

These conditionants can be taken advantage of for pressurised irrigation, as they enable simulation techniques to be applied and justify their productiveness, permitting high exactitude levels with low modelling effort compared to other contexts: as there is low uncertainty in the input data, and as these are limited in number, we can predict more precise results.

IMPROVED AND GENERALISED NODE ANALYSIS TECHNIQUES

While we could take advantage of the computer tools used in the analysis of supply systems for hydraulic simulation of irrigation systems, it is a fact that the calculation packages available for supply are not suitable for the idiosyncrasies of irrigation networks, and do not permit them to be used efficiently in everyday design and management.

This insufficiency in programmes for supply systems when used in irrigation not only affects the lack of graphic and operational utilities for simple, easy configuration of discontinuous demand scenarios and conditions, typical of irrigation networks, but more problematically, also affects previously available calculation algorithms, which are the heart of simulation systems, and do not address various particularities of irrigation networks.

GESTAR’s quasi stationary simulation module for hydraulic and power analysis implements original matricial numerical techniques specifically adapted to the characteristics of pressurised irrigation systems, using extensions of the Node Analysis Method, (Aliod et al, 2007), (Estrada et al. 2009) which permits dealing with simulations of networks of any topology, (branching, looped, mixed, etc) and a general, compact treatment of all types of contour conditions and regulating devices.

These techniques are based on the transformation of the complete system of non-linear equations characterising every node and Element of the network, together with the contour conditions, in a system of equations admitting a pseudo-linear matricial formulation, given that the coefficients of the matrix of the system of equations depend in turn on unknown variables whose solution is sought. To resolve this indeterminacy iterative processes are used, optimised to accelerate the convergence rate of the solution.


23

In the case of Emitter lines, these components form part of the general matricial calculation system as Continuous emitter elements, with flow emitted per unit of length depending on local pressure, Emitter lines which are modelled through an integrodifferential approximation (Warrick and Yitayew, 1988) which is extended and generalised (Estrada, 2000), (González and Aliod, 2005) (González and Aliod, 2007).

In the Node analysis the number of contour conditions relating to Nodes and Elements which can be set and the number of hydraulic unknowns which can be resolved are equal to the number of Nodes in the network. A condition is usually established for each node: In demand or supply nodes with a known flow rate a flow condition is specified, while in nodes connected to given pressure points (tanks, regulators, releases to the atmosphere, etc.) the total head is specified. The calculation will return the value of the other node variable, height or flow rate respectively. However, the GESTAR simulation module introduces the innovation, in the context of nodal methods, of being able to relax these conditions, making it possible to make a general and flexible choice from the range of data and unknowns, which is extremely useful for the purposes of regulating. Optimising and looking for parameters, a technique known as a whole as Inverse Network Analysis.

The most relevant numerical aspects related to the hydraulic solver are listed below:

♦ Quasi steady hydraulic solver uses an evolved Nodal Head type method, combined with Newton Raphson algorithm, for solving the system of non linear equations, with several extensions to handle with the specific irrigation network components, (Aliod and Gonzalez 2007).

♦ Dynamic memory allow to analyze networks with unlimited number of components.

♦ Unknowns, either node heads or flow rate, are computed coupled and relaxed at each iteration step.

♦ Jacobian matrix computed for general non linear elements constitutive equations.

♦ Direct flow rate computation at known head nodes, coupled with the rest of unknowns.

♦ Pressure dependent flow emission modelled as specific element with constitutive equation given by the individual pressure-flow emitter response, with a final node where total head equals to altitude.

♦ Low resistance elements treated with the Campos (1993) technique allowing the direct and coupled computation of the low resistance element flow rate.

♦ Matrix direct inversion routines and matrix operation libraries specially adapted for a non symmetric matrix, by means of the linked lists technique (Duff et al. 1986). Routines are optimized for sparse matrices and compact storage.

♦ Solution convergence control by two independent criteria: maximum average flow residue at the nodes, respect the average flow rate in the elements, and maximum difference between the value of the head in the nodes, or the relative flow rate in elements, between two consecutive iterations.


24

♦ Regulation valves simulation by direct calculation of their operational parameters coupled with the whole equation system.

♦ Dual modelling of hydrants depending on the pressure level on the network: when the pressure rises above the hydrant pressure setting, the node is modelled as a pressure independent flow demand, but when the network pressure falls below that level, the node demand is modelled as an emitter.

♦ Pressure dependent continuous-like flow emissions (for modelling drip irrigation tubing) are links modelled by means of a generalization (Aliod and González, 2007), of the integrodifferential approach of Warrick and Yitayew (1988).

♦ Inverse analysis allows the direct computation of unknown control parameters at node or elements, and computation of a common roughness or diameter for a group of elements, using a modified system of equations (Aliod and González. 2007).

♦ Volume level time evolution in extended period simulation is performed by means of the Rao and Bree (1997) formulation.

♦ Head loss generalized computation by monomic correlations or D-W expression with fully implicit formulae.

♦ Cubic spline fitting of characteristic curves (head, power, NPSHR) of pumps vs flow rate, and of curves describing the reservoirs volume vs level.

GESTAR models the behaviour of pumping equipment (and reservoir supply curves) using the pump head, power (or efficiency) and NPSHR performance curves according to the pumped flow rate, given by discrete points, with an analytical interpolation between them using splines. This type of adjustment means a series of important advantages, raising the generality and productivity of the application:

PERFORMANCE CURVES FITTED BY SPLINES

♦ A more precise and continuous approximation is obtained of the performance curves in the entire range of flow rates, with fewer points introduced, while improving the exactness of predictions of pressure and power consumption.

♦ It enables real performance curves to be introduced, even with multiple inflection points and upward slopes in the pump head curve, an exclusive characteristic enabling GESTAR to work with arbitrary height-flow curves, not just monotonously decreasing ones.

♦ Ensured stability and convergence in simulation routines, as there is continuity in the first derivative of the pump head curve for all flow rates, avoiding instabilities associated with discontinuities produced by a linear adjustment between given points.

The introduction of the points of the performance curves of discharge equipment can be done in tabular form or automatically, using the selection utilities from the Pumps Database, incorporated in the GESTAR installer.


25

The automatic loading of the points of the performance curves can be done using the direct selection menus, where you can choose manufacturer, series, model and size of runner from those registered, or establishing a desired functioning point (pump head and flow rate) and use the search engine of the database to find the combinations which best fit the point, with pumps ordered from higher to lower efficiency. In this last case, for each pump selected the best trim for the runner is estimated to obtain the exact point desired.

The possibility of introducing performance curves arbitrarily is also a

determinant for the very simple, although rigorous implementation of the behaviour of direct pumping stations with any type of regulation enabling a system curve to be followed, using one or more variable speed pumps (or the net pump head curve of the parallel association if all the groups are fixed speed). For this, it is sufficient to represent the pumping station as a whole using a pseudo-pump where the pump head vs. flow curve is precisely the system curve set on the pumping station robot, and the net power (or efficiency) vs. flow curve corresponds to the composition and type of regulation used.

These curves can be set in tabular form by the user or obtained automatically using the tools which GESTAR provides under the menu “Regulation of the Pumping station” (see p. 167).

GESTAR, since its 2008 version, extends the set of power supply variables which can be viewed as graphs or tables, with momentary power consumption and efficiency values, evaluated individually for each group and for all the pumping stations (García et al. 2008). According to the momentary power values, GESTAR computes the net power consumed over time, together with the corresponding economic costs, according to the associated electricity prices and voltages, modulated in as many time intervals and annual periods as desired. A specific utility enables the user to introduce the contracted prices (or those being negotiated) with total flexibility.

CALCULATION OF MOMENTARY AND TOTAL POWER PARAMETERS

Notably, it also incorporates the calculation of the energy efficiency indicators established in the Energy Audit Protocol for Irrigation Associations (IDAE, 2008), such as Energy Efficiency in Pumping (EEB) and estimated Energy Supply Efficiency (ESE). These indicators are calculated for each moment and as an overall balance sheet over the period of the simulation. GESTAR’s computation of these parameters not only is useful in the context of energy audits and improving existing installations, but just as importantly, its preventive quantification at the design stage makes it possible to detect malfunctions, if any, and apply the corrections needed from the start of the project.

To summarise, the main computational aspects which are paid special attention in the GESTAR hydraulic/energy simulation module, are:

♦ Presence of sections without circulating flow, from the last open hydrant in a branch, including absence of flow in all sections of the network when there is no demand.


26

♦ Existence of venting to the atmosphere through emitters with flow rate dependent on pressure.

♦ Modelling the behaviour of hydrants, not exclusively as set demand points, but also including the simulation of its regulating devices and the hydraulic behaviour of the plot being watered.

♦ Detection of Nodes disconnected by the action of closing valves in the pipelines feeding them.

♦ Robust action of flow limiting valves and pressure sustaining valves inserted in branching networks.

♦ Fitting pumping group performance curves using splines.

♦ Modelling pumping stations using joint action curves.

♦ Integro-differential treatment of emitter lines with flow rate emitted dependent on pressure

♦ Coupled resolution of flow rates and pressures in regulating valves

♦ Calculation of energy parameters, power, and efficiency, momentary or accumulated with the possibility of defining complex price bands for voltage and energy.

♦ Flexible treatment of the range of data and unknowns (Inverse Analysis), in order to answer immediate design, regulation and optimisation problems which would otherwise require a tedious or impracticable process of trial and error.

The possibility of rehearsing, before, during or after construction of the network, the real behaviour of the system as a whole and of its components when faced with any type of demand, easily modifying the details of construction, and receiving the interactive response of the system to these changes, constitutes a powerful engineering instrument which increases the productivity of the draughtsman, the reliability of the design and the hydraulic and energetic optimisation of management.

Some of the most frequent applications of these resources, completed by the optimal sizing tools, in the design and execution phase, and applications connected to management of the system once it is operational, are listed below.

APPLICATIONS OF THE ANALYSIS TOOLS

CHECKING THE BEHAVIOUR OF OPTIMISED SIZING RESULTS

♦ Checking for absence of errors in data loading

♦ Checking for satisfaction of default pressures

♦ Identifying areas with kinks or blockages and other malfunctions


27

♦ Diagnosis of the origin of malfunctions

♦ Definition of corrective or palliative measures for malfunctions (structural or organizational, turns, irrigation)

♦ Validation of Design flow rates and head flow rates

♦ Influence of variations in the available total heads

STUDY OF VARIANTS IN DESIGN AND MANAGEMENT

♦ Alternatives for operating the network (feeding directly or via a reservoir, irrigation on demand or rotational)

♦ Study of possible sectorising in different pressure levels

♦ Selection of the most suitable price bands

♦ Selection of irrigation times or days

♦ Influence of alternative layouts

♦ Influence of range of diameters and material used

♦ Introduction of new branches

♦ Study of the location of tanks

♦ Study of multiple supply points for the network

♦ Influence of levels in tanks in the behaviour of the network

♦ Calculation of volume in tanks

♦ Introduction of new connections or pipelines

ANALYSIS RELATING TO DEMAND POINTS

♦ Specification of maximum flow rates depending on the agronomic parameters

♦ Study of the influence of the degree of freedom in the intakes.

♦ Distribution of pressures and flow rates in the network with different maximum flow rates in the hydrants

♦ Maximum values which can be extracted for each individual user

♦ Determination of real flow rates from emitters

♦ Effect of regrouping, incorporation or elimination of hydrants


28

♦ Introduction of new consumers

♦ Variation in main crops

♦ Prediction of flow rates effectively supplied in hydrants lacking active pressure regulators

♦ Simulation and location of leaks

STUDY OF THE NETWORK’S RESPONSE TO DIFFERENT LEVELS OF DEMAND

♦ Distribution of pressures and flow rates in a given network with arbitrary connectivity and number of Nodes and Elements under different hypotheses of momentary demand.

♦ Determination of the maximum demand simultaneities which can be handled by the network as a whole

♦ Determination of the maximum demand simultaneities which can be handled by each branch

♦ Behaviour with peak or minimum consumption

♦ Location of the most and least favourable zones

♦ Detection of maximum and minimum pressures

♦ Location of bottlenecks and Elements restricting pipeline capacity

SPECIFICATION OF DEFAULT VALUES

♦ Calibrating relief valves and flood prevention valves

♦ Set point values in pressure and flow regulators

♦ Generation of set points for pumping stations

♦ Determining system curves for pumping equipment

♦ Prediction of opening coefficients for regulating valves

ASSESSING THE EFFECTS OF THE DETERIORATION OF THE NETWORK

♦ Analysis of the influence of the aging and/or silting up of the conduits

♦ Prediction of the hydraulic effects caused by deficiency in the execution of the installations

♦ Analysis of the influence of the degradation of the pumps


29

♦ Prediction of the effects of leaks, cracks and incorrect consumption

♦ Prediction of the effects of breakages and extreme events

APPLICATIONS IN NETWORK MANAGEMENT

♦ Planning routine operations

♦ Planning emergency actions

♦ Updating regulation and control set points

♦ Detection and identification of unexpected malfunctions

♦ Supervision and remote control

♦ Decision-making support systems

♦ Training operators

♦ Complete monitoring of the network

♦ Definition of modifications

♦ Managing excess demand in peak periods

INVERSE ANALYSIS

♦ Formulation of system curves of pumping stations in order to follow the evolution of the network over time

♦ Determination of the pressurisation levels needed to ensure the flow rates demanded at the pressures required at the least favourable points on the network

♦ Precise actions to regulate valves or pumps to fill or empty multiple tanks at a given speed

♦ Set points of pressure-regulating valves to protect a given sector

♦ The type of pipe (diameter, roughness or length), and degree of opening of regulating valves needed to fulfil a given supply

♦ Calibration of parameters of the network model

♦ Detection of leaks via simultaneous measurement of pressures and flow rates at certain points of the network and the inverse calculation of loss coefficients at possible leak sites


30

♦ Reduction of diameters of arteries through the siting of Elements which produce networks tending to make pressures more uniform or to raise them

We present below the main features and resources accessible for use in hydraulic/energy analysis.

FEATURES OF THE ANALYSIS TOOLS

NODES WHERE THE TOTAL HEAD IS SET.

Dam: Given steady free surface height.

Pressure Node: Given steady level and pressure head.

Reservoir: Established in terms of capacity (volume stored according to level) for a minimum of three levels, floor level and initial level. In the analysis of networks with temporal evolution, GESTAR 2008 will calculate the evolution of the level and volume stored over time.

NODES WHERE THE DEMAND IS SET.

Known consumption nodes: Consumption is known, and independent of local pressure. The maximum flow rate and momentary demand are specified. Optionally, if dealing with an irrigation hydrant, the data for the plot being supplied (surface area, fictitious continuous flow rate, pressure set point) and the network (irrigation times) can be loaded, obtaining the probability of opening and the degree of freedom of demand. Alternatively the degree of freedom of demand can be set, and the required maximum flow rate obtained. If consumption is not on demand but rotational and based on established turns, the node can be assigned to a given turn.

Junction node: There is no consumption.

NODES WHERE DEMAND DEPENDS ON FEED PRESSURE:

Emitters: All types of components with an emitted flow, Q, depending on the feed

pressure head, H, according to the relationshipNKQH = . In particular the values of K

and N for sprinklers selected from the corresponding database, in the form of tables, flow emitted/pressure, are calculated automatically. If this database contains information on the reach of the emitter according to pressure, the corresponding reach of the calculated pressure can be evaluated and represented as a graph. The properties of an associated feeder conduit can be added, with all the characteristics of the pipe-type elements. If consumption is based on established turns, the node can be assigned to a given turn.

Regulating Hydrants: These have a hybrid behaviour, combining the behaviour of the Known Consumption Node when pressure is above a certain threshold (pressure set point), with that of the Emitter Node when pressure drops lower than the pressure set point. If consumption is not on demand but rotational and based on established turns, the node can be assigned to a given turn.


31

Sprinklers: These constitute a particular type of emitter in which the point of emission is represented in the node where the emitter joins the network, the junction node, facilitating its representation and configuration in the design of irrigation in plots with hundreds or thousands of components.

TYPES OF ELEMENTS ADMITTED.

Pipes: Conduits with a constant cross-section, with options to incorporate singular head losses and throttle valves. The values of Interior Diameter and Roughness can be loaded in the Pipes Database, according to manufacturer, Material and pressure rating, or set by the user. Optionally for each pipe an arbitrary number of accessories and a throttle valve (or retention valve) can be incorporated, with a variable degree of opening with single

losses of the type gVkH2

2

=and generalised single losses formulated

NKQH = . The coefficients k of the singular losses in accessories is automatically communicated from the databases parameterised according to the type of singular element. In the case of

valves the values of k are computed as: 2

21

d

d

CC−

the discharge coefficient )(αdC being included in the interval (0.1), and being a function of the degree of opennessα and valve

type. )(αdC is loaded from the valve databases. Alternatively, the values of K and N, reproducing the dissipation of total head in any devices, must be supplied by the user in the corresponding dialogue boxes, with utilities for adjusting to experimental data. Each pipe admits logical retention and independent closure devices and registers the design flow rate (equipped for the sizing phase) and celerity in order to facilitate the migration of the results to transient analysis packages.

Pumps: Discharge elements defined in terms of increasing height through energy according to the flow rate, optionally considering total power consumption (or efficiency) and the NPSHR. The performance curves of the Element can be loaded using tabular values defined by the user, or automatically from the pump databases, which provide additional resources for choosing pumps adapted to a nominal point. Each pump incorporates a logical retention device. The performance curves are modelled using splines, permitting a precise fit throughout the range of flow rates for any type of geometry of the curve (maximums, minimums, inflection points). Thanks to this, GESTAR 2010 can exclusively offer a simple form of detailed modelling of the functioning of pumping stations as a whole, defining a pseudo-pump which takes as performance curves the conjoined curves of height-flow rate and power-flow rate, which GESTAR 2010 supplies directly in the “Pumping stations” module, according to the system curve, type and number of groups, and type of regulation.

Automatic regulating valves: Pressure reducing valves, pressure sustaining valves, flow limiting valves and acceptable combinations of these, configured by algorithms which enable a correct implementation of the operational states and limits of all of them in numerous contexts, including their placement in branches. The head loss coefficients K, for totally open positions, can be introduced manually or from the database of regulating valves.


32

Emitter Lines Pipes with a continuous flow emitted by unit of length q, where the flow rate emitted is not constant, but dependent on local pressure through relationships of the

type: x

d HKq =.

An integro-differential model is applied which enables the calculation of pressure and flow rate distributions throughout the Emitter line and evaluates locally emitted flow rates. When the Emitter lines have a closed end, the definition is admitted of various sub-sections with homogeneous properties as to the type of emitter and spacing, slope, Interior diameter and Roughness. If the end has another type of connexion (for example, to another Emitter line or pipe) only one section is admitted, and it will be automatically detected if there is a feed at one or both ends, and in this last case, the emitter behaviour will be simulated, detecting the internal point of zero velocity (neutral).

CONFIGURATION OF DETERMINIST SCENARIOS

HYDRAULIC ANALYSIS TOOLS

Stationary scenario: Opening/closing Known Consumption Nodes and regulating hydrants by point and click or by order executed by identifier.

Table of programming in quasi-stationary evolution over time: specification of the time interval of opening of each Node with flow demand, sprinklers and pipe elements, and pumping groups. Intervals and duration configurable by time lapse (or number of intervals) and length of interval.

Programming turns: Specification of the number of turns, duration of each of them and definition of Nodes (Known Consumption, Hybrid, Sprinkler) belonging to the turn. Extension of the table of programming over time to programme the start of each turn.

Logical commands in quasi-stationary evolution over time: Control orders, complementary to programming tables qualifying the opening/closing of Nodes with demand, pipes and pumps, according to the value of the characteristic variables (pressure or flow rate) regarding control values in Nodes and Elements.

Factors modulating demand: For each demand node it is possible to define factors modulating the assigned maximum flow rate, to reproduce the operation of shared hydrants, seasonal variations, etc.

Generator of energy prices. As many prices and price bands can be generated as desired (by day of the week, by month, by season, etc) with 24 periods of discrimination for each of them, both in terms of energy consumed and of available power, specifying the maximum power to be contracted in each period.

CONFIGURATION OF RANDOM SCENARIOS.

Generation of random demand scenarios: Distributions of demand nodes open or closed at random, satisfying a pre-established percentage of open intakes and including the probability of opening of each intake.


33

Assignation of non-conditional demand status: Opened or closed status can be set which are not affected by the generation of random demand status, making it possible to analyse mixed scenarios combining determinist (turns) and random demand conditions.

Network analyst: By generating a high number of random scenarios (with restrictions marked by the Nodes in non-conditional demand status) the maximum, minimum and average values are determined for all variables. Optionally, scenarios which generate alarms can be separated and saved individually for later analysis.

ALARMS AND REPORTS

Configuration of alarms: Options for setting a range of acceptable values for the variables: speed in pipes, aspiration in pumps, in valves, in emitter lines, head losses per unit of length, pressure in demand nodes, in junction nodes, and flow rate in hydrants. Threshold alarms can also be defined: maximum - minimum levels exceeded in reservoirs, pump cavitation, contracted power exceeded, negative pressures at any point and pressure in Hydrants below the Pressure set point (with adjustable tolerance). If an alarm is triggered, the component is marked graphically and noted in a report.

Alarm report: Exhaustive list of alarms (exportable to ACCESS file) generated in successive scenarios of evolution over time or random, indicating the scenario number, the component which generated the alarm, value of the variable producing the alarm and units of the variable. Includes a summary of the number of breaches per component (Element or Node) and percentage of pressure breaches in demand nodes.

The number of duplicate requirements in target nodes must be the same as the number of degrees of control freedom (not to be confused with the degree of freedom of demand in an irrigation hydrant) available for adjustment.

TOOLS FOR INVERSE HYDRAULIC ANALYSIS

NOTE: Arbitrarily set duplicate requirements may not be consistent, leading to badly constructed problems, without a solution in the space of physically viable solutions.

Double Condition Nodes: Nodes simultaneously specifying demand and pressure conditions to be met simultaneously in an operating network. These constitute the restrictive conditions to meet which the parameters of degrees of freedom for control must be adjusted in other free nodes and free elements, or free pipe sets.

Free node: Degree of freedom for control associated with point values which will determine the pressure and flow rate which should be supplied to the node in question in order to meet the requirements set by double condition nodes.

Free element: Degree of freedom for control associated with elements where the necessary energy jump and circulating flow to meet the requirements set by double condition nodes will end. If the resulting element is passive, it will be calculated as a dimensional coefficient of losses (or if two of the three parameters, length, interior diameter and roughness are supplied, the remainder will be determined) and if the element is active, the functioning point of the required discharge group will be calculated.


34

Free pipe sets: Group of connected or unconnected pipes sharing: either Interior Diameter or Roughness. The shared diameter or roughness is the degree of freedom for control which is adjusted to meet the requirements set by double condition nodes. Utility for the calibration of models, determination of unknown properties of pipes, adjustment to existing networks. Badly formed problems (physically impossible conditions) should be avoided.

Modulation of consumption: In demand nodes through a common factor.

OTHER COMPUTATIONAL RESOURCES

Automatic calculation: A new simulation will be executed automatically each time the status of a component is changed or there is any modification in construction data.

Adjusting by least squares: Utilities for adjusting a series of points to a second degree polynomial or an exponential function.

Head losses: Possibility of calculating head losses in pipes through different expressions: Hazen-Williams, Blasius, Manning, Darcy-Weisbach, with or without including laminar regime.

Calculating NPSHA: If the NPSHR of the pumps is introduced, and the NPSH alarm is activated, the system will trigger an alarm if NPSHA < NPSHR

Parameters Advanced users can access and modify various parameters for adjusting calculations

3.4 OPTIMISATION OF PUMPING STATIONS AND EVALUATION OF POWER COSTS

The GESTAR application, from its 2008 version, extends and improves the tools available to evaluate, in a rational and detailed manner, efficiencies and energy costs in irrigation networks with discharge systems. The results are useful both in the design stage, for optimising networks and designing the corresponding pumping stations, and for auditing processes, formulating improvements in installations and guidelines for exploitation of operating networks.

The process of implementing new irrigation systems and especially the modernisation of traditional irrigation through pressurised irrigation systems often requires pumping systems to balancing reservoirs or directly to the network, involving energy consumption. These aspects are increasingly attracting even attention due to the rising costs of generating electricity and the regular changes in electricity prices and bands. Meanwhile, in many functioning networks, low energy efficiency needs to be improved, due to divergences between the exploitation pattern found in practice and the original project, or to poor system design, undersizing or oversizing. This justifies the need to use advanced design and management tools which enable the optimisation of design processes and management of pumping stations and the networks they feed, facilitating decision making, the correct definition of all components, the optimisation


35

of their regulation and the obtaining of reliable assessments of costs, possible savings and maximum energy efficiency.

The system curve of the pumping station for on-demand systems can be set in GESTAR by the user, if known, or can be calculated using the tool which includes an application for determining it automatically.

SYSTEM CURVE

Given the adopted system curve and the composition and type of regulation of discharge groups, GESTAR calculates the complete family of action curves for the pumping station, consisting of the collection of functions characterising the behaviour of the station as a whole, depending on the total pumped flow rate q (Net Elevation Height, H

ACTIVITY CURVES OF PUMPING STATIONS

t

GESTAR is totally flexible and generally applicable for configuring any pumping station design, permitting compositions with arbitrary numbers of fixed speed pumps (BVF) and variable speed pumps (BVV), of the same or different sizes, and in the case of variable speed pumps, can consider the action of the changers sequentially (a variable speed pump regulating flow at all times) or simultaneously (various variable speed pumps regulating simultaneously with the same rotational speed). The programme also supplies a proposal (which can be modified by the user) for the launch sequence of the composition.

; Total Power Consumption, P and Overall Efficiency, η), and that of each of the pump groups making it up, including rpm depending on flow rate, q, for variable speed groups).

While the calculation and comparison of the action curves of various alternative configurations of a pumping station provide relevant information for making decisions on its composition and regulation, the realistic assessment of the energy costs of each alternative requires consideration of flow rate demands as well, as the pressure requirements given by the system curve and associated efficiencies are not usually constant, but depend on the pumped flow rate, which in turn depends on the selected composition and regulation.

ASSESSMENT OF ENERGY CONSUMPTION AND COSTS

The power consumption of the pumping station, P(q), is one of the action curves obtained directly from the composition and regulation chosen to follow the system curve, (until the functioning of 100% of the groups at maximum speed, after which point the pump head follows the composition in parallel of the groups).

In direct pumping, the energy consumed depends on the momentary power absorbed, which is a function of the flow rate, q, pumped at any time, and the time the pumping station has been functioning under this regime, so that the energy consumption must be calculated through integration, obtaining the Detailed Energy Consumption (CEDkWh), in kWh.


36

The specification of head flow rate demand over time is equivalent to knowing the distribution of the frequency of served flow rates, in terms of the Probability Density Function (PDF) of demand (López Cortijo et al. 2007), (García et al. 2008).

Where T is the total irrigation time available in the period studied, according to the definitions given, the Detailed Energy Consumption (CEDkWh

) in kWh in the period will be calculated as:

∫∫∫ ⋅⋅=⋅⋅=⋅=Qmax

0

T

0

T

0kWh dqFDP(q)P(q).T

Tdt(q)P(q).TdtP(q(t))CED

Equation 3-1Detailed Energy Consumption

It is important to point out that the product P(q)FDP(q) in Equation 3-1 is associated with the energy absorbed in a flow interval (q, q+dq).

In branching type on-demand irrigation networks, head flow rates correspond to a succession of different random scenarios, which are modified with the opening and closing of irrigation intakes. Consequently, the head flow rate can be considered a continuous random variable, whose PDF is estimated by GESTAR by combining monthly Gaussian type Probability Density Functions, depending exclusively on the daily water needs of each month, for a network with given hydrant maximum flow rates, plot areas and distribution of crops. In rotational irrigation networks, or in systems in use where there are experimental records of networks in use, the PDF can be introduced directly after inferring the irrigation schedules according to existing crops and established turns, or using these records to determine the frequency of occurrence of each flow rate.

In the abbreviated optimisation procedures for branching irrigation networks with direct pumping stations, Energy Consumption is computed in a simplified form, supposing a flat system curve (constant pump head, H

REFINED COMPUTATION OF ENERGY COSTS IN THE OPTIMUM SIZING OF NETWORKS WITH DIRECT PUMPING.

d, equal to that corresponding to the design pressure for the design head flow rate) and that the efficiency of the pumping station as a whole is also a constant estimated value, ηd, obtaining a simplified version of Equation 3-1 computing the Simplified Energy Consumption (CESkwh

dp

kwh H36001000

VCESη

γ⋅⋅

⋅=

):

Equation 3-2Simplified Energy Consumption


37

where γ is the specific weight of the water (kgm-2s-2) and V is the pumped volume in the period considered (m3

If the result of Equation 3-2 is multiplied by the weighted average price per kWh, this will give the estimated Simplified Energy Cost, CES

).

€

The detailed assessment of energy consumption using

. As can be seen, for the same volume supplied per year, and supposed efficiency, the CES grows lineally with the design height, Hd and annual volume, V.

Equation 3-1 is also applicable in the optimum sizing process of irrigation networks with direct discharges through the “sweep technique.” In this method for a supposed discharge height, Hx, the network is optimised and the resulting system curve obtained. With this system curve and predicted pumping composition(s) the CED can be evaluated using Equation 3-1. Adding the annual amortisation costs of the corresponding network, we obtain a value of the total cost associated with the supposed discharge level. Varying Hx in a range of possible solutions the minimum sum of costs of amortisation of the conduits and energy costs is found.

FIGURE 3.1 Results of the optimum sizing of directly pumped networks using the detailed (CED) or simplified (CES) calculation of energy costs.

FIGURE 3.1(Paño et al., 2009) (García et al, 2008), (López Cortijo et al. 2007) shows that while the energy consumption evaluated with the Equation 3-2Simplified Energy Consumption is rigidly proportional to the design height, Hd

Equation 3-1 Detailed Energy Consumption, in its refined

evolution, , the tendency for energy costs to grow according to head height, Hd, is less marked, so that the optimums found using the CED are sometimes different to those found when applying the CES, presuming the former to be more realistic in all cases.

Shown below are the main features and resources available in GESTAR for modelling, regulating and optimising pumping stations, by obtaining system curves,

TOOLS FOR MODELLING, REGULATING AND OPTIMISING PUMPING STATIONS


38

Action Curves and Probability Density Function of flow rates (PDF), which together establish energy costs for a certain period.

Pump Selection: Automatic incorporation in the pump type Elements of the performance curves of discharge equipment from databases of pumps, by direct search by model or search for the pump which best suits a determined nominal functioning point.

Estimation of simplified performance curves: Parabolic type curves are determined for a pump type adapted to a nominal functioning point according to basic parameters.

Obtaining maximum, average and recommended system curves: Given an arbitrary network with one or more points of known total head, the maximum, minimum and recommended system curves are determined for any pumping station feeding the network through a simulation of multiple random states for each flow demand percentage in the pumping station.

Obtaining system curves of a given reliability. The information needed to build various system curves for a determined degree of reliability can be extracted from the process of simulating multiple random states.

Pumping station Operation Curves: Calculation of head-flow rate, power-flow rate, efficiency-flow rate, and spin speed-flow rate curves, and stop-start transition points for pump groups with arbitrary compositions of fixed pumps and variable speed pumps, of the same or different kinds.

Determining the PDF of flow occurrence: For on-demand irrigation conditions, in branching irrigation networks fed from one point, the Probability Density Function of the flow rate at the feed point for an irrigation campaign. Possibility of dividing by low demand, shoulder and peak demand bands.

Set demand curves: Introduction by the user of estimated or experimental demand probability density curves.

Determination of energy consumption: Combining the curves of the pumping station (head-flow rate and power-flow rate) and the Probability Density Function of the flow rates (with option to split into low, shoulder and peak) a calculation is obtained of energy costs reflecting the dependence of the results on the performance curves of the pumps, the number and size of the equipment, the regulation strategies used and the network system curve.

3.5 IN-PLOT DESIGN

GESTAR 2014 incorporates new modules for projecting and modelling irrigation networks in plots, applicable to total coverage with sprinklers, drip irrigation and micro-spray, in the context of plots and greenhouses, gardening, golf courses, sports complexes, etc.


39

Two-way communication with AutoCAD enables detailed cartography and building plans to be generated effortlessly.

The hydraulic modelling of individual or distributed emitters with emitted flow rate depending on pressure gives precise, interactive and context-sensitive results.

The analysis and simulation of networks and emitter elements admits all types of configuration, normally branching in agricultural irrigation, and usually as a mesh in garden irrigation.

The sizing of components and hydraulic and energy analysis reuses the powerful resources of GESTAR for optimum sizing and simulation, obtaining economical designs and exact predictions of all hydraulic parameters, even in plots with very irregular plans and topography.

Definition of turns: Specification of the number of turns, duration of each of them and definition of Sprinklers and Nodes belonging to the turn.

Generation of sprinkler distributions in AutoCAD: according to the framework provided by the user, and adjusted to the contours and plans of the plot or selected sectors, following pre-set orientation lines, including the layout of lateral connection pipes. Automatic placement of sector sprinklers in the contours.

Generation of branch distributions in AutoCAD: according to the framework provided by the user, and adjusted to the contours of the plot or selected sectors, following pre-set orientation lines.

Importation of distributions of sprinklers, drip feeds and main, secondary and lateral pipelines from AutoCAD to GESTAR, generating connectivity of sections and categories of types of pipe.

Optimum sizing of Secondary and Lateral pipes (optional) for irrigation sectors in the case of sprinkler coverage in branching topologies. Optimum sizing of main pipes for rotation with branching topology. Modelling all types of additional components: regulating valves, pumping equipment, cut-off valves. Integration of user-accessible databases (sprinklers, drip feeds, valves, pumps, pipes, etc). Automatic simulation of turns using opening/ closing orders for the complete turn.

Calculation of flow rates emitted by each sprinkler and reach radius according to local pressure.

Calculation of the distribution of pressures and flow rates issued along each Emitter line

Extension of the table of programming over time to programme the start of each turn.


40

Export to AutoCAD: Generation of plans with representation of emitter pipelines and data on construction and operation.

Measurements: Generation of lists with measurements, description of components and budget.

3.6 DATABASES

GESTAR facilitates the work and makes it more flexible, while avoiding possible errors in loading data, by offering the user all the hydraulic parameters and technical information usually affecting the behaviour and hydraulic results of distribution networks, structured in databases which transfer information directly to the corresponding forms. These relational databases (ACCESS) are open, initially configured in the installer with basic data as examples, and can be modified, adjusted and extended according to the needs of the user and the project. For this, the user can access the relational structure of the tables directly, or use the modification tools incorporated in GESTAR (recommended).

Pipes: Interior Diameter, Roughness and cost per ml by manufacturer (or any other category), Material, pressure rating and DN.

Singular losses: dimensionless Coefficient according to the type of singularity and an associated parameter.

Properties of fluids: Dynamic Viscosity, Density and Vapour Pressure at working temperatures.

Throttle valves: Discharge coefficient Cd for computing singular losses according to type of valve, subtype and degree of closure.

Automatic regulating valves: Singular losses for completely open hydraulic regulation valves according to type and size.

Electricity prices and bands: Price per kWh and installed kW, according to type of band and considering bonuses and surcharges.

Pumps: Performance curves of pump head, power consumed and NPSHR according to flow rate, by manufacturer (or any other parameter) and model.

Sprinklers: Emitted flow rate, reach and pluviometry according to feed pressure, by manufacturer (or any other parameter) and model.

Emitter Lines Emitted flow rate, reach and pluviometry according to feed pressure, by manufacturer (or any other parameter) and model, inserted in drip feed tubes by manufacturer, material and nominal diameter.


41

3.7 COMMUNICATIONS

GESTAR can exchange information in various formats (Office documents: EXCEL, ACCESS, WORD and text files) and communicate directly with various programmes.

Most of its information is structured in tables compatible with EXCEL, and various files of final and intermediate results are saved or dumped automatically to EXCEL files.

Programming irrigation and modulations of demand in analyses over time, the definition of alarms and the list of warnings from alarms found are exported and/or imported in ACCESS format, permitting information to be exchanged with other environments and the later processing of results. These databases are compatible with the TELEGESTAR architecture, which reuses the format, avoiding the need for remote control and management systems backed up by TELEGESTAR functions to create specific forms.

In general, GESTAR can communicate with any GIS, CAD, or SCADA system through ACCESS databases. (In the case of SCADA, remote control and management programmes, direct interactive communication is specifically developed using the TELEGESTAR solution, with other formats possible for databases, SQL, XML). There are also tools for direct conversion between AutoCAD 2002-2008 (two-way communication) and EPANET 1.1e (export), which are listed below:

I/O ACCESS/GESTAR: Export from GESTAR and import to GESTAR of network models, both for complete data and for results, using ACCESS 97 files, with tables permitting the configuration of all types of Nodes and Elements (except Emitter lines, which are pending), their connectivity and topology. From any GIS/CAD (or any environment permitting information to be structured in tables) containing the minimum cartographic and constructive data, the model can be generated automatically in GESTAR, using the database as a communications interface. Exporting any GESTAR network to database creates a file which can be used as a template to be filled in from other applications with all the necessary network data for changing between networks. Exporting /importing network models to ACCESS 97 enables search and/or replace operations to be carried out with all types of filters and conditions on the database, for later importation of the changes made.

AUTOCAD 2002-2008: Exporting network models from GESTAR to *.dwg files for AUTOCAD 2002 (or greater), and importing *.dwg files containing the topology of a network of pipes and nodes, to the GESTAR network model format (*.network). In exporting, optionally, the dwg file writes up to four construction parameters or data on pipes and nodes (e.g. ID, Material-pressure rating and DN in pipes, and the ID, maximum flow rate, pressure set point, and level in hydrants) so that complete building plans or thematic plans based on a variable can be automatically generated. In importing lines and Polylines (2D-3D) of the selected layers they are transformed into pipes with pre-selected properties, and blocks of selected layers into nodes of the pre-selected type. Placing the objects in the right layers, different types of pipes and nodes can automatically be incorporated in the model. If the ends of the Polylines do not retain


42

connectivity with the blocks or adjacent Polyline (with a tolerance margin) the pipe resulting from the transformation of the line or Polyline will incorporate an extra node.

EPANET: Most components can be exported to the formats *.INP and *.MAP for EPANET 1.1e (compatible with later versions of EPANET). Pipes are transferred to the [PIPES] block of EPANET 1.1e, demand nodes (known consumption and hybrid nodes) and junction nodes are assigned to the [JUNCTIONS] block and known Pressure nodes, Reservoir and Dam to the [TANKS] block. The other types of components are not exported, but as they are usually less used, they can be incorporated manually into EPANET


43

4 OPERATIONAL PROTOCOL

The correct hydraulic design of pressurised networks demands at least three phases be covered: sizing conduits and equipment, hydraulic and energy analysis and analysis of transients. The analysis phases following sizing will confirm or modify the initial sizing, making it possible to design protection and control elements correctly and, with simulation techniques, enabling prediction of the behaviour of the system and all its devices, both in routine and exceptional situations. The necessary combination of the optimal sizing process with simulation and hydraulic analysis of the system leads not only to safer and better quality designs, but sometimes, more economical operating solutions than those directly generated by an optimisation algorithm.

This chapter describes in conceptual terms a protocol for the use of GESTAR tools and models for efficient use of resources.

This protocol can be applied as a whole or partially, depending on the requirements of the case. We recommend it be followed completely for new designs.

In the application installation folder

C:/Program Files/GESTAR/ Worked Example

there is an example job which has been completely worked out, and which gives users a step by step example of design in all phases. Applying each step in the procedure shown requires the use of tools and resources documented in this User’s Manual.

This folder also contains all the information needed for following the case study. This includes the document Worked_example.pdf, which will guide you through the process, showing initial data and intermediate results. The various *.network files show results for the different stages, and there are also EXCEL and ACCESS files containing required information and results. Their content and use are described in Worked_example.pdf.


44

CREAR BASE DE DATOS TUBERÍAS CREAR BASE DE DATOS BOMBAS

CREAR BASE DE DATOS TARIFAS ELECTRICAS

CREAR DIBUJO EN GESTAR

CREAR DIBUJO EN AUTOCAD

IMPORTAR DIBUJO AUTOCAD

DEFINIR CAUDALES DE DISEÑO

INGRESAR DATOS MANUALMENTE

DIMENSIONADO RED A TURNOS

DIMENSIONADO RED A LA DEMANDA

SIMULACIÓN HIDRAULICO_ ENERGÉTICA Y

REDIMENSIONADO

SELECCIÓN y REGULACIÓN DE BOMBAS

DISEÑO FINAL INFORMACIÓN TÉCNICA

DE LA RED

INGRESAR DATOS MEDIANTE Access

DEFINIR TURNOS

FIGURE 4. 1 Diagram of the stages and options of the protocol for designing an irrigation network.


45

FIGURE 4.3 ¡Error! Secuencia no especificada. Diagram of the stages and options of the protocol for modelling an irrigation network.

CREAR BASE DE DATOS TUBERÍAS CREAR BASE DE DATOS BOMBAS

CREAR BASE DE DATOS TARIFAS ELÉCTRICAS

CREAR DIBUJO EN GESTAR

CREAR DIBUJO EN AUTOCAD

IMPORTAR DIBUJO AUTOCAD

INGRESAR DATOS MANUALMENTE

SIMULACIÓN HIDRAULICO ENERGÉTICA

RESUMEN INFORMACIÓN TÉCNICA

DE LA RED

INGRESAR DATOS MEDIANTE Access


46

5 TOOLBARS

The GESTAR programme has a graphic window or map where networks can be built and analysed, and a Toolbar with a series of icons for opening, saving or printing networks, and selecting the different types of Nodes and Elements used in the construction of a network. It also provides a series of additional useful tools for the creation, analysis and visualisation of networks.

This chapter provides references for each of the Nodes, Elements and options available on the toolbar.

FIGURE 5.1 Toolbar.

The Toolbar (FIGURE 5.1) consists of two rows of buttons or icons. The upper row is always visible, while the lower row is available only when the graphic window is active, i.e., when creating, analysing or visualising a network.

The icons can be activated by clicking with the main mouse button on the corresponding figure on the toolbar.

After a toolbar tool is activated, it can be deactivated by clicking with the secondary mouse button (right clicking) on the icon, or simply choosing another operation.

5.1 INDEX OF ICONS

Each icon is presented below, with the keystroke combination which activates it and the page where its functions are described.


47

UPPER ROW:

NEW NETWORK (CTRL + N) 49

OPEN NETWORK (CTRL + O) 51

SAVE NETWORK (CTRL + S) 51

IMPORT / EXPORT AUTOCAD NETWORK 52

PRINT 53

CUT (CTRL + X) 54

COPY (CTRL + C) 54

PASTE (CTRL + V) 54

UNDO 54

REDO 54

FIND NODE/ ELEMENT (CTRL + F) 54

ZOOM IN 55

ZOOM OUT 55

NETWORK SIZING 56

RANDOM SCENARIOS 60

EVOLUTION OVER TIME 64

CALCULATE 66

EDIT COLOUR KEY (CTRL + L) 66 DELETE RESULTS 67

RESULTS 67 GRAPHS 70

ALARMS 70

SEE VALUES IN NODES (F7) 71

SEE VALUES IN ELEMENTS (F8) 72

LOWER ROW

SELECT 72

RECTANGULAR SELECTION 72

IRREGULAR SELECTION 74

COMMENTS 74

DELETE NODE/ ELEMENT 75

SPLIT PIPE 75

OPEN/ CLOSE HYDRANTS 76

RESTRICTIONS ON RANDOM SCENARIOS 76

JUNCTION NODE 78

DAM NODE 78

RESERVOIR NODE 79


48

KNOWN PRESSURE NODE 81

KNOWN CONSUMPTION NODE 82

HYBRID NODE 85

DOUBLE CONDITION NODE 90

FREE NODE 91

EMITTER NODE 91

PIPE ELEMENT 95

DRIP ELEMENT 106

PUMP ELEMENT 110

VALVE ELEMENT 115

FREE ELEMENT 119

FREE PIPE SETS

At the bottom of the GESTAR window the X and Y coordinates are specified for the point on the network where the cursor is situated at any time, relative to the point of origin.

120

Nodes, when activated, can be positioned on the Map by clicking on the desired location.

To situate an Element on the map, its end Nodes must be previously defined. Elements are created, when activated, by clicking on the first Node and then the last Node. If the last Node is the same as the first, the creation of the Element is cancelled.

The option Point to ID Nodes and Elements on the View menu, which is enabled by default, makes a small label appear in the GESTAR graphic window when mousing over a Node or Element. This label shows the identifier of the Node or Element.

When creating Elements, the cursor becomes a cross, making it easier to identify the Node being clicked on, and a flexible line links the initial Node with the cursor. Until the Element is created or creation is cancelled, this line will accompany the cursor. If the Element creation button is deactivated or another option is activated before the Element is created, creation will be cancelled. In the case of Pipe Elements polylines can be used. Their vertices are generated consecutively after each click of the mouse until the end Node is clicked.

Depending on the type of Node or Element placed, a dialogue window will appear on the map, asking for the parameters needed for its definition. This dialogue window can also be consulted at any time in order to verify or change data, by simply double-clicking on the desired Node or Element.

The parameters of all the data you introduce will be in International System units (metric) unless otherwise specified. They may also be in exponential or scientific notation, which may use commas or periods as decimal points. Invalid or illogical numerical values will not be accepted (negative pipe lengths or roughness values, etc). Alphanumerical labels are accepted for Nodes and Elements. Windows keyboard


49

shortcuts can be used for cutting, copying and pasting text (CTRL+X, CTRL+C and CTRL+V respectively) between the various fields in each definition window of Nodes and Elements, and the Tab key for moving from field to field. Nodes and Elements scan also be selected as a group which can then be moved, cut, copied or pasted.

5.2 ICON FUNCTIONS

UPPER ROW:

This enables a network to be created in the GESTAR graphic window using the tools provided by the application.

NEW NETWORK (CTRL + N)

FIGURE 5.2 Pipes database management

Using the dialogue represented in FIGURE 5.2, the user must associate a newly created Pipes Database with the new network (see section 12.1 PIPE DATABASES, p. 428).

A dialogue will then appear (FIGURE 5.3) enabling the user to configure the origin of the coordinates and the exact maximum coordinates for the window, and the initially visible area. These variables can be changed later using the option View/ Scale in the menu toolbar..


50

FIGURE 5.3 Scale.

♦ Maximum Coordinates of the Map. From this quadrant the coordinates are entered of the upper right corner of the area seen on screen: the maximum coordinates. The Force option enables the user to change the areas of the network map seen on screen along one or both axes. If you want to Force the dimensions of both axes, XMax-X Origin will correspond to the horizontal width of the area of the map shown on screen with No Zoom, and YMax-Y Origen will correspond to the vertical height of the area of the map shown on screen with No Zoom, but the on-screen visualisation will be distorted and out of proportion. If you prefer to display the network in its true proportions, adjusted to fit the vertical and horizontal resolutions of the monitor, select Force in one of the dimensions only. The programme will establish the other maximum coordinate so that the relationship of distances shown onscreen on the network map, in XMax and YMax, agree with the horizontal/vertical ratio of the resolution.

♦ Percentage in Window. The scroll bar lets you select the part of the map you wish to see first on screen. GESTAR displays the percentage of the map chosen interactively in the window to the right.

♦ Minimum Coordinates of the Map. The visualisation area must define the coordinates of the Point of Origin, which will coincide with the bottom left corner of the map. Negative coordinates may be used, although Nodes and vertices will be created only in areas with positive coordinates. The network map on screen will show as a maximum, with No Zoom, the area of the network between XOrigin-Xmax and YOrigin-YMax.

♦ Move Origin. This field will be useful later. Clicking it will bring up the dialogue in FIGURE 5.4 specifying the positive or negative movements in direction X or Y of the coordinates (X Origen, Y Origen) of the current Point of Origen of the visualisation. When the Accept button is clicked in the Move window, the new values will be shown for the Point of Origen of the visualisation in the window of FIGURE 5.3. .


51

FIGURE 5.4 Moving the Origin of Co-ordinates.

This opens a previously created network in the graphic window.

OPEN NETWORK (CTRL + O)

FIGURE 5.5 Open network dialogue.

Once the network is opened it can be analysed and modified with the GESTAR tools. The files containing the construction topology of the GESTAR networks are called Network Files, and their extension is “.red”.

Clicking this icon saves the network currently in the window with its previous name and location. If the network is new, its name and location will have to be specified in the dialogue which will now appear (

SAVE NETWORK (CTRL + S)

FIGURE 5.6).


52

FIGURE 5.6 Save network dialogue.

The files containing the construction topology of the GESTAR networks are called Network Files, and their extension is “.red”.

This icon gives users access to two different functions. If no network is open, the process will begin of generating a GESTAR network based on an AutoCAD drawing, using the form shown in

IMPORT / EXPORT AUTOCAD NETWORK

FIGURE 5.7. (This process is described in detail in section 7.5.1 REQUIREMENTS FOR DRAWINGS TO IMPORT FROM AUTOCAD).

FIGURE 5.7 Dialogue for Importing network from AutoCAD

After opening the network in GESTAR, use this icon to access a new dialogue (FIGURE 5.8). This tool enables the automatic generation of the drawing of the network in AutoCAD with the desired information on the Nodes and Pipes used, as described in more detail in section 7.5.3 EXPORTING NETWORK TO AUTOCAD.


53

FIGURE 5.8 Dialogue for exporting network to AutoCAD.

Prints the current contents of the window, If no graphic interface window is open, nothing will be printed.

PRINT

FIGURE 5.9 Print dialogue.

To print the results of a given scenario, use the Print button in the Results window (p. 161).


54

First select an area with the Rectangular or Irregular Selection button (see p.

CUT (CTRL + X)

72 and after), and cut the selection with this button, so that you can then paste it with the Paste option.

First select an area with the Rectangular or Irregular Selection button (see p.

COPY (CTRL + C)

72 and after), and copy the selection with this button, so that you can then paste it with the Paste option..

Once a Rectangular or Irregular Selection has been cut or copied (see p.

PASTE (CTRL + V)

72 and after), this option lets you paste it in the programme window. Pasting is done in the upper left corner of the window. The pasted area can be dragged by keeping the mouse button down and moving it to the desired location.

When pasting a group of Nodes and Elements, the new Nodes or Elements automatically acquire a default label. A form will appear letting you add two characters to the name.

This button undoes the last action carried out in GESTAR. Only one action can be undone.

UNDO

All meaningful user actions can be undone. Mouse over this button to see a label showing the last action carried out.

The Redo tool becomes active after undoing an action, and enables you to go back to how things were before using the Undo tool.

REDO

Click this button to bring up the window in

FIND NODE/ ELEMENT (CTRL + F)

FIGURE 5.10, enabling you to search on the map for any type of Node or Element


55

FIGURE 5.10 Searching

♦ Find Node/ Find Element. The user should first consider if he is searching for nodes or elements.

♦ Id. This option is enabled by default. Enter the Identifier of the Node or Element you are looking for in this field.

♦ By Comment. If you choose this option, the Identifier search remains inactive. All the components sharing this exact set of characters will be found and highlighted.

♦ Highlighted on map. If you choose this option, a white circle will appear in the map window showing the location of the selected Node(s) or Element(s).

♦ Show Data. If this option is activated, after clicking on Search, as well as the location on the plan, GESTAR will display the definition window for the Node or Element you are looking for. If searching by comment, it will show the window of the first component found with this comment.

This tool allows you to zoom in on any area of the map, selected with the mouse. Click on a corner of the area you want to zoom in on and drag the mouse to the opposite corner, then release. The rectangle you are marking will change colour while the mouse is dragged, and the width and height of the rectangle will be shown on the bottom left of the screen. The maximum zoom is 1% of the total size (to scale) of the map.

ZOOM IN

Each time you click on this button the network view size is halved (to scale), making the visible area four times bigger. The single fixed point is the upper left corner of the window.

ZOOM OUT

This icon shows the maximum possible scale map view according to the values defined for the point of Origin and Maximum Coordinates of the map, which can be edited in View/ Scale.

EXTENSION


56

To move the viewed area of the network map, select this tool, hold down the left mouse button and drag the icon.

DRAG

GESTAR uses this tool to facilitate the sizing of strictly branched networks, i.e., a network without meshes with a single intake point (with a known or unknown total head). This is equivalent to the Sizing Network command on the GESTAR file menu.

NETWORK SIZING

As this function is complex and important, and relates directly to other processes, chapter 0 of this manual deals with Sizing Strictly Branched Networks, analysing in detail the optimisation process activated by clicking on this icon (see subheading 8.3 ENERGY COST CALCULATION

In networks created with a pump element at intake, power consumption is computed in a simplified form, supposing a flat system curve (constant pump head, Hd, equal to the design pressure for the design flow rate at intake) and that the efficiency of the total pumping station is an estimated value, also constant (Weighted Efficiency), ηδ, obtaining a simplified version of Equation 3-1 computing the Simplified Power Consumption (CESkwh).

p

d

p

dkwh

VHgdtqHgdtq

qqHgCESη

ρη

ρη

ρ ⋅⋅⋅=⋅

⋅⋅=

⋅⋅⋅= ∫∫

T

0

T

0 )()(

V is the volume to be elevated during the campaign, which with the weighted efficiency of the pumping station and the volume to be pumped, are the data the user must enter, as Hd is the object of calculation of the optimization process.

The economic value of this energy is obtained multiplying the kWh needed for the price of the kWh. As the price of the kWh varies according to the time of day of consumption, the above expression is applied, adding the contributions of the pumped volumes in each time bracket (for example, off-peak, shoulder, peak, or in each period P1, P2,….P6) with the corresponding price per kWh.

)(36001000€ ppllllvv

p

d PkWhVPkWhVPkWhVgHCES ++⋅⋅

=η

ρ

Or for the same result, multiplying the estimated energy required for the period by the average price per kWh, weighted according to the volumes pumped in each time bracket:


57

PkWhVgH

PkWhVPkWhVPkWhVgH

CESp

dppllllvv

p

d

ηρ

ηρ

⋅⋅⋅

=++⋅⋅

⋅=

36001000)(

36001000€

Consequently, it is the same to supply GESTAR with the pumped volumes for each time bracket, and the prices applied to each one (in the form of surcharges and discounts) as to assign an arbitrary time bracket to all the pumped volume and consider a base price per kWh corresponding to the average price weighted in volume of the kWh, previously calculated by the user.

The average price per Kwh weighted in volume will be evaluated in the case of distinguishing three time brackets:

VPkWhVPkWhVPkWhV

PkWh ppllllvv ⋅++=

)(

and in the overall case, where the consumption price is structured in NP time periods, with the price of each period PkWhi and pumped volume Vi in the respective period

V

PkWhVPkWh

NP

iii∑

=

⋅= 1

The expression used by GESTAR in the optimum sizing module to compute the kWh prices at each period is

)IkWh

(1PkWhPkWh ibasei 100

+⋅=

basePkWh : Base Price kWh

iIkWh : Surcharge / Discount of the price per kWh in the period in %

The Simplified Power Cost, €CES , is calculated using NP energy cost periods:

incAnualreaci

NP

1ibasei

p

d KK)IkWh(1PkWhVHgCES ⋅⋅+⋅⋅⋅⋅

⋅⋅= ∑

= 10036001000€ ηρ

Where:

iV : the Volume (m3) elevated annually by the station in each period i


58

reacK : Reactive power term according to cos ϕ .

10021cos171

2 −+=

ϕreacK If Kreac > 1,47; Kreac=1,47; If Kreac< 0.96; Kreac=0,96

When ϕcos is 0,8997 (value by defect), reacK , = 1

incAnualK : Term of annual increase in power cost.

1001)1001(

IanTIanK

T

incAnual−+

= Ian annual increment of energy prices in %

Power

The Power Term Cost corresponds to the estimated total annual cost of the pumping power contract. This is evaluated as the sum of the annual cost of the kW contracted for each period according to the electricity prices used.

Term.

In order to estimate the maximum power necessary it is use the term Nominal Power Needed, kWPNN to pump the design flow rate, dQ , from the intake pipe at the nominal design head, dH , with weighted efficiency pη .

p

ddkW

QHgPNN

ηρ

⋅⋅⋅⋅⋅

=1000

.Electricity prices normally divide the day into different periods (P1 - P6), in which the cost of each kW of power supply varies.

As it is not always necessary to sign up for the maximum power needed, kWPNN , for all the time bands, this expense is calculated as the sum of the annual cost of the kW contracted for each period according to the electricity price rate used.

To record the price variations of the power supply in GESTAR, enter a Base

Price for Power Supply ( basePkW ) which is the cost in € per month per kW in a given period of reference, and then indicate the Surcharge on the price per kW (or discount

with a negative sign) as a percentage of the Base Price for Power Supply corresponding

to each period, iIkW .

)100

1( ibasei

IkWPkWPkW +⋅=

basePkW : Base price per kW per month in the reference period


59

iIkW : Surcharge/Discount % in relation to the base price per kW/month in the period i

Using the concepts and nomenclature defined, GESTAR estimates the annual cost of the contracted power supply, CPC; using the expression:

incAnualreaci

NP

ibase

i

p

dd KKIkWPkWRHQgCPC ⋅⋅⋅+⋅⋅

⋅⋅⋅⋅

= ∑=

12)100

1(1001000 1

€ ηρ

where

iR : The Coefficients of distribution of the contracted power supply for the period i



As an alternative to user-specified individual coefficients iIkW and iR , you can

enter directly as Base Price kWh ( basePkWh ) the weighted price per kW contracted, PkW , previously calculated using the expression:

)100

1(100

11

1i

NP

ibase

iNP

IkWPkW

RNP

PkW +⋅⋅= ∑=


60

NETWORK OPTIMISATION), ), and the requirements of the previous generation of the strictly branched network to be sized (see subheading 8.1 PREVIOUS GENERATION OF TOPOGRAPHY AND DEMAND) together with the Design flow rate calculation process (see subheading 8.2 ON-DEMAND DESIGN FLOW RATES).

MEASUREMENTS

FIGURE 5.11. Measurements window

Click on the icon to go to the window in FIGURE 5.11. By default, the table includes information on all the Pipe Elements defined in the network (if the All Categories option is enabled in the first drop-down menu). The first column contains the Identifier of the Pipe Element, with the other columns showing the Identifiers of its Start Node and End Node, Length (m), Material, Pressure Rating, Nominal D (mm), Price (€/m), Segment Price (€) and Type (1, 2, 3, primary, secondary, tertiary).

To calculate the segment price the pipe price must have previously been saved to the database (see p. ¡Error! Marcador no definido.). The Total Amount (€) presented in the lower right corner of FIGURE 5.11 is the sum of the prices of the segments included in the table (sum of the column Segment Price).

In the first drop-down menu, users can filter the Pipe Elements included in the table of measurements, considering only the Elements present in a category or building


61

unit. This function will be very useful when drawing up partial budgets for the building work. Use the drop-down menu to enable the following categories: Primary+Secondary+Sprinkler Riser Branches, Secondary+Sprinkler Riser Branches, Primary, Secondary, Sprinkler Riser Branches Sector, etc. If the category Sector… is selected, the second drop-down will be active (FIGURE 5.11), where you can choose the number of the Sector to analyse. The Total Amount of the window (FIGURE 5.11) will be updated to show the sum only of the Pipe Elements shown in the table.

♦ Export List. The information included in the table can be saved as an Excel spreadsheet using this field. Optionally, you can export it as a results output file (extension .sal), or text file, txt.

♦ Materials List. A new table shows the summary of Measurements depending on the type of pipe (see p.¡Error! Marcador no definido.).

This tool randomly generates a wide range of scenarios under different simultaneity conditions. Random scenarios of this type are very useful for analysing the behaviour of irrigation networks with a large number of hydrants. Clicking on the Random Scenario button calls up a window (

RANDOM SCENARIOS

FIGURE 5.11) where different conditions can be set to generate scenarios in different operating conditions. Each random scenario generated can be simulated with the tool.

FIGURE 5.12 Random network dialogue.

♦ Percentage of Active Hydrants. Use the scroll bar to set the percentage of active hydrants you want to remain open of the total number of hydrants in the network. The panels to the left of the bar (Scenario Criteria and Result) informs the user as to the number of unconditionally open nodes, unconditionally open nodes (see p. 76),


62

assignable nodes (i.e., which are not in either of the above two states) and total nodes in the network. You should take into account that the (unconditionally closed or open) hydrants deactivated by the Random Scenario Restrictions button (p. 76) will not change state with the random action. As you move the bar, GESTAR shows how the Scenario Criteria (% open) and the Result (number of open or closed Nodes) changes for each situation.

♦ Type of Criterion. By default the option In Number appears, randomly opening Nodes of the types Known Consumption Node and Hybrid Node, until they meet the specified percentage of open nodes, compared to the total number of nodes or the set of assignable nodes. GESTAR will enable a second option in later versions, In Flow Rate, in which the open percentage is associated with the total demand flow rate at the head.

• Homogeneous Probabilities. The default option, this considers that each hydrant has the same probability of opening when generating the Random Scenario.

• Different Probabilities. Checking this box, the Random Scenario will take into account the probability of opening of each hydrant. For this option to be effective certain specific fields need to be defined in the windows corresponding to all the Known Consumption and Regulating Hydrant Nodes, enabling their probability of opening to be known (See the methodology used to calculate the probability of opening of each hydrant in Appendix IV, p. 469, and in the windows defining the Known Consumption Nodes, p. 82 and the Hybrid Node, p. 85).

♦ Generating the Scenario. After selecting the percentage of open hydrants, click the Generate Scenario button to view on the screen the open/closed hydrants generated by GESTAR. If you are not satisfied with the distribution and/or percentage obtained, or if you want to generate a new scenario, you can reset the percentage as often as needed.

♦ Exit. To validate the distribution, click the Exit button. Because of the way GESTAR generates Random Scenarios, with networks with very few active hydrants slight deviations from the set values may appear in the results.

As each Random Scenario is the random creation of a possible range of demand scenarios which can be analysed hydraulically and in terms of energy, obtaining conclusions on the overall behaviour of the network with a set percentage of active Nodes cannot depend only on the results of a single scenario, or a few manually obtained ones. The individual or averaged results of a wide range of cases should be analysed to get a more complete view of how the network works and to identify extreme favourable and unfavourable conditions.

This analysis can be carried out by the user by running a series of Random Scenarios and the subsequent calculations, remembering the behaviour of previous cases when looking at new scenarios, or GESTAR can be left to automatically generate and analyse multiple scenarios, using the Multiple Scenarios option.


63

♦ Automatic. If this option is selected in the dialogue in FIGURE 5.11, a new window will appear (FIGURE 5.12). This window lets you set the number of random scenarios which will be automatically generated and calculated.

FIGURE 5.13 Random Scenarios

• Number. In this box the user can determine the number of random scenarios to analyse for a percentage of open hydrants and operating conditions to be defined as described below.

• % General Opening. This box sets the number value for the percentage of general opening which will be applied to the number of random scenarios specified in the previous box.

• Type of Scenario. This panel is the same as the dialogue of FIGURE 5.11 for a single Random Scenario, and lets you define the conditions of the random scenario for each Number - % General opening pair.

• Add. Once a Number -%General Opening pair has been entered and the conditions for the random scenarios selected, click the Add button for them to be added to the list of multiple scenarios.

• Delete. To delete a pair of values from the list enabled in the middle of the dialogue window, select them by clicking on them with the mouse, and then click the Delete button.

• This button opens an Analysis File (extension “.srt.”), containing a list of Number -% General opening pairs previously generated from this window.

• Click this button to save the current list of Number -%Opening pairs in a Multiple Scenario File (extension “.srt.”) for use in later analysis.

• This button lets you configure the alarms to be taken into account for simulating all the automatically generated random scenarios (information on alarms on p. 161).


64

• Accept. After setting a list of Multiple scenarios and configuring the alarms, the Accept button will generate as many random scenarios as specified with the simultaneity percentage set for each. As the scenarios are generated, the corresponding hydraulic simulation will be run and the results filtered by the set alarms. When the sequence of scenarios has been created, calculated and filtered with the range of alarms, a brief report will appear at the bottom of the window with the number of steps calculated (total scenarios proposed by the user), the number of successes (number of valid scenarios where the variables remained within the ranges defined in the configuration of the alarms) and the number of errors of calculation produced, if any.

• Selecting the Recalculate option will begin the simulation of each scenario with the results of the calculations of the previous scenario, accelerating the process somewhat. Unless the simulations take a very long time, this option is not recommended.

Using this tool the user can analyse a network over a period of time. In evolution over time, a set of determinist scenarios are resolved sequentially, where each scenario simulated differs from the others in the state of the network components (Demand Nodes, Regulating Hydrants, Emitters, Pipes, Pumps) specified by the user, using temporal and logical orders, and in the levels of fluid in the accumulation points where levels can change, the Reservoir Node, all calculated by the programme.

EVOLUTION OVER TIME

A chapter is devoted to analysing this process (see ref).

Activating the Evolution over Time button brings up the window shown in FIGURE 5.13.


65

FIGURE 5.14 Evolution over Time settings window.

This window determines the period of the scenarios to be resolved and the total time of the simulation using two alternative procedures:

♦ Total Time of the Simulation. Specifying this value in the adjoining boxes and the length of each period at the bottom of the window, the total number of periods is indirectly determined (with a maximum of 768 according to the default values of the file "Gestar.ini").

♦ Number of Intervals. Defined by moving the marker in the centre of the window. The default maximum number of intervals is 768. Together with the value specified as the length of each interval, this determines the total time of the simulation.

♦ Start time. The starting point in time of the simulation is established so that GESTAR associates an absolute moment in time to each of the proposed scenarios, according to the length of the intervals. If these fields are not filled in, the times will be relative.

♦ Characteristics of the Simulation. The time between two resolutions or calculation step will be set independently in this panel.

♦ Alarms. Lets you enable the current alarm setting at any time during the simulation. The setting can be changed using the Configure button. Clicking the button brings up the Alarms window, described on p. 162. If the Alarms option is disabled, the alarm criteria of the configuration will be disabled during the simulation over time.


66

♦ Warning. This option means that if the Alarms option is disabled during calculation, a warning will appear every time one of the scenarios proposed by the user exceeds the ranges set in the configuration of the alarms.

♦ Ignore. When this option is enabled, there will not be a warning when an alarm is triggered, but the event causing the alarm will be logged on the report and shown in the graphic report of the results when the process is finished.

♦ Configure. Accesses the Alarm Configuration window.

♦ Patterns. Lets you specify the opening status of the hydrants and pump groups. (See p. 281).

♦ Scripting. Advanced tool for “custom” simulations, which makes it possible to open and run a text file of commands (extension .txt) previously generated by the user (see p. 293).

♦ Run. Click this button to begin calculations. After this the graphic solution of the network is shown, accompanied by a scrolling window which allows you to pass from one case to the next (see p. ¡Error! Marcador no definido.).

♦ Hot Start. If an Evolution over Time is calculated with the Hot Start option selected, for each step in time after the first one, the calculations for the solution of the new step in time will begin using the results of the previous period.

♦

After creating a single scenario, whether using deterministic or random tools, click this button to send all the data to the calculation module, which processes the information, resolving the hydraulic problem posed. Once the scenario is calculated, the results go back to the graphic module and appear in the network layout on the screen with the specified variables and colour code. Each Node is represented by a circle with a colour indicating the range of values in which the value of the selected variable is located according to the Colour Key (p.

CALCULATE

66). Similarly, Elements will be coloured according to the values of the chosen variable in the Colour Key. The numerical values of the parameters selected are also shown in the list of variables of Nodes and Elements corresponding to the buttons See Node Values and See Element Values, p. 71.

Depending on the options selected in the Calculate menu (see p. 242), the calculation process will begin without taking earlier results into account, or using the results of the last calculation.

The results of a network scenario are shown by a colour key, with ranges which can be modified. Clicking this button brings up the window in

EDIT COLOUR KEY (CTRL + L)

FIGURE 5.14 where you can change the range of values and associated colours used to represent the different


67

variables in the graphics. You can also select which variables will be shown, for Nodes and for Elements. GESTAR sets default ranges and colours, based on the maximum and minimum values found in the execution of the case or series of cases.

FIGURE 5.15 Colour Key

As the operations of input and output of results are dealt with more thoroughly in Chapter 6, the details for operation of this window are covered on p. 208.

Clicking the Delete Results button deletes the numerical results displayed and corresponding colour coding, refreshing the screen with the network in its scenario editing state as it was before calculation.

DELETE RESULTS

Complete information on result outputting is given in section 6.2, Results Output (p. 207).

After a network has been calculated, whether as a single scenario or a set of scenarios, the Results button enables numerical lists of results to be created.

RESULTS

The type of table which appears by default when clicking the Results button corresponds to that in FIGURE 5.15, summarising the complete information of a scenario.


68

FIGURE 5.16 Numerical List from a scenario.

The Results window of FIGURE 5.15 shows all the variables referring to each Node or Element, both those entered as data and those produced by calculating the network. The status of the pumping and regulation components is indicated in the corresponding positions. As well as accessing this table after calculating a single scenario, it is similarly possible to consult the results of an analysis with Multiple Scenarios, which will show the mean, maximum or minimum values of the variables according to the option selected in the upper left of the window (FIGURE 5.15). In the case of consulting an Evolution over Time, all the data will be shown for each of the set intervals, with the possibility of seeing the data sequentially, leaving this window open and selecting the video option (button ) in the Evolution window, while the different scenarios are also displayed as a graph on the map.

The Results window also contains the following options:

♦ Save button ( ). Saves all the information in the window in a file with the extension “*.res”. This can be opened later from the GESTAR main menu in the section File/ Open Results. Results can also be stored as an Excel file (“.xls”) or plain text file (“.txt”).


69

♦ Print button ( ). Prints the results shown in the table.

♦ Filter Results button ( ). Can be used to show only certain types of Nodes or Elements on the Results Table (FIGURE 4.13). In the Filter Results Table window, mark the components to be shown in the Results Table.

FIGURE 5.17 Choice of type of results

♦ File Menu. The commands of the File menu enable the Save, Print and Personalise

Table options described above.

♦ Signal menu. The Signal command of this menu will draw a white circle on the network at the location of a Node or Element corresponding to the row of the Results Table currently selected.

♦ Bar graph. For use only when carrying out a hydraulic analysis with the Multiple Scenarios tool.

The labels at the top of the table give information on the number of iterations required for the convergence of the calculation and the time used in it.

A complete description of the structure of this table is also given in Chapter 6, p. 178.


70

After running simulations with Evolution over Time, GESTAR lets you obtain tables and graphic representations registering or visualising the value over time of one or more variables selected by the user.

GRAPHS

FIGURE 5.18 Table of evolution over time.

From the temporal tables (FIGURE 5.18), covering the evolution over time of the variables, figures can be generated for representing the evolution over time of hydraulic variables in graphs. There are various options for selecting the Nodes, Elements and variables listed. Creating tables and graphs is covered in Section 9.5.3, p. ¡Error! Marcador no definido..

See description in the section Alarms Menu/ Configuration (p.

ALARMS

162).

From this option you go to the window in

TURNS

FIGURE 5.19, where you can assign irrigation Turns to the Hydrants in the open Network.


71

FIGURE 5.19 Turns Window

Its operation and use are described in detail in Chapter 8.6, ESTABLISHING IRRIGATION TURNS, p.¡Error! Marcador no definido..

The attached drop-down menu at the end of the top row of the toolbar enables the user permission to open the hydrants or sprinklers included in the irrigation turn.

FIGURE 5.20. Drop-down menu, Opening Hydrants/ Sprinklers in a Turn

Clicking this button lets the user see in the network nodes the numerical values of a selected variable from the list on the toolbar next to the button. The variable can be changed by selecting another on the list.

SEE VALUES IN NODES (F7)

Accessible variables (according to the type of Node) for Nodes are: Identifier, Level, Maximum flow rate, Demand, Probability, Irrigated Area, Fictitious Continuous Flow Rate, Comments and Diameter.

After calculating the list of Nodes we can add Pressure, Pressure set point, Pressure margin and Total head. Pressure margin is defined as the difference between calculated Pressure and the Pressure set point, a variable which exists as long as a pressure set point is defined for that Node.


72

When one of more of these variables are not defined for a Node, because it is irrelevant or is an unknown which has not yet been calculated, no numerical value will be shown associated with the Node.

When the results of the last calculation are deleted, going on to a new editing stage, the variables calculated for Nodes and Elements will no longer be shown. The variable selected from the list stays the same from one calculation to the next.

Clicking this button shows on Elements the alphanumerical values of a variable chosen from a set of parameters in the list on the toolbar next to the button. The variable can be changed by selecting another on the list.

SEE VALUES IN ELEMENTS (F8)

Variables for Elements are: Identifier, Length, Diameter, Roughness, Material, Pressure rating, Flow rate, Velocity, Head loss, Head loss per unit of Length, Comments, Nominal Diameter + Material + Pressure rating, Design flow rate, Celerity, Nominal Diameter, Power (kW), Efficiency (%) and Type.

When one of more of these variables are not defined for an Element, because it is irrelevant or is an unknown which has not yet been calculated, no numerical value will be shown associated with the Element.

When the results of the last calculation are deleted, going on to a new editing stage, the variables calculated for Nodes and Elements will no longer be shown. The variable selected from the list stays the same from one calculation to the next.

LOWER ROW

To select a Node or Element, click on it after enabling the Select tool. The selected Node or Element will become greyed. To cancel the selection of a Node or Element, click anywhere in the window. Only one Node or Element can be selected at a time.

SELECT

This tool enables a Node or Element of the network to be selected in order to generate its graphs for Temporal Evolution easily, using the Tables for Graphs window with the Graph selection option selected (see p. 70).

IMPORTANT: The grey colour of the selected Nodes and Elements might be confused with the colour code assigned to discharged Elements or Nodes without consumption (see p. 76).

The Rectangular Selection tool enables a group of Nodes and Elements in a rectangular area of the window to be selected (clicking and dragging the mouse), for Moving, Duplication (cutting or copying) and Multiple Editing operations:

RECTANGULAR SELECTION


73

♦ Moving. After a group of Nodes and Elements is selected, and after clicking in the selected area with the main mouse button, they can be moved by dragging the selected rectangle with the mouse. When a selection is moved the X and Y coordinates of the Nodes are changed (to those of the final location), while the other parameters of the Nodes do not change. The ends of the Elements adjacent to the moved Nodes will be sited in the new locations. Also, if there are Pipe Elements in the form of polylines, only the vertices inside the selected area will be moved.

♦ Duplication (Cutting or Copying). Rectangular Selection lets you copy or cut the selected Nodes y Elements to the Windows clipboard, using the corresponding tools in the Editing Menu or the GESTAR toolbar. This lets you paste the selection in the window. After pasting, the rectangle can be dragged to position it properly.

When pasting a group of Nodes and Elements previously copied or cut with the Rectangular Selection tool, the new Nodes or Elements will automatically acquire a default identifier, which can have two characters added at the beginning, using a form (FIGURE 5.18 and FIGURE 5.19).

FIGURE 5.21 Form for Adding Prefix Text. Dialogue 1

FIGURE 5.22 Form for Adding Prefix Text. Dialogue 2

♦ Multiple Editing. Rectangular selection also enables editing the parameters defining the selected Nodes and Elements in two ways:

1. Selective Multiple Editing. After making a Rectangular selection and selecting a type of Node or Element in the selection from the toolbar, the corresponding editing window will appear with blank fields. After clicking Accept for this window, the fields which have been filled in will be set on all the Nodes or Elements of the chosen type present in the selected area. This permits, for example, setting the same maximum flow rate for all Known Consumption Nodes selected.


74

2. General Multiple Editing. After making a Rectangular Selection, double click on one of the Nodes or Elements located in the selected area to show the editing window for this Node or Element, with all its values in the respective fields. After clicking accept (or OK) on this window, all the fields (modified or not) will be set on all the Nodes or Elements of the same type as the selected one, except for the field for the Identifier, and in the case of Nodes, the X and Y coordinates.

Irregular Selection permits the selection of a group of Nodes and Elements enclosed in a polygon defined by the user. After clicking the Irregular Selection button, click on the map to define the vertices of the desired polygon. To close the polygon when the selection is finished, click with the secondary mouse button. Irregular selection permits Moving, Duplication (copy and paste) and Multiple Editing, described under Rectangular Selection (p.

IRREGULAR SELECTION

72).

Used for adding comments about the network for better understanding and visualisation of it.

COMMENTS

After enabling this option, the cursor becomes a text insertion icon. Mouse click on the window where you want the comment to appear, which you can specify in the Comments window (FIGURE 5.20) which will appear.

FIGURE 5.23 Comments Window

Write the desired text at the top of the window. In the middle of the window you have the option of modifying the point of origin coordinates of the text, with the coordinates of the place previously clicked on the map appearing by default. You can also decide if the text will be visible on the map (Visible checkbox) or will only be seen in the list of comments, and set the font (Fonts button).

After clicking Accept, the text will be part of the list of comments at the bottom of the window, with the specified characteristics.


75

To edit again or delete existing comments, see the Edit Comments option (p. 144).

If you click on a Node or Element while this tool is selected, a warning will appear (

DELETE NODE/ ELEMENT

FIGURE 5.21) asking if you want to delete this Node or Element; if you confirm, it will be deleted. To delete an emitter, simply delete its associated Node or Element. Only isolated Nodes can be deleted, so that the Elements adjacent to the Node must be deleted first, and then the Node.

FIGURE 5.24 Deletion Warning.

This tool lets you split a Pipe Element by inserting a new Junction Node which creates two new lines. After selecting this option, click on the Pipe Element where you want to insert the Junction Node to bring up the dialogue in

SPLIT PIPE

FIGURE 5.22. The level of the new Junction Node and the lengths of the two new lines are interpolated by default, and can be adjusted by the user. We recommend a systematic review, and adjustment where necessary, of the length values of each pipeline produced, confirming total length, the sum of each stretch, to be the same as the original, as well as checking the default level given by the application.

FIGURE 5.25 Inserting a Junction Node

The insertion of Junction Nodes, splitting a Pipe, can be exploited in numerous ways: inserting new branches, introducing vertices in the layout of a pipeline, reducing very long stretches to a series of shorter stretches to make it possible to adjust sizes, identifying high and low points to adjust Pressure rating, or locating suction cups or drains, monitoring pressure at intermediate points, creating specific stretches for inserting Elements such as valves, elbows, reducers, etc.


76

If you click with this tool on a Known Consumption Node or Hybrid Node, they will close automatically (null consumption), while if already closed, they will reopen with the instantaneous demand they had before closing. Unconditionally open or closed Nodes (Restrictions on Random Scenarios button, p.

OPEN/ CLOSE HYDRANTS

76) cannot be modified with this tool. Open hydrants will be light blue, while closed ones will be white.

Lets you permanently open or close a Known Consumption Node or Hybrid Node (unconditional opening or closing), so that its status cannot be modified by the Random Scenarios tool (p.

RESTRICTIONS ON RANDOM SCENARIOS

60) or the Open/Close Hydrants tool (p. 76).

If you click on a hydrant while this tool is enabled, it will become unconditionally open; if you click again on the same hydrant, it will be unconditionally closed; a third click will leave it open but subject to the results of Random Scenarios.

The status of a hydrant is shown by its icon. The icon will be circular if the hydrant is a Known Consumption Nose and square if it is a Hybrid Node:

(blue) Open hydrant (subject to Random Scenarios).

(white) Closed hydrant (subject to Random Scenarios).

(blue with white stripe) Unconditionally open hydrant.

(grey) Unconditionally closed hydrant.

TYPES OF NODES

Every Node is associated with a window with a similar structure and characteristic icon. The most complete case is shown in FIGURE 5.23.


77

FIGURE 5.26 Hybrid Node.

All Nodes, regardless of type, have the following data in common:

♦ ID: Identifier of each Node. This is alphanumerical (maximum 15 characters); there cannot be two Nodes on the same network with the same identifier. Some characters can be reserved for designating the area they are in; for example, all those corresponding to a given sector of the network can begin with a certain digit or have a certain prefix.

♦ Comment: A string of alphanumerical characters (maximum 20 characters) where you can add any information for each Node. Can be used to as comments such as date, owner, area, etc.

♦ Type: Indicates the type of Node. The parameters required in the window depend on the type of Node.

♦ Position: The planimetric (X and Y) and altimetric coordinates (level Z) of each Node expressed in metres. The origin of Cartesian coordinates is at the bottom left corner; X increases to the right and Y upwards.

The type of Node can be selected using the Toolbar or the list of types of Nodes. According to the type of Node, data should be added in the definition window, such as maximum flow rate, instantaneous demand or pressure head, regulation, etc. The fields containing the new variables which must be defined when changing from one type to another appear filled in with the values corresponding to this variable in the last open Node with the same variable.

The various types of Nodes appear in the lower row of the Toolbar.

The lower part of the windows also includes a Help button taking us to the GESTAR file with information on the programme.


78

There is also a button with a question mark on the upper right of all definition windows. This button offers Context-Sensitive Help, with explanations for the various parts of the windows. Click on the button and then on the part of the window you want information about, and GESTAR will show superimposed text with a brief description.

A specific case of a Known Consumption Node (p.

JUNCTION NODE

82), where the value assigned to external consumption equals zero. No flow rate definition window appears, as it will be interpreted as a null flow rate, but its coordinates must be specified. It can be used to represent any singular point on the network, such as forking branches, changes in diameter, Elements closed at one end, changes in direction of Pipes, intermediate points or where pressure must be controlled, etc.

It is possible to lay out a Pipe with multiple vertices to represent changes in the direction of the Element (see p. 95). In this way there is no need to create a Junction Node just for this purpose.

When placing a Junction Node its dialogue window does not automatically appear, as the default coordinates and identifier are regarded as acceptable. To bring up the window for a Junction Node or any other component, (FIGURE 5.24) edit the Node by clicking on it.

FIGURE 5.27 Junction node.

Junction Nodes are useful for configuring many aspects of distribution networks:

inserting new branches, introducing new vertices in the layout of an existing pipeline, reducing very long stretches to a series of shorter stretches to enable size adjustments, identifying high and low points to monitor extreme pressure levels and adjust Pressure ratings, locating suction cups or drains, monitoring pressure at intermediate points, creating specific stretches for inserting Elements such as valves, elbows, reducers, etc.

The Dam Node (

DAM NODE

FIGURE 5.25) is a particular kind of Pressure Node (p. 81), in which the value automatically assigned by the programme at the pressure head is null. The boundary condition which must be supplied for the Dam Node is the free surface


79

level (in relation to the overall level reference), which must be entered in the Surface field (m).

Thus, this type of Node simulates an intake of fluid from an open-air system where the free surface level is constant throughout the simulation period.

Reservoirs, tanks at a constant level, and dams with enough capacity not to suffer short term variations in level, are examples of intake points which can be configured with this type of Node.

FIGURE 5.28 Dam Node.

An intake node used for simulating the behaviour of the network over time (see sections

RESERVOIR NODE

9.5.2 and , referring to the creation and analysis of deterministic scenarios with Temporal Evolution). Using the window in the FIGURE 5.26 the Reservoir Node will be associated with the following information:


80

FIGURE 5.29 Reservoir Node.

♦ Base Level: Level of the bottom of the reservoir. This value must retain a reference level in common with the rest of the Nodes forming the network.

♦ Min. Level: Minimum level of liquid possible in the dam reservoir in relation to the base level. Under this level, an alarm will be generated.

♦ Start level: Value of the initial level of liquid in the dam reservoir in relation to the base level. To reduce the influence of this value in the behaviour of the network, when arbitrary values are taken, a long simulation time is needed.

♦ Max. Level: Maximum acceptable level of liquid in the reservoir in relation to the base level. This value cannot be above the last definition point in the Volume curve.

♦ H/V Table Defining the Capacity Curve: Using this table, the user must define how the volume of the reservoir changes at different levels of fullness, using at least three pairs of values. These values must be registered on the table in order from smallest to largest, and for adjustment to be reliable, specifying the pair of values for height 0 in relation to the base level. In any case, the range of values defined in this table must include the minimum and maximum levels assigned to the adjoining fields, as explained above.

♦ Adjustment: Click this button for GESTAR to analyse if the reservoir capacity values entered by the user are consistent, launching the appropriate warning if this is


81

not the case. Once the set of parameters is consistent, GESTAR will produce a graph representing the Volume/Level curve of the reservoir at the bottom of the dialogue window. (FIGURE 5.26). We recommend reviewing the curve produced by interpolation and adding points if needed to make the capacity curve smoother.

During the option of Temporal Evolution (p. 64) the data supplied will be taken into account; all other instant calculation options take the start level as their value.

Up to the version GESTAR 1.5, Dam Nodes were assimilated into a reservoir in the form of a truncated cone, with different requirements for its definition (see APPENDIX VIII, p. 494).

The two types of Dam model cannot exist on the same network at the same time. GESTAR automatically detects the type of Dam in the “*.red” file and the application opens with the appropriate option. Before creating the first Dam Node, the user can modify the type of definition from the Options menu/ Default Values / Nodes (see p. 141).

In this type of Node the boundary condition is the known total head, expressed in International System units (metres):

KNOWN PRESSURE NODE

H zpg

m= +ρ

( )

where z is the level of the Node in relation to a reference level common to all the

Nodes, and

pgρ is the pressure head of the Node, in relation to a reference level

common to all the Nodes (usually atmosphere), expressed in metres of water column (mWc).

FIGURE 5.30 Pressure Node.


82

In the definition window of the Node (FIGURE 5.27) z will be entered in the

level field and

pgρ in the pressure head field. The most common cases of the latter,

depending on the point which the Node is identified with, are:

♦ Pressure Regulator with Known Pressure P0 : The pressure head is

Pg0

ρ . (General case). For example, this type of Node can represent the pressure regulators which feed a plot at a constant pressure, in order to simulate the hydraulic behaviour in its network.

♦ Free surface: The pressure head is null.

♦ Base level of a tank, canal or reservoir: The level of the free surface in relation to the bottom will be noted.

♦ Storage systems with a variable free surface level over the long term.

A Node where the boundary condition is External Consumption, a known supposition and independent of pressure. Consumption may be taken to mean supply or extraction of flow from the network.

KNOWN CONSUMPTION NODE

FIGURE 5.31 Known consumption node.

Normally, Known Consumption Nodes (FIGURE 5.28) correspond to a simple model of hydrants with pressure regulators and flow rate limiters, feeding a given device at a constant rate set by the flow rate limiter, as long as the feed pressure is above a set threshold characteristic of the installed regulation elements. (Detailed information in APPENDIX II. MODELLING HYDRANTS, p. 457).


83

IMPORTANT: If the pressure in the network is lower than the regulation value of the hydrant, it will not be able to supply the flow rate initially set as the demand value, so that in such cases the Known Consumption Node will not reproduce the behaviour of the hydrant correctly. To consider these cases, consult the Hybrid Node (p. 85).

Throughout this manual and the GESTAR programme, the term “hydrant” (not specifically mentioning a Hybrid Node) refers to the set of Known Consumption Nodes and Hybrid Nodes, modelling irrigation hydrants.

It is advisable to distinguish between the terms: Maximum flow rate, Demand and Consumption, which although often used as if they were the same thing, in the context of the GESTAR programme have precise and different meanings.

Maximum flow rate: The allocation of the maximum flow rate which can be extracted from a hydrant.

Demand: Flow rate which the farmer wants to extract when opening a hydrant. This value is the same as or less than the maximum flow rate.

Consumption: The Flow rate which is really extracted from the network at a given Node. In a Known Consumption Node, the Consumption value will be the same as Demand when the Node is opened, but this will not be the case for Regulator Hydrant Nodes if there is not enough pressure (p. 85). In Emitter Nodes, Consumption will always be set by the feed pressure.

In a Known Consumption Node, Consumption is the flow rate value, C, which appears in the Demand text box (FIGURE 5.28) in the Node (in m3 s-1). Whether this is positive or negative will depend on whether this flow is supplying or extracting from the network, with the following conventional signs:

♦ C positive ( > 0): Demand flow rate from the network = output

♦ C negative ( < 0)*: Supply to the network = input

Demand in a Node representing an irrigation hydrant can be defined by two alternative procedures, selected in the consumption sub-heading in the definition window of the Known Consumption Node (FIGURE 5.28):

Specifying maximum flow rate. In the first procedure the maximum flow rate of the hydrant is specified by the user, corresponding to the maximum consumption possible for the Node. Once maximum flow rate is defined, the user can also vary Demand, between a value greater than zero and maximum flow rate, using a scrollbar. GESTAR will not allow a null instantaneous demand value to simulate closing a hydrant. To close one, use the Open/ Close Hydrants tool (leaving the hydrant enabled for Random Scenarios) or Restrictions on Random Scenarios (which will not be modified by created scenarios).

Specifying the Degree of Freedom. In the second procedure, the user supplies the Degree of Freedom (GL) of the hydrant, i.e., the inverse of the probability that an outlet of this type is open (see APPENDIX IV p. 469). In this option a set of additional


84

parameters must also be provided: Irrigated Area (ha), Fictitious Continuous Flow rate (l s-1) and Operational Efficiency, in the corresponding dialogue boxes.

These variables are noted and defined as follows:

♦ GL: Degree of Freedom (dimensionless). Inverse probability that the outlet is open.

♦ D: Maximum flow rate for the plot supplied by the hydrant (m3 s-1).

♦ r: Operational Efficiency (dimensionless). Quotient between the real and theoretical durations of the irrigation campaign. This must take a value between 0 and 1.

♦ qfc

♦ S: Irrigated Area of the Plot from the Hydrant (ha).

: Fictitious Continuous Flow Rate (l s-1ha-1). Flow rate needed, given an uninterrupted supply of water 24 hours a day.

The ratio establishing the maximum flow rate according to the above variables is documented in APPENDIX IV (p. 469) and is:

GLr

SqQ pfc

dot ⋅⋅

⋅= 310

The user can then vary Demand, with a value greater than zero and up to the maximum flow rate, using the scrollbar.

The probability that a hydrant is open is indicated in the sub-heading Opening in the definition window and is updated when the window is closed or the Calculate button is clicked for the Consumption sub-heading. The calculated probability that the hydrant is open is evaluated according to the option selected for defining maximum flow rate:

Specified Maximum Flow Rate

The values for GL, D, r, qfcFIGURE 5.28

and S must be supplied in the sub-block opening of the where the probability is:

rQSq

Tt

rTtp

dot

pfc

r

110

13 ⋅

⋅

⋅=⋅==

The values supplied must be consistent. Probability values greater than one are not permitted. Probability is calculated with the maximum flow rate of the node, which is the minimum probability of opening, as if Demand is configured with values lower than the maximum flow rate, the calculated probability of use will be greater than the value indicated by GESTAR.

Specified Degree of Freedom

The probability is directly inverse to the Degree of Freedom, greater or equal to one in all cases.


85

p = GL-1

If desired, the set point value can be established for the pressure reducer associated with the hydrant, ensuring that if the network reaches this pressure, consumption will be the same as the set demand. During the output of results graphics, Nodes with insufficient feed pressure will be automatically detected, showing the Pressure Margin variable, which is the difference between the calculated pressure and the Set Point Pressure shown in the sub-heading Regulation of the window in FIGURE 5.28. The real consumption in practice in these situations will not be the same as those set in the Demand field, whose value will still be set as a consumption condition.

Finally, in the lower right field, the diameter of the hydrant can be defined, as an information-only field, using a sequence of alphanumerical characters.

This type of Node (

HYBRID NODE

FIGURE 5.29), a generalisation of the Known Consumption Node, enables the reproduction of the complete behaviour of a hydrant equipped with a pressure reducing regulator and flow limiter, for the whole range of feed pressures. When the network pressure is higher than the set point value, the Hybrid Node behaves like a Known Consumption Node, supplying a consumption flow rate equal to the set point value of the Demand field. All the options and parameters which can be defined in the Known Consumption Node are present in the Hybrid Node. However, if the feed pressure of the hydrant is lower than the set point, the Hybrid Node adds the simulation of the behaviour of the hydrant-plot set using the pressure-flow rate response curves. It also includes the simulation of the flow rate limiter of the hydrant’s regulating valve, to avoid in any case the extracted flow rate exceeding the plot set point.

FIGURE 5.32 Hybrid Node.


86

The conceptual aspects of the operation of hydrants equipped with pressure regulators and flow rate limiters, and the numerical strategy of their implementation in GESTAR, are covered in Appendix II (p. 457), and briefly, consist of a hybrid formulation of the hydrant, so that if the network pressure goes over a certain limit, H limit = Ks Qdot N

NS QKH ⋅=

, the hydrant behaves like a Known Consumption Node, with consumption the same as demand, but if the pressure is not enough the Node behaves

like an emitter with a behaviour curve of the type .

The calculation module in each iteration checks the pressure level which will exist after the hydrant with the regulation Elements completely open, Hcal (calculated network pressure less the losses from the valve(s) corresponding to the completely open hydrant(s)), and modifies the modelling of the hydrant, according to the relative values of Hcal and Hlimit

H

, as follows:

cal > H

If the pressure after the hydrant, Hcal, is the same as or more than Hlimit the hydrant is configured as a Known Consumption Node with consumption the same as maximum flow rate. Network pressure can even go below the set point value, Hc, without modifying the flow extracted from the hydrant, as long as Hcal remains above Hlimit.

limit

Hcal > H

If the pressure after the hydrant, H

limit

cal, is lower than Hlimit, the hydrant will be configured as an emitter with the response curve Hp = Ks Qp

N, with the values Ks

To give the hydrant these possibilities, enable this option in the definition window, and the pressure set point (mca) must be indicated, which will be the same as or more than the limit pressure for the functioning hydrant, and the coefficients Ks (s

and N specified in the definition window.

2/m5) and N of the plot. Optionally, you can specify the losses in the hydrant of the plot when this is completely open (operating conditions of the hydrant as emitter node), giving the Ks (s2/m5

2QKH S ⋅=

) value of the hydrant, which we suppose has a loss equation of this type:

♦ Set point pressure: Pressure in mca for rating the hydrant’s pressure regulator.

♦ Ks Hydrant: Coefficient of losses in the completely open hydrant, according to the expression:

2QKH S ⋅=

♦ Ks Plot and N Plot: Parameters of the equation of losses in the plot network, according to the expression:

NS QKH ⋅=


87

The default values of N of the plot and Ks of the hydrant are 2 and 0.01 respectively. In order to test the consistency of the data entered in the regulation block, when entering the values of the pressure set point, Hc, and of Ks and N for the plot. Check that they fulfil the relation:

NdotSC QKH ⋅=

Otherwise an error message appears showing the limit value of Ks for the plot, accepting as correct the value of N of the plot, which verifies the earlier relation. If there is no more precise information on the hydraulic behaviour of the plot, it is suggested that you set N=2 and leave the Ks value of the plot blank at first, then re-enter the value supplied by the programme as the Ks of the plot as a response to the deliberate configuration error.

If desired, you can disable the hybrid behaviour of the Hybrid Node, which is then exactly like a Known Consumption Node, deselecting the regulation block of the Hybrid Node. The values loaded in this block will be saved for later activation.

The Sprinkler

SPRINKLER

is a hybrid component consisting of a Node and a Pipe Element. At the position of the node associated with the Sprinkler the flow discharges to the exterior of the network, with local atmospheric pressure at the discharge point. It is configured the same way as the Emitter, but the Sprinkler differs in that its icon is placed over the node where it is inserted, while Emitters can be placed anywhere on the Network Map. The Sprinkler is used systematically in the design of pressurised sprinkler irrigation networks on the plot (chapter 11 IN-PLOT DESIGN). If pressures are taken in the network in relation to the atmosphere, the relative pressure at the point of emission is null, and consequently, the total head at the point of emission is known and the same as the level. Thus, a Sprinkler Node is a Node with a known total head, which GESTAR assigns automatically as the same as the level.

The Sprinkler Node is a hybrid, as it is always accompanied by a Pipe Element (rectilinear, without intermediate geometric vertices) which is permanently attached to the Sprinkler Node and whose identifier and definition window are the same. In this Element, the hydraulic modelling of the behaviour of the sprinkler (APPENDIX III, p.465) is introduced through a function of this type: ∆H = Ks QN

To create a Sprinkler Node, just click on the chosen position for emission on the map and then click on another previously created one. The element associated with the Sprinkler Node is defined in the opposite direction to the creation of its end nodes.

which characterises the response of the emitted flow, Q, according to the feed pressure in relation to the atmosphere, ∆H.

After placing a Sprinkler Node, the window shown in FIGURE 5.33 will appear, where you must enter all the parameters identifying the emitter referring to the Emitter Point, the Associated Pipes and the possibility of implementing single losses or Valves.


88

FIGURE 5.33 Sprinkler Node.

♦ Emitter: The application lets you select a series of emitter characteristics to define the type of sprinkler suited to the irrigation design.

♦ Position. Its position is determined by the coordinates X, Y and its elevation by Level Z (all values in m).

♦ Origin. Name of the Junction node where the Emitter is inserted.

♦ Length. In m, length of the sprinkler riser.

♦ Manufacturer and Type of Emitter. The programme’s database provides a range of modern sprinkler devices currently used for in-plot irrigation design, including a table with their data, pressure-flow-reach operating curves, flow rate, working pressure and the sprinkler reach radius. You can add to and modify the sprinkler database from the menu File/ Modify databases, option Emitters (p. ¡Error! Marcador no definido.).

♦ Risers. The second panel in the sprinkler configuration window (FIGURE 5.33) is for defining the pipe where the sprinkler will be installed, the riser. The Manufacturer, Material, Pressure Rating and Diameter of the Riser must be determined using the same method as for specifying these parameters in the Pipe Element (see , p. 95)


89

♦ Valve. A specific panel is included which lets you insert this type of single element in the riser. Implementation is described in detail starting on p. ¡Error! Marcador no definido..

♦ There are Accessories and/or Losses. If this option is activated you can insert in the Riser any single loss different to those produced by Choke Valves, which needs to be included in hydraulic modelling, using the window in FIGURE 5.34. A detailed explanation of how to use this window begins on p. ¡Error! Marcador no definido..

FIGURE 5.34. Emitter window. There are Accessories and/or Losses.

♦ Roughness. The interior roughness of the riser is entered at this point. By default, if the Riser material was defined using the Pipes database (see p. ¡Error! Marcador no definido.) this will be loaded in the associated Roughness field. You can edit this value in the data field whenever you want.

Turn. From the drop-down menu at the top right of the window, the user can specify the individual turn assigned to the sprinkler, an essential step when sizing a sprinkler irrigation network (see Chapter 11, IN-PLOT DESIGN).


90

This is a Node in which we want to impose the two possible boundary conditions at the same time: total head (i.e., level and pressure) and consumption. This type of node is used to set the local service conditions or requirements to be met, in Inverse analysis techniques.

DOUBLE CONDITION NODE

Like the Known Consumption Nodes, a consumption is specified which is the same as Demand (FIGURE 5.30), after setting the maximum flow rate (maximum consumption), taking into account that positive values indicate flow coming out of the network, and negative values indicate flow going in. The total head also has to be specified, supplying level and pressure values in the Node in the same way as for a Known Height Node.

The specification of consumption cannot be assigned using Degrees of Freedom, given that these Nodes will not necessarily correspond to the modelling of hydrants. Consequently, in Double Condition Nodes the Node probability is also undefined, and cannot be worked around using the random scenario generators.

FIGURE 5.35 Double Condition Node.

IMPORTANT: For each set Double Condition Node an additional degree of freedom should be set, i.e., a Free Node (p. 91), a Free Element (p. 119), or a Free Pipes Set (p. 120) which will be calculated to reach the set point values of height and flow rate.

The combined use of Double Condition Nodes with Free Nodes and Elements without Passive Characteristics requires a series of conditions to be met for a solution to exist to the system of equations corresponding to the case. IMPORTANT: Always remember that an arbitrary combination of data and unknowns may not have a physical solution!!!. For example, in a branch where there are only Known Consumption Nodes, you cannot impose pressure and flow rate conditions on one of the Nodes using an Element of control on the same branch downstream from this Node. Unfortunately, not all incompatible conditions are as obvious as this, so you must use every precaution and common sense when working with the Inverse analysis tools.


91

This node (

FREE NODE

FIGURE 5.31) is free of boundary conditions in Inverse analysis. No boundary condition is set on the Free Node, constituting a degree of freedom in the system (not to be confused with the term Degree of Freedom defined as the inverse of the probability of a hydrant being open, p. 82) which the programme will adjust to reach the conditions set in the Double Condition Nodes.

No window will appear to specify variables in flow or pressure. The programme will calculate the values of head and exterior flow rate needed in order to meet the rest of the specifications of the network. These values enable pressure levels to be set at the feed points or determine the operating point of the necessary discharge pump. To be able to impose a Node of this kind, another Double Condition Node must already exist, so that the number of set conditions is still the same as the number of Nodes of the problem.

FIGURE 5.36 Free node.

This is a hybrid component consisting of a Node and a Pipe Element. At the position of the node associated with the Emitter the flow is discharged outside the network, with local atmospheric pressure at the discharge point. It is configured the same way as the Sprinkler, but the Sprinkler differs in that its icon is placed over the node where it is inserted, while Emitters can be placed anywhere on the Network Map. . If pressures are taken in the network in relation to the atmosphere, the relative pressure at the point of emission is null, and consequently, the total head at the point of emission is known and the same as the level. Thus, an Emitter Node is a Known Total Head Node, which GESTAR assigns automatically as the same as the level. An Emitter Node will simulate correctly the end point of all devices in contact with the exterior atmosphere and whose emitted flow rate depends on pressure. Sprinklers with no pressure regulator before them, misters, open hydrants without active regulation elements or without enough pressure for these to function, hoses, emissions through valves, breakages, relief valves, etc, fit this schema.

EMITTER NODE


92

The Emitter Node is a hybrid, as it systematically accompanies a Pipe Element (rectilinear, without intermediate geometric vertices) which is permanently attached to the Emitter Node and whose identifier and definition window are the same. In this element the hydraulic modelling of the behaviour of the emitter (APPENDIX III, p.465) is introduced through a function of this type: ∆H = Ks QN

To create an Emitter Node, just click on the chosen position for emission on the map and then click on another, non-emitter Node already created. The element associated with the Emitter Node is defined in the opposite direction to the creation of its end nodes.

which characterises the response of the emitted flow rate, Q, according to the feed pressure in relation to the atmosphere, ∆H.

After placing an emitter node, the window in FIGURE 5.32 will appear, where you must enter all the parameters identifying the emitter referring to the Emitter Point, the Associated Pipes and the Hydraulic Response of the Emitter.

FIGURE 5.37 Emitter Node

The only information referring to the emitter point which must be entered is its position, given by default according to the coordinates of the click creating it, and the level of the emitter point, as GESTAR assumes that the pressure there is that of the

CONFIGURING THE DATA OF THE EMITTER POINT


93

atmosphere. The length, which will also be assumed according to its graphic representation, can be modified in the same way using the corresponding field.

The data relating to the pipe associated with the Emitter correspond to the same concepts and operations as any other pipe, although the dialogues are found in different places in the window, so that we refer to the description of Pipe Elements (p.

CONFIGURING THE DATA OF THE ASSOCIATED CONDUIT

95) to learn about them. Defining the parameters referring to the pipe is obligatory, so that in the case of this pipe not really existing (leaks, emitters directly connected to the network), it should be given very large arbitrary diameters (e.g., 5000mm) and/or tiny lengths (e.g., 0.001m), so that the head loss introduced by the conduit will be negligible.

CONFIGURING THE HYDRAULIC RESPONSE ∆H = KS QN

When formulating the hydraulic behaviour equation of the emitter (Appendix III, p.

OF THE EMITTER

465) ∆H = Ks QN , the values of Ks

♦ Supplied by the user or by GESTAR as a singular loss in the Element (see the corresponding section on the Pipe Element, p.

and N can be specified:

95).

♦ Supplied by GESTAR, which will automatically adjust the values of Ks and N to the pressure/flow rate data loaded from the database (see p. 436) of emitters, referring to the chosen emitter.

KS

In the first case, the singular loss(es) are consigned by the specification, if applicable, of the type of valve and the open percentage in the pipe, and/or using the configuration windows and tools for singular losses, accessed by clicking on the field There are Accessories and/or Losses in the

AND N SUPPLIED BY THE USER OR BY GESTAR AS A SINGULAR LOSS

FIGURE 5.32, to the lower left. If this box is blank it means that no device was loaded which would introduce singular losses.

Thus, for example, if the Emitter Node corresponds to a direct discharge from a pipe through a valve, the type of valve and its open percentage would be configured in the fields of the lower right corner of the window in FIGURE 5.32. If the emission takes place through any other Element recognised in the database of elements of accessories or if the user knows the values of Ks and N or has pairs of pressure/flow rate values for adjusting them, the field There are Accessories and/or losses will be activated, giving access to the respective options via a similar window to that in FIGURE 5.37 (see configuration details on p. 103 ).

IMPORTANT: If emission to atmosphere is a real discharge section S, with an appreciable kinetic energy, the kinetic contribution should be included as a single loss of the type ∆H = Ks QN

gSKS ⋅⋅

=21

2

where the kinetic contribution is:

; 2=N


94

KS

When selecting an emitter from the database, using the manufacturer’s specification and/or emitter model, a table appears with the characteristics loaded in the database, showing at least the emitted flow rate depending on the feed pressure. With these values GESTAR automatically, using least square techniques, brings the cloud of pressure/flow rate points closer to a function of the type ∆H = K

AND N SUPPLIED BY THE EMITTER DATABASE

s QN

The first time an emitter is created while GESTAR is running, the selection windows Manufacturer and Type of Emitter appear, launched by default with the options <All> and <None> respectively. Thus it will not load the characteristics of any emitter unless the user specifies it, selecting it from among the Type de Emitter drop-down list.

, supplying the coefficient Ks and the exponent N. Another type of data, which can be useful when selecting a certain type of emitters in sprinkler irrigation, such as pluviometry and reach according to feed pressure, are shown, although they play no part in the hydraulic simulation.

The Type of Emitter drop-down list shows the complete list of emitters whose characteristics are currently loaded in the Database of Emitters, corresponding to the manufacturer chosen from the Manufacturers list next to the Type of Emitter list.

If the option <All> is chosen from the Manufacturer list, the Type of Emitter list will contain a full list of all the emitters from all manufacturers. If a value is selected from the Manufacturer list, the Type of Emitter list will show only the emitters from that manufacturer. As you can see, the Manufacturer category can be used to structure and order products from the same firm by ranges, in order to simplify and reduce the size of the Type of Emitter list.

Once an emitter has been selected from the database to create an Emitter Node, the new Emitter Nodes created will appear with the Type of Emitter previously chosen as a default in order to speed up the repetitive loading of identical emitters.

In any case, to add other singular losses to an Emitter Node, the checkbox There are Accessories and/or Losses must be ticked. However these losses are not added by default to the emitters created later.

5.2.1 TYPES OF ELEMENTS

An Element establishes a connection between two Nodes. To incorporate an Element in the graphic window, the two Nodes it will connect must be previously created. If this is the case, just select the taskbar button corresponding to the desired Element and click on the start and end Nodes. By default a dialogue will appear (except with Pipe Elements) where you can set the parameters and characteristics of the created Element.


95

Just as with Nodes, any characteristic of an already created Element can be modified by double clicking on it. This will bring up the dialogue box corresponding to the Element in question.

All Elements have two common characteristics in their dialogue boxes:

♦ ID: Identifier of each Element. This is alphanumerical (maximum 15 characters); there cannot be two Elements on the same network with the same identifier. Some characters can be reserved for designating the area they are in; for example, all those corresponding to a given sector of the network can begin with a certain digit or have a certain prefix.

♦ Comment: A string of alphanumerical characters (maximum 20 characters) where you can add any information for each Node. Can be used to add comments such as date, owner, area, etc.

The lower part of the windows also includes a Help button taking us to the GESTAR file with information on the programme.

There is also a button with a question mark on the upper right of all definition windows. This button offers Context-Sensitive Help, with explanations for the various parts of the windows. Click on the button and then on the part of the window you want information about, and GESTAR will show superimposed text with a brief description.

This type of Element is the most common in distribution networks. It corresponds to a conduit with a circular section and constant diameter which can contain additional singular head losses. You can work with conduits with a constant non-circular section, interpreting the Diameter as Hydraulic Diameter.

PIPE ELEMENT

GESTAR offers the possibility of reproducing the real geometry of the conduits using the Pipe Elements layout with multiple vertices. These Elements are created by clicking on the start Node, again on each of the vertices defining the geometry of the Pipe, and again on the end Node.

In a Pipe Element with multiple vertices, the user can only define or modify the levels of the start and end Nodes. The levels of the intermediate points (vertices) are calculated automatically by interpolation. FIGURE 5.33 shows the interpolation process in graphic form (at the top of the Figure the Pipe Element appears as shown by GESTAR, and below, we see the real pipe layout in perspective). GESTAR calculates the plan (plan P in the figure) which contains the end Nodes of the Pipe (points A and B) and which has as the line of maximum slope the line (line r) connecting the Nodes. The level of the intermediate Nodes (in the example only point M) is equivalent to the level of the intersection point between plane P and the vertical line (line s) which goes through coordinates x and y defined when placing the intermediate Node. The length assigned to the stretch is the sum of the lengths of each of the stretches making up the pipe, after placing the intermediate points as described. Obviously, this length can be modified by editing the Pipe (double clicking on it).


96

FIGURE 5.38 Conduit with multiple vertices.

The Pipe Elements are opened by double-clicking on any point on them (they are also opened when Pipe Elements are created if the Open when Creating option has been chosen on the Options/ Default Values/ Elements menu; by default this option is disabled). The window in FIGURE 5.34 will appear, showing the start and end Nodes of the Pipe (these can be swapped with the button to their left), and the following data must be supplied in their respective fields:

♦ Length of the Element. By default length is calculated automatically according to the three-dimensional coordinates of the Pipe Element layout vertices, supposing there to be a straight stretch between two vertices and the length of the Pipe Element to be the same

as the sum of the lengths of each stretch. As the levels are only set at the start and end Nodes, the levels of the intermediate vertices are established assuming that all vertices

are on the same plane. In any case, the user can modify length according to need.

♦ Design Flow Rate. When running the option Design flow rates from the Sizing menu (see p. ¡Error! Marcador no definido.), the Design flow rate obtained for each stretch will be loaded, and will be displayed using this field, which you can use to modify the result manually if desired.


97

FIGURE 5.39 Conduit Element.

♦ Interior Diameter of the Element. Given by default in the menu Options/ Default values/ Elements, and from the moment of modification, all Elements created later will take this value by default. It is set using two alternative options accessed by the corresponding buttons:

• Database: Selecting the conduit from a list of standard diameters, which will change according to the manufacturer, material and pressure rating chosen from the Pipes Database "pipes.mdb" (p. 428) according to the procedure described below.

• Personalised: Set by the user, as in the previous option, this must correspond to the Internal Diameter of the conduit, which will not always agree with the Nominal diameter (default option when creating the first Pipe element).

The Internal Diameter value will appear in the Personalised Diameter (interior) field, whether the conduit was chosen from the database (greyed-out values cannot be modified and are loaded from the database) or entered directly (values can be modified in the field).

♦ Roughness Factor. Must agree with the chosen losses formula. For example, if using a Hazen-Williams formula, it will be the Hazen-Williams coefficient CH for the Material used. If using the Colebrook formula, the absolute roughness of the Element (in metres) will be used. Changing the type of loss calculation changes the value requested for the Roughness Factor. The formulation for calculating losses in selected


98

using the Calculations/ Characteristics menu (see p. 157), and must be consistent with the specified roughness factor. When Pipe Elements are chosen according to the database, the Roughness parameter in the database will be loaded. Although normally the values in the Pipes Database correspond to absolute values of Roughness (metres), the user can of course alter this field in the database (see p. 428) to fit other loss formulas. When Internal Diameter is set by the user, the default roughness factor is the value shown in the menu Options/ Default values/ Elements. As the Roughness Factor varies widely depending on the age of the conduit, its state of conservation, the characteristics of the water, etc, the field where the Roughness Factor appears can be edited under any option, so that the user can always modify this parameter as desired. This change does not affect the entries in the Pipes Database. Whenever the Roughness Factor is changed from the default values, this change will persist in the creation of new conduits as long as none of the selections are changed which define the chosen component in the Pipes Database.

As well as the required information above, you can optionally include information on the manufacturer, material, pressure rating and celerity of the conduit. This information can be added manually or selected from the entries in the Pipes Database associated with the network. If using the Pipes Database, the default value for the internal diameter and Roughness are directly set by the database.

When creating a new Pipe, the following fields are configured by default with the same values as the last conduit created.

♦ Manufacturer/refs. To use the information on pipes in the database, select a manufacturer or technical reference number other than <None> from the drop-down list. The characteristics of the conduit will be taken from among their products. When selecting a manufacturer or reference from the list, the contents of the fields Material, Pressure Rating and Diameter/ Database will be configured as lists of parameters showing the available ranges of the chosen Manufacturer/reference entered in the database "Pipes.mdb". A diameter can be assigned to the pipe now, by default, selecting the Nominal diameter from the list associated with the field Diameter/ Database, a list which depends on the additional selections of Material and Pressure Rating.

♦ Material: Covers the code or features of the pipe material. If something other than <None> was selected for the Manufacturer/reference field, the Material can be selected from the drop-down list presenting filtered Materials from the database according to the chosen Manufacturer/reference. If <All> was chosen from the list of Manufacturer/references next to the Material window all the references to different Materials from all manufacturers in the database will be shown. The same Material assigned different codes in the database will be shown according to the codes as different Materials (e.g., fibre cement, Fibre cement).

♦ Pressure rating: Contains the code or numerical value of the nominal pressure of the Pipe. If a Manufacturer/reference has been selected, the Pressure rating will be determined by choosing from among the commercial values in the database and shown in the list of the Pressure rating field, a list which will depend on the previous selections in the Manufacturer/reference and Material fields (see FIGURE 5.34). If <All> is selected for Manufacturer/reference, the Pressure rating field will show all the pressure ratings with different codes from all of the manufacturers supplying the selected


99

Material. In this case, if the same pressure ratings appear registered with different codes for different manufacturers, they will be shown and interpreted as different pressure ratings (e.g., PN10 ATM and PN1 Mpas).

♦ Celerity: Contains the numerical value of the celerity, i.e., the propagation velocity of pressure perturbations throughout the length of the conduit, depending on the properties of the conduit and the fluid. If the option Diameter/ Database was used, the celerity value registered for this diameter in the database will be loaded. For any option, manual modification is possible from this field.

♦ Diameter (Database): For this field to be enabled, a selection other than <None> should be shown in the field Manufacturer/reference. In the field Diameter (Database) a Nominal diameter value will be selected from the associated drop-down list containing the Nominal diameters corresponding to the manufacturer, material and pressure rating selected in the respective field. If <All> is selected for Manufacturer/reference in the Diameter/Database field, all the different nominal diameters from all of the manufacturers supplying the selected Material and pressure rating will be shown. Given that the nominal diameters are standard values coinciding in different manufacturers for the same standard material and pressure rating, the characteristics of internal diameter, roughness and thickness associated with a Nominal diameter which may differ from one manufacturer to another are those entered for the first manufacturer supplying this material and pressure rating found in the database.

If the diameter you want to install does not appear among the values in the Pipes Database, this can be set manually (always the internal diameter) activating the "Personalised Diameter" option. The parameters set for the fields Manufacturer, Material, Pressure Rating and Roughness persist, whether specified manually or via the database.

Singular Elements linked to the Pipes can be added in order to include them in the simulation, avoiding the need to introduce too many different components. These do not include regulating valves, which are specified independently (p.

SINGULAR ELEMENTS

115). The equation of pipe behaviour therefore corresponds to the sum of one pipe plus singular losses (see Appendix I, p. 441):

NS QK

SQk

DL

gH +

+=∆ ∑ 2

2

21 λ

The following points must be taken into account regarding the inclusion of singular elements:

When a Conduit contains Singular Elements, an icon will appear in the centre of the graph identifying the existence and type of Singular Element included. The possible symbols and their meanings are listed below:

Sectioning Valve

Anti-return Valve


100

Throttle Valve

Singular Elements

As shown in the window in FIGURE 5.34, two entry procedures are enabled: through the specific panel for Valves, or the panel for Singular Elements. If a pipe has more than one type of Singular Element defined, using both procedures, the icon appearing in the Pipe will reflect the type of valve associated with it through the Valve option.

The topological placement of the Singular elements will be undetermined for the pipe as a whole, as it is irrelevant for calculating the net energy losses in the conduit with a constant section. Consequently, there is no need to specify any relative position for them. If you want to position any device in the network precisely, e.g. to find out the exact difference in pressure between the ends, a Pipe element must be defined specifically for this device, with diameter or length values for the associated conduit according to the singular element (e.g., the same diameter as the diameter of the singular element, the same length as the length of the device or a very small arbitrary value in order to minimise lineal losses).

All the Singular Elements installed in a Pipe must have the same Internal Diameter as the pipe, so that if there is a device with a different diameter to the conduit, a pipe should be created in order to house this element.

VALVES

♦ Closed Valve. When editing any Pipe element, the Valves panel will show the Valve Closed checkbox, enabling closure of the conduit. Thus, if using this option, it is not absolutely necessary to specify the type of valve associated.

IMPORTANT: In branched networks you need to be sure, when closing the flow of a conduit, that no node downstream from the closed conduit where consumption is known, even if null (Known Consumption Node, Junction Nodes, Hybrid Node), is disconnected from all the Nodes of known total head (Dam, Reservoir, Known Pressure, Double Condition and Emitter nodes). If not, there can be no solution to the system of equations. Intuitively, this phenomenon can be interpreted as the physical impossibility of supplying the flow rate set for a Node if a conduit supplying the Node is closed. GESTAR detects the existence of isolated Nodes (i.e., with no connection to a reference total head, similar to network feed points), giving the user a warning of "Set of Nodes without total head reference" and highlighting all the isolated nodes on the network graph with a circle. Therefore, the Sectioning Valve should NEVER be enabled for conduits feeding Nodes at the end of branches where consumption is known, even if null, to close an outlet, as the system would become physically incompatible. To close an outlet or hydrant simply use the operation Open/Close Hydrants (p. 76) on the Toolbar. This way the node will appear as a Closed Node in the graph, clearly establishing the real state of the hydrant.


101

♦ Add/Modify Valve. Click the Add/Modify Valve button to bring up the window in FIGURE 5.35. The valves are introduced in the simulation including the singular loss which they add according to the characteristic equation ∆H = Ks QN, where Ks and N are determined internally and automatically by GESTAR using the values found in the Valves Database, according to the type of valve and the degree of closure in the case of a sectioning valve. Maintaining and increasing the valves recognised in Type and setting the values of Ks and N according to the degree of closure can consulted in section 12.4 VALVE DATABASES (p. 471). The type of valve is selected from the list in the Type field.

FIGURE 5.40 Add / Modify Valve Manual option

• If the selected valve type is a Sectioning Valve, the degree of closure will be accessible in the field % Closure, where you can set manually the desired percentage for the whole Actuator Element to close the valve (value under 100% in any case; to close the valve the specific field Closed Valve will be enabled). Thus, a completely open ball valve will have a % Closure of 0%, while if the actuator has turned 45º the % Closure will be 50%. If the closure percentage is high, from about 90% closure, we recommend viewing the results obtained with caution, as in these circumstances there is high uncertainty in determining the dimensionless loss coefficients, and the conduit is also mostly blocked, which can affect the convergence of the solution. The same preventive steps described for Closed Valves (p.100) in branched networks are applicable for a high closure percentage.


102

• When dealing with an Anti-Return Valve, to enable fluid to pass, GESTAR will check that the total head of the start node of the pipe is higher than the total head of the end node, as mere differences in pressure are not significant when the ends of the Element may be at different levels.

• If the Manual default option is modified in the Catalogue panel, permitting the selection of a generic valve type, and the Database option is enabled, a specific commercial model can be associated. The valve selection window will be as shown in FIGURE 5.36. From the Diameter panel you can request that only valves which fit the diameter of the pipe be shown. Choose the type and subtype (second drop-down menu) of the valve, to leave a list of the different valves available for these requirements in the Database. For the valve selected from this list, the corresponding fields will show the data loaded from the Database referring to Manufacturer, Series number, Code, Nominal diameter, Nominal Pressure, Price and Description of the Series.

FIGURE 5.41 Add / Modify Valve Database option


103

SINGULAR ELEMENTS

FIGURE 5.42 Add/ Modify Singular Elements

♦ Add/ Modify Singular Elements. Any singular loss, other than those produced by Throttle Valves, to be included in the hydraulic modelling of the Pipe will be entered in an additional window which appears when clicking the button Add/ Modify Singular Elements. The equation of Singular Element losses is the type ∆H = Ks QN, where Ks and N can be automatically assigned by GESTAR, using the Accessories Database (p. 431), or defined explicitly by the user. The identification codes and parameters of the losses introduced using the first procedure are listed in the Pipe element definition window, FIGURE 5.34, under the heading Accessories. At the same time, the losses set by the user by specifying Ks and N are listed under the heading Singular Losses, showing the loaded values of Ks and N. The coefficients can be adjusted exponentially introducing sets of points from their behaviour curve (see p. 105). When Add/ Modify Singular Elements is enabled, the Singular Elements definition window appears, FIGURE 5.37, with the differentiated blocks: Accessories and Singular Losses.

• Accessories. The head loss coefficients in the junctions between stretches, elbows, tank input and output, reductions, measuring devices, and other singular elements found in the Accessories Database can be incorporated automatically. Singular losses in Accessories can be expressed thus:

222

1 QSg

kH ⋅⋅⋅

⋅=∆


104

where k is the dimensionless coefficient of losses of the singular element, provided by the database, and S is the transversal section of the pipe, given by virtue of its diameter.

Use the Type field to select from the list of types of accessories in the database.

According to the type of Accessory selected, e.g. angular elbow, you will have to specify another parameter to identify the Singular element, e.g., turning angle in the case of an angular elbow. This parameter can be selected from those available in the list appearing to the right of the Type field. This second list will indicate the parameter to be specified, which will of course depend on the Singular Element in question.

When the characteristics of the Accessory make it unnecessary to specify another parameter, the second field will disappear.

Finally, the number of singular elements identical to those specified in the above field or fields is indicated in the Number field.

It is assumed that the various singular elements which may appear are far apart enough for there to be no interaction between them (e.g., the losses corresponding to two distant 45º elbows can be added, but the loss from a 90º elbow cannot be regarded as equivalent to that from two 45º elbows next to each other). After the Accessory and its number are defined, introduce the device in the pipeline by clicking the Add button. The data for the Accessory will be shown on a list which also shows the value of k taken retrieved from the database.

• Singular losses. Devices which are not specified in the Database, or which you want to configure in a particular way (e.g., special devices, singular losses in emitters, kinetic energy terms in a free discharge, etc.) can be entered supplying the values of Ks and N in the behaviour equation:

Ns QKH ⋅=∆

and the number of similar devices in the corresponding fields. Click the Add button in the Singular Losses block to enter these values in the network, where they will appear listed in the Singular Losses block.

If you want to delete an Accessory or Singular Loss included in the network, just go to the Add/ Modify Singular Losses field and select the Element to delete from the appropriate list, then click the Delete button.

Often, the values of Ks and N are not known directly or by the user, but there are results of tests which determine the fall of total head according to the circulating flow rate. The pairs of values can be fitted to an expression of potential using a least square technique. To facilitate this, the Singular element definition window, FIGURE 5.37, includes the Fit


105

Ks and N button, which gives access to a window where you can evaluate and transfer these parameters. This window is described below.

To give the user tools for fitting experimental data to curves of the type

AUTOMATIC FIT

∆H K QSN= ⋅ (potential fit)

or

− = + +∆H AQ BQ C2 (square fit)

in various windows with different functions there are buttons giving access to a utility for fitting pairs of points (Q , ∆H) using the least square method which works identically in both cases.

There are three components which give access to the fitting window:

♦ Conduit Element: Add/ Modify Singular Losses window; Fit Ks and N button (FIGURE 5.37, p. 103) (potential fit).

♦ Emitter Node. When the There are Accessories and/or Losses checkbox is checked in the definition window (FIGURE 5.32, p. 92), the same dialogue as in FIGURE 5.37 appears, with the corresponding Fit Ks and N button (potential fit).

♦ Pump Element: menu Options/Default Values/ Elements, Fir button (FIGURE 6.13, p. 142) (square fit).

In the potential fit, at least two pairs of flow rates and height points must be

introduced to reach the values of KS and N . For the square fit, at least three pairs of points are needed (or two if you want B=0) in order to calculate the three parameters, A , B and C .

In any of these cases an Fitting window like that in FIGURE 5.38 will be opened.


106

FIGURE 5.43 Fitting Window

All the pairs of flow rates and height points must be entered in the Q and ∆H H fields one by one, and the Add button pressed after each one. You can add as many points as you need, with the minimums stated above, and remembering that all values must be positive. As the points are added, they will be displayed on an adjacent list, where they can be deleted or modified.

After adding all the desired pairs of points, click the Fit button to obtain the values of the parameters of the corresponding curves by the least squares method, and a graph showing the curve and the points fitting it.

Even after fitting, pairs of points can be modified, deleted or added, and then fitted again.

After fitting, click the Accept button for the parameters of the calculated curve to automatically appear in the corresponding fields of the original window.

For a parabolic fit, if you want the interpolated curve to fit better in a given range of empirical points, the weight of this area can be increased by least squares, introducing new pairs of points (∆H, Q) in the desired sector. The utility accepts the introduction of the same point several times to increase its weight.

GESTAR uses the Emitter line element to enable the modelling of branches with continuous outflow, where the flow rates which enter and leave are different due to the existence of emitters along the route, whose consumption varies according to pressure.

EMITTER LINE ELEMENT

This type of Element is used for simulating lateral drips, seep hoses, lines of sprinklers, and in general, any circumstances producing emission along the route.

This section describes the process of creating the Emitter line elements. To construct a drip feed, click the Emitter line element icon , in the GESTAR toolbar. After selecting the tool, you can create the element. The start and end nodes which the


107

element will run between should already have been created. The Emitter line element can be divided into different stretches, each with different characteristics.

To create the first stretch of an Emitter line, click on the node marking the start of the Element. Then end the first stretch by selecting any other point on the plan. To create the next stretches of the Element consecutively, follow the same procedure. To finish the construction of the Element, select the end Node with the mouse.

Each time a stretch is created, GESTAR requests the necessary information via a definition screen (FIGURE 5.39). Before the Emitter line can be shown on the plan, a set of parameters must be defined on this screen, which will appear every time a new stretch is added.

FIGURE 5.44 Definition window of an Emitter Line

The form in FIGURE 5.39 is in two parts: Properties of the EMITTER and Properties of the CONDUIT.

1. EMITTER properties:

♦ Emitter manufacturer: Drop-down list where you can specify the manufacturer of the emitters to be placed along the pipe supporting the current Emitter line.

♦ Emitter type: Drop-down list where you can specify the model of drip feed to use from the different models available from the specified manufacturer. After choosing the type of emitter, a table will automatically appear in the lower panel, showing the flow rate emitted by each drip, totally defined by the above properties, for different pressures. These flow rates are also provided by the manufacturer.


108

The drop-down lists of emitter manufacturers and types of emitter are directly connected to the database called Emitters.mdb, supplied with GESTAR. This database covers emitter manufacturers and a range of different emitter models with their characteristics.

CAUTION! This database includes all the emitter types used in GESTAR. This makes it advisable to pay close attention to the type of emitter you choose, as the choice of a type which is not intended for drip irrigation would probably cause an error, or simply not provide the flow rate demanded for the emitter through drip irrigation pipes (narrow diameter) for certain pressure conditions.

♦ Ks: Based on the data shown in the table, a parabolic fit will be made with least squares, and the programme will obtain this constant and coefficient N.

♦ Coefficient of Emitter Kd and Exponent of Losses from Emitter x: Based on the parameters Ks and N, Kd and n are obtained automatically with a simple transformation:

Having N

s QKH ⋅= , and wanting an expression x

d HKQ ⋅= , the first

expression is simply transformed to arrive at the second one. Thus S

N

KHQ =

,

elevating the whole expression to 1/N, we obtain: Ns

N

K

HQ 1

1

=

.And we need only compare:

Ns

dK

K 11

⇒

Nx 1

⇒

The values of Kd and x are for units of Q and H expressed in the international system. It is advisable to take this into account as the size of Kd varies according to the units in which these formulas are expressed.

♦ Grouping Emitters. This enables the number of irrigation points per plant to be increased, and is useful for simulating drip irrigation of trees, among other things.

2. Properties of the CONDUIT:

♦ Length: Length of the stretch in metres.

♦ Space between Emitters: Distance in metres between the emitters defined in the EMITTER Properties panel.

♦ Sub-node level: The end point of each stretch is called a sub-node. In this space, the level of this point is determined. In the case of the last stretch, this panel will show the level of this node, and cannot be modified.


109

♦ Manufacturer: As with emitters, a manufacturer of the conduit of the Emitter Line Element will be chosen from the list. The choice will be based on the drip feed database, Drippers.mdb, which is installed along with GESTAR.

♦ Material: Shows the available Materials available for each manufacturer chosen from the drop-down list above.

♦ Interior Diameter and Nominal Diameter (Database): If there is a selection of Manufacturer and Material, a Nominal Diameter should be selected from those available in Drippers.mdb. If there is no selection, the conduit diameter can be introduced manually,

Once all the stretches in the Emitter Line are created and defined, a new window will appear (FIGURE 5.40) showing the overall characteristics of the Element.

FIGURE 5.45 Definition window of an Emitter Line

♦ Identifier: An identifier must be assigned to the Emitter Line. GESTAR assigns a default identifier in the form: GOTx, where x is a number, so that the first Emitter Line created will be GOT1, the second will be GOT2, and so on.

♦ Comments: Used for adding notes or other comments as a reminder of anything unusual about the element.

♦ Number of Sub-elements: This will remind us of the number of stretches making up the Emitter Line element, with their different properties.

♦ Length: Shows total length as the sum of the lengths of all the stretches.

♦ Table: This table will have as many rows as there are Sub-elements making up the Emitter Line. On each row, five cells show the most important parameters for each emitter Line. Thus, in five columns, from left to right, the table will show:


110

Manufacturer, Material and Length of the pipe, the exponent of losses and the emitter coefficient.

♦ See/ Modify Elements: This button will be enabled if only one row on the above table is selected. Its function is to show a screen with all the parameters of the Emitter Line corresponding to the selected row, in order to make any changes or simply to see the data.

WARNING: The units of the Emitter Lines for visualising the flow rate are different from the other Elements. This is because the flow rates working with drip feeds are too small, in most cases, to be expressed in m3/sec. For this reason emitter consumption is entered and shown in l/h.

This is the active Element providing pump head

PUMP ELEMENT

∆H < 0 in a given stretch.

To create a pump element, just click with the main mouse button on the start node, and drag the mouse to end the creation with another click on the end node. All the parameters the programme needs for the construction and simulation of a pump are contained in the pop-up window shown in FIGURE 5.41. In the upper part of the window, available under any tab, the Start Node (intake) and End Node of the pump appear, and can be swapped with the button next to them; there are also two fields defining the identifier (Id.) and possible comments (Comment.).

FIGURE 5.46 Pump Element Definition Window.


111

The Pump Data tab is used to enter data characterising the pump, enabling various options for defining it in GESTAR:

♦ Tabular data Entry: Data entry is done through a single panel in the lower part of the dialogue in FIGURE 5.41, with copy/paste/cut/ properties compatible with Office objects. A minimum of three pairs of flow rate - pump head values must be entered, and we recommend including data from null flow rate (closed pumping valve) to the maximum predictable flow rate. Flow rate values should be entered in ascending order and there cannot be two the same.

♦ Pump Stopped. When this option is enabled, the pump is in the Stopped position. This enables the pump to be in the Working/Stopped position whether or not the pumping valve is closed. If this valve exists, it cannot be closed at the same time as the pump is stopped, as it would leave the pump node isolated. IMPORTANT: Confirm that stopping the pump, which involves closing the retention mechanism, does not leave the system fed by the pump with no reference head height.

♦ Intake Diameter The diameter of the intake flange, it may be the same as the passive element before it. Used for computing the speed of the intake flange, needed in order to determine the available NPSHA.

♦ Additional Performance Curves. This panel optionally lets you define the curves for Power Consumption, Efficiency and NPSH of the pump. As you can see, it is not essential for the construction and basic hydraulic simulation of the system, but these data can give us valuable information when considering power use and cavitation prevention.

• Flow rate – Power. Enable this option if you want to obtain the pump's Power Consumption and Efficiency curves. From the data entry table, you will need to insert one of the values, Power/ Efficiency, for each pair of H-Q data of the pump. The remaining parameter, Efficiency/Power, will be defined secondarily. We recommend entering Power Consumption data rather than efficiency, as the latter parameter is deduced from direct measurements of power and Power consumption for a zero flow rate is undetermined.

• Flow rate – NPSHR. Selecting this option, the NPSHR column will be available in the data entry table, permitting the inclusion of the points for constructing the curve. This curve will be taken into account when testing to see if the pump cavitates. The cavitation check will be carried out during computation. Check the Cavitation option on the Alarms screen beforehand if you want to be notified. When the programme finds a pump during its computation process, it will check to see if the cavitation alarm button was enabled, and if so will calculate the available NPSHA for the calculated flow rate, and will take the value of the required NPSHR of the curve entered by the user. If it finds that the value of available NPSHA is lower than required NPSHR, it will show the user a warning to notify him of the situation. This warning will vary according to the type of computation carried out.


112

FIGURE 5.47 Choosing a pump from the database.

♦ Database. The points defining the pump curves can be taken from a database using this button, Database (FIGURE 5.41), bringing the user to the window of FIGURE 5.42. From this window you may select the pump directly, choosing a Model and Runner Type from each Pump Database, using the appropriate drop-down tabs. The data for the selected pump (Pump Head, Power Consumption, NPSH and Efficiency) are given in the table Operational Performance Curve, representing its H-Q curve and the point sought graphically.

12.6

In turn, in the panel Selected Pump Characteristics, we find the most relevant parameters defining the chosen pump, stored in the Database (to see the procedure for creating and editing Pump Databases, see Section PUMP DATABASES, p. 437). If dealing with a multi-stage pump, this same panel will show the Stages field, where you can specify the desired number of stages connected in a series.

• Search. This button automates the process of searching for the best pump for the operating conditions, from those in the selected Pump Databases. In the Search Criteria panel, the Position of the pump (horizontal or vertical) and


113

the Service Point (flow rate and pump head). The selection criteria filter for pumps supplying a head equal to or up to 20% higher than the service Point and a flow rate higher than that of the Service Point, which lets you adapt the selected pumps by turning the runner (or reducing rpm) if the curve does not exactly fit the service point. At the end of the process, a new field will appear in the window with the list of pumps found, ordered by efficiency.

• Apply Turning. This option will remain visible when the pump search starts from the definition of the service point. If the pump found does not exactly fit this point, the panel Service point found will show the new diameter which the runner should be turned for, and the head, power and efficiency values which will be obtained for the service point flow rate after turning. Clicking the Apply Turning button will show the operating curve of the pump with the modified runner.

• Add Pump. The Add Pump button loads all the pump interpolation points in the data entry table in the dialogue shown in FIGURE 5.41. If the Apply Turning process has previously been carried out, the definition points of the pump curve with the new runner diameter will be loaded. If dealing with a multi-stage pump, with a number of stages other than one, the values of the operating curve for the number of stages set will be obtained.

• Fit Curves. Clicking this button in the window in FIGURE 5.41 will transfer the data for Pump Head, NPSHR, Energy Consumption and Efficiency according to Flow rate from the table to the graphic representation module, and the interpolated curves between given values. Access them using the tabs Q-H-P Graph, Q-H-R Graph and Q-H-NPSHR Graph, shown in FIGURE 5.41. Each shows simultaneously the Pump Head - Flow Rate curve and another curve (Power Consumption, Efficiency and NPSHR), if defined.


114

FIGURE 5.48 Graphic representation of the Pump Head and Power curves.

♦ R.P.M. This panel allows the new pump operating curve to be predicted as its speed is varied, based on the tabulated entry data (at least three pairs of H-Q need to have been defined).

• Simulate N2. With the value corresponding to the new RPM defined in the field N2, clicking this button in GESTAR will provide a new operating curve at N2 rpm tabulated and the graphs will include representations of the earlier and the present curve.

• Calculate N2. The user should first fill in the fields H and Q making up the found service point. When Calculate N2 is clicked, GESTAR calculates the new turning speed in RPM which the pump should be working at for its H-Q performance curve to pass through the service point. Once the value of the new RPM is obtained, the new operating curve can be obtained with the Simulate N2 button, as described above.

If you prefer, you can access formulation with a single parabolic fit over the entire range of flow rates from the menu Options/Preferences/Elements, by disabling the Splines option in the Pumps panel, but the two types of formulation cannot exist at the same time in the same network. GESTAR 2008 automatically detects the type of definition of the pump contained in the *.red file and the application opens with the


115

appropriate option. To change from one model to another, all the pumps can be deleted, and after enabling/disabling the desired type (menu Options/Preferences/Nodes), you can redefine the pump groups.

The Pump Element by default has a one-way valve (logic device) which prevents backwash. Therefore, additional one-way valves should NOT be placed downstream from the pumps, as when the pump is stopped the pump end node would be isolated.

RECOMMENDATION: In networks with direct pumping, to avoid leaving the network without a pressure reference (isolated nodes) in situations where the pumping equipment is stopped (and its internal one-way valve is closed), place a By-Pass with one-way valve between the intake point and the discharge area.

Similarly, if the circulating flow rate is higher than the maximum value allowed for the pump, i.e., if the total head in discharge is less at the output than the intake of the pump, and the pump behaves like a power sink, a Pump Overflow warning will appear. For computing the operating point of the pump in this circumstance, the same polynomic fit of the pump performance curve is extrapolated for the region of peak negative impulsion (loss of positive head).

In the case of calculations with Temporal Evolution, if a pump overflows at any time, the warning appears at that time. If the warning is ignored, the programme continues the calculation routine, and if the network is later reconfigured according to the specified scenarios, the same pump may return to normal working or may overflow again.

Clearly, this warning simply notifies the user that the network situation may be different than expected, as GESTAR understands that this state, where there is a higher head at intake than discharge, is not normal.

The most commonly found automatic single function regulating valves are implemented: pressure reducing valves, pressure sustaining valves and flow control valves.

REGULATING VALVE ELEMENT

All these valves present active regulation states when their operating conditions are produced, and states in which they are completely open and inactive when their regulatory action is not needed or ruled out by the flow conditions. GESTAR automatically detects these limit states, making the necessary checks to detect the state of the valve and, if necessary, modify their status as a regulating or passive element, depending on flow conditions.

The regulating valves are elements designed to maintain a given pressure in a node, or upstream or downstream from it. For system values to be interpreted correctly, the regulating valves between two nodes at the same level must be defined.


116

Flow Control Valves are devices which are activated when the flow passing through them exceeds a given level, set as the set value for regulation, throttling the flow of fluid as necessary to keep the flow rate under the set threshold. When the flow rate does not exceed the set value, the valve stays completely open and behaves like a passive element.

Once this tool is selected, click on the start node and the end node, and the window shown in FIGURE 5.44 will appear automatically, showing the start and end nodes of the selected valve (these can be swapped with the button next to them).

FIGURE 5.49 Valve Element.

♦ Catalogue.

• Database. Using this option, choose from the valves registered in the database (see section 12.4 VALVE DATABASES, p. 432), to find the best one for your needs. In the selection list, only the valves corresponding to the type specified in the tab above will appear. Depending on the data loaded in the Database, the Nominal Diameter (mm), Nominal Pressure, Series number and Code for each valve will be listed. These characteristics, and the price and series description for the chosen valve, will be shown in independent fields to the right of the list, and can be edited.

• Manual. If the valve you want to use is not registered in the database, you can enter it manually, enabling this option. The DN (mm) field will be enabled, where you can specify the Nominal Diameter of the valve.


117

♦ All / Manufacturer. This panel is available when selecting the valve from a database. By default the enabled option is All. If you choose the option Manufacturer you can access the drop-down field where the different manufacturers with data entered for the current valve type will appear, if there are more than one on the database. In the valve selection list (FIGURE 5.44) only valves from the chosen Manufacturer will be shown.

♦ Type of Valve Use this field to choose the type of device for modelling.

• Pressure Reducing. The regulated node is the next downstream node in the flow direction defined for the element.

• Pressure Sustaining. The regulated node is the next upstream node in the flow direction defined for the element.

• Flow limiter. The regulated node is the next downstream node in the flow direction defined for the element.

♦ Open Valve Coefficients.

• Ks (in IS: s2/m5

2QKH S ⋅=): This is the dimensional coefficient of the expression

, determining singular head losses in the valve when completely open and not regulating. Null Ks are not acceptable. To get good behaviour from these devices in a simulation, realistic values must be provided for them, as arbitrary values which are too high or low can lead to anomalies.

• Kv (in IS: m3

/s): This is the coefficient for flow with the valve completely open, in metric units. This design factor relates the difference in pressure (Δp) between valve intake and outflow with the flow rate (Q). When the valve is entered manually, if the value of Ks is unknown and we only have the Kv information supplied by the manufacturer, GESTAR will use this to calculate the value of Ks (Calculate Ks button). The computation expression is:

sp

Q∆

=)Kv(θ

where p∆ is the variation in pressure or head loss and s the relative density of water.

The expression relating both coefficients is:

2))(/(10)( θθ KvKs =

♦ Set Point Values. The value which should be set in this field, at the lower left of FIGURE 5.44, will be modified according to the type of valve.


118

• Set Point Pressure (m.c.a.). The pressure in metres to be maintained in the regulated node. This should be set for Pressure Reducing and Sustaining valves.

• Flow Limit (m3

In Pressure Reducing valves the set point pressures will be maintained as long as the pressure in the upstream node is higher than needed to reach the set point downstream. If the upstream pressure is lower than the set point pressure and the head losses associated with the valve when completely open, the regulating function cannot be carried out, and the device will be completely open, behaving like a passive singular element connecting the upstream and downstream pressure.

/s). The set point value which should be assigned to Flow control valves.

If the fluid tends to backwash, i.e., if pressure in the regulated node is higher than the node first defined as upstream, the valve will close completely, behaving like a one-way valve.

In pressure sustaining valves, when upstream pressure is higher than a value set as threshold, the sustaining valve will open completely, connecting both ends with no controlling action. Pressure sustaining valves are activated when pressure upstream from the valve falls below the set point, throttling the flow as needed to reduce it to the point where upstream pressure remains at the set point. If the fluid tends to backwash, the valve will close completely, like a one-way valve.

PRECAUTIONS FOR USING REGULATING VALVES.

When configuring some regulating valves care should be taken not to enter contradictory operating conditions, especially in branched networks. There can be two types of incompatibility:

Incompatibility in branched networks.

Special care should be taken that whatever the status of the regulating valve, all nodes are connected to points with reference pressures. Thus, for example, a Flow Control Valve at a point of a branch where all downstream emitter nodes are Known Consumption nodes will create incompatible conditions in the system solution (2.6) when the sum of the flows in open hydrants is higher than the set point flow rate, i.e., when the valve actually begins working. Similar phenomena occur when a pressure sustaining valve begins to work which is inserted in a branched pipeline with only known consumption nodes downstream. GESTAR will warn of incompatibilities, marking with a red circle nodes isolated from reference pressures by valve actions. However, in order to calculate the real state of the network in such conditions, efficient techniques have been researched and implemented which reproduce the real behaviour of flow control valves and pressure sustaining valves. These operate by throttling the flow and reducing pressure downstream in the branch where they are inserted, until the pressure regulators on some of the hydrants (the least favourable ones) no longer have enough pressure, becoming completely open and supplying a flow to the plot dependent on pressure and definitely less than when the pressure is adequate.


119

Thus, if the regulating valve is located on a branch, the downstream emitters should be modelled as Regulating Hydrant Nodes (see p. 85 for the definition of Regulating Hydrant Nodes). GESTAR will detect the Regulating Hydrant Nodes which act like emitter nodes and will automatically configure the boundary conditions needed for finding the real distribution of flow in the branches when the regulating valves are working.

Incompatibilities and instability in combinations of valves.

Finally, different types of valve can be combined, as long as their physical compatibility is respected. For example, it is obvious that two pressure reducing valves cannot share the same downstream node with different set points. Therefore these combinations should be implemented with great caution, in order to avoid impractical boundary conditions or unstable behaviour.

The Free Element enables designs, fitting and the obtaining of control parameters for optimising a network without the need for trial and error procedures. When this Element is defined between two given Nodes in the network the flow rate and difference in total head of the ends is obtained, and used by GESTAR to determine the hydraulic resistance needed for the stretch, if this turns out to be passive (∆H and Q of the same sign), or the operating point of the discharge element which will need to be located in the stretch, if the Element is active (∆H and Q of different signs).

FREE ELEMENT

FIGURE 5.50 Free element:

Depending on the parameter to be set, whether Diameter, Length or Roughness (absolute), the unknown variable is selected in the window and the others will be specified in the other fields displayed. By default the hydraulic resistance coefficient is


120

determined K

HQS =∆

2. In the case of an active element (pump) the list of results

will set the operating point, ignoring the other options.

IMPORTANT: The Roughness value used in the definition or determining of variables in the Free Element is always absolute roughness (expressed in metres), whatever the expression of head losses used for simulating the network, and consequently, whatever the roughness coefficient used in defining the Pipe elements.

When the Free element is an Inverse analysis tool adding a new unknown to the system, new data will have to be added as a boundary condition of the problem, i.e., for each Free element defined, a Double Condition Node must be included (see p. 90).

This tool makes it possible to adjust the diameter or roughness common to a group of pipes or Free Pipe Set. The initially unknown value of each set, which must be adjusted, becomes a new unknown variable in the system.

FREE PIPE SETS

For each free pipe set, the network must contain a Double condition node (see p, 90) for the system of equations (2.6) to be soluble.

when this tool is activated, a window will appear (FIGURE 5.46) where you can configure one or two of the types of sets mentioned (Unknown Diameter and Unknown Roughness). Start by selecting the Pipes in the list of identifiers which you want to form part of a Free Pipe Set, then click the buttons Find Diameter or Find Roughness to transfer the identifiers from the left-hand list (Pipes) to the right hand list of Free Pipe Sets. Currently an element can be part of only one Free Pipe Set, although future versions will permit the existence of various free pipe sets of unknown diameter or unknown roughness, and an element will be able to be part of one group of each type.

To delete a pipe from a free pipe set, use the Return button, available when a pipe is selected on a list.


121

FIGURE 5.51 Free Pipe Set.

As sets are created they will be shown on the graphic map in different colours: magenta for sets fitting by roughness and yellow for sets fitting by diameter. After defining the free pipe sets and clicking accept, GESTAR will take the created sets into account. Thus, when showing identifiers, if an Element belongs to the first set of elements to be calculated with unknown diameter, its identifier will immediately become (GD-1)X where X is its former identifier, if it is in the second group it will become (GD-2)X and so on. Similarly, if the unknown variable is roughness, the identifier will be (GR-1)X.

When the user chooses to take one of the pipes belonging to a Free Pipe Set out of the set, its identifiers and colours will return to the normal types for Pipes.

5.2.2 IN-PLOT DESIGN ICONS

For in-plot design, the need to calculate by sectors means the sectors must first be defined. If you have not imported them from AutoCAD using this icon,

DRAW SECTOR

or via the menu In-plot design /Assign Sector, you can generate and assign sectors using the same method as for making an irregular selection (p. 74), i.e., defining a polygon around the components making up each sector, clicking on the map to define the vertices of the polygon. To close the polygon, if you have finished assigning the sector, click with the secondary mouse button.


122

After selecting the sector (right button on outline) use the icon

SECTOR SIZING

(or the menu In-plot Design/ Sector sizing) to access the window shown in FIGURE 6. 36.

FIGURE 5. 52 Sector sizing window

For more detail on how to use it, see 11. 4. 5 SIZING SECTORS. (Sprinkler Irrigation) p. ¡Error! Marcador no definido..

This icon opens the Optimisation Assistant for sizing primary pipes in the sprinkler irrigation network (

SIZING MAIN PIPES

FIGURE 6. 37), also accessible from the menu In-plot Design /Sizing Main Pipe. The previous steps for configuring the network and the use of the assistant are described in Chapter 11. 4. 6 SIZING THE MAIN PIPES (Sprinkler Irrigation), p. 372.


123

FIGURE 5. 53 Optimisation Assistant. Step 2: Review flow rates

This enables the Calculated Reach of the Sprinklers, with red circles showing the real reach of the water according to the data entered in the network. Click the icon

SHOW CALCULATED REACH

to view the irrigation overlap and variations from the Nominal Reach, and thus analyse its quality or weaker areas.


124

6 PROGRAMME MENUS

The GESTAR programme is managed by a series of menus, which are dealt with in this chapter. Learning and becoming familiarised with these menus and the use of the toolbar will help you get the most out of the programme. Is you will see, the available options offer a wide range of possibilities when designing and calculating, and are simple and intuitive to use.

The options for each menu may appear enabled (in black) or disabled (in grey) depending on the functions which are operating in GESTAR at the time. Some of the orders and options contained in the menus can be run using icons in the toolbar, in which case you can refer to the information given above.

The complete menu bar is shown in FIGURE 6.1:

FIGURE 6.1 Menu bar.

The options for each menu are listed below, with the keystroke combination which activates them and the page where their functions are described in detail.

New Network (CTRL + N)

FILE MENU 126

Open digitalisation...126

Open Network (CTRL + O) 128

Open Results 128

Open Alarm Report 128

Import 128

Calculate Database 128

Close Network 129

Save Network (CTRL + S)129

Save as... 129

Export 129

Join Networks 129

Insert Background 130

Modify Databases 130

Printer Options 130

Print... 130

Copy network to Clipboard 130

Configure Virtual Printer for Sizing 131

Quit 131 131


125

Undo.../Can't undo (CTRL + Z)

EDITING MENU 131

Redo.../Can't redo (CTRL + Z) 131

Cut (CTRL + X)132

Copy (CTRL + C) 132

Paste (CTRL + V) 132 132

Find (CTRL + F)

VIEW MENU 132

Scale... 132

Zoom 132

Visualisation 132

Labels 133

See Direction Arrows 135

Show Nodes (F5) 135

Show Elements (F6) 135

See values in Nodes (F7)135

See values in Elements (F8) 135

See Emitter Icons 135

136Show Numbers in Nodes and Elements (F9)

Key 135

136

Preferences

OPTIONS MENU 136

Default Values 136

Random Demand...141

Modular Consumption... 143

Open/Close Hydrants... 143

Edit Comments... 143

Network Report 144

Cost of selected Elements 145 146

Flow Rates in Line

SIZING MENU 146

Optimisation ¡Error! Marcador no definido. 148

Calculate (CTRL + E)

CALCULATIONS MENU 242

Recalculate (CTRL + R) 153

Automatic (CTRL + A) 153

Parameters... 154

Characteristics... 155

Free Pipe Sets.. 157

160

Numerical List...

RESULTS MENU 160

Results in Evolution 161

Colour Key (CTRL + L)161

161


126

Configuration...

ALARMS MENU 161

Alarm Report 162

Reservoir Levels 165

Save Critical Cases 167

Overflowing Hydrants 167

Pump Cavitation 167 167

System Curve

PUMP REGULATION MENU 167

Pump Selection 167

Probability Function of Pumped Flow Rate 168

Pump Regulation 169

Power Costs 169 170

Help

HELP MENU 178

About GESTAR 178

6.1 FILE MENU

178

The File menu is mainly oriented to the programme interface, enabling data to be loaded and saved, importing and exporting files from other programmes, printing results and quitting the programme.

Enables a network to be created using the tools and options implemented in GESTAR, so that the cursor acts as a digitiser introducing the Nodes and elements into the network. A new Map window is created containing the whole network.

New Network (CTRL + N)

The dialogue shown in FIGURE 6.2 will appear, where the user must associate a Pipes Database, newly created or already existing, with the new network.


127

FIGURE 6.2 Pipes database management.

Next, the window in FIGURE 6.3 lets the user configure the Point of Origin of the visualisation and the Maximum Coordinates for the graphic window, and the area visible at start-up. These variables can be changed later using the option View/ Scale in the menu bar (p. 132). The use of this window is described on p. 49

FIGURE 6.3 Scale.


128


Offer the possibility of using data from a points digitalisation exclusively obtained through GIS/CAD type packets, saved in an ASCII file, and working from these.

Open Digitalisation...

For more information on this option, consult section 7.3 OPENING DIGITALISATION in this manual (p.183).

For opening a network in the graphic window which was previously saved using the option Save network or Save As. Once the network is opened it can be analysed and modified with the GESTAR tools.

Open Network (CTRL + O)

Files containing networks saved in GESTAR have the extension “*.red”.

This option can be used to display the results of calculating networks saved with the Save button in the Results window (see p.

Open Results

161).

Files storing the results of GESTAR calculations have the extension “.sal”.

To print a results file, open it in a word processing programme and print from there.

Lets you open Alarm files saved from the Alarms window (see p.

Open Alarm Report

161). Alarm files have the extension *.ifa.

From AutoCAD.

Import

Enables the creation of network topology based on an AutoCAD drawing (versions from 2002 to 2008). The AutoCAD drawing should first be opened in AutoCAD, which should remain on during the transformation process so that it can be correctly captured by GESTAR.


129

This option is only accessible if there are no networks open in GESTAR.

There is a detailed analysis of this procedure in section 7.5.1 REQUIREMENTS FOR DRAWINGS TO IMPORT FROM AUTOCAD (p.192).

ACCESS database.

Lets you open networks saved in ACCESS format (extension “*.mdb”) with the option Export/ACCESS database.

For more information on this option, consult section 7.4.3 IMPORTING THE NETWORK FROM AN ACCESS DATABASE (p. 191).

Closes the network currently on the screen. If this network has not been saved, the programme will prompt you to save it.

Close Network

Files containing networks saved in GESTAR have the extension “*.red”.

Clicking this icon saves the network currently in the window with its present name and location. If the network is new, its name and location will have to be specified in the dialogue which will now appear.

Save Network (CTRL + S)

Lets you save the network with any name you specify (a useful option for creating networks with slight differences).

Save as...

AutoCAD

Export

This menu option enables the network drawing to be created in AutoCAD with the information you choose about its Nodes and Pipes. The AutoCAD programme should already be open, with a blank drawing open, where GESTAR will add the topology of the network with the variables required by the user.

For more information on this option, consult section 7.5.3 EXPORTING NETWORK TO AUTOCAD (p.202).

ACCESS database.

Lets you save networks in ACCESS format (extension *.mdb).

Detailed information on this option can be found in section 7.4.1 EXPORTING THE NETWORK TO ACCESS DATABASE (p. 187).


130

Epanet file.

Thanks to this option, GESTAR can communicate with the EPANET application, creating files for use in version 1.1e.

Exporting network data to EPANET is done by creating the corresponding “*.map” and “*.inp” files for the current network in the graphic window. This option is applicable only to networks containing only passive Elements. It cannot accept Pumps, Regulating Valves, Elements with any type of singular losses or Free Elements, and will only accept numerical identifiers for Nodes and Elements (restrictions in EPANETv1.1e). However, it will accept Junction Nodes, Known Consumption Nodes and Pressure Nodes.

This command enables a GESTAR network to be created from two already existing networks. The networks to be joined must have been previously saved. The procedure is described in detail in section

Join Networks

7.6 JOINING NETWORKS (p. 204).

Enables an image file to be used as background in the GESTAR graphic window. Accepted image types are “*.bmp”, “*.gif” and “*.jpg”.

Insert Background

When a background has been added to a network, you can use this command to remove it (Remove Background).

This command works like the Network Sizing button in the Toolbar (see p.

Network Sizing

56)

GESTAR offers the possibility of carrying out maintenance of the whole system of databases (Pipes, Drip feed pipes, Accessories, Valves, Emitters, Pumps and Electricity Prices) in the programme itself, without the need to use ACCESS.

Modify Databases

The procedure is described on p. 427

In printing, this option lets you specify the printer, paper type, feed source and paper orientation.

Printer Options

Prints the current contents of the window, If no graphic interface window is open, nothing will be printed.

Print...

First a window opens where you can specify the printer and the number of copies to be printed. Click Accept for the system to print using these parameters and those specified in the previous Printer Options.


131

To print the results of calculations, use the Print button in the Results window.

Copies the current image on the screen to the clipboard. You can then paste it in other applications.

Copy Network to Clipboard

A virtual printer is a

Configure Virtual Printer for Sizing

programme which acts like a driver for a non-existent printer, creating documents in the format “*.pdf”. When this option is selected, GESTAR opens the window in FIGURE 6.5, where you can choose from the virtual printers available on your computer to save the sizing report.

FIGURE 6.5 Configure virtual printer

When creating these documents in GESTAR with this driver, the software will print the document to a file configured by the user.

The computer will need a virtual printer, such as the one supplied with the GESTAR installer, the free CutePDFTMWriter. An internet connection is needed during installation.

This closes GESTAR, after asking if you want to save changes to the current network if applicable.

Quit

6.2 EDITING MENU

The Editing menu lets you cut, copy and paste some types of Nodes and Elements, and undo or redo some of the actions carried out in GESTAR.

This option is the same as that described in

Undo.../Can't Undo

54, for the icon .

http://es.wikipedia.org/wiki/Software�

http://es.wikipedia.org/wiki/Driver�

http://es.wikipedia.org/wiki/Impresora�

http://es.wikipedia.org/wiki/Archivo�


132


Redo.../Can't Redo

54, for the icon .


Cut (CTRL + X)

54.


Copy (CTRL + C)

54.


Paste (CTRL + V)

54.

6.3 VIEW MENU

The View menu operations affect the visualisation of objects in the Map window, and some of their attributes.

This option is the same as that described on p.

Find (CTRL + F)

54, for the icon .

This option is described on p.

Scale...

49

FIGURE 6.6 Scale.


133


Zooms In or Out on the image in 50% increments of the displayed area. When the Zoom In option is activated, the map can be moved with the scrollbar. When the displayed area is increased or reduced it retains the centre of the previous view as a fixed point.

Zoom

Selecting the Visualisation option brings up the Preferences window shown in

Visualisation

FIGURE 6.8, with a total of six tabs. This window can be opened from various menus, and sets the default options for the overall programme.

The Visualisation tab affects viewing options only.

FIGURE 6.8 Preferences/ Visualisation.

You can change the background colour and the colour-coding of the lines representing different types of Elements when not showing results, through the window brought up by clicking the text of the components (pipes, valves, pumps, free elements,


134

selection, emitter line and background). You can also change the font type and size of the texts associated with Nodes with the Nodes Font button, or of Elements with the Elements Font button (FIGURE 6.10). The thickness of lines and nodes can be chosen from three pre-set options. Finally, you can choose whether to show arrows indicating the direction of flow in the pipes depending on the result of calculating the network. (Direction arrows field).

The options changed can be saved for the next time or allowed to revert to GESTAR's default values (Configuration panel).

FIGURE 6.9 Colour.

FIGURE 6.10 Element text font.


135

This option opens the Preferences window at the Labels tab. Here we can change the prefix texts which GESTAR adds by default when creating a Node or Element in the Identifier field in the definition window (

Labels

FIGURE 6.11).

FIGURE 6.11 Preferences/ Labels window.

Activating this option for the graphic output of any simulation shows an arrow indicating the direction of flow for each element in the network.

See Direction Arrows

Shows or hides the icons of Known Consumption, Junction, Hybrid and Emitter nodes in the Map window. Other types of nodes, usually coinciding with network intake points, are always shown.

Show Nodes (F5)

Shows or hides the icons associated with elements in the map window. Even when icons are not shown, the colour coding of the different types of element means they can be identified while results are not shown.

Show Elements (F6)


See values in nodes (F7)

71, for the icon .


See Values in Elements (F8)

72, for the icon .


136

Enabling this option will add the icon

See Emitter Icons

to each Emitter Line element, to make it easier to find these elements on the screen.

When this option is enabled, when mousing over a node or element a text will appear specifying the type of node or element and its identifier. This can be used to ensure you select the right node or element, or to confirm the identifier when visualising another numerical variable.

Show Numbers in Nodes and Elements (F9)

Shows the key to the colour code for graphic output of results, for Nodes and Elements.

Key

Complete information on the output of results is on p. 207.

6.4 OPTIONS MENU

Choose Preferences from the Options menu to bring up the window in

Preferences

FIGURE 6.8 (p. 133) with six tabs. Clicking on any tab brings up a different sub-window. This multi-window lets you define the default values of the parameters which must be specified in components of the network, convergence control and precision parameters for the calculation module, and the calculation and visualisation options. Each of these sub-windows can be called up by more specific commands from the Menu bar, so their content is described in specific sub-window commands.


137

FIGURE 6.12 Preferences/ Nodes.

The Preferences sub-windows are listed next to the page documenting their content:

♦ Nodes. Sets the default values of all parameters relating to Nodes. Called specifically from the Menu: Options/ Default Values/ Nodes.

♦ Elements. Sets the default values of all parameters relating to Elements. Called specifically from the Menu: Options/ Default Values/ Elements, p.142, FIGURE 6.13.

♦ Parameters. Sets the parameters relating to convergence control, stability and precision of the network calculation driver, NETCAL. Called specifically from the Menu: Calculations/ Parameters, p.155, FIGURE 6.19.

♦ Characteristics. Determines the properties of the fluid circulating in the network and the type of formulation for calculating losses. Called specifically from the Menu: Calculations/ Characteristics, p.157, FIGURE 6.20.

♦ Labels. Shows the default prefixes on labels of Nodes and Elements. Called specifically from the Menu: View/ Labels, p.135, FIGURE 6.11.

♦ Visualisation. Sets the options for displaying the components of the graphic window. Called specifically from the Menu: View/ Visualisation, see p. 133, FIGURE 6.8.

♦ Magnitudes. Defines the values of the Unit System, and the preferred Precision for viewing results. Precision corresponds to the maximum significant figures you want to be shown, except for currency units, which are not affected by changes to this


138

field. Language value definition is inactive, and can only be accessed during installation, when the default language of Spanish can be changed to English or French.

FIGURE 6. 13 Preferences/ Magnitudes

♦ Select the unit system. You can use this drop-down to change the selected unit system (FIGURE 6. 13). By default, the Gestar unit system is selected, which is based on the International System (m, s, kg) but with certain variations in some magnitudes, where units are adapted to the irrigation environment, such as pressure (mca), continuous fictitious flow rate (l/sha), plot area (ha). The Imperial System uses the units used in much of the English-speaking world. The User System is configured exactly like the Gestar System initially, but can be changed by the user. Any other defined personalised systems will also appear.

♦ View System. Click on the View System button to see detailed information on the active Unit System. The Gestar unit system cannot be modified by users.


139

FIGURE 6. 14 View System/ GESTAR System

2. Personalised unit system. The User unit system can be changed by the user to create a personalised unit system if desired, based on the GESTAR System. After selecting the User Unit System from the drop-down menu (FIGURE 6. 13) and using the View System button, a window like that in FIGURE 6. 14 will open, with the new selected system (User) specified in the System Name section. The user can use the descriptive table of variables in the window of FIGURE 6. 14 for the User System to change the Unit assigned to each Variable (see FIGURE 6. 15).

When you use the mouse to select the section Selected Unit of the Variable you want to change, the drop-down menu in FIGURE 6. 15 will appear, where you can select another Unit from those available, or define a New Unit. To add a new unit, click the Add Unit button to activate the table at the bottom of FIGURE 6. 14, and add the symbol of the new unit in the Unit column, and the coefficient in the Conversion Factor column which will convert the new unit to the unit which appears in the Reference Unit column. Save the changes and click Accept to close the window (FIGURE 6. 14). (FIGURE 6.14).


140

FIGURE 6. 15. Detail, View System/ User

To save the changes made in the Magnitudes window (FIGURE 6. 13) choose Apply, and click Accept to close the window. We recommend going on to Close and then Open the network so it is correctly associated with the new setting.

Description of the Variables.

Every physical magnitude used in the application is associated with at least one Variable to which a Unit of Measurement is assigned. For the Magnitudes where various measurement units must be used in the GESTAR application, a new Variable must be designed for each use; this is the case for the magnitudes of Length and Flow Rate, which have the specific uses shown below.

Magnitude: Length.

Variable: Long_1. Length of pipes, pressure head, etc.

Variable: Long_2. Measurement unit assigned exclusively to Water Needs.

Magnitude: Flow rate.

Flow rate: Q_1. Unit of measurement of flow rate in pumps, pipes, etc.

Flow rate: Q_2. Unit of measurement of flow rate in sprinklers.

Flow rate: Q_3. Unit of measurement in the Characteristic Curve table and Graph H-Q of the Selected Pump in the Choosing Pump form (see FIGURE 5.48: Choosing the pump from a database).


141

Flow rate: Q_4. Unit of measurement of flow rate in drip feeds.

It should be pointed out that using Unit Systems other than the Gestar System is associated with the GESTAR file with the extension .red, including the output results. This is not the case with the different databases generated and/or used by GESTAR, which are available only in the Unit System labelled Gestar, which is the only one used to edit and modify them.

At the Configuration panel, all options modified under any of the tabs can be saved as default. Similarly, GESTAR's own default options can be restored at any time. The result of the change can be viewed (Apply button), before accepting them.

The default Values option from the Options menu facilitates the creation of network components by assigning a series of characteristic values which will appear by default when creating a new node or element. GESTAR provides default values which the user can modify in these component creation windows. There is also the option to save these user-defined values for later definitions, and the option of restoring GESTAR default values (Configuration panel in the Preferences window).

Default Values

IMPORTANT: When changing a Node from one type to another, the values appearing in the fields of the new variables to be defined do not correspond to the default values of this section, but to the values of the last node opened or created where this variable was part of the definition.

If selecting Default Values/ Nodes the dialogue in FIGURE 6.12 appears, enabling you to set the default level of Nodes, the pressure head and the maximum flow rate in newly created nodes requiring these variables.

You can enter the values you wish to set as default for Hybrid Nodes: Set Point Pressure, the value of the coefficients Ks for the hydrant or the plot, and the value of coefficient N (see Chapter 4 in the sections Known Consumption Node, p. 82and Hybrid Node, p. 85), as well as the values relating the Probability of Opening and Maximum Flow Rate (Irrigated Area, Fictitious Continual Flow Rate and Efficiency).

For Reservoir nodes the Splines field is enabled by default, permitting the volume to be determined by analytical fit of storage systems (reservoirs, tanks, dams, etc) where levels may vary due to water intake and outflow. If this option is disabled, the reservoir will act similarly to a truncated conical tank, with the fields accessible for setting default values of Slope and Section. In both cases default values for initial, maximum and minimum levels of the reservoir can be set here.

The two types of reservoir model cannot exist on the same network at the same time. Whatever option is selected under the tab in FIGURE 6.12, GESTAR


142

automatically detects the type of reservoir contained in the “*.red” file and the application opens with the appropriate option.

The selection of Default Values / Elements shows the window in FIGURE 6.13, where you can define the diameter and roughness which will appear by default when an element is created. In the Open when created field you can choose whether creating a new pipe should automatically open the window where its data are specified. In this dialogue you should also introduce default values for pumps, regulating valves, emitters and emitter lines.

With Pump elements, if the Splines field is enabled (default option), the performance curve of the pumps will be modelled by cubic spline interpolation. This method enables a smooth curve to be obtained, which goes through a series of known points, defining the behaviour of the pumps.

FIGURE 6.16 Preferences/ Elements.

If the Splines field is disabled, the formulation will be as in earlier versions, with a single parabolic fit over the entire range of flow rates. As already described for the icon , p. 110, the two types of pump model cannot exist on the same network at the same time.

In both cases, the default values of the following parameters can be modified:

♦ Intake Diameter: the diameter of the intake flange, it may be the same as the passive element before it. Used for computing the speed of the intake flange, needed in order to determine the available NPSHA.

♦ A, B and C: the coefficients of the second degree polynomial which fits (for a single parabolic fit) the pump performance curve representing the behaviour of the Element H QB ( ) thus:


143

− = = + +∆H H Q AQ BQ CB ( ) 2

When the fit is done with Splines, the values A, B and C will be used to determine three pairs of head-flow rate values, with null, maximum and minimum flow rates, corresponding to this equation, which the spline interpolation will be based on. The default values implemented by GESTAR are useful in the optimal sizing phase, in situations in which the pump head is unknown for calculating in the optimization process (see p. 234). Using the Fit button, the three parameters A, B and C can be calculated using the least squares method, based on at least three pairs of flow rate and head points.

Default set point values, i.e., set point pressure and set point limit flow rate, can be set for Regulating Valves. For emitters, the level of the outflow point, the diameter and roughness of the emitter feed conduit and for emitter lines, the diameter and roughness of the element and the distance between emitters can be set.

This enables the random setting of overall scenarios of closing and opening hydrants which are not disabled. This option is the same as that described in Chapter 4, p.

Random Demand...

60, for the icon .

The Modular Consumption option enables the multiplication of the values of the variable of maximum flow rate and demand in all known consumption and hybrid nodes in the network, by the factor specified in the dialogue (

Modular Consumption...

FIGURE 6.14) which appears when this function is selected.

FIGURE 6.17 Modular Consumption.

The option Open/Close Hydrants (

Open/Close Hydrants...

FIGURE 6.15) establishes the status of the Nodes which can be used to model hydrants (known consumption nodes and hybrid nodes) as open or closed, according to the command selected and run from the option Open (or Close) for the node identified in the field Hydrant ID. It can also warn if the hydrant entered does not exist.


144

FIGURE 6.18 Open/Close Hydrants.

The closed or open states given with this option are subject to the restrictions set by the button described on p. 76. Thus, the command given by this window will not be effective if it contradicts the state configured by Unconditional Opening/ Closing. The hydrants opened or closed by this command will be subject to the same conditions as any other hydrant in later operations (they can be sorted using the icon , opened or closed using the icon , or restricted by the icon ).

The Edit Comments option (

Edit Comments...

FIGURE 6.16) lets you modify the comments entered in the graphic window of the current network using the button (p. 74) on the toolbar. Comments can be changed, relocated, made visible, hidden or deleted.

FIGURE 6.19 Edit Comments.

All the texts entered with the Comments button appear in the bottom panel of the Comments window. to edit one, just click on it. This will bring it to the upper panel, where you can change its content (rewriting the text), the position of its origin (modifying fields X and Y) and the font (Fonts button). The Visible field lets you decide if a comment should appear in the graphic window or not. The Delete button deletes the text selected in the upper part of the Comments window.


145

Network Report

FIGURE 6.20 Network Report.

This option can be used to produce a report summarising the most relevant data of the network. The dialogue in FIGURE 6.17 will appear, with five headings grouping the information obtainable by the user. Activating the field to the left in one of them will bring up the information referring to this heading in a window. The content for each case is listed below:

♦ Consult Topography. The maximum and minimum values of the coordinates X and Y locating the Nodes, the Identifier of the corresponding Nodes, and the difference between both values in each direction. Similarly, it indicates the maximum and minimum levels, which Nodes these correspond to and the difference between both.

♦ Known consumption nodes. Total number of Nodes, maximum and minimum values (indicating the Node they correspond to), sum and average of demand parameters, irrigated area, fictitious continuous flow rate and set point pressure. If the network has been calculated, maximum and minimum pressure (with the node identifier) and total head.

♦ Hybrid Nodes. Total number of hydrants, maximum and minimum values (indicating the Node they correspond to), sum and average of demand parameters, irrigated area, fictitious continuous flow rate, efficiency and set point pressure. If the network has been calculated, maximum and minimum efficiency (with the node identifier), pressure, total head, and consumption.

♦ Pipes. Maximum, minimum (with Element identifier) and average values of length and slope. If the network has been calculated. maximum and minimum values (and Identifier of the associated Element) for flow rate, head losses and velocity.

♦ Network Ratios. Total Length of pipes, maximum flow rate per hectare, metres of pipe per hectare, accumulated flow rate at intake, design flow rate at intake, simultaneity (Q design/Q accumulated).


146

The headings selected using the fields to the right of the network will be shown in a report created by clicking the button Save Complete Report. When this button is clicked the user will set the name and location for saving the document. The format of the report can be changed according to the options defined in the window of FIGURE 6.17.

The cost will be evaluated of the pipes selected with the polygonal or rectangular selection tool, according to the installation costs registered in the Pipes database. Material diameters and pressure ratings must be configured from the same database.

Cost of Selected Elements (not available in current version

Enables the rapid evaluation of costs for adjustments, manual modifications and alternatives.

6.5 SIZING MENU

The Direct Pump Network Sectorisation tool available from the Sizing menu lets you identify hydrants with similar energy requirements, and thus can constitute a “pressure floor” or set of outlets which should be supplied simultaneously independently of other outlets when hydrants have very different energy needs. Sectorisation is done by characterising the hydrants, assigning them a head loss with a constant hydraulic slope and attending to the static pressure margins compared to the set point.

Direct Pump Network Sectorisation

FIGURE 6. 21. Direct Pump Network Sectorisation


147

The user must provide the value of the EDI (effective day of irrigation) in hours and the number of sectors (No. Sectors) in the corresponding fields (FIGURE 6. 21). These values must be defined to carry out the Sectorisation process. The user sets the number of groups or sectors according to the available irrigation time per day and the irrigation time needed for the hydrants to meet the water needs with the assigned supply. Another factor to take into account when determining the number of sectors will be the observed topology of the network. In networks with different levels, these zones will mark groups or sectors in advance. A default value is given for the Hydraulic Slope, but can be edited by the user. After filling in the relevant fields, the Sectorisation process is begun by clicking the button Group. The hydrants are characterised in an n-dimensional space, as shown in the graph in FIGURE 6. 21 after Sectorisation. This set is partitioned into as many groups as there are sectors. The hydrant will belong to the group closest to the mean. The dimensions taken for the characterisation, in the ordinate axis, are the Static Pressure Margin (MPE), and in the abscissa axis Head Loss with a constant hydraulic slope (PCpcte). Where

Equation 6-1 Static Pressure Margin

Equation 6-2 Head Loss with constant hydraulic slope

The sum of both variables (MPE and PCpcte) is the maximum pressure available at the head needed to ensure the set point pressure at the hydrant, assuming a constant hydraulic slope, independent of sizing the network. FIGURE 6. 21 shows how the hydrants are characterised for an example network after a Sectorisation. In this network one of the hydrants has a negative MPE value. This indicates that there is no need to supply pressure to this hydrant, as it reaches the set point by natural pressure, as long as the head loss does not exceed the absolute value of the negative margin. The upper table in FIGURE 6. 21 lists the hydrant characterisation values: dimensions for grouping (MPW and PCpcte), H needed (pressure needed at the head considering hydraulic slope etc), T nec (hours of irrigation needed to cover water needs) and the sector in which it was classified after processing the data and applying the grouping algorithm. To sum up, the lower table in FIGURE 6. 21 shows the number of hydrants forming part of each sector or storey, the maximum necessary irrigation time, the flow rate and the surface area of the sector, the estimated required pressure considering the constant hydraulic slop, and the hydrant determining it (critical hydrant).


148

This information is for guidance purposes, proposing groups of hydrants with similar energy needs. Other conditionants such as cumulative flow rates in branches, uneven irrigation times etc can be considered with technical supervision of the groups.

From this option the user accesses the window in

Design Flow Rate.

FIGURE 6.18, where GESTAR will assign the Design Flow Rates to pass through each of the elements making up the network in demand networks with strictly branched topology. In this dialogue you can decide whether to set these flow rates to coincide with the Accumulated flow Rates or let them be calculated according to the Clement method (see p. 230) for which one or more design criteria must be established, according to whether a percentage of Overall Guaranteed Supply is set, or if you prefer to do so Selectively.

FIGURE 6.22 Design Flow Rates

Detailed information on this option can be found in section 8.2 ON-DEMAND DESIGN FLOW RATES, p. 230.

GESTAR uses this tool to facilitate the sizing of strictly branched networks, i.e., a network without meshes with a single intake point (with a known or unknown total head). From this option you can access the wizard for optimising diameters for this type of network, the use of which is described in section

Optimisation

8.3 ENERGY COST CALCULATION


149

In networks created with a pump element at intake, power consumption is computed in a simplified form, supposing a flat system curve (constant pump head, Hd, equal to the design pressure for the design flow rate at intake) and that the efficiency of the total pumping station is an estimated value, also constant (Weighted Efficiency), ηδ, obtaining a simplified version of Equation 3-1 computing the Simplified Power Consumption (CESkwh).

p

d

p

dkwh

VHgdtqHgdtq

qqHgCESη

ρη

ρη

ρ ⋅⋅⋅=⋅

⋅⋅=

⋅⋅⋅= ∫∫

T

0

T

0 )()(

V is the volume to be elevated during the campaign, which with the weighted efficiency of the pumping station and the volume to be pumped, are the data the user must enter, as Hd is the object of calculation of the optimization process.



p


=η

ρ


PkWhVgH

PkWhVPkWhVPkWhVgH

CESp

dppllllvv

p

d

ηρ

ηρ

⋅⋅⋅

=++⋅⋅

⋅=

36001000)(

36001000€



VPkWhVPkWhVPkWhV


)(

and in the overall case, where the consumption price is structured in NP time periods, with the price of each period PkWhi and pumped volume Vi in the respective period


150

V

PkWhVPkWh

NP

iii∑

=

⋅= 1


)IkWh


+⋅=




incAnualreaci

NP

1ibasei

p


⋅⋅= ∑

= 10036001000€ ηρ

Where:



10021cos171

2 −+=




1001)1001(

IanTIanK

T

incAnual−+


Power


Term.


151


p

ddkW

QHgPNN

ηρ

⋅⋅⋅⋅⋅

=1000


As it is not always necessary to sign up for the maximum power needed, kWPNN , for all the time bands, this expense is calculated as the sum of the annual cost of the kW contracted for each period according to the electricity price rate used.


Price for Power Supply ( basePkW ) which is the cost in € per month per kW in a given period of reference, and then indicate the Surcharge on the price per kW (or discount with a negative sign) as a percentage of the Base Price for Power Supply corresponding


)100

1( ibasei

IkWPkWPkW +⋅=




incAnualreaci

NP

ibase

i

p


⋅⋅⋅⋅

= ∑=

12)100

1(1001000 1

€ ηρ

where





152



)100

1(100

11

1i

NP

ibase

iNP

IkWPkW

RNP

PkW +⋅⋅= ∑=


153

Optimising on-demand networks+

-

GESTAR facilitates the sizing of strictly branched networks, i.e., a network without meshes with a single intake point (with a known or unknown total head) which is operated on demand. From this option you can access the wizard for optimising diameters for this type of network, the use of which is described in section 8. 4 OPTIMISING ON-DEMAND NETWORKS. p. 258.

GESTAR facilitates the sizing of strictly branched networks, i.e., a network without meshes with a single intake point (with a known or unknown total head) which operates by scheduled rotation. From this option you can access the wizard for optimising diameters for this type of network, the use of which is described in section 8. 7 OPTIMISING ROTATIONAL NETWORKS, p. 283.

Optimising turn-based networks

CALCULATIONS MENU

The Calculation Menu contains the options for running the previously configured simulation and controlling the convergence of the numerical solution. It is also used to access windows controlling the characteristics of the fluid circulating in the network as incompressible, and the formulation of head losses in the conduits you want to use, which must agree with the type of roughness introduced in the elements.

This option is described in the description of the Calculate button

Calculate (CTRL + E)

in the toolbar, p. 66.

Once a simple scenario is calculated using the button

Recalculate (CTRL + R)

, if the option Recalculate is chosen from the calculations menu, a new calculation will be made of the scenario, and the iterative system solution process (2.6) launches with the results of the earlier calculation. If a Temporal Evolution is carried out with the Recalculate option selected, for each step in time after the first one, the calculations for the solution of the new step in time will begin using the results of the previous period. The same will happen in calculating consecutive scenarios in the Multiple scenarios option.

Using this option enables reducing the number of iterations needed for reaching convergence in the solution of each scenario, as if the starting values are close to the solution of the current scenario, the convergence of the Newton -Raphson algorithm is much higher. However, it should be noted that for this supposed advantage to materialise, the new scenario calculated based on an earlier scenario must be relatively similar to the one used as starting values. That is, the new scenario should not contain radical changes, as otherwise the previous solution could be as far from the current scenario as an arbitrary solution.


154

Thus, the Recalculate option has a series of restrictions on its use, so that if these are not complied with, previous results will be ignored and the process will behave as if the Calculate option were enabled.

Thus, for example, two scenarios will be relatively close to each other if changes made in the network do not affect the topology, such as opening or closing hydrants, changing levels, altering the length of Elements, etc. If Nodes or Elements are introduced or deleted, the variables corresponding to the new components will not be defined at all. so that the Recalculate option will not be operational until the network has been calculated.

The only valid operations, for Nodes and for Elements, accepting the Recalculate option are:

♦ Nodes:

• Changing the X and Y coordinates. • Changing the level. • Changing the maximum flow rate. • Changing the instantaneous demand. • Changing the pressure head.

♦ Elements:

• Changing the length. • Changing the diameter. • Changing the roughness parameter.

The operations, apart from changes in the topology, which will not be valid (in prevention of different behaviour of the network before and after changes) include:

♦ Nodes:

• Changing the node type.

♦ Elements:

• Adding or deleting sectioning valves.

• Modifying, adding or deleting one-way valves, throttle control valves, accessories and singular losses.

Any change in regulating valves, discharge pumps and free elements.

As can be seen, in Temporal Evolutions, changes from one moment to another are essentially due to changes in the opening of hydrants, so that the Recalculate option is always suitable.

If the Automatic option is chosen on the Calculate menu, each time changes are made to the Map of the scenario of an already calculated network (changes which do

Automatic (CTRL + A)


155

not affect its topology and which are subject to the same restrictions as the Recalculate option) a Recalculation of the scenario will be run as soon as the changes are accepted in the corresponding window, without the need to activate the command Calculate (icon

).

Similarly, in the Calculation/ Automatic option the simulation will reload automatically each time that

• a hydrant is opened or closed with the Open/Close Hydrants tool .

• a random scenario is created with the Run button in the Random Scenario window .

This option in the Calculation Menu gives a high degree of interactivity between programme and user, with reloaded results every time a change is formulated.

Enables modification of a series of parameters controlling the launch of the iterative system resolution process (2.6), convergence and precision in the results. The dialogue appearing when this option is selected is shown in

Parameters...

FIGURE 6.19.

FIGURE 6.23 Preferences/ Parameters.

This block of parameters is configured by default. To change them, if necessary, it is advisable to have a certain degree of experience in the use of the programme, and in calculating networks, in order to modify them safely and make efficient use of them. The parameters are:


156

♦ Maximum number of iterations. Advisable: 20. In Inverse Analysis: 50.

♦ Type of dynamic error (in flow rates or heads). Advisable in heads.

♦ Dynamic error. Advisable 0.01 m

♦ Dimensionless residue tolerance. Advisable: 0.0001 (in Inverse analysis 0.001)

♦ Type of launch. Advisable in velocity, with pump median point.

♦ Launch value. 1 m/s

♦ Relaxation coefficient. Advisable 0.5

♦ Coefficient of condition (KCL). Advisable equal to or less than 0.1

Appendix VI (p. 475) gives a more detailed description of each of these parameters. We recommend careful reading of this after first exploring the programme.

IMPORTANT: Among the above values, the Coefficient of Condition KCL is the most important to ensure that GESTAR works correctly. Its values are in the range (0.1). As KCL increases the number of equations solved decreases, and so the calculation time of each iteration is reduced, but the number of iterations may increase due to greater instability in the iterative process. On the other hand, if KCL is reduced, the number of equations solved increases, as does the time for each iteration, but the system is more stable and converges in fewer iterations.

A recommended value for most occasions for KCL is 0.1. As long as the maximum number of iterations established for convergence is exceeded (normally, fewer than 20) we recommend reducing KCL by another order of magnitude. If necessary KCL can be reduced to a null value in order to ensure maximum convergence.

This window also lets you create an iteration file showing the intermediate results of the calculation process. This information is only of use to GESTAR programmers in the purge and fit stages of the NETCAL calculation driver, and is not useful for most users.

SIZING OPTIONS.

From this panel you can vary the default value of the slope in bifurcations and the slope of the 1st path. These can be modified using the diameter optimisation wizard in STEP 3: INTAKE DATA. Consult section 8.3, page 242, for a better understanding of these parameters and how they affect the calculation for obtaining optimum sizing.

Click the configure button to select a virtual printer for the reports generated after sizing. You can call up this tool from the menu: File/ Configure virtual printer for sizing (see p. 131 for detailed information).


157

This option sets the physical properties of the circulating fluid, which are taken to be constant throughout the network, and the type of formulation to be used for continual head losses. It also permits inclusion of automatic calculation of losses at bifurcations.

Characteristics...

Each part of the window corresponding to this action in the Programmes menu (FIGURE 6.20) is explained below.

FIGURE 6.24 Preferences/ Characteristics.

♦ Fluid Data.

A dialogue will appear (FIGURE 6.20) where the block called Fluid Data defines, for the circulating fluid at operating temperatures, the values of viscosity of the fluid, µ, its density, ρ, and vapour pressure Pv

Below we have the Fluid Database button. This brings up a window (

in International System units. The default values correspond to water at 15 ºC.

FIGURE 6.21) where we can see the types of fluid already entered in order to enter their data directly in the corresponding fields in the Preferences/ Characteristics window. In this window there is a database for: introducing new fluids, Add button, delete fluids from the database, Delete button, after selecting it in the table, and entering the data for the desired fluid in the main window, Accept button.


158

FIGURE 6.25 Fluid database.

♦ Formulation for Calculating Losses.

In the block to the right, Formulation for calculating losses, we can choose one of the formulations offered for evaluating continuous head losses in Pipes.

VERY IMPORTANT: Depending on the selected formulation, the parameter is established which must be entered in the Roughness Factor field defined in Pipes, p. 95, and Emitters, p. 91.

BE CONSISTENT WHEN DEFINING THE FORMULATION OF CONTINUOUS HEAD LOSSES AND THE SPECIFICATION OF ROUGHNESS FACTORS FOR ALL ELEMENTS!!

The Reynolds number of the conduit is evaluated as Re VD= ρ µ . Next, the formulations offered and the significance of the Roughness Factor corresponding to each case are identified.

♦ Laminar. Uses the Darcy-Weisbach formulation for calculating losses but with λ = 64 Re (the Roughness Factor will have an arbitrary non-null value).

♦ Hazen-Williams. The Roughness Factor corresponds to the values of CH , given in tables; this formulation is valid only for water. Head loss is calculated using the expression:

( )V C D H LH= 0 355 0 63 0 54, , ,∆ equivalent to ∆H L Q

C DH

=10 376 1 85

1 85 4 86

, ,

, ,

♦ Laminar + Hazen-Williams. The head loss is calculated as with Hazen-Williams except if 2000<Re , where the calculations are carried out as for Laminar.


159

♦ Blasius. The Roughness Factor will have a value of C =

( )20 13164

751

4

4 7g,

ρ µ

=

for water. The element is modelled as a smooth tube. The formula used is:

( ) ( )V g D H L=

20 13164

14

4 75 7 4 7

,ρ µ ∆

equivalent to ∆H L C Q

D=

1 75

4 75

,

,

♦ Manning. The Roughness Factor will take the values of n given in tables. Used in rough turbulent conditions. Calculations use:

( )VD H L

n=

0 4 2 3 1 2, ∆ equivalent to

∆H L n QD

=10 3 2 2

5,33

,

♦ Darcy-Weisbach, λ according to Colebrook. The roughness Factor will be absolute roughness in metres. The following formula is used:

( )∆H Re LD

Vg

= λ ε,2

2 with λ ε

λ− = − +

1 2 23 71

2 51log,

,Re , e=rug/D

♦ Laminar + Darcy-Weisbach, λ according to Colebrook. Calculations are done as in Darcy-Weisbach, λ according to Colebrook except if Re < 2000 , in which case the procedure is the same as Laminar.

♦ Other Monomics. User-defined. (Not available on this version).

In the Roughness Factor field for Pipe Elements, p. 95, and Emitters, p. 91, a text appears to remind you of the selected formula and the type of factor to be entered.

IMPORTANT: If the head loss formulation is changed, the Roughness Factors introduced in the already created Pipe and Emitter elements will not be translated to the new formulation, but will remain as initially created. Be careful not to mix different definitions of the Roughness Factor for different Elements.

If you want to change the formulation, first find the approximate equivalences between the old and new values and use the Menu option to export the network to an ACCESS database: File/ Export/ ACCESS Database. Next, open the ACCESS file containing the exported network and in the table corresponding to Pipes (and/or Emitters) modify the field associated with the Roughness Factor for all the affected Elements, with the help of the database search and replace tools if necessary.

♦ Losses at bifurcations

In a pipe network, intersections or bifurcations produce singular losses which, although their values are not very high individually, should be taken into account for their cumulative effect. The commonest intersections and bifurcations consist of three


160

branches which join or split at a point. Junctions of four or more pipes are much less common, as multiple junctions are usually made by successive T-joints. When the field Losses at bifurcations is enabled, GESTAR will add singular head losses in the adjacent stretches at all the Nodes where three conduits meet, following the methodology and expressions in BLEVINS, R. D. (1984): “Applied Fluid Dynamics Handbook”. P. 91. The intersections in this reference are taken as orthogonal, with various combinations of intersection and division of waters depending on the direction of circulation of the fluid in the three conduits. Depending on the flow direction in the conduits, GESTAR detects the appropriate combination and calculates the correct expressions. In any case, we recommend checking the differences found in the results when including or excluding losses at bifurcations by enabling or disabling the field Losses at bifurcations.

If an intersection or bifurcation is special (multiple conduits, very different angles of insertion, etc.), and you have the information needed to characterise it, it can always be regarded as a Singular Loss and incorporated in the adjoining Pipe Elements. In this case, take into account that if the Node is a triple junction, the singular losses entered by the user will be superimposed on the losses incorporated by GESTAR when the field Losses at bifurcations is activated. Normally this effect would be irrelevant (and also favour safety) but if you want to eliminate this error, simply as a new conduit to the junction, with an arbitrary length and diameter and closed at the other end, so that GESTAR does not incorporate singular losses to the stretches of the Node (as this is a Node joining four Pipes), and includes only those added by the user.

If singular losses are included manually in the conduits adjacent to the Nodes (whether by joining Pipes or by changing the diameter), take into account the possibility of the flow direction being different from those supposed, or changing during the simulation, which would alter the value of the coefficients introduced.

In Appendix VI (p. 471) losses at bifurcations are considered in detail.

♦ Singular Loss

Permits the definition of equivalent lengths for incorporating singular head losses in a simplified, distributed manner. When this option is selected, the field to the right becomes accessible, where the equivalent length can be determined as a percentage to add to the length defined in each stretch.

This option is the same as that described for the icon

Free Pipe Sets

. (see p. 120).

6.6 RESULTS MENU

The Results Menu offers options for consulting the results of the various types of simulations which can be run in GESTAR, Simple Scenarios, Random Scenarios and Temporal Evolution, and the possibility of configuring the range of colour coding.


161

The Numerical List option in the results menu enables the results obtained in the current scenario to be shown in the Map window in numerical form, after calculation.

Numerical List...

The window which appears when the Numerical List option is selected is seen in FIGURE 5.15, and explained in detail in a specific chapter (p. 178). The values shown for Nodes and Elements correspond to the current scenario.

When the simulation is of a simple scenario, the values shown are the only ones available. In this case the option corresponds to the action of the icon on the GESTAR toolbar.

When a critical scenario from a Random Scenario is shown in the Map window (p. 60) the results of the Numerical List correspond to this critical case. In this case the option corresponds to the action of the icon in the Critical Cases window.

When a scenario associated with a temporal step in a Temporal Evolution is shown in the Map window (p. 64) the results of the Numerical List correspond to this time period. In this case the option corresponds to the action of the icon in the Temporal Evolution cursor window.

If the network has been analysed using Multiple scenarios and there are valid scenarios (which have not set off any configured alarms), the numerical list shows the maximum, mean or minimum values, as selected in the Colour Key window.

The option is active when a Temporal Evolution simulation has concluded. It shows the Temporal Evolution Table appearing in

Results in Evolution

FIGURE 5.17 and thus equivalent to the action of the icon after a temporal simulation.

When this option is selected a window will appear where you can specify the colours to represent the different variables in the graphic output, both for Nodes and for elements, and the numerical intervals for each colour and the way they are assigned, manually or automatically.

Colour Key (CTRL + L)

More information on this option can be found under the description of the button on the toolbar (p. 66).

6.7 ALARMS MENU

This menu establishes the creation of alarms during any of the types of simulation which can be run in GESTAR. An alarm is a notification to the user during the simulation of the scenario, in the form of a graphic marker and/or text, warning that some variable is below or above the maximum and minimum values which were


162

previously specified. These alarms facilitate the detection and analysis of dysfunctions in the network caused by excess demand, speed, unsuitable consumption, leaks, etc., facilitating a preliminary filtering of problematic configurations which can then be studied in detail. These functions will be extremely useful when designing and managing networks.

DESIGN

Establishing a sequence of automatically concatenated tests with different random consumption conditions, with constant or variable simultaneity percentages, only the cases which breach the restrictions set will be extracted and stored for later analysis, detecting the points which systematically or occasionally become critical.

Also, running simulations which establish anomalous states in the network, due to stopped pumps, excessive consumption, breakages, improper uses, blockages, etc, enables the most sensitive variables and areas to be immediately located and generates a library of dysfunctional states, synthesised by certain values which are characteristic of the hydraulic variables at suitable monitoring points or sections.

MANAGEMENT

When a simulation is run of an irrigation programme, the configuration of suitable alarms for speed, pressure, deposit level, etc, facilitates the verification of the correct behaviour of the network throughout the process, immediately warning of any dysfunctions found.

With this option a window will appear to establish the range of acceptable values for a series of control variables, so that when calculating simple scenarios or with the Multiple Scenarios option (p.

Configuration......

60) or Temporal Evolution (p. 64) the variables which are out of range in the scenario will be detected and pointed out to the user. The Alarms window (FIGURE 6.22) not only establishes the margins of validity of the variables, but can also store them, retrieve them and set some other options.

In relation to the definition of variables suitable for monitoring and the demarcation of their respective ranges, the present version allows for the configuring of generic alarms for:

Module of speed in Conduits.

Module for Head loss per unit of length in Conduits.

Module of speed in intake flange in Pumps.

Module of velocity in Regulating Valves.

Module of velocity in Drip Elements.

Pressure head in Consumption nodes and Hybrid nodes.


163

Pressure head in Junction nodes.

Module of consumption in Consumption nodes and Hybrid nodes.

To configure one of the above alarms introduce (FIGURE 6.22) the minimum and maximum values of the variable in question and activate the appropriate field. The interval between the minimum and maximum values is the correct operating margin. If the field is not enabled, although the correct operating margin may be defined, it will not be taken into account for generating alarms.

FIGURE 6.26 Alarm Configuration window

There are also additional options and buttons in the Alarms window.

♦ Special alarms.

♦ Reservoir Levels

This option makes sense only in analysis with Temporal Evolution (p. 64), as it sets an alarm to go off during a Temporal Evolution if the levels in Reservoir Nodes exceed the maximum or fall below minimum levels, values defined for each Reservoir in its definition window (p. 79).


164

♦ Pump Cavitation

Activate this option when you want to be notified of cavitation events in the installed pumps. This situation always occurs when the value of the NPSH available in the intake flange of each pump is less than required by the performance curve supplied by the manufacturer. Logically, the NPSHR curve should be defined for the monitored pump.

The term N.P.S.H. means Net Positive Suction Head, and is the value of absolute pressure p1

IMPORTANT: When cavitation exists, the pump functions are degraded and the hydraulic and power results obtained with performance curves introduced with the definition of the pump are not valid.

/rg at the entrance to the pump.

♦ Pressure below set point in Hydrants.

When this option is enabled the Map window will mark with a yellow circle the Nodes in a situation which:

If the hydrant is simulated by a consumption Node (with the regulation pressure option specified and activated), network pressure falls below the set point pressure.

If the hydrant was simulated with a Hybrid node, the pressure falls below the hydrant's minimum operating pressure (equal to or less than the set point).

For both cases, in the field to the right of the option a Tolerance margin can be assigned to reduce the number of false alarms, so that there will be alarms only in Nodes where pressure is lower than the value obtained by subtracting the Tolerance margin from the Set point pressure

♦ Negative pressure.

If this option is enabled, after the simulation Known Consumption nodes and Hybrid nodes where negative pressure values are obtained will be marked, whether or not the regulation pressure option was enabled.

♦ Installed Power.

Useful during the Temporal Evolution analysis. If activated, this launches a warning for scenarios where the power requirements in the pump groups are higher than the estimated installed power supply (see p. ¡Error! Marcador no definido.).

♦ Save Critical Scenarios.


165

This option can only be activated after previously going to the Multiple scenarios window (p. 273) as it will store for later consultation and analysis the scenarios created by the Multiple scenarios tool which triggered an alarm.

♦ Save Report in database.

Useful only for analysing Temporal Evolution. When this option is selected, the user must specify the name and route of the document, which will be saved in “*.mdb” format.

Useful for communicating with third party applications, and the format for creating alarms in TELEGESTAR. Storing alarms in database format enables information processing operations, such as statistical analysis, calculating penalties for excess power consumption, etc. If local (as in Pressure lower than set point) or global level alarms have been defined with values such that all scenarios are critical, this will directly obtain a complete description of the results obtained in all the simulated scenarios.

♦ Button

Alarm configurations can be saved automatically in independent files for later retrieval. Alarm files by default have the extension “.mdb”. The Save button will bring up a dialogue to set the name and directory where the file will be created.

♦ Button

To retrieve a previously created alarm file, click this button to bring up a dialogue which will enable you to show and see files with the extension “.mdb”.

♦ See Report button

The See Report button enlarges the window to give access to the list (FIGURE 6.23) constituting the report which identifies the origin of the alarms produced in the simulation. This report has a maximum size of 1612 lines of text. The complete report can be saved as a text file with the Save Report button (which appears in this enlarged window) in order to conserve and analyse the list of alarms in plain text. These files will have the extension “*.ifa” or “.txt”.

The window in

Alarm Report

FIGURE 6.23 appears and offers the content of the alarm report (up to a maximum of 1612 lines of text).


166

FIGURE 6.27 Alarms/ Report

The Alarms Report offers different information depending on the type of calculation which has taken place:

♦ Simple Calculation. This lists every Node or Element which has triggered an alarm, accompanied by the value of the triggering variable.

♦ Temporal Evolution. The information for the scenario in which each alarm was triggered will be added.

♦ Multiple Scenarios. It also lists a Breakdown of alarms by components, showing the number of times that each Node or Element in the network has breached the restrictions set by the alarms. It also reports on the 5 consumption Nodes with the lowest minimum pressures among the runs which have not triggered alarms. This information can be found in the Alarms Report even if these alarms were not activated by the Save Critical Cases field in the Alarms Window. The information is complemented by a series of statistical data of use depending on the active alarms (average breaches in each Random Scenario, percentage of open Nodes which do not reach the set point pressure, etc.).


167

The information in the Alarms Report can be saved to file using the Save Alarm Report button. When this is clicked, a dialogue lets you create the Alarms File (extension “*.ifa”) or a plain text file (extension “*.txt”).

The information in this report can easily be loaded to an *.xls file for processing and analysis. The list of all the values of use in Multiple Scenarios can be obtained by defining alarms with a range or value which is systematically or selectively breached.

Activates or deactivates the corresponding field in the Alarm Configuration window (p.

Reservoir Levels

162)


Save Critical Scenarios.

162)


Pump Cavitation

162)


Pressure below set point in Hydrants.

162)


Negative pressure.

162)

6.8 PUMP REGULATION MENU

Detailed information in chapter EVALUATION OF POWER COSTS AND OPTIMIZATION OF REGULATIONS IN PUMPING STATIONS, p. 302.

Using this option the user can calculate the network system curve, i.e., the relationship between the pressure head supplied at intake, which must be enough for all the operating nodes, and the flow rate demanded for each of the possible scenarios. For this, random combinations of operating scenarios are created with percentages from 0 to 100% of the possible demand, and in each scenario the head required at intake to supply the least favourable node is determined.

System Curve

From this menu the window in FIGURE 6.24 appears.


168

FIGURE 6.28 System demand curve

The purpose of this menu is to select the pumps which will make up the pumping station to be installed. There are two procedures for this. The first permits the calculation of a theoretical pump, taking into account a series of suppositions, and the second permits the selection of a pump from a database using the design point. The dialogue in

Pump Selection

FIGURE 6.25 is used.

FIGURE 6.29 Pump Selection.

Using the first panel, GESTAR permits a theoretical pump to be calculated taking into account a series of suppositions. We advise the use of the theoretical model when commercial catalogues are not available, or when sizing the network without


169

having yet specified the type of pump group to be installed. This strategy enables approximate values to be obtained for the characteristics which the commercial pump which will eventually be implemented must have to meet the design and operational demands of the system. To obtain the coefficients defining the curve of the pumps to be estimated, some initial data are needed, described in detail in section 10.6.2 STATION REGULATION (p. 317).

The second panel gives access to the Pump Database, and using the tools to search for pumps by nominal operating point, or directly selecting the type, model and runner, common to the configuration of Pump Elements (see p. 110), the performance curves of the selected pump are obtained in tabular form.

This menu permits the calculation of demand distribution in the pipes at the intake of an irrigation network with branched topology, by combining the probability density functions of flow rates, which may be normal, monthly, dependent on the daily water needs of the month, on the topological configuration, on hydrant capacity, and on plots and crops, leading to the supposed probability density function for network demand. The user accesses the window in

Probability Density Function of Pumped Flow Rate

FIGURE 6.26.

FIGURE 6.30 Probability Density Function of Flow Rate

A detailed explanation of each of the operations of this window is given in

This takes us to the window shown in

Pump Regulation

FIGURE 6.27. From here, users can set the composition of the pumping station, i.e., the implementation of the type and number


170

of pumps of fixed and variable speed, permitting a wide range of combinations and setting the system curve for the installation, introducing its coefficients manually or calculating them with GESTAR. Finally, a new EXCEL file can be obtained, showing the performance of the pumping station, including results such as the power consumption of each pump, efficiency, head supplied by the station, head demanded by the system, usable power and overall efficiency, among others.

FIGURE 6.31 Pump Regulation

For a detailed description of this function, see section 10.6.2 STATION REGULATION (p. 318).

This menu includes the steps needed to calculate in detail the annual power costs of the pumping station in question, considering all flow rates throughout the year.

Power Costs

The process consists of four stages accessed by four tabs: Network data, Pumping Station Regulation, Power data and Power Results. See information on the complete process in the specific article.


171

6.9 IN-PLOT DESIGN MENU

Based on an arbitrary plot outline, GESTAR can generate meshes of sprinklers automatically in the AutoCAD environment (circular inside and in sectors at the edges) with frameworks assigned by the user and the tertiary pipes. The generated meshes of coverage are made up of lines formed by the pipes connecting the sprinklers.

Sprinkler distribution

With this command, GESTAR lets you generate coverage in the AutoCAD environment, consisting of the mesh of sprinklers and its tertiary pipes. Window b opens, shown in FIGURE 6. 32, requiring a set of data for configuring coverage.

FIGURE 6. 32 Sprinkler distribution window

The mode of use is shown in detail in Chapter 11.4.1 GENERATING COVERAGE (Sprinkler irrigation), p. 333.

Specific command for generating local irrigation coverage in the AutoCAD environment. Accesses the window in

Distribute emitter lines

FIGURE 6. 33.


172

FIGURE 6. 33 Drip feed line distribution window

Detailed explanation in the chapter on Drip Irrigation.

This command lets you take apart pipes (primary, secondary and tertiary) in AutoCAD to ensure the connections between them are exact and to be able to supply the whole network after importing it to GESTAR.

Sprinkler distribution cut-offs

FIGURE 6. 34 Sprinkler distribution cut-offs window


173

Detailed information on its application in Chapter 11. 4. 3 GENERATING STRETCHES AND CUT-OFFS. (Sprinkler irrigation) p 333.

For the network generated in AutoCAD to be suitable for importing to AutoCAD, the pipes must be taken apart using this command, which opens the window in

Drip distribution cut-offs

FIGURE 6. 35.

FIGURE 6. 35 Drip distribution cut-offs window

More details on its use in the chapter on Drip Irrigation.

For in-plot design, the need to calculate by sectors means the sectors must first be defined. If you did not import them, you can use this command to assign the sectors, using the same method as for an irregular selection (p.

Assign sector

74), i.e., defining a polygon around each sector, clicking on the map to define the vertices of the polygon. To close the polygon, if you have finished assigning the sector, click with the secondary mouse button.


174

After selecting the sector (right button on the outline) the command Sector sizing opens the window in

Sizing the sector

FIGURE 6. 36.


For more detail on how to use it, see 11. 4. 5 SIZING THE SECTORS (Sprinkler Irrigation) p. ¡Error! Marcador no definido..

Available in future versions of GESTAR.

Size drip sector

Option which opens the Optimisation Assistant for sizing the main or primary pipes in the sprinkler network (

Sizing the main pipe

FIGURE 6. 37). The previous steps for configuring the network and the use of the assistant are described in Chapter 11. 4. 6 SIZING THE MAIN PIPES (Sprinkler Irrigation), p. 372.


175


This option in the menu In-plot design shows the user a statistical representation of the uniformity of the flow rates calculated for the open sprinklers.

Uniformity coefficient

FIGURE 6. 38. Uniformity Coefficient results.

The user must open the sprinklers he wants to analyse (usually included in an irrigation Turn, see p. ¡Error! Marcador no definido. et seq.) and select Uniformity Coefficient to open a window like FIGURE 6. 38, with the Uniformity Coefficient value resulting from applying Equation 6-3 calculated.

Equation 6-3 Uniformity Coefficient

Where M is the mean value of the calculated flow rates emitted by the open sprinklers, n is the total number of sprinklers and S|d| is the sum of the absolute values of the deviations from the mean of the flow rate calculated in the sprinkler.

1 100d

CUM n

∑= −

⋅


176

This command can activate and deactivate the Nominal reach circles. When active, GESTAR shows the nominal reach of the sprinklers which is the theoretical trajectory of the water from the sprinklers, creating a blue circle around each sprinkler, indicating the reach of the water when the sprinklers receive the exact pressure required.

Show nominal reach

This activates the Calculated Reach of the Sprinklers, with red circles showing the real reach of the water according to the data entered in the network. This tool lets you see the irrigation overlap and variations from the Nominal Reach, and thus analyse its quality or weaker areas.

Show calculated reach

COST OF SECTIONS

Measurements

FIGURE 6. 39. Measurements window.

This command opens the same window as the icon . Its use is described on p. 60.


177

MATERIALS LIST.

FIGURE 6. 40. Measurements. Materials List.

This command opens a Summary of Measurements; for Materials it includes, for each Pressure Rating and Diameter the sum of Lengths present in the network and their Cost, a function of the Unit Price previously defined in the database (see p. ¡Error! Marcador no definido.).

SPRINKLERS SUMMARY

This command returns a list of Sprinklers by Sector, and their cost, if the unit price has been defined in the database (see p. ¡Error! Marcador no definido.).

DIRECTION OF CIRCULATION

Tools

This command reviews and changes, if necessary, the assigned Start Node and End Node in the Pipe Elements (see p. 95) making up the network, so their definition matches the direction the water flows in. This ensures that the network is configured correctly for applying the optimum sizing algorithms. For this tool to work properly, we recommend placing each sprinkler over a one-way valve (p. ¡Error! Marcador no definido.).


178

DIFFERENT LEVELS IN THE SECTOR

After selecting a sector by clicking the secondary mouse button anywhere on its outline, you can use the Different Levels in Sector tool, from the In-Plot Design menu. This opens a window like that in FIGURE 6. 41, with the result of the difference in levels between the highest and lowest sprinklers in the sector.

FIGURE 6. 41. Different Levels in the Sector

This information will be very useful for determining the acceptable pressure margins when sizing the sector (see p. ¡Error! Marcador no definido.).

CONVERT SECTOR ENTRANCE TO REDUCING VALVE

At the end of the process of sizing the sectors, the intake at the entrance to the sector modelled as a Regulated Pressure Node can be converted to a Reducing Valve (p. 115) directly with this Tool. The only previous requirement is to select the sector where you want the conversion (secondary mouse button on sector outline).

6.10 HELP MENU

The Help menu gives access to the GESTAR help file (Gestar.hlp) and a set of general information on the programme.

This menu gives access to the help file GESTAR.HLP, with all the information on operating GESTAR. The file can also be accessed by pressing F1 on your keyboard at any time while using GESTAR.

Help

This section gives information on the bodies and people who work on the programme.

About GESTAR


179

7 EDITING THE MODEL

7.1 INTRODUCTION

This chapter describes the different methods available in GESTAR for creating and editing networks, and the possibilities of interfacing with other applications. It also describes the modes for visualisation and documentation of the results of calculations.

Meanwhile, regardless of the tools used to build a hydraulic model for sizing and/or simulation, precise information must first be gathered to specify the three types of data comprising the scenario: constructive topology of the network, determinate boundary conditions, and configuration of specific control devices. (see Appendix I, p. 441). Each of these blocks requires the following information to be specified, according to the type of functionality used. A table is given below summarising these requirements, according to the function to be carried out, from the following:

♦ a SIZING process (case 1),

♦ a HYDRAULIC ANALYSIS (case 2),

♦ a POWER ANALYSIS when the system curve is unknown (case 3).

When the corresponding field is darker in colour, this means this that implementation of this requirement is obligatory; if lighter in colour, its implementation is optional.


180

1 2 3

Node levels

Hydrant capacity

Hydrant consumption

Set point pressures

Pipe length

Pipe diameter and roughness

Power levels at intake

Hydraulic characteristics of pumping equipment

Special parts installed

Hydraulic characteristics and overall behaviour of plots

Agricultural data

Electricity prices

Table 7-1 Summary of Requirements

There are various ways of defining a network in the GESTAR graphic window:

♦ Graphic environment. The user defines the Nodes and Elements of a network interactively in the Map window based on the tools available for this in GESTAR. (p. 181). This native methodology is self-sufficient for creating any scenario, and can be used as a complement to any of the alternatives mentioned below. To use this procedure as a basis for work, use the menu File/ New network if the network dos

not exist (also available via the first button on the toolbar ) or the menu File/ Open network if the file has already been created earlier (also available via the

second button on the toolbar )


181

♦ Open Digitalisation. Menu option File/ Open Digitalization, imports the points coordinates of a digitalization, saved as an ASCII file, configured as Junction Nodes, based on which the user will construct the rest of the network interactively using the tools available for this in GESTAR (p.183).

♦ Importing a database from ACCESS. Menu option File/ Import/ ACCESS database, offering the possibility of importing network information from an ACCESS database (p.191).

♦ Data entry from AUTOCAD. Offers the possibility of creating (and exporting) the topology of the network with the application AutoCAD (p. 192).

♦ Join Networks Menu option File / Join networks, permitting the creation of a new network based on two existing ones (p. 204).

GESTAR also permits the exporting of data and results efficiently via various procedures:

♦ Exporting the network to an ACCESS database. Menu option File/ Export/ ACCESS database enables the exporting of information from any network to an ACCESS database (p. 187).

♦ Exporting data and results to AUTOCAD. Creates a plan with the network topology and desired information in *.dwg format (p. 202).

♦ Graphic environment. The graphic environment is used to implement tools which interactively facilitate the study and analysis of data and results obtained via the different calculation protocols, which can be saved to files of different formats (p. 207).

7.2 CREATION USING THE GRAPHIC ENVIRONMENT

Element is taken to mean any hydraulic component which a fluid can run through. The Elements available in GESTAR are: Pipe, Pump, Regulating Valve, Free Element and Emitter Line.

A Node is defined as the intersection of two or more Elements, or the free end of an Element. Junction Node, Reservoir, Dam, Pressure Node, Known Consumption Node, Hybrid Node, Double Condition Node, Free Node and Emitter Node are the different types of Node available in GESTAR.

To begin the graphic creation of a network, activate the command New Network

(available in the File menu or the first button on the toolbar, ). Using the dialogue represented in FIGURE 7.1, the user must associate a newly created or existing Pipes Database with the new network (see section 12.1 PIPE DATABASES, p. 428).


182

FIGURE 7.1 Pipes database management.

A dialogue will appear (FIGURE 7.2) enabling the user to configure the origin of the coordinates and the exact maximum coordinates for the window, and the initially visible area. These variables can be changed later using the option View/ Scale in the menu toolbar.

This window is described on p. 49

FIGURE 7.2 Scale.

To place a Node in the graphic window, click with the main mouse button on the corresponding toolbar button, and then on the point in the window where you want to place the Node. To place an element, the start and end nodes for the element must already be created; select the corresponding button on the toolbar and click on the start


183

and end nodes in turn. If the same node is the start and end of the element, or if an element already exists between those nodes, the creation of the new element will be cancelled.

After placement, a dialogue will appear (except in Junction Nodes and Pipe elements, which by default do not show a dialogue) where you can specify the exact position of the node or element, and the different parameters needed for their correct definition. Double-clicking on any element or node already in position brings up their dialogue panel, where you can change any of their parameters. Clicking on the secondary button over a node or element brings up a window with the known variables and parameters.

7.3 OPENING DIGITALISATION

The command Open Digitalisation... appears in the File menu.

If this option is selected, the dialogue shown in FIGURE 7.3 will appear, specifying a type of ASCII file (with extension “*.dig” or “*.txt”) containing the coordinates and identifiers of individual points. This type of files will have been created previously using any resource, either manually, with the help of tools for digitalising points on plans (on paper or electronically), or using spreadsheets and/or databases.

The points contained in the file will be automatically imported into GESTAR as Junction Nodes on a new map window. When creating the ASCII file, include all the points which are relevant to the definition of the network, which you want to place precisely (according to the supplied coordinates) and automatically, and not just the points which are strictly Junction Nodes according to the hydraulic schema of the network. Thus, as well as Junction Nodes (bifurcations, changes in diameter, control points, etc) it is advisable to specify as points in the file, hydrants, important vertices, the position of important accessories and valves, intake points, the location of discharges, etc.

Next, use GESTAR tools to change Node types, add new Nodes and lay out the Elements which make up the network, taking the cloud of created points as a reference.

The process begins with the enabling of the menu option File/ Open Digitalisation... which brings up the selection window in FIGURE 7.3 where the file containing the digitalization can be selected (by default this shows files with the extension *.dig). The file must be ASCII with the data associated with each Node registered in a line of text, and with any type of number format (decimal, whole or scientific). The data defining each point are separated by commas. Use the point (dot) to express decimals.


184

FIGURE 7.3 Open digitalisation.

Once the opening of a file containing the points of a digitalization is accepted, a window appears like that in FIGURE 7.4. This shows the content of the selected file below, so that the user can check or remember the recorded data structure. Above, various options are selected, some of which may need to be reconfigured in order to specify in GESTAR the structure of the imported digitalization.

FIGURE 7.4 Recording the structure of the ASCII file data.

The order of the data associated with a node on each line of the *.map file must be strictly as indicated in the panel Digitalization data in FIGURE 7.4, optionally


185

including the Identifier of the node and Level Z. If these values are supplied in the ASCII file, the corresponding fields should be enabled. The X and Y coordinates are the only obligatory data which must be assigned to each and every node.

If the fields Node Identifier and/or Level Z are enabled, all the lines in the file should include these data. If the information is not available for any of them (e.g., level), fill in the space with an arbitrary value, but never leave a field blank.

The Node identifier will be an alphanumerical sequence, different for each node. When importing an ASCII file, if the Node Identifier is not included, GESTAR automatically assigns NUX identification, where X is a number assigned to each Node correlatively, as it appears in the ASCII file.

If the ASCII file does not specify levels for the Nodes, GESTAR will assign level zero to them as they are created.

After clicking Accept in the window in FIGURE 7.4, a similar window will open to the one seen via the menu View/ Scale (p. 132) where the maximum dimensions associated by default to X and Y can be modified, as well as the point of origin of the coordinates relative to the user’s point of view. If the network Nodes are very far from the origin of the coordinates (e.g., U.T.M. coordinates), it is advisable to select Move to origin in order to set a new origin of coordinates near the closest node to the initial origin.

When all these requirements are complete, click Accept in the window FIGURE 7.4 and the Scale window (FIGURE 7.2) described above will appear. It is advisable to increase the values Xmax and Ymax of the maximum size of the Map in order to ensure the visualization of the furthest Nodes, as sometimes these can be hidden by the scroll bars. After clicking the Accept button in the last window, the definitive map window will appear with the cloud of entered Nodes and their identifiers. Check that they have all been extracted correctly, and proceed to build the network with the help of the imported structure of Junction Nodes.

7.4 COMMUNICATION WITH ACCESS DATABASE

Via the option File/ Import/ ACCESS database, GESTAR offers the possibility of importing all the relative data of a scenario (construction topology, boundary conditions and configuration of devices) from an ACCESS file (extension “*.mdb”) containing the necessary set of tables, described in detail in Appendix VII, p. 479.

GESTAR can also export (menu File/ Export/ ACCESS database) the complete data of a scenario to an ACCESS type database, with the same structure as in the case of importing, where if desired, the values of the network parameters can be inspected, changed and analysed.

Thus, to facilitate the construction of a complete or partial model of the system, using the resources for importing/exporting to databases, a seed *.mdb file can be used, to be filled in completely using external resources, or which can be found partly completed in the GESTAR graphic environment. In the first case, this seed or template


186

file is obtained by exporting, with the option File/ Export/ ACCESS database, a simple or prototype network, containing all the types of Nodes and Elements desired, and then editing and inspecting the corresponding tables in the ACCESS file thus created, and modifying and/or extending them as needed to adapt them to the complete case. In the second case, the topology of the network and part of the constructive information of the model already existing in the GESTAR model are exported to an ACCESS database, and the corresponding tables are edited to complete the necessary information.

In these communications operations GESTAR uses the version format for MS ACCESS 97. There are problems of incompatibility with ACCESS 2007 and later versions, as with the default format for ACCESS 2007, databases in the ACCESS 97 format cannot be displayed or created. GESTAR can still interact (import/export) with ACCESS 97 databases even where ACCESS 2007 is installed. If you do not want to replace ACCESS 2007 on your PC with an earlier version, you must supply databases for GESTAR 2008 in ACCESS 97 format, creating them on another PC with pre-ACCESS 2007 versions, and view the databases generated by GESTAR in ACCESS 97 format in the same way.

FIGURE 7.5 Possibilities of communication using Databases

The tools for Import / Export to databases are useful, among other applications, for:

♦ Bidirectional transfer of topologies and constructive data from GIS and CAD environments which permit, directly or indirectly, extracting information in the required structure and format.


187

♦ Bidirectional communication and information migration between GESTAR and alternative third party engineering applications (sizing, analysis, etc) or complementary applications (transitories, measurements, earth moving, etc.).

♦ Exporting and formatting in tables the data and measurements listed for a specific system and design, in order to document the data and results, draw up definitive measurements, etc.

♦ Carrying out searches, setting filters, making overall or selective changes, using conditioning criteria and all the power of organization, search and manipulation of information (exported from GESTAR) provided by ACCESS, later incorporating these modifications automatically in the network model using the import operation (for example, searching for and selectively modifying a type of pipe, replacing one capacity with another, an Id for another, etc.).

♦ Facilitating the immediate integration of the various calculation modules in GESTAR into REMOTE MONITORING and REMOTE MANAGEMENT systems with the TELEGESTAR Toolkit, with libraries which take in and put out topological and constructive data on the network, from the Import /Export database, where the REMOTE MONITORING and REMOTE MANAGEMENT systems dump information on the status of the network and read the results.

7.4.1 EXPORTING THE NETWORK TO ACCESS DATABASE

An ACCESS database can be created which contains all the information relating to the scenario shown on the Map (in the current version, excepting the Free Pipe Sets and Emitter Lines) using the command File/ Export/ ACCESS database. This database includes both set parameters for the network construction and boundary conditions, and values of the variables calculated for Nodes and Elements.

The storage of a network in database format has a fundamental characteristic which differentiates it from directly saving the network in “.red” format (using the option File/ Save Network). In the database, the components of the network are grouped by types in different tables, in a format which can be edited and modified by the user, while a “*.red” file saves the network data in binary format for later use in the GESTAR programme.

7.4.2 EDITING THE ACCESS DATABASE

Open the saved .mdb file using the Microsoft ACCESS data management programme.

GESTAR uses the ACCESS 97 format, and when *.mdb are edited or changed they should always be saved in ACCESS 97 format. If working with ACCESS 2000 or later, when you try to enter the database a message will appear asking if you want to open the database as read only or convert it to a more recent format. You should always


188

choose Open database, as if you convert it, GESTAR will not recognise the format later. This way, you can use versions later than ACCESS 97 (except for the incompatible ACCESS 2007 and later versions) to edit and modify the values of the fields, but not modify the structure of the database (this should never be done).

Alternatively, you can open the database with conversion to different formats, but before closing it again you should save it in ACCESS 97 format, although this is not as recommendable as the previous option.

IMPORTANT: Opening the database in read-only mode does not permit changing the structure of the database, as this would change the structure and/or format of the fields, making it impossible to import into GESTAR; but it does allow the local or overall modification and manipulation of the numerical and alphanumerical values of the fields (including copying and pasting tabulated values), and adding or deleting entries in all the tables.

A database created in GESTAR looks like the one in FIGURE 7.6 when opened in ACCESS.

FIGURE 7.6 GESTAR network as database (v 2008).

The present version contains a total of 19 tables with all the network information visible in the graphic window at the time of creation, including, if applicable, the values of the hydraulic variables of the calculation, if this has been done. The number of tables will be increased in future versions to include new components and functions. For a homogeneous structure in the databases with information on any GESTAR network, the 19 current tables are created in the database regardless of whether all types of Nodes and Elements, and their respective configuration information, exist. For example, even if there are no Reservoir Nodes in the network, a Reservoirs table will be created, with all its fields, and a single blank entry.


189

The list of tables is given below, with the page in this manual describing the information relating to the fields associated with each type of node or element.

♦ Accessories. Information on the accessories associated with the Pipe Elements (p. 95) or the stretches associated with Emitter Nodes (p. 91).

♦ Reservoirs. Information on Reservoir Nodes (p. 79) referring to location and head (x, and level), levels (Max. Level, Min. Level, Initial Level, Present Level) and if modelling assimilates the reservoir to a truncated conical tank, Section and Slope (see Menu: Options/ Default Values/ Nodes, p. 141).

♦ Reservoir Splines. Information on Reservoir Nodes referring to the H/V table defining the Volume curve (p. 79).

♦ Pumps. General information on Pump Elements (p. 110), and in the case of choosing a single parabolic fit for the whole range of flow rates, on the parameters referring to this formulation (see Menu: Options/Preferences/Elements, p. 141).

♦ Pump Splines. Information on Pump Elements referring to the definition table for fitting using Splines (see p. 110 and 141).

♦ Pipes. General information on Pipe Elements (p. 95). This table is usually the largest, as Pipes are the basic element of any irrigation network. As GESTAR can take Pipes data from a complete database, the list of Pipes in the network is very large and useful.

♦ Known Consumption. Information on Known Consumption nodes (p. 82).

♦ Polytube Detail. Information on the intermediate vertices of Pipe Elements.

♦ Double condition. Information on Double condition Nodes (p. 90).

♦ Elesk. Information on Free Elements (p. 119).

♦ Dams. Information on Dam Nodes (p. 78).

♦ Emitters. Information on Emitter Nodes (p. 91).

♦ Hydrants. Information on Hybrid Nodes (p. 85).

♦ Junction nodes. Information on Junction Nodes (p. 78).

♦ Losses. List of all the singular losses existing in the network. In one of the fields of this table losses are related with the stretches where they occur: Pipe Elements (p. 95) or the stretches associated with Emitter Nodes (p. 91).

♦ Known Pressure. Information on Pressure Nodes (p. 81).

♦ Sectors. Topographical information on each of the vertices of the outline defining the Sectors (see p. ¡Error! Marcador no definido.).


190

♦ No condition. Information on Free Nodes (p. 91).

♦ Sub-elements. (Detailed explanation in upcoming versions).

♦ Subnodes. (Detailed explanation in upcoming versions).

♦ Turns. Information on the number of hours assigned to each turn (H) and the value of the flow rate (Q) (p. ¡Error! Marcador no definido.).

♦ Valves. Information on Valve Elements (p. 115).

♦ Vis. Information on the parameters for visualising the network: map size and visible part. These parameters can be modified in GESTAR via the option View/ Scale (p. 132).

Appendix VII (p. 479) describes briefly the fields of each of the tables.

Any information in the database can be modified in ACCESS, so that if the information is re-entered in GESTAR using the option File/ Import/ ACCESS database, the changes will be taken into account.

It is important to remember that if a network has been calculated before exporting to ACCESS (i.e., it has been simulated hydraulically, obtaining results for pressure, head losses, speed, flow rate, etc.), the results of the calculations will also be saved in the database. These data are saved in the appropriate table of Nodes or Elements for each case; thus for example, the value for the flow rate through a given conduit will be stored in the Pipes table, in the Flow Rate field and the row corresponding to the stretch in question.

When the user edits the database of a collective network, pending sizing, exported from GESTAR, to load the characteristics of the hydrants it supplies in this ACCESS database, a set of fields must be filled in and some recommendations should be taken into account. Thus, the values of the fields listed below must be assigned. This way the user can be sure that the importation (the process is explained below) of the database from ACCESS will be successful and consistent, as all the necessary parameters will be complete. The remaining data can be filled in optionally, automatically assigning default values from GESTAR if they should be empty.

RECOMMENDATIONS FOR EDITING NETWORK DATABASES FOR NETWORKS IN A SIZING PROCESS

FIELDS TO FILL IN OBLIGATORILY IN THE PIPES TABLE

Id (unique alphanumerical identification)

Start Node

End Node

Length (m)


191

FIELDS TO FILL IN OBLIGATORILY IN THE KNOWN CONSUMPTION TABLE


X (coordinate X)

Y (coordinate Y)

Level (m)

Capacity (m3/s)

FIELDS TO FILL IN OBLIGATORILY IN THE JUNCTION NODE TABLE


X (coordinate X)

Y (coordinate Y)

Level (m)

7.4.3 IMPORTING THE NETWORK FROM AN ACCESS DATABASE

As already mentioned, the command File/ Import/ ACCESS database makes it possible to retrieve a network in database format in order to view it as usual in GESTAR.

The information in this database will have been entered in its entirety by transferring the data contained in another type of graph or calculation application based on a seed file used with a template, or may come from previously updating a database in a GESTAR network.

All the information and/or modifications to the topology, construction and boundary conditions in ACCESS will be taken into account when importing the network.

While the database may also include the values of the variables (consumption, total head, flow rate, speed, head loss) from a previous exportation, corresponding to the last hydraulic calculation before exporting the network, these results are not incorporated from ACCESS in the importation process.

Importation can begin without a network being open. Selecting the menu option File/ Import/ ACCESS database, a dialogue opens which will permit the specification of the *.mdb file. During the importation process, when an item of information cannot be validated, GESTAR will launch a warning message indicating the table and field of the error. Similarly, according to the criteria of the above section, the Degree of Freedom


192

and Probability fields will be checked for consistency. Click the Enter key repeatedly to accept the consistency warnings launched by GESTAR.

To finish the importation successfully, associate a pipes database with the new network. The network graph created with the information from the database will now be visible, but the *.red file has not yet been generated. It is advisable to create this file immediately, using the menu option File/ Save Network, or the icon on the toolbar.

7.5 COMMUNICATION WITH AUTOCAD

A network of conduits defined using the computer assisted design programme AutoCAD, with 2D and 3D lines and polylines, and blocks (which will represent a specific type of Node, usually hydrants), can be converted into an equivalent model in GESTAR, using the import/export tool between AutoCAD and GESTAR.

Files to import from AutoCAD must have their proprietary format, with the extension *.dwg. In turn, AutoCAD facilitates editing files from other platforms using the format *.dxf, permitting the importation of this type of archive into GESTAR. Similarly, normally the GIS (Geographic Information System) environment allows its coverage to be exported to .dxf format, which can then be converted to .*dwg for migration to GESTAR.

In the opposite direction, a network configured in GESTAR can be transferred to *.dwg format, generating a plan where up to four items of constructive or hydraulic information are identified for each Pipe (e.g., Material, Pressure Rating, Nominal Diameter and Length) and the configuration data for hydrants (a maximum of four can be selected, such as capacity, size, set point pressure and level).

To ensure these communications tools are operational, an AutoCAD version between 2002 and 2008, inclusive, should be used; we recommend the use of the version AutoCAD 2005.

In principle, the application functions correctly with AutoCAD MAP versions equivalent to the versions of AutoCAD from 2002 to 2008. As we have not worked intensively with AutoCAD MAP, in some cases results might be unpredictable.

7.5.1 REQUIREMENTS FOR DRAWINGS TO IMPORT FROM AUTOCAD

For the import process to be successful, the drawing in *.dwg format must comply with a precise syntax, given below.

In the directory where GESTAR is installed, in the Files Worked Example folder, an example is given (Worked_example OK transfer to GESTAR.dwg) to serve as a guideline. In the same folder, you will find the file Worked_example KO transfer to GESTAR.dwg as an example of a wrong configuration of the network, with problems in the connection between programmes, although the drawing looks the same.


193

If dealing with old plans where the rules and criteria given below were not followed, it might be more efficient to redraw the Nodes and Pipes on the existing plan, respecting the conditions given below.

PIPES

OBLIGATORY REQUIREMENTS

♦ Each stretch of conduit where there can be a change in diameter, material or pressure rating must be represented by a single geometric entity of the type line, polyline (2D) or 3D polyline. The sequence for creating the entity will be taken into account in defining the direction of the fluid in the pipe.

♦ The lines, polylines (2D) or 3D polylines representing pipes are in layers reserved exclusively for representing Pipes. Any other linear object present in these layers will be interpreted as a Pipe.

♦ The geometric entities used for defining pipes cannot form part of a block (an AutoCAD tool for drawing and managing serial objects). If this should happen, before importing, use the AutoCAD menu option Modify /Ungroup to undo the block reference in the components.

NODES

♦ Each singular point or component to import as an equivalent to any GESTAR node type will be represented in AutoCAD as a Block. Each block in AutoCAD which you want to associate with a GESTAR type node (with special or generic characteristics) will have a set name (arbitrary, but the same for Nodes of the same type) and a point of insertion which will coincide with the start or end point of a line, polyline (2D) or 3D polyline representing a stretch of pipe. These Blocks associated with Nodes in GESTAR can be placed in any layer.

♦ If the types of Blocks in AutoCAD representing a type of Node are created defining an associated Identifying Attribute, this identifier will be automatically assigned as Id to the equivalent node imported to GESTAR. It makes no difference if the Identifying Attribute is visible or not.


194

FIGURE 7.7 Illustrative example Transformation of blocks with attribute to nodes

CONNECTIVITY OF PIPES AND NODES

♦ The connections of the graph must be rigorously ensured for the network made up of lines, polylines (2D) or 3D polylines, representing stretches of pipes, and blocks, representing Nodes. That is, there must be connectivity among all the lines, 2D polylines and 3D polylines, representing stretches of pipes, (or at the points of insertion of the Blocks representing Nodes) at the start and end points. All the ends must be connected to other pipes (e.g., bifurcations) or blocks (e.g., blocks representing hydrants). The ends without Node connection (e.g., intake points, dead ends, etc) will later be treated as limits of the network, with the user assigning a default type of node to them in the transformation configuration window.


195

IMPORTANT: The intermediate vertices of a polyline are NOT valid start or end points, nor points of insertion in blocks representing nodes.

♦ To make it easier to ensure connectivity, we recommend that while laying out the network in AutoCAD the necessary reference modes are set using the menu Tools/ Drawing parameters/ Object Snap so that points of insertion of the hydrant Block or end of polyline (Junction or significant node) coincide with the start or end of the new polyline.

RECOMMENDATIONS

♦ In branched networks with a single intake point, we recommend that the order of creation of the pipes is according to the direction of circulation of flow.

♦ It is advisable to define, for all the points representing hydrants, a type of Block with Identifying attribute which after the transformation, will become the Identifier of the Node in GESTAR. In the directory where GESTAR is installed, in the Files Worked Example folder, an example is given (Worked_example OK transfer to GESTAR.dwg) containing the Block HYDRANT_ID to serve as a reference, which can be copied to new plans.

♦ We recommend starting or ending the drawing of a stretch at the high and low points of a layout, in order to permit changes in pressure rating, location of suckers, drains, etc. It is also recommendable to end the drawing of a stretch at intermediate points of the layout, where you would like the GESTAR model to later provide a pressure control point.


196

♦ In the case that the plan to import will be used for optimum sizing of branched networks, it is recommended to draw stretches of LESS than 300m long, to enable the GESTAR sizing module to later make a telescopic fit of diameters at this intermediate point.

♦ When the plan to be imported will be used for optimum sizing of the pipes in branched networks, you should NOT draw pipes or stretches less than 20 metres long. This is the case for small branches connecting hydrants to the collective network. It is preferable to locate the insertion points of the Blocks representing hydrants in the network stretches themselves.

♦ The bifurcations and other Junction Nodes or singular points (intakes, etc.) do not need to be defined specifically, as during the transformation stage, these Nodes will be free ends, and will be transformed into Junction Nodes automatically when imported, with an Id assigned by GESTAR. Thus, bifurcations and intermediate junction nodes in pipes will be directly configured, and the special nodes which are not Junction Nodes can later, in the GESTAR environment, become the right type of node.

♦ Create the topology of the networks of pipes without going into the local details of construction, such as swan necks, connections of pipes to hydrants, connection layouts at pumping stations, etc, which are not relevant in sizing.

♦ We advise the use of UTM coordinates for geo-reference of the model.

7.5.2 IMPORTING FROM AUTOCAD

After launching GESTAR, with no networks open, go to the window in FIGURE 7.8 via the icon or the menu option File/ Import/ From AutoCAD.


197

FIGURE 7.8 Import Network from AutoCAD.

The drawing to be associated should already be opened in *.dwg format. The drawing should be in the active window of AutoCAD during importing, so that GESTAR captures it correctly. Also, during the creation of the network in AutoCAD the instructions given in section 7.5.1 REQUIREMENTS FOR DRAWINGS TO IMPORT FROM AUTOCAD should have been followed. These conditions being met, the following sequence (FIGURE 7.9) should be respected during the import process to ensure success.

FIGURE 7. 9 Steps for using the Import from AutoCAD window

NODES Transform

ELEMENTS Transform

Create network


198

For the process of importing from AutoCAD during in-plot network design, see the chapter on IN-PLOT DESIGN detailing how to use the tool for this type of design.

The first step is to capture the entities of the AutoCAD drawing which will become Nodes generated from the drawing in *.dwg format. The different types of nodes (Known Consumption, Junction, etc.) will be created by successive transformations, taking into account the parameters listed below. Thus, the user can sequence the transformations of the different types of Nodes modifying these variables, gradually accumulating the results of the transformations to create the new network.

TRANSFORM NODES

♦ Objects to Transform. GESTAR permits the transformation to nodes of AutoCAD objects of the Block and Point types. When the user opens the window in FIGURE 7.8, GESTAR will have captured the collection of Points and Blocks from the open and active AutoCAD drawing, presenting it as a drop-down list in the first panel. The type of objects to be transformed into Nodes can be selected, as many as desired, from this list. The geometric property of elevation of each object to be transformed will be captured and associated with the Node created in GESTAR.

♦ Work Layers. The application lets you restrict the layers which will form part of the selection process of the objects to be transformed. This second panel can be used to select one or more layers, and if none is selected (default option), it will not filter by layer, the equivalent of selecting all the layers.

♦ Node type. The type of node to be created must be selected from the drop down list of all the node types defined in GESTAR (Junction, Reservoir, Dam, Pressure, Consumption, Hybrid, Free and Double Condition Nodes). The search area created in AutoCAD is used to find the types of blocks selected in the window for importing from GESTAR, which are transformed into the type of node chosen from the drop-down menu. When the object to transform has an associated Identifying Attribute, this will be come the identifier Id of the GESTAR network. Otherwise, a default identifier will be assigned to it, formed by the suffix defined for the type of Node (UN; EMB, BAL, PRG, CC, HID, SCN, DCN) followed by a number.

♦ Default Variables. Next, the dialogue shows a series of variables which can be defined by the user, and which GESTAR will assign to the created Nodes if these are Consumption or Hybrid types. The initial data to be assigned be default to all Nodes of the type described are: capacity (m3

7.4

/s), surface area (ha), set point pressure (m.c.a.) and diameter of the hydrant (inches). If there is an adequate distinction between types of Blocks and/or layers, according to the characteristics of the Node, successive selective transformations can be run with different default values of these variables, so that the default data correspond to the real values. However, if the network to import is among the first design stages and the hydrant data are subject to change, it is more recommendable to create Nodes of the same type with a single type of Block, with arbitrary default values, and to update these values later with the database import tool (see section COMMUNICATION WITH ACCESS DATABASE p. 185).


199

♦ Tolerance. When an AutoCAD object is transformed into a Node in a GESTAR network, the programme checks that the Node was not created in an earlier transformation. The check consists of comparing the X, Y, and Z coordinates of the existing nodes with the object being transformed.

FIGURE 7.10 Checking the X, Y and Z coordinate in nodes

If the difference between the three coordinates is below the Tolerance value marked in the dialogue (FIGURE 7.8), the application will consider it to be the same object, and will not create a new Node, but keep the already created node. This resource is useful for facilitating the connectivity of stretches and blocks of the network graph, so that small drawing errors are automatically recovered from, where using the option Object Snap Mode (see p. 195) was not enough to connect the objects in points of insertion and ends of lines and polylines. Thus, all the ends and points of insertion found within tolerance will be considered as the same Node. This parameter must be set correctly, as a very small value would not have the connecting effect sought, and one that is too high would join nodes which should be separate. We recommend that tolerance be lower than the length of the shortest pipe in the plan. Special care must be taken in the small stretches connecting the network to the hydrants; where these are very short, we recommend skipping these stretches and inserting the block representing the hydrant directly on the network conduit. If the end nodes of an element are joined into one by the tolerance criteria, this element will not be created.

♦ Check Labels. If this option is selected during the transformation process the programme will check if the Identifier assigned by GESTAR is being used by another node. This function notably increases the runtime of the transformation, so that disabling it will speed up the importing process.

♦ Transform. Once the parameters explained above have been set, click the Transform button to start the process of accessing AutoCAD and identifying the Elements to be transformed. Automatically, the open, active AutoCAD drawing will appear, where the user will be asked to Select Objects to Transform framing them in a designation


200

window. Designate them using rectangular selection, beginning by clicking with the main mouse button on the top left of the area to be transformed, and dragging the rectangle which appears until the area to transform is covered. When the rectangle covers the desired area, click again with the main mouse button to finish reading AutoCAD objects and begin the conversion process. When returning to the window in FIGURE 7.8, information can be obtained on the progress of the process via the cursor to the bottom right. When the message Transformation of Elements Finished appears, a new event can be run, necessary for generating the network (a new transformation of Nodes or Elements).

FIGURE 7.11 Selection of objects to transform from AutoCAD

♦ Objects to Transform. The application permits the transformation of AutoCAD objects of the types Line, Polyline (2D) and 3D Polyline into Pipe Elements

TRANSFORM ELEMENTS

. Using the ELEMENTS panel in the dialogue in FIGURE 7.8, the user can select various types of object to transform simultaneously. In the case of transforming entities of the 3D Polyline type, the levels of the end vertices will be automatically captured. When there is a transformed node on a vertex, the elevation associated with the node in transformation will have precedence over the level of the 3D Polyline. The lengths imported for Pipes correspond with those of the Lines, Polylines (2D) and 3D Polylines.


201

♦ Work Layers. Similarly to the Nodes, GESTAR lets you filter the layers which you want to form part of the transformation. One or various layers can be selected, which will be taken into account by the programme, and if none is selected (as set by default), no type of filter by layer will be taken into account. It is very important that in the selected layers, all the types of line existing in the selected rectangle really correspond to conduits, and not to any other layout element.

♦ Transform Free Ends into. On this drop-down list, where all the types of node defined in GESTAR appear (Junction, Reservoir, Dam, Pressure, Consumption, Hybrid, Free and Double Condition nodes), select the type of node to be created at the ends of the transformed lines or polylines when the ends do not coincide with the points of insertion of Blocks or Points already transformed through the Nodes Panel.

♦ Default Variables. Two variables can be set for GESTAR to assign to the created pipes, as shown in FIGURE 7.8, the values of Internal diameter (mm) and Roughness.

♦ Transform. The process of transforming Lines, Polylines (2D) and 3D Polylines into Pipe Elements is launched and handled similarly to the transformation of Nodes. When the message Transformation of Elements Finished is shown, a new event can be run, necessary for generating the network (a new transformation of Nodes or Elements). Bear in mind that a new transformation of Elements which have already been transformed will duplicate the Pipes in the imported network.

The tolerance value assigned in the Nodes Panel also controls the transformation of Pipes. Thus, if the difference in coordinates of an end vertex and another Node is closer than the value set for Tolerance, GESTAR will generate a single Node in its place. We advise the user to analyse the proximity of the different hydrants and junction nodes on the AutoCAD plan before setting the tolerance value. It will also be vitally important to delineate the network correctly in AutoCAD. We recommend activating the Object Snap Mode (command REFENT), to connect stretches and objects correctly, as if they exceed the Tolerance value they can create duplicate Nodes in the network. In the case of plans combining Lines, Polylines, 3D Polylines and Blocks, end vertices may appear which coincide in floor but not in level, so that the objects will not be connected. Given that the tolerance criteria are checked in all three coordinates, this will produce independent superimposed nodes in the GESTAR model, with different levels, and stretches isolated in the network.

After the transformation sequence is finished, the Create Network button (

CREATE NETWORK

FIGURE 7.8) must be pressed for the import process to finalise. The programme will ask for the name and location for saving the new network in *.red format.

Once the network is created it will not open automatically. To open the network, check the result of the transformation and continue working as normal, and the programme will ask to associate the created network with a Pipes Database, after which the network can be edited as normal in GESTAR.


202

7.5.3 EXPORTING NETWORK TO AUTOCAD

When GESTAR finds an open network, using the icon , a new dialogue appears (FIGURE 7.13). This tool enables the network drawing to be created in AutoCAD with the information you choose about its Nodes and Pipes. The AutoCAD programme should already be open, with a blank drawing open, where GESTAR will add the topology of the network with the variables required by the user.

The network is drawn in AutoCAD using a series of predefined symbols (FIGURE 7.12) to represent the different types of Nodes and Elements. They can be found in the installation folder, in the Symbols folder. Each icon corresponds to a *.dwg file, enabling it to be edited in AutoCAD and modified as desired, taking into account that the origin of coordinates (0, 0, 0) will be the reference point for inserting the symbols in the new plan exported from GESTAR.

FIGURE 7.12 Representation of nodes and elements in AutoCAD

FIGURE 7.13 Export network from AutoCAD


203

In the new network plan in *.dwg format, nodes will be represented as Block entities with the appearance shown in

NODES

FIGURE 7.12, and their elevation contained in the field Level in GESTAR. A layer will be created for each type of Node. Next to the node will appear a table with four cells (see FIGURE 7.14). These new drawing entities will be associated with the InfoNodes layer. For each Node two lines will be created which form the limits of the quadrant and text objects (as many as there are active fields) which will contain all the information associated with the Node chosen by the user through the window in FIGURE 7.13. Mark the corresponding checkbox for the quadrants where you want information to appear, and use the drop-down list to select the chosen variable for the quadrant from the following data: Label, Level, Diameter, Capacity, Demand, Irrigated Area, Probability, Set point pressure and Comments. By default the values of Label, Capacity, Irrigated Area and Set point pressure will appear in quadrants 1, 2, 3 and 4 respectively.

FIGURE 7.14 Appearance of Node information in *.dwg drawing

The following parameters referring to appearance can also be modified:

♦ Text style. The user can choose the style to be associated with text objects among those defined in the open AutoCAD drawing.

♦ Text height. This value usually needs adjusting.

♦ Precision. Lets you choose the numerical precision for the data which will appear (from 0 to 4 decimal points).

♦ Scale. Depending on the size of the network, a scale factor will have to be applied when drawing node icons. This scale factor appears automatically in the export window (FIGURE 7.13). However, the user can set the preferred scale value manually.

Pipes are represented in the new *.dwg drawing by 3D Polylines, whose vertices will have an elevation coinciding with the levels assigned for the Nodes. In the case of polytubes, the elevation of the intermediate vertices will be interpolated according to the length of each of the stretches.

PIPES AND EMITTER LINES


204

The information associated with the Pipes will appear slanted, aligned in the same direction as the pipes as a Text Object on a single line. Mark the corresponding checkbox (1, 2, 3, or 4) in the Pipes quadrant (FIGURE 7.13) to select the variables to export and their order. Use the drop down lists next to each one to choose from the following parameters: Identifier, Length, Diameter, Roughness, Material, Pressure rating, Flow rate, Speed, Head loss, Head loss/Length, Comments, Line flow rate, Celerity, Nominal Diameter. By default the four selected positions appear, with the following values. Identifier, Nominal diameter, Material, Pressure rating.

In a network it is normal for pipes to have quite different lengths. GESTAR implements options to improve visualization of the information:

♦ Show information in pipes based on a minimum length. Activating this option, information will appear associated with pipes over the length defined in the adjacent field.

♦ Text size proportional to pipe length. When this option is enabled, text size will vary according to the length of the pipe, up to a Maximum text size set in the corresponding field.

FIGURE 7.15 Information on elements in *.dwg drawing (text proportional to pipe length)

♦ Polytubes. If there are pipelines formed by various stretches with different orientations, you can choose between presenting the associated text centred and aligned relative to the longest stretch of the polytube, or relative to the central stretch of the polytube.

♦ Text Style The user can choose the Style to be associated with the text objects from those defined in the open AutoCAD drawing.

7.6 JOINING NETWORKS

The menu option File /Join networks lets you create a GESTAR network based on two already existing ones. The networks to be joined must have been previously saved. When the command is launched, no networks should be open. Next, specify the routes of the two network files to be joined. (FIGURE 7.16).


205

FIGURE 7.16 Specification of the routes of networks to be joined.

Both networks must coincide in the definition of the parameters referring to the fluid and the calculation in order to avoid confusion during the joining process (see Menu: Calculations/ Characteristics, p. 157). If not, the parameters assigned to the first of the two networks selected from the window in FIGURE 7.16 will be used (quadrant Route of the first Network to join). Similarly, if each of the networks should have a different Pipes database associated with it (see p. 428), the pipes database of the first of the selected networks will be assigned to the final network.

After selecting the routes of the two networks to be joined, you can determine (FIGURE 7.17) a text string (to a maximum of 5 characters) for each of the two initial networks, so that the labels of the components of the final network will be preceded by the string corresponding to their original network. Bear in mind that the maximum total length of the resulting Id is 15 characters (if this is exceeded after joining, the identifier will consist of the new prefix and the characters of the network identifier up to 15 characters, losing the rest).

The values of the origin of coordinates of the map containing the resulting network will coincide with the values X and Y of the origins of coordinates of the two networks before joining, closest to the values 0,0, thus ensuring that all the Nodes and Elements of both networks will be visible in the GESTAR graphic environment.

Also, from the same window in FIGURE 7.17, the user can modify the position of the nodes and elements of one or both networks, affecting the X and/or Y coordinates of all the components of the original network with the value, positive or negative, assigned in the fields enabled for Moving this network.


206

FIGURE 7.17 Dialogue on Text for labels

Once the route where the resulting file will be saved has been specified, a message like the one in FIGURE 7.18 will inform you of the creation of the new network file and any incidents relating to the existence of Nodes or Elements in both joined networks with the same Id. This duplication of ID in the final network is incompatible with the working of the application, so the process should be cancelled, unless the nodes with the same ID have the same coordinates, in which case the nodes will be interpreted as the same one, identified in the final network as a single node.

FIGURE 7.18 Dialogue Analysis of final network

The resulting network will be saved to the specified route, available for editing in GESTAR as normal.


207

7.7 RESULTS OUTPUT

Once the calculations associated with the network have been run, the results obtained will be accessible in different forms, described below.

♦ Colour Coding for network magnitudes: As long as there are results of a calculation, the network visualisation will offer this option, with a colour code configurable by the user (p. 208).

♦ Table of Numerical Values of the magnitudes of a scenario: Two complete numerical tables, one for Nodes and another for Elements, will appear, ordered as chosen by the user, showing the most notable hydraulic magnitudes of the scenario whose results are seen on the screen (p. 211).

♦ Export to EXCEL spreadsheet or ASCII file of the table of Numerical Values of the magnitudes of a scenario: An EXCEL or ASCII file is generated with a replica of the Table of Numerical Values of a scenario (p. 215).

♦ Visualisation of Numerical Values of magnitudes over the whole network. The value of a magnitude selected from the toolbar appears next to each Node and/or Element (p. 215).

♦ Drop-down list of numerical values of the magnitudes of a network component: Consists of a drop-down menu of the most relevant parameters and calculated variables of a Node or Element when clicking on it with the secondary mouse button (p. 216).

♦ Exporting the scenario to ACCESS: A file in *.mdb will be created, including all the configuration parameters of an individual scenario and its respective calculated variables (see section 7.4 COMMUNICATION WITH ACCESS DATABASE, p. 185).

♦ Temporal Evolution Tables: Tabulated representation of the variation in hydraulic and power consumption magnitudes over time in temporal simulations (see section

♦ Temporal Evolution Graphs: Graphic representation of the variation in hydraulic and power consumption magnitudes over time in temporal simulations (see section

♦ Visualisation of Reports: Generation of summary reports with selected data which can be saved in various formats. Two types of report are available:

♦ Alarms Report (see Menu: Alarms/ Alarms report, p. 165).

♦ Network Report (see Menu: Options/ Network report, p. 145).

♦ Results in EXCEL format: Some GESTAR processes generate spreadsheets with the extension “.xls” (p.). This enables the gathered information to be used and processed


208

with the calculation and graphic tools available in EXCEL. This type of document can be obtained in the following circumstances:

♦ Table of Numerical Values of the magnitudes of a scenario.

♦ Obtaining the System Curve. (p. 315).

♦ Calculation of the Probability Function of the pimped flow rate (p. 316).

♦ Calculation of the Pumping Station Performance (p. 318).

♦ Results saved in PDF format: At the end of the network optimisation process (explanation of the process on p. 234), a printable document is created with information about:

♦ The Initial Data in the optimisation: general criteria, values of Nodes, Pipes and Material.

♦ Results obtained for each stretch: Nominal Diameter, Length (m), Velocity (m/s), Cost (€), Static pressure (m.c.a.) and Dynamic pressure (m.c.a).

♦ Economic breakdown of Pipes.

The options Visualization of Numerical Values, List of Numerical Values, Export of scenario to ACCESS and Network Report, can be called up at any time, although there are no results calculated for the unknown variables, in this case showing only the parameters which have been defined.

7.7.1 COLOUR CODING

By default, just after calculation, the network map window will show a circle for each node, the colour of which will indicate the range of values where the value of the selected magnitude is located. The size of the circle can be selected from the menu Options/ Preferences in the Visualization section. Similarly, Elements will be laid out with a coloured line corresponding to the value obtained, and of the thickness specified via the same menu Options /Preferences/ Visualisation tab.

To change the magnitudes to be displayed, the limits of the numerical ranges associated with each colour, the method by which they are assigned or even the colours representing them, go to the menu Results/ Colour codes, or click the Colour Codes

button ( ) on the toolbar. The window shown in FIGURE 7.19 will appear.


209

This window shows two completely independent parts: the left half, for specifying the colour codes for Nodes, and the right, for Elements. Both consist of a list of magnitudes which can be displayed on the network map, a Show button to make the keys visible, the type of selection of ranges (auto or manual), six text boxes where the start and end of the ranges for each colour can be entered, and five colour rectangles.

In the case of Nodes, the only magnitudes which can be represented by colours in this version are: Consumption, Total head, Pressure and Level; for Elements, Flow Rate, Velocity, Head loss and Internal diameter can be represented. The option you select from the list of magnitudes will automatically be represented.

By default, the limits of the ranges are generated automatically; i.e., given a minimum and maximum value for the selected magnitude in the calculated scenario, five identical ranges will be created. In the automatic creation of ranges, nodes whose Consumption, Total head or Pressure are negative or null will be represented with dark grey to help detect them, and in the case of Consumption, negative values will be excluded in the definition of ranges. This means that the important negative values for consumption which are always present and associated with intake points in the network will not

affect the creation of these ranges. Similarly, the discharged Elements, i.e., those whose Flow rate, Velocity or head loss are null, will also be represented with grey.

If the selection is manual, this option being enabled by clicking on the respective field in FIGURE 7.19, the user sets the six numerical values, in ascending order, the smallest on top and the largest at the bottom, which mark suitable limits for the ranges, writing them in the corresponding fields. The colour associated with each range can also be chosen from the palette of colours (FIGURE 6.9, p. 134) which will appear if you double-click on the field containing the colour to be modified. After making changes, click Accept for them to be operational. GESTAR will check that the sequence of ranges is correct, giving a warning if not.

By manual configuration, only the variables within a certain preferred range will be represented with an assigned colour (no colour will be given to nodes and elements with values for the selected variable outside all the ranges). As an example of this utility, for example, it helps to locate the branches of a network where the fluid circulates at an excessive velocity. As a desirable velocity is about 1 m/s, the magnitude Velocity can be displayed, using manual selection of ranges, and writing in the size limits of the ranges from 1.5 to the maximum. This way, Elements with a velocity of less than 1.5 m/s will not be shown (they will stay the same colour as the background.

FIGURE 7 19 C l C d


210

i.e., invisible), and only areas of the network with high velocities will be represented. Similarly, elements with low velocities can easily be detected.

The type of definition of ranges (manual or automatic), their limits, and the five colours used to represent the ranges, are associated with each magnitude independently and saved with the network, so that when it is reopened the colours and range will persist, enabling the optimum configuration for presentation to be kept.

FIGURE 7.20 Key

The button closes this window of keys for Nodes and Elements and eliminates colour coding and the results of the calculation, configuring the network map for a new stage of data editing.

The Show buttons launch pop-up windows (FIGURE 7.20) which can be located anywhere in the window and which show the range of colours associated with the magnitude represented on the Map. These windows are automatically updated when the magnitude to be displayed is changed or any change is accepted.

To end the description of FIGURE 7.19, the fields at the bottom of the window, Max., Med. and Min., show the maximum, average and minimum results, respectively, of the values of each Node or Element taken from all the valid scenarios (critical cases are not included in averaging) calculated in a Multiple scenario. Thus, after running a multiple scenario, the Results window is activated (FIGURE 7.22) and depending on the option chosen, we can see the numerical values of all these options. We will also see that the ranges of our Colour Codes window, and thus the Keys window, will also change, as the five ranges will be created based on different results, from all the maximums, minimums or averages, as applicable, of the values of the variables. This option also lets us see all the changes in the Results and Colour codes windows at once, in the graphic map.

If the Alarms window (menu Alarms/ Configuration) has set a restriction which has been breached, the colour code of magnitudes will tell you which Nodes and


211

Elements set off the alarms. The Nodes in question will appear surrounded by a circle (coloured according to the type of alarm), while the Elements will be represented by a dashed line. FIGURE 7.21 shows an example.

FIGURE 7.21 Graphic representation of an alarm being triggered.

The coding of magnitudes also shows the direction of the fluid in each of the Pipes with an arrow. If you do not want these arrows to appear, disable the Direction Arrows field in the Visualization window (menu View/ Visualization) or directly in the menu option View/ View direction arrows.

7.7.2 TABLE OF NUMERICAL VALUES

The data and results of an already calculated scenario shown on the network map can be consulted using the Table of Numerical Values in FIGURE 7.22 (reached by the

icon ) which contains all the Nodes and Elements in ascending order by identifier, and which supplies the values of the following hydraulic magnitudes for Nodes: Total head (m), Pressure (m), Consumption (m3

For the

/s and in the case of Emitter Lines, in l/h), Level (m), Set Point pressure (m), Pressure Margin (m) and Comments. In the cases where certain values are not defined, whether due to the type of Node or because they are not required, the value 0.00 will appear in the corresponding field.

Elements

Double clicking on any column will order the rows in ascending or descending order depending on the content of the column.

information is offered on some constructive and hydraulic magnitudes in fields headed Start Node, End Node, Length, Diameter, Roughness, Head loss, Flow rate, Velocity and Comments. If the Element is not a Pipe, the information in any of the above fields will be replaced by other relevant information or left blank.


212

Also, clicking on the secondary mouse button means the content of a selection can be affected by the following actions: Copy, Paste, Delete or Cut, making it available for use in other applications.

Pipes: The values shown correspond to the fields: Start node, End node, Length, Diameter, Roughness, Head loss, Flow rate, Velocity and Comments.

Emitters: The same data as for Pipes referring to the conduit associated with the emitter.

Pumps: The Diameter field contains the intake diameter, the Velocity corresponding to the intake flange, the Roughness field, the power of the pump (kW) and the Length field is different when the calculation is of a simple scenario or a temporal evolution. In the first case it contains a null value. while in the second case, it contains the Power Consumed until that time.

It should be remarked that if we have not calculated the fit curves Efficiency-Q and Power-Q the Length field will contain a null value, even for a temporal evolution, and the Roughness field will be blank.

Automatic Regulation Valves: The Length field contains the text: “VRP”, “VSP”, or “VLQ” depending if the valve is pressure reducing, pressure sustaining or flow limiting, respectively. The Diameter field will contain the diameter of the flange connecting to the valve, the Roughness field will contain the texts “regulating” or “passive” according to its current state. The Velocity corresponds to the connection flange.

Free element: If the option chosen in the Free Element definition window is the evaluation of the resistance coefficient Ks

Free Pipe Set: In the present version of GESTAR each component Element of a Free Pipe Set (see p.

, the fields Diameter, Length, Roughness and Velocity will be blank. If the calculation option is any of the others (calculation of the diameter, length or roughness, knowing the other two magnitudes) the corresponding fields will contain the complete information for the calculated pipe. When the Free Element calculated corresponds to a discharge Element, the Element's drop down menu shows the pump head needed and the flow rate transferred to meet the conditions set in the network.

120) is a Pipe whose diameter or roughness is calculated by the programme, with the other parameter and the length being known. Consequently, once a scenario has been successfully calculated, the complete data are known for the conduit and shown in the respective fields.

Emitter Line elements: We see that, for the case of Emitter Lines, an Element is used for each Emitter Line, and as many stretches as sub-elements configure the total Emitter Line (see p. 106). This is because there are some properties which may vary along the length of an Emitter Line, so that they make sense at the Emitter Line level only, and not at the element level. This is the case for diameter, roughness or velocity, for example.

IMPORTANT: The velocity shown for each Emitter Line refers to the velocity of the fluid at the entrance to it, as later this will vary, as the flow rate decreases when it


213

passes the emitters. The data shown in the Flow rate cell refer to the flow rate emitted throughout each Emitter Line.

The units of consumption of Emitter Lines will be l/h. This is because the flow rates working with drip feeds are minimal, and in most cases, to be expressed as m3

It should also be remarked that the table for the case of calculations with multiple scenarios varies with respect to the table shown for calculating collective networks when showing data for Emitter Line Elements. The difference is because the results are no longer shown for each component Emitter of an Emitter Line, but only those relating to the whole Element. The reason for these changes was the fact that an excessive amount of data was being processed to show information which was perhaps not all that valuable.

/sec, many decimals would be needed to show meaningful information.

FIGURE 7.22 Table of Numerical Values

In the case of visualising the results of valid scenarios for the analysis of multiple scenarios, an option will be enabled in the upper left part of the window (FIGURE 7.22) which lets you choose to display the maximum, minimum and average


214

values of the variables in these scenarios. For the other simulations this option is replaced by information referring to the calculation time which was needed for the process of simulating the scenario, and the number of iterations required by the Newton-Raphson resolution method to reach convergence according to the criteria set in the Calculations/ Parameters window (p. 155).

The width of the columns can be changed by moving the separating lines to fit the amounts shown in each field.

The toolbar in the window Table of Numerical Values contains the following functions:

♦ Button Lets you save the results in files with the extension “.xls” (see p. 217) or “.txt”. Option also available in the menu under File/ Save.

♦ Button Enables results to be printed. Option also available in the menu under File/ Print.

♦ Button . Enables you to choose the types of Nodes and Elements we want to appear in the Table of Numerical Values. Option also available in the menu under File/ Personalise Table. The user accesses the window in FIGURE 7.23. To make the selection process easier, the user can Disable all or Enable all types of Nodes and Elements appearing in the table using the corresponding buttons. Click the button Cancel to return to the table without changing its configuration.

FIGURE 7.23 Filter for table of results.

The menu options in the window in FIGURE 7.22 are:

♦ File/ Personalise Table. The user accesses the window in FIGURE 7.23. (see button ).

♦ File/ Save. Lets you save the results in files with the extension “.xls” (see p. 217) or “.txt”.


215

♦ File/ Print. Enables results to be printed.

♦ File/ Quit. Closes the window of the Table of Numerical Values.

♦ Map/ Mark. Use this option to mark the Nodes and elements you want to find quickly in the map window (e.g., to identify elements with a value out of range). To do this, click on the identifier of the Node or Element in question (grey columns in the Table of Numerical Values). A solid coloured circle, contrasting with the background colour, will appear centred on the component in question in the network map window. If you click again on the table on a marked node or element, its circle will disappear. When the component to be marked is outside the area of the network map on screen, GESTAR will change the displayed area, maintaining scale, and place the component being looked for in the centre of the screen. The zoom tools

( and ) delete the markers.

7.7.3 ASCII FILE OF NUMERICAL VALUES

ASCII files containing the content of the Table of Numerical Values can be generated from can be generated from the table with the Save button. Select the extension “.sal”, as by default the extension ”.xls” appears. These are plain text files where the fields are separated by spaces. Suitably named, the files can be stored to register the results of different scenarios for comparison and analysis.

Using the menu option File/ Open Results (see p. 128) a dialogue opens which lets you open one of these output files onscreen and interactively compare the numerical values saved in a previously calculated case with the results shown on the current map.

7.7.4 VISUALISATION OF NUMERICAL VALUES

Both before calculation, while constructing or modifying the network, and after calculating a scenario, using the commands Values in Nodes and Values in Elements in

the View menu, or the equivalent icons and , a magnitude can be displayed next to each Node and Element selected from the lists in the toolbars associated with the above icons (p. 71).

In the case of Nodes, magnitudes can be chosen from: Identifier, Level, Total head, Maximum flow rate, Consumption, Pressure, Probability, Set point pressure, Pressure margin, Irrigated area, Fictitious Continuous flow rate, Comments and Nominal diameter (of the emitter where the consumption takes place).

In the case of Elements, magnitudes can be chosen from: Identifier, Length, Internal diameter, Roughness, Material, Pressure rating, Flow rate, Velocity, Head loss, Head loss per unit of Length, Comments, Nominal Diameter + Material + Pressure rating, Line flow rate, , Celerity, Nominal Diameter, Power and Efficiency.

These can be interchanged by selecting another from the list next to the buttons.


216

The available magnitudes may not be defined for all components, either because they are optional, or because they are not applicable to all types of Nodes or Elements, or because they are variables which have not yet been calculated. When the value of a magnitude is not defined in a component for one of these reasons, no numerical or alphanumerical value will be displayed for it.

The magnitudes selected for visualisation will persist from one simulation to the next, with the numerical values of the magnitudes resulting from the calculation disappearing once the earlier results are deleted.

7.7.5 DROP-DOWN LIST OF NUMERICAL VALUES

In order to show the value of the most relevant magnitudes of each node or element at the same time in the hydraulic simulation, click with the secondary mouse button on the node or a point of the element.

If simulation calculations have not been run for a scenario, when right-clicking on any node or element, a drop-down menu will show the most relevant configuration data for each component, marking in grey the magnitudes of the component which are still unknown and cannot be shown because they have not yet been simulated. The magnitudes which are known or unknown depend on the type of node or element.

When the network map shows an already simulated scenario, the pop-up window shows the values of the relevant magnitudes, including the values given as data and those obtained from the calculations, as seen in FIGURE 7.24.

FIGURE 7.24 Drop-down List of Numerical Values.

The magnitudes shown after simulation in pop-up windows are identical, if they exist, for all Nodes (Identifier, Level, Consumption, Total head, Pressure head and Pressure margin) but differ for Elements. Thus in Pipe Elements, Emitters and passive Free Elements (where Ks

FIGURE 7.24is not calculated), the data shown coincide with those

appearing in . For Automatic Regulating Valves, Pumps, Emitter Line


217

Elements and active Free Elements, or where Ks is determined, the pop-up window contains information adapted to the characteristics of the Element. The conduits forming part of the Free Pipe Sets are treated as Pipes when showing results (when the network has not yet been calculated, the pop-up window says that the unknown variable has not been calculated).

Also, in the contextual menus for Elements after a calculation with multiple scenarios (valid scenarios), the maximum, average and minimum values are shown for certain results (see p. 273).

7.7.6 RESULTS IN EXCEL FORMAT

As remarked above, some processes implemented in GESTAR can generate *.xls files. These are workbooks which can be edited with any version of EXCEL except EXCEL 2007, containing information organised in one or more spreadsheets.

Values are ordered in rows and columns, as is normal for this application, and the gathered information can be used and manipulated with the calculation and graphic tools available in EXCEL, and easily printed out.

The button List of Results

Table of Numerical Values of the magnitudes of a scenario.

offers the option of saving the information

presented in the Table of Numerical Values (see p. 211). When you click the button (FIGURE 7.22), by default a workbook is saved with the extension “.xls” with the information shown in each table. If you decide to use the option Personalise Table in the same window (see p. 214) the document in EXCEL will be loaded with only the selected types of Nodes and Elements.


218

FIGURE 7.25 EXCEL spreadsheet with Numerical Values of Elements.

Two spreadsheets will be created, one with the data referring to Elements (Identifier of the element, Start node, End node, Length, Internal diameter, Roughness, Head loss, Flow rate, Velocity and Comments) and another showing the magnitudes associated with the Nodes (Identifier of the node, Total head, Pressure, Consumption, Level, Set point pressure, Pressure margin and Comments).


219

FIGURE 7.26 EXCEL spreadsheet with Numerical Values of Nodes.

The Menu option Pump Regulation/ System Curve offers the tool for calculating the System Curve (see p.

System Curve

315). This is defined as the relationship existing between the pressure head needed at intake and the flow rate required for each scenario. The network must meet a series of requirements for the System Curve to be calculated. The results are saved as an EXCEL file as seen below:

FIGURE 7.27 EXCEL spreadsheet of System Curve Results.

The values represented in each column of the spreadsheet correspond to:

♦ %: The percentages of demand at head, resulting from comparing the transferred flow rate with accumulated flow rate, for which the required number of Random Scenarios has been run.


220

♦ Q MAX (m3

♦ H MAX (m): maximum height found necessary for supplying enough pressure to all open hydrants in the random scenarios analysed for this percentage of demand at head.

/s): value of the maximum flow rate corresponding to H MAX obtained from among the random scenarios analysed for this percentage of demand at head.

♦ Q REC (m3

♦ H REC (m): Recommended value for the set point head for this percentage of demand at head (see specific Appendix, p.

/s): value of the flow rate corresponding to H REC obtained from among the random scenarios analysed for this percentage of demand at head.

441).

♦ Q MIN (m3

♦ H MIN (m): minimum height found necessary for supplying enough pressure to all open hydrants in the random scenarios analysed for this percentage of demand at head.

/s): value of the flow rate corresponding to H MIN obtained from among the random scenarios analysed for this percentage of demand at head.

The average values recommended (Q REC and H REC) represent the System Curve, which guarantees the pressure supply to the least favoured points with a similar degree of reliability (the probability that the pressure requirement will not be exceeded) consistent with the guarantee of the design flow rates at head using the Clement formulation. The maximum system curve is obtained when representing the maximum values Q MAX and H MAX. This is the envelope of the absolute maximum pressure requirements throughout all the demand percentages analysed. The minimum system curve is defined by the values of the columns Q MIN and H MIN, where this is the envelope of the absolute minimum pressure requirements throughout all the demand percentages analysed.

When calculating the System Curve an option can be enabled which lets you Export intermediate cases. The resulting EXCEL workbook will be increased by several spreadsheets, one for each of the demand percentages which have run Random scenarios (FIGURE 7.28).


221

FIGURE 7.28 EXCEL spreadsheet of System Curve with intermediate cases.

For each scenario, the user will know which nodes are open, what pressure head is required for each of them, the transferred flow rate and the critical pressure demanded, and will be able to set system curves to measure with variable reliability or guaranteed percentiles of scenarios (see specific Appendix, p. 441).

Optionally, from the Menu: Pump regulation/ Probability Function of the Pumped Flow rate (see p.

Probability Density Function of Pumped Flow Rate

316), an EXCEL file can be generated with the tabulated results of the monthly and annual probability of demand obtained for each of the flow rate values required.


222

FIGURE 7.29 EXCEL spreadsheet for Probability Function

You can also choose to Export Averages and Variance, creating a new Excel spreadsheet in GESTAR (FIGURE 7.30).

FIGURE 7.30 EXCEL spreadsheet for Averages and variance


223

This spreadsheet stores the monthly values of averages (arithmetical average of observations) and variance (a measure of variability, it is the average of the square of the distances between each observation and the average of the set of observations) referring to the demanded flow rate.

The results of calculating pump performance (see section

Pumping Station Performance

10.6.2 STATION REGULATION) are shown exclusively in an *.xls file.

Given the adopted system curve and the composition and type of regulation of discharge groups, GESTAR calculates the complete family of action curves for the pumping station, consisting of the collection of functions characterising the behaviour of the station as a whole, depending on the total discharge flow rate q (Net Elevation Height, Ht

The EXCEL file includes the tabulated results (example in

t; Total Power Consumption, P and Overall Efficiency, η ), and that of each of the pump groups making it up (including rpm depending on flow rate, q, for variable speed groups).

FIGURE 7.31).

FIGURE 7.31 EXCEL spreadsheet of Pump station performance.


225

8 SIZING COLLECTIVE BRANCHED

NETWORKS

GESTAR facilitates the sizing of strictly branched networks, i.e., a network without meshes with a single intake point (with a known or unknown total head) which is operated on demand or in turns.

8.1 PREVIOUS GENERATION OF TOPOGRAPHY AND DEMAND

Before any type of calculation, the network will have to be implemented, being careful to comply with the restrictions given below:

FIGURE 8.1 Example Network without Pump Element at head (gravity feed, known total head).

♦ The network must be strictly branched.

♦ The Head node will be a Known Pressure, Reservoir or Dam node, with the alphanumerical identifier node zero. “0”.

♦ Only one line can come out of the head node; i.e., this node will connect to a single Element, as shown in the example in FIGURE 8.1. This requirement is needed for GESTAR to assume that the loaded network is strictly branched.


226

♦ In each line (Pipe Element or Pump) the upstream and downstream nodes will be defined according to the direction of water flow. Therefore, there cannot be two lines with the same downstream node.

♦ The ends of branches in the network must have a consumption and required minimum pressure assigned. Dead end branches without consumption should be eliminated from the model before any sizing stage begins.

Also, the topology and demand will be loaded combining the following types of nodes or elements exclusively:

♦ Known consumption nodes/hybrid nodes: these will represent hydrants. Consumption and level must be defined for each node (see , p. 82) or Hybrid Node (see , p.85 ). We recommend using Known Consumption nodes. In sizing, we do NOT recommend working with hybrid nodes, as this type of node needs its definition to include the values of the coefficient of losses for the completely open hydrant, and of one of the parameters of the equation of network losses in the plot (see , p.85 ), which involves more complex modelling and additional configuration work, giving it no advantage compared to the Consumption node in the sizing phase.

♦ Independently of the calculation method used to assign Design Flow Rates, the nodes representing hydrants which will form part of the design cannot be in a closed state. Otherwise, they will be taken to be null consumption nodes.

♦ In the normal case that a required minimum pressure is desired for these, we recommend that this appear as a Set Point Pressure (together with the selected regulation field) when sizing begins.

♦ If Design flow Rates will be calculated using the Clement method, it is essential to include the values for Irrigated Area, Fictitious continuous flow rate and Efficiency for each hydrant.

♦ Junction nodes: Correspond to bifurcations where demand is null and only the level must be entered. Junction nodes cannot form the ends of branches.

♦ Known consumption, Reservoir or Dam nodes: can be sited alone at the head, to indicate the only intake point with a known total head. If the level is specified of a free surface, this means specifying a null pressure value in relation to the atmosphere. If the level of a bottom or other point is specified, the pressure will be the same as the water level in relation to this point. If inserting a pumping station of undetermined height (see recommendations below regarding the Pump element) the resulting total head corresponds to the intake point of the pumping station.

♦ Pressure Node. The user will assign in the Level field the height of the point where the start node of the first stretch of the network will be located, and enter the right value for the pressure head for this node leading to the network. During the sizing process GESTAR will adopt the sum of both values as the starting total head (see

, p. 81).


227

♦ Dam Node. The free surface level, with null pressure, designated via the corresponding dialogue (see , p. 78), will be taken by GESTAR as total head during the sizing process.

♦ Reservoir Node. For this type of Node, the total head taken into account in the process will be the sum of the geometric height assigned in the Level field and the value of Initial Level of the liquid in the reservoir in relation to the bottom (see , p. 79).

♦ Pipe element: the length in the corresponding field will be used for optimisation. The assigned selections for material, pressure rating, diameter and roughness will be ignored, except for stretches which will later be forced, where the values given at the launch of the optimisation module will be used.

♦ Pump Element: IMPORTANT: in the cases where the total head at intake, given by a pumping system, is a variable to calculate as part of optimisation, this condition will be indicated in the graph, inserting a Virtual Pump connecting the head node with the upstream node of the first stretch of pipe in the network. . The performance curves entered for the Virtual Pump are arbitrary and are defined with the values which GESTAR provides by default. Only one line can come out of the Junction node downstream from the Pump Element, as shown in the FIGURE 8.2.

FIGURE 8.2 Example network with Pump Element at head.

• Previous checks. Before beginning the sizing process, check that the direction of the pipes has been assigned to coincide with the direction of the flow. To check this, we recommend assigning high diameters to

WARNINGS


228

Conduit Elements, and with all hydrants open, run the function Calculate Scenario (see on the toolbar, p. 66).Once the scenario is calculated, you can display the flow rates onscreen (see , p. 72) or from the numerical list (see , p. 67), ensuring that negative flow rates have not been obtained for any Element, i.e., against the direction of the Elements. If there are any, go on to change the direction of these Elements (see p. 95). The process of changing the direction of all the Elements with a negative flow rate can be run automatically from the Menu: Plot Design/ Circulation direction. From the GESTAR 2014 version, the programme carries out this check itself and changes the orientation automatically when beginning an optimal sizing operation.

• Consumption nodes. All consumption nodes (Known Consumption and Hybrid nodes) at the ends of branches must be open, and we also recommend they have a Set Point Pressure assigned and the regulation field enabled, if you want to set this pressure as the required minimum pressure, in order to avoid having to assign individual minimum pressure levels later, when running the Sizing Assistant. If a consumption node at the end of a line is closed, the programme cannot run any sizing.

• If the sizing will be on-demand check that NO Consumption Node is assigned to a possible Turn.

• If the sizing will be by Turns check that ALL Consumption Nodes are assigned to a Turn. The only exception will be Consumption Nodes which are Unconditionally Open.

• Junction nodes. If you are going to use the tool for calculating Design Flow Rates, there cannot be a Junction node at the end of any branch, left behind by the transformation of drains, dead end branches, suckers, as this leaves the flow rate of the branch undetermined.

• Pipes Database. GESTAR will use the Pipes Database associated with the current network. The later optimisation of the network will be based on the costs per linear metre of conduit specified in this database, so that its correct definition is vitally important. If you want to modify the database of Materials, read the corresponding Appendix carefully (p. 475). We recommend:

• That you predict what type of Material should be projected for each range of diameters and create a specific database for the project, containing only the material, pressure rating and diameters you intend to use. By duplicating an existent database, you can create a new Pipes Database where (by restriction and/or extension) only the materials, pressure ratings and diameters selected as candidates appear.

• The database must contain all the materials which could be used, including various alternative designs, where each alternative can be selected later thanks to the sizing wizard, in its STEP 9: MATERIAL.


229

• Revise carefully the prices set for each material, pressure rating and diameter, without accepting the defaults in the existing databases, and update prices. These prices should not only include the costs of installed pipes, but also earth moving, infill, and if affected by the choice of material, the estimated price per ml/ of special pieces and valves.

• Check carefully that the prices by unit of length for each Material and Pressure rating RISE with the Nominal Diameter. Neglecting this requirement may lead to errors and faulty sizing.

• Check carefully that the prices by unit of length for each Nominal Diameter in all Materials rise with the Pressure rating . Neglecting this requirement may lead to errors and faulty sizing.

• Sizing based on a Pipes Database with various types of material for each diameter and pressure rating can give undesirable sizing results from the point of view of construction, for example if there are changes in diameter, material or pressure rating in short stretches, which can later by modified in the analysis stage using rational criteria.

• When initialising sizing routines for each pressure rating, the data referring to the diameter of conduits and their cost per linear metre fit an exponential function. Before loading the database, it is advisable to represent the Cost/ Internal diameter graphs and the corresponding exponential fit (for example, with the help of EXCEL) to find out how good the fit is (see FIGURE 8.3) . We recommend NOT including in the database the diameters which, due to excess or shortfall, are outside the predicted range of diameters to be used, NOR the intermediate ones which you want to exclude a priori, as they may force and unsuitable fit for the exponential curve in the area of useful diameters. If even in this case you find areas with points which are far from a single fitting curve, we recommend subdividing the material and pressure rating into two or more sub ranges, creating pseudo-materials which cover areas of different diameters, with different names (e.g., FD-A, FD-B, etc).

FIGURE 8.3 Example Exponential fit pairs of values Cost/ Diameter


230

• In no circumstance assign arbitrary costs to diameters which you intend to exclude from sizing (for example, giving very high values), as this would completely skew the price fit curve. Diameters you want to exclude should be deleted from the databases.

• If the range of diameters to use depends on the selection of the combination of materials or the design hypothesis, we recommend defining a different database for each combination. We recommend not including the diameters excluded in the sizing option in each database, in order to improve optimisation results.

• As the sizing method fits, as an exponential function, the data of diameters and costs of Pipes for each pressure rating, at least two different diameters for each pressure rating will have to be loaded in the Pipes Database.

• The programme will occasionally ask for another diameter to be added in the series of a material for a given pressure rating, even when this diameter is not chosen. In this case, we recommend entering a price which corresponds to the tendency to fit of the rest of the pairs of values diameter/price.

CALCULATING POWER COSTS IN THE SIZING PROCESS

8.2 ON-DEMAND DESIGN FLOW RATES

The user can calculate Design flow Rates in GESTAR, before optimising the branched network, using the Sizing menu, option Design Flow Rates. As remarked above, it is essential that the topology and boundary conditions of the network are generated as specified in the section 8.1 so that GESTAR can calculate Design flow Rates.

To reduce investment in the pipes of a distribution network for irrigation, the elements of the network can be sized for turns or for demand, but only when the flow rates are lower than the most extreme consumption rates.

Normally pressurised networks for irrigation on demand are sized to let the system work properly with a high degree of probability (Guaranteed Supply), even in the most demanding conditions of irrigation volumes (peak period), but without supplying the largest flow rates possible. This is because the highest demand only happens a few days a year, and ensuring functioning at any level of demand, even the least probable ones, means oversizing the main pipes with the largest diameter, and so causes high costs for pipes which will be underused most of the time.


231

Use the dialogue in FIGURE 8.4 to select the design criteria you want for GESTAR to use in calculating Design Flow Rates.

FIGURE 8.4 Dialogue on Design Flow Rates

♦ Cumulative flow rates. when the option Cumulative flow rates is selected, GESTAR

calculates the Design Flow which will circulate through each pipe, under the hypothesis that all the Known Consumption nodes will be working at the same time (except those configured as closed or unconditionally closed, at the time of launching the Design Flow Rate function, as explained in section 8.1 PREVIOUS GENERATION OF TOPOGRAPHY AND DEMAND).

♦ Equivalent Clement flow rates. If you think that the network under study meets the right conditions (a high number of hydrants, suitable values for the Degree of Freedom, etc.) it will be useful to choose the option Equivalent Clement flow rates for assigning Design flow. GESTAR will calculate the design flow rate of each line following the formula established by Clement, whose approximation is the most widely used for on-demand distribution networks, enabling the reduction of the diameters of pipes obtained in the sizing process, and thus the execution costs of the network. When this option is enabled the panel referring to Guaranteed Supply appears, letting the designer set the parametric according to the function of the network:

• Overall Guarantee of Supply. The user defines the percentage of Guarantee of Supply of the network in the appropriate field. The value is constant for all the pipes, independently of the number of hydrants fed by each line, including end branches with a single hydrant.

• Selective Guarantee of Supply. when this option is activated, the dialogue on the right in FIGURE 8.4 appears. This lets the you define a scale of guarantees according to you preferences, depending on the


232

number of hydrants fed by each pipe. For elements which supply fewer hydrants than the minimum number for guaranteeing supply, the design flow will be the same as the cumulative flow rate. Do NOT use a 100% Guaranteed Supply value to indicate the accumulation of flow rates.

EXAMPLE: FIGURE 8.4 illustrates the configuration of the following scaling of Guarantees of Supply.

Cumulative flow rate up to 3 hydrants (inclusive) downstream.

99% Guarantee of Supply from 4 to 19 hydrants.

95% Guarantee of Supply from 20 to 49 hydrants.

90% Guarantee of Supply, 50 hydrants or more.

♦ Start Node Label: For any of the available calculation options, it will be necessary to note the Start Node Label, i.e., for the head node, in the appropriate field.

When the process of determining Design flow rates is running, the window in FIGURE 8.5 will appear. This can be used for modifications and editing, as described below.

FIGURE 8.5 Table of Flow Rates in Line.

♦ Save. Using this icon, you can save the results obtained for each pipe referring to cumulative flow rates, Clement flow rate, design flow rate, number of hydrants supplied and area irrigated, in files with the extension *.sal, *.xls or *.txt, which can be edited later.


233

♦ Print. Prints the table of results in any of the printing devices configured for the PC.

♦ Edit Design Flow Rate. This option, to the bottom right of the dialogue, will be enabled by default, as it is the only one available in the current version. When one of the identifiers of the pipes forming the network is selected, the field will appear as in FIGURE 8.5, letting you modify manually the design flow rate value for the chosen pipe.

♦ Apply to the network. Use this button to load the results of the design flow rates shown in the table to the current network.

♦ Cancel. When you do not want to modify the network with the results obtained for line flow rate, click the Cancel button to leave the parameters of the network as they were before beginning the calculation process.

♦ Personalise Table. Click this icon to bring up the dialogue in FIGURE 8.6. This enables the pipes shown in the table to be marked in order to facilitate the analysis of results.

FIGURE 8.6 Dialogue for Personalising Table of Line Flow Rates.

• Filter by Hydrants. Restricts the sample of results to the Pipes which feed a number of hydrants within a range defined by the user via the fields Lower Range and Upper Range. At the same time you can specify the ranges you prefer.

• Filter by Surface Area. The procedure for defining this filter is the same as for the Filter by Hydrants, in this case showing the pipes which water a number of hectares within the added ranges.


234

• Personalization Options. If both filters are implemented, GESTAR provides two options for personalising the table. The first, Y (must pass both filters), is more restrictive, as the pipes shown must pass through both filters. The second option, O (must pass one of two filters), widens the search to all the pipes which can pass through at least one of the filters.

• Updating the Table of Flow Rates. Once the filters are defined, select the button Update flow rate table and GESTAR will present a window like the one in FIGURE 8.5, with the pipes which meet the necessary filtering requirements. If you then select the button Apply to Network, only the results for the line flow rates for pipes which passed through the filters, i.e., the values presented in the table at that moment, will be loaded to the current network.

OPTIMISATION OF THE ON-DEMAND NETWORK.

8.3 ENERGY COST CALCULATION

In networks created with a pump element at intake, power consumption is computed in a simplified form, supposing a flat system curve (constant pump head, Hd, equal to the design pressure for the design flow rate at intake) and that the efficiency of the total pumping station is an estimated value, also constant (Weighted Efficiency), ηd, obtaining a simplified version of Equation 3-1 computing the Simplified Power Consumption (CESkwh

p

d

p

dkwh

VHgdtqHgdtq

qqHgCESη

ρη

ρη

ρ ⋅⋅⋅=⋅

⋅⋅=

⋅⋅⋅= ∫∫

T

0

T

0 )()(

).

V is the volume to be elevated during the campaign, which with the weighted efficiency of the pumping station and the volume to be pumped, are the data the user must enter, as Hd


is the object of calculation of the optimization process.


p


=η

ρ



235

PkWhVgH

PkWhVPkWhVPkWhVgH

CESp

dppllllvv

p

d

ηρ

ηρ

⋅⋅⋅

=++⋅⋅

⋅=

36001000)(

36001000€



VPkWhVPkWhVPkWhV


)(

and in the overall case, where the consumption price is structured in NP time periods, with the price of each period PkWhi and pumped volume Vi

V

PkWhVPkWh

NP

iii∑

=

⋅= 1

in the respective period


)IkWh


+⋅=




incAnualreaci

NP

1ibasei

p


⋅⋅= ∑

= 10036001000€ ηρ

Where:



10021cos171

2 −+=



236



1001)1001(

IanTIanK

T

incAnual−+


Power Term


.


p

ddkW

QHgPNN

ηρ

⋅⋅⋅⋅⋅

=1000


As it is not always necessary to sign up for the maximum power needed, kWPNN , for all the time bands, this expense is calculated as the sum of the annual cost

of the kW contracted for each period according to the electricity price rate used.


Price for Power Supply ( basePkW ) which is the cost in € per month per kW in a given period of reference, and then indicate the Surcharge on the price per kW (or discount with a negative sign) as a percentage of the Base Price for Power Supply corresponding


)100

1( ibasei

IkWPkWPkW +⋅=





237

incAnualreaci

NP

ibase

i

p


⋅⋅⋅⋅

= ∑=

12)100

1(1001000 1

€ ηρ

where






)100

1(100

11

1i

NP

ibase

iNP

IkWPkW

RNP

PkW +⋅⋅= ∑=


238

8.4 NETWORK OPTIMISATION

GESTAR uses this tool to facilitate the sizing of strictly branched networks, i.e., a network without meshes with a single intake point (with a known or unknown total head).

Access to the optimisation process is through the command Size Network in GESTAR's File menu, or the icon on the toolbar. It will first be necessary to create the strictly branched network that you want to size, as specified in section 8.1, and assign design flow rate values to each of the pipe elements (see section 8.2).

When beginning sizing by any of the procedures mentioned above, the dialogue shown in FIGURE 8.7 will appear.

FIGURE 8.7 First dialogue for network sizing

♦ Create a new input file. If you decide to create a NEW file for data entry, GESTAR will use the parameters enabled in the current network and the materials database associated with it in the sizing process. Next, the DIAMETER OPTIMISATION assistant will launch.

♦ Begin the optimisation process based on an existing file. If you do not want to create a NEW input file, the window in FIGURE 8.8 will appear, enabling optimisation based on an existing Input file previously created by GESTAR (with format GESTAR2008*.opt or TEXT*.txt). This type of file created in GESTAR can be modified by the user in the application in the case of *.opt (option not available yet) or with a text editor in the case of *.txt files, facilitating minor changes in the entry parameters without having to go through all the steps of the assistant. Once the *opt or *.txt file is selected, GESTAR will optimise the network directly, without the need to re-run the assistant described below, making later sizing much more flexible for studying alternatives or sensitivity to given parameters.


239

FIGURE 8.8 Open OPTIMISATION input file

As mentioned above, if you decide to create a new input file based on the current network the assistant for OPTIMISATION OF DIAMETERS will open. You can use the buttons at the bottom of any screen of the assistant to Cancel the sizing process, go to the Next dialogue when you have filled in the obligatory fields, or modify data in previous screens of the assistant with the Back button.

ASSISTANT FOR OPTIMISATION OF DIAMETERS

With the data from the input file, GESTAR will distinguish between two cases:

♦ The intake pressure is given (see example in FIGURE 8.1). Steps 6 and 7 of the assistant are inactive, as they define the parameters of the pumping station, not relevant in this case.

♦ There is a Pump Element at intake (see example in FIGURE 8.2). It is interpreted that the network is fed by pumping and the assistant steps referring to the pumping station and electricity prices are enabled.

STEP 1: PROJECT TITLE. FILES.

The first dialogue of the assistant deals with the specification of the data needed to save the input file, as well as offering several options, listed below.


240

FIGURE 8.9 DIAMETER OPTIMISATION assistant. Step 1: Project title. Files.

♦ Rote to Pipes Database. At the top of the dialogue screen the route is shown to the materials database associated with the current network, which will be used in the calculation process.

♦ Compatible input *.txt files from earlier versions. In future versions of GESTAR the input files will be created in binary GESTAR2008*.opt format exclusively, which can be consulted with the assistant (option not available yet). Selecting this option (enabled by default), the file will still be saved in TEXT*.txt format, as in earlier versions, so it can be read in any text editor.

♦ Route of Creation of Optimization Input File. Use this field to set the name of the input file. By default GESTAR will save the file in the same folder as the current network. This route can be modified with the button Browse, to the right of the field.

*RECOMMENDATION: The name of the input file should not contain punctuation or repeated symbols. Otherwise, when the assistant closes, an error message will appear, and optimization will not take place.

♦ Project title. You can optionally fill in this field with the title of the current project, which will appear on the document of results.

♦ Improved Optimization Method. You can request optimization of the network using the Economic Series Method, derived from DIOPCAL, or via an improved algorithm, which synthesises a generalization of the Economic Series Method and a discontinuous Labye type procedure (Labye et al. 1988).

♦ Show 1st series. When this section is enabled, after optimization, you will receive information about the point of the network with limiting supply conditions, indicating the path from the intake to the unfavourable Node. This warning will be very useful as these values can overwhelmingly condition the results obtained throughout the network, permitting cost reductions by reducing the set point pressure in this Node. The Node indicated will be the next candidate for reducing the required pressure in order to reduce the costs of the network.


241

STEP 2: REVIEW FLOW RATES.

FIGURE 8.10 DIAMETER OPTIMISATION assistant. Step 2: Review flow rates.

The second screen of the assistant lets you check the value of the flow rate of the line assigned to each Element. For the current version of GESTAR the button Review Flow rates is not enabled, and the assistant must be cancelled in order to make any changes. These modifications can be made in various ways, most usually from the dialogue for the Pipe Elements (using the various GESTAR tools which let you select one of more Elements), or via the menu Sizing to the option Design Flow Rates.

STEP 3: INTAKE DATA

FIGURE 8.11 DIAMETER OPTIMISATION assistant. Step 3: Intake Data

♦ Intake Data One of the options shown below will be enabled, according to the topology of the network being analysed.

• Known Pressure. For the case of networks without a Pump Element at intake (gravity feed). GESTAR loads the values defined at the intake Node referring to the Identifier, Level, Known Pressure and Total Head. Selecting the Edit button, you can access each cell and modify the data.

• Unknown Pressure. For calculating networks with a Pump Element at intake. The values of Known Pressure and Total Head appear as unknowns. You can Edit the data as explained above.


242

♦ Slopes.

• Slope Bifurcations. In Nodes with bifurcations there is a minimum pressure requirement corresponding to the greatest pressure needed to reach all the end Nodes fed by the bifurcation with the total head required, taking a minimum hydraulic slope of 0.0015 m/m. It has been observed that if the value of this minimum slope is relaxed, occasionally the final result tends to be more economical. This option enables expert users to tweak the total head requirement in the Nodes corresponding to branches, in terms of modifying the minimum hydraulic slope to reach the total head required in all Nodes with pressure requirements and which are fed from a given bifurcation. Recommendation: Trial and error with values from 0.002 to 0.0001 m/m

• Slope 1st path. Used exclusively for networks with direct pumping. For estimating the intake head at the first approach, the optimization process uses a set hydraulic slope for all Nodes of the network, so that the critical Node is the one that needs the most head at intake, with this assumed slope. The expert user can modify the value of the (hydraulic) slope of the 1st path, which can lead to obtaining different critical Nodes for different intake heads, which can sometimes provide slightly improved optimisation solutions. RECOMMENDATION: Sizing the networks with direct pumping using minimization of the sum of costs of amortization de Pipes and energy costs, resulting from a sweeping process. With such a strategy this parametric no longer intervenes.

STEP 4: MINIMUM PRESSURES

The minimum pressures requested by the user for optimization will obviously be a decisive factor in calculating sizing and obtaining results.

FIGURE 8.12 DIAMETER OPTIMISATION assistant. Step 4: Minimum pressures

GESTAR provides four options which are MUTUALLY EXCLUSIVE. For the first three, the user must set the minimum pressure in m.c.a. in the field to the right.


243

♦ Common Minimum Pressure in all Consumption Nodes. The set minimum pressure will be taken into account in the calculation process only for Known Consumption nodes.

♦ Common Minimum Pressure in all End Nodes. The minimum pressure value will affect exclusively the Nodes at the end of the line.

♦ Common Minimum Pressure in all Nodes. The assigned minimum pressure relates to Consumption and Junction nodes, and is the most demanding option.

♦ Set point Pressure in Hydrants. In this case the user needs to have enabled the field referring to regulation in Consumption or Hybrid nodes, listing the set point pressure for each Node you want to be considered in the optimization process.

♦ Minimum Pressure at Specific Nodes. From this dialogue you can enter minimum pressure requirements in certain nodes. Enter the number identifying the node and the minimum pressure in m.c.a. for each pair of data. Its use is OPTIONAL and COMPATIBLE with any of the above alternatives. The parameters filled in with this option do NOT OVERWRITE the current network, and affect only the input and output files of results generated in the optimization process. This is useful for assigning minimum pressures to pass-through nodes and for making minor changes in the set point pressure.

STEP 5: RESTRICTIONS

For the assistant to continue with the optimization process, it requests the design limits set by the designer for the velocity of circulation of the fluid in the conduits, and various economic data.

FIGURE 8.13 DIAMETER OPTIMISATION assistant. Step 5: Restrictions

♦ Velocity.

• Minimum Velocity. In this field the minimum acceptable velocity must be set, in m/s, to serve as an alarm for indicating situations where the acceptable head loss (relating to velocity) is too low..


244

• Maximum Velocity. The maximum acceptable velocity is set to avoid problems of erosion, cavitation and transitories in the pipes. The overall costs of the network will be sensitive to this parametric, and will reduce as the maximum velocity increases. However, it should be considered that increasing this value will have a direct impact on the reliability of the installation. A detailed analysis of transitories in the network will identify this acceptable maximum as high as possible, without compromising safety.

♦ Installed Pipes. If there are stretches of the network already executed or inherited from an earlier optimization whose diameter you do not want to change, you can block them by activating them as Installed Pipes in the dialogue in FIGURE 8.14. The data on Internal Diameter (mm), Length (m) and Roughness (mm) must have been previously defined, during the process of creating the network, as this window can only check these parameters.

FIGURE 8.14 Definition of Installed Pipes

♦ Amortisation data.

• Years of Amortisation. In this field the amortization period of the investment must be formulated, i.e., the years of useful life considered for the projected installation according to your criteria. Where the intake pressure is unknown, there may be a question as to which is the amortization period to enter, that of the Pipes or of the pump groups. The latter is usually lower, but its cost is not significant in the optimization process, not only because it costs less than the network, but because it also depends less on the pump head, making the preferred definition of the amortization period that of the Pipes.


245

• Years of Amortisation. Similarly, you can set the expected interest rate of the amortization expressed as a percentage.

STEP 6: PUMPING STATION

In networks created with a pump element at intake, the dialogues on Pumping Stations and Electricity Prices will be enabled.

FIGURE 8.15 DIAMETER OPTIMISATION assistant. Step 6: Pumping Station

♦ Pumping stations.

• Efficiency %. Set the efficiency of the pumping station as a percentage in this field. (By default a value of 70% is applied).

• Cos (φ). In this field, enter the value of the reactive power factor of the station. The default value assigned in GESTAR is 0.8997, which supposes no surcharges or discounts.

• Volume (m3

∑=

=NP

1ii VV

). The estimated volume pumped per year in each tariff bracket will be specified, Vi. If V is the total annual volume to pump by year, it should be satisfied:

• Calculate Volume. If the yearly pumped volume is unknown, this lets it be assessed by GESTAR, according to the total irrigated area and an annual maximum flow rate of m3

/ha. The calculated volume will be set in an arbitrary time bracket, by default P1, and can later be redistributed among the different price brackets according to the user's estimates.


246

STEP 7: ELECTRICITY PRICES

As already noted, the definition of this window will be needed only for sizing networks with pumps at intake.

FIGURE 8.16 DIAMETER OPTIMISATION assistant. Step 7: Electricity prices

• Annual Increase in Power Costs (%):

Annual increase in % of the base prices (energy and power) during the period of amortisation of the investment. Taken to be constant every year.

Base Price of kWh and kW in the reference Period:

• Base Price of kWh (€/kWh

basePkWh): The value will be specified of the parameter

(price per kWh in the reference period), to be used in the expressions of section 8.3 for calculating energy costs. If not distributing the volume in periods (all the annual volume assigned to a single period in STEP 6), enter as Base price per kWh, basePkWh , the weighted

average cost PkWh (see section 8.3), and null surcharge values (0%) will be established for the Surcharge on the Price per kWh in all the periods of FIGURE 8.16

• Base Price of Power in kW (€/kw/month):basePkW

The base price will be specified for the Kw contracted for the reference period, , used to calculate the expressions of section 8.3 for calculating energy costs. If there is no discrimination for the power contracted for the different periods, i.e., 100% of the Nominal Power Needed

p

ddkW

QgHPNN

ηρ

⋅⋅⋅

=1000


247

formally available in all the periods, the weighted average cost of the contracted power, PkW (see section 8.3) is entered as Base Price per kW in the reference period, basePkW , and null surcharge values (0%) are set for the price per kW in all periods of the Surcharge on Price per Kw in FIGURE 8.16.

• Type of Base Prices: basePkWh A combination of and basePkW is selected from those registered in the database of Electricity Price Rates, or they can be entered manually selecting the value “Personalised” (default option).

Surcharge per kWh by Periods kWh (P1 to P6):

Price Surcharge kwh (%):V

If, for calculating power costs in the previous STEP 6, we have opted to distribute the elevated annual volume , over different price band

periods, iV , so that:

∑=

=NP

1ii VV

Next to the Base Price per kWh, basePkWh , the coefficients must be indicated for Surcharge kWh (and discounts, with negative sign), IkWhi , in % applied to each period in relation to the Base Price per kWh, so that the expression of Simplified Power Cost,

€CES , is calculated:

incAnualreaci

NP

1ibase

p

id KK)IkWh(1PkWhVHgCES ⋅⋅+⋅⋅⋅⋅⋅⋅

= ∑= 10036001000€ η

ρ

where






• Type of Discrimination: A type of distribution of surcharges by period is selected from those registered in the database of Electricity Price Rates,


248

or they can be entered manually selecting the value “Personalised” (default option).

Surcharge per kWh by Periods (P1 a P6):

• Surcharge on Price per kwh (%):

iIkW

If non-uniform contracted Power Distributions are specified for calculating the cost of the contracted power, other than 100% for all periods, the coefficients must be indicated of the Surcharge on the price per kW (and discount, with a minus sign) in relation to the Base Price of Contracted Power, corresponding to each period, (%). FIGURE 8.16. GESTAR estimates the annual cost of the contracted power, CPC; using the expression:

incAnualreaci

NP

ibase

i

p


⋅⋅⋅⋅

= ∑=

12)100

1(1001000 1

€ ηρ

where




reacK : Reactive power term according to cos ϕ

incAnualK : Term of annual increase in power cost

The Power Term Cost corresponds to the estimated total annual cost of the pumping power contract. This is evaluated as the sum of the annual cost of the kW contracted for each period according to the electricity prices used. Electricity prices normally divide the day into different periods (P1 - P6), in which the cost of each kW of power supply varies. To record the price variations of the power supply in GESTAR,

enter a Base Price for Power Supply ( basePkW ) which is the cost in € per month per kW in a given period of reference, and then indicate the Surcharge on the price per kW (or discount with a negative sign) as a percentage of the Base Price for Power Supply

corresponding to each period, iIkW . FIGURE 8.16

If not using time bands for the power supply contracted, enter the average cost, weighted as indicated below, and 0% in the Surcharges on the price per kW for all the periods. FIGURE 8.16

Distribution of the power supply contracted by periods:


249

Distribution by Periods:iR

Coefficient of Distribution of the Power Supply

for Period i, , corresponding to the % of power supply contracted for each period in relation to the Nominal Power Needed, kWPNN to pump the design flow rate, dQ , from the intake pipe at the nominal design head,

dH , with weighted efficiency pη .

p

ddkW

QgHPNN

ηρ

⋅⋅⋅

=1000

With the Coefficients of Distribution of the Contracted Power Supply, it is

possible to consider a uniform contract for all the periods equal to kWPNN ( iR = 100% in all periods) or suppose that in certain more expensive periods less power will be used. To configure periods with no power supply, the respective Coefficient of distribution of contracted power supply will be 0%.

If you want to record a contracted power supply of more than kWPNN , for example to include the power consumption of equipment, losses and safety margin, you

can indicate values of iR higher than 100%.

Alternatives to entering distributions and surcharges per periods for power and energy using average weighted values:



As an alternative to user-specified individual coefficients iIkWh and iV , you can

enter directly as Base Price kWh ( basePkWh ) the weighted price per kWh contracted, basePkWh , previously calculated using the expression:

V

)IkWh(1PkWhVPkWh

NP

i

ibasei∑

=

+⋅= 1 100

and then establishing iIkWh = 0% in all the fields in FIGURE 8.16




250

)100

1(100

11

1i

NP

ibase

iNP

IkWPkWRNP

PkW +⋅⋅= ∑=

and then establishing iR =100% and iIkW = 0% in all the fields in FIGURE 8.16

If the contracted power supply in all the periods is the same (constant iR ) and

equal to 100% of kWPNN , PkW it will be:

)100

1(11

1i

NP

ibaseNP

IkWPkWNP

PkW +⋅⋅= ∑=

That is, the average weighted price of the contracted power supply is simply the sum of the prices per kW per month of the contracted power supply, extended to all periods.

Example:

♦ Base Price per kWh: Base price, for example that of the cheapest period. 0.054 €/kWh.

♦ Base Price of Contracted Power Supply, for example that of the cheapest period, 0.1 €/kW per month.

P1 P2 P3 P4 P5 P6

Volume Distribution (m3) 62.408 124.817 303.129 303.129 900.472 2.763.825

Volume Distribution (%) 1,4 2,8 6,8 6,8 20,2 62

Energy Surcharges (%) 110 90 70 30 10 0

Power Distribution (%) 30 30 50 50 100 100

Power Surcharges (%) 80 50 40 40 10 0

The equivalent parameters of this specification, using average weighted values for the price per kWh and per contracted Kw would be:

♦ Base Price per kWh = Average Volume weighted price:

+⋅+⋅+⋅= − 3,1068,01,1202,00,1620,0(€054,0 1kWhPkWh


251

)1,2014,09,1028,07,1068,0 ⋅+⋅+⋅ = 0,060955 €/kWh.

♦ The total annual volume, , 4.457.783 m3, is assigned to the first period, P1, being the surcharges in the energy terms null in all periods: 0%, 0%, 0%, 0%, 0%.

♦ Base Price of Contracted Power Supply: Price per kW/ month weighted in contracted power

+⋅+⋅+⋅⋅= − 4,15,01,10,10,10,1(€1,061__& 1

61 kWperiodmonthPkW

)8,13,05,13,04,15,0 ⋅+⋅+⋅+ = 0,449 /6 = 0,074833 €/kW month & period

♦ Surcharge on base price of contracted power supply: 0%, 0%, 0%, 0%, 0%, 0%

♦ Distribution of contracted power supply: 100%, : 100%, : 1000%, : 100%, : 100%, : 100%.

Editing electricity prices:

Databases of Electricity Prices.

An access window lets you see and manage the data in the Electricity Prices database, which stores the prices of energy and power, and different price discriminations for both invoicing terms. These data can be selected in step 7, dealt with in this section. The “Prices” button (Figure 8.16) accesses this tool for managing Electricity Rates (Figure 8.17), described in section 11.7 Electricity Price Databases.

FIGURE 8.17 Editing panel Electricity prices and time bands.


252

STEP 8: UNFAVOURABLE PREDICTIONS

This dialogue gives the designer the possibility of defining a series of safety margins in parameters where there is uncertainty about the real values. The sizing assistant lets you set simultaneous generic criteria, applied to all stretches of the network, and others specially defined stretch by stretch for specific Pipes.

FIGURE 8.18 DIAMETER OPTIMISATION assistant. Step 8: Unfavourable Predictions.

♦ Singular losses: Lets you define equivalent lengths for incorporating singular head losses.

• Overall Added Equivalent Length, or an equivalent length as a percentage to add to the length defined for each stretch, to include the existence of specific singular losses.

• Define Equivalent Length by stretches. Enables setting, for each stretch of the network (via the window in FIGURE 8.19) an equivalent length, disabling for sizing purposes the length specified for the element in the current network (without OVERWRITING it).


253

FIGURE 8.19 Define Equivalent Length by stretches.

♦ Forced Roughness. Similar to the above case, lets you set, overall or for a group of Pipes, different roughness to those set in the pipes database for each Material during optimization.

♦ Increased Static Pressure for pressure rating. Increases in static pressure for the pressure rating of Pipes can be set overall or by stretches of Pipe, enabling the cost of the network to be refined and reduced, if using an analysis of transitories in the network the pressure increases are adjusted by areas or stretches, according to the maximum surge values calculated in the network transitory.

STEP 9: MATERIAL

GESTAR uses the database of Materials associated with the network, in Microsoft ACCESS 97 format


254

FIGURE 8.20 DIAMETER OPTIMISATION assistant. Step 9: Material.

♦ Materials available. All the materials defined in the database associated with the network appear in the selection list.

♦ Material to Use. Include in the list the Materials you want taken into account for optimization.

♦ Range of Internal Diameters. This option lets you restrict the size of Pipes taken into account in optimization for each material.

♦ Range of Working Pressures. Lets you limit the Pipe Database which will form part of the optimization for the Material selected from the list of Materials to use according to the working pressure they can withstand.

As mentioned in section 8.1, when making recommendations for creating Pipe elements, a correct definition of the Materials in the economic optimization process will be of vital importance for obtaining optimal dimensions.

STEP 10: SUMMARY

FIGURE 8.21 DIAMETER OPTIMISATION assistant. Step 10: summary

♦ Save Data. If you choose this option, the data defined during the sizing process will be saved and accessible for later sizing by the user via the OPTIMIZATION assistant.


255

As explained in the dialogue in the last step of the assistant, when a network with a Pump element at intake is sized, GESTAR will transform the Junction node downstream of the Pump element into a Known Pressure node, as seen in the example in FIGURE 8.22. This Node will function like an intake node, disabling the real intake node and Pump element. From the new Known Pressure node, the user will receive information about the nominal pressure required from the pumping station to meet the requirements defined with the obtained diameter results.

FIGURE 8.22 Example OPTIMIZED Network with Pump Element at intake.

When the optimization process finishes successfully, the results obtained will be loaded onto the network, and saved as a PDF file for later consultation (see section 7.7 RESULTS OUTPUT, p. 207).

8.5 DEFINITIONS AND CRITERIA FOR SIZING TURN-BASED NETWORKS.

For the design of irrigation networks based on taking turns, each section will have as many design flow rates as there are turns in which it participates. The design flow rate of a section depends on the turn, and each of these design flow rates will equal the sum of the maximum flow rates of the hydrants (or Consumption Nodes in general) downstream, considering all the hydrants in the turn to be open. The greatest design flow rate of the first stretch or main pipe of the network will be the Nominal Flow Rate of the turn-based strictly-branched network (QNt). Due to the tendency to exponential growth of prices of the largest diameters, most of the savings when designing a turn-based network come from reducing the flow rate in


256

conduits shared by most of the network, especially in networks with very long main pipes. Therefore, establishing a division of turns which reduces the flow rate circulating in a significant amount of the network, compared to what would be obtained with a probabilistic design of the flow rates for demand-based networks, will be a strategic goal when establishing irrigation turns. To get a lower QNt than the Qd of on-demand networks, the maximum flow rates of the hydrants, irrigation times and the duration and number de turns must all be addressed.

The maximum flow rates are established to supply the daily volume needed by the plot, in the month of most need, within the JER.

Ratio of Maximum Flow-Number of Turns.

In the case of turn-based networks, the effective irrigation time of the hydrant is the duration of the irrigation turn, as it cannot be opened outside the turn. Therefore, the Effective Day of Irrigation of the Turn (JERt) is the same as the duration of the turn.

Equation 8-1. Effective Day of Irrigation of the Turn

The number de turns of the network, NT, is set so that the total duration of all the turns does not exceed the time established as the JER of the network. The maximum flow rates, together with the surface area and assigned fictitious continuous flow rate, determine the times the hydrants need for irrigation. The irrigation times of the hydrants condition the duration of the turn and how many turns are possible in a given JER. Theoretical Flow (Dt) is the minimum flow rate needed to supply the volume that meets the needs of the crops in the hydrant area on one day of the month with the highest need, in a given irrigation time shorter than the JERt.

To calculate the Dt of each hydrant in a turn-based system, the following expression is

applied:i

ii T

hrsSupQfcDt 24⋅⋅=

Equation 8-2. Calculation of Theoretical Flow Where Dt Theoretical Flow (l/s) needed to supply the volume needed by the plot on one day in the month of highest need, with the established irrigation time. i Hydrant T Established irrigation time of the hydrant (hrs) Qfc Fictitious continuous flow rate of the area (l/s ha and day) Sup Surface area (ha) For various reasons, the Theoretical Flow is usually corrected to a Standard flow (DN). Thus, the irrigation Tnec is not the same as the one initially established and most be recalculated, applying the expression of the Equation 8-25, setting the DN as the supplied flow. . If the new irrigation times of the hydrants are lower after the correction, some freedom is allowed regarding the time when the hydrant is opened within the JERt, allowing more flexibility in the use of the network, or the possibility of adding another turn.


257

TNecMaxJERTurnosn <=º

Determining the number of turns, NT

The number of turns in which the irrigation outlet openings can be grouped depends directly on the Effective Day de Irrigation (JER) considered. This figure, which depends on the type of network and on various agricultural factors, will determine the good design of the irrigation operation and the sizing of the pipes. When establishing the number of turns, there must be enough time, within the limits of the initial Effective Day of irrigation, to water all the turns with the established flow rate; i.e., the time assigned to each turn lets the necessary volume of water be supplied to the plots associated with the turn, for the month of highest need. To find the highest possible number of turns, the times the hydrants need for irrigation will be assessed, applying the following expression:

Ni

ii D

hSupQfcTnec 24⋅⋅=

Equation 8-3. Irrigation Time of Hydrant with Standard flow.

Where Tnec Time needed to supply the volume needed on one day in the plot in the month of highest need, with the established standard flow. (hrs) i Hydrant DN Established standard flow (l/s) Qfc Fictitious continuous flow rate of the area (l/s ha and day) Sup Surface area (ha)

Equation 8-4. First approximation

of no. of Turns

The maximum Tnec of all the hydrants of the network should determine the initial number of turns, and the minimum irrigation time the turns should have.

JERt = T Nec Max Equation 8-5. Effective Day of Irrigation of the Turn

The irrigation times depend on the set flow rate and will condition the number of irrigation turns. The size of the surface areas, the needs of the crops and the JER are parameters set by the characteristics of the area, the crops, and the type of pressurised feed of the network, which are properties of the network which cannot be modified. At the design stage, the maximum flow rates can be adjusted so that the irrigation times favour establishing turns. To reduce the flow rate at intake and thus obtain more economical sizes, as many turns as possible will be sought, ensuring that the sum of the duration of all the turns does not exceed the JER, and that the irrigation time of the hydrants does not exceed the duration of the turn they belong to.


258

Sometimes not even two turns can be accommodated in the network, even when the flow rates are increased as much as possible, with the maximum irrigation Tnec exceeding the JERt. In these cases, by evaluating the Tnec of the hydrants and establishing irrigation turns of different durations, it may be possible to fit in more turns than the guidelines suggest. The turns of different duration will be applicable and effective in the cases where the Tnec of the hydrants are heterogeneous, with the Tnec of only some of the hydrants exceeding the initial guideline JERt.

Turns of different durations to fit in an many turns as possible

FIGURE 8. 22 shows a case in which, thanks to the use of turns of different durations, two turns could be established where the initial indications, without analysing the irrigation times in detail, were that a turn-based network would not be possible.

FIGURE 8. 23 Distributing turns of different durations

The minimum duration of the turn must be the maximum Tnec of the hydrants grouped in the turn. If the irrigation times are not uniform, some freedom is possible in when to open the hydrants with the lower Tnec. Even with this phenomenon, the design flow rate for the turn will be the cumulative flow rate, or the sum of all the maximum flow rates, as a conservative measure. If the irrigation times are not uniform, giving some freedom as to when to open the hydrant, a probabilistic design flow rate could be considered within each turn. This approach would reduce the intake flow rates and the cost of the pipes, but the other effects of this must be taken into account: rigidity in management and a lack of room to manoeuvre if unexpected events require changes to the operations..


259

8.6 ESTABLISHING THE IRRIGATION TURNS

The process of sizing a network with irrigation turns requires turns to be assigned to each hydrant beforehand. To get the desired savings from turn-based irrigation, the groups of hydrants which will be watering at the same time must not be arbitrary, but should be grouped according to one or more criteria. The properties of the hydrants to consider when distributing them among the different irrigation turns include their level, maximum flow rate, the time needed for irrigation, etc., and other topological and operational properties depending on the individual characteristics and uses of each network. In order to lower the costs of the system, it is preferable to distribute the intakes corresponding to a turn throughout the network, so that most of the conduits transport approximately the same flow rate in all the turns. This will give a lower but permanent flow rate in the conduits, reducing the cost. IMPORTANT: assigning all the hydrants in a branch or sector to the same turn (a management configuration sometimes used in poorly organised and/or low-tech systems, as it is easy to control) is not economical, as it means sizing branches so that all the hydrants can be open simultaneously a small part of the total time. This configuration of turn irrigation is actually more expensive than an on-demand design. Once the numbers of turns and their JERt are organised, the hydrants can be grouped. The criteria and strategies proposed for this grouping are:

♦ Design flow rate at intake (maximum flow rates of the hydrants). The hydrants are grouped in the different turns, adding up to a flow rate at the intake which is lower than that obtained with the Clèment formula, and as homogeneous as possible for all the turns. If there are large differences between the maximum flow rates of the hydrants, to facilitate this operation, we recommend classifying the hydrants by ranges of maximum flow rates, making it possible to distribute them equitably.

♦ No accumulation of the flow rate in end branches. In the branches, the turns will be assigned so contiguous hydrants on the same branch do not coincide in the same turn, to avoid overloading it.

♦ Necessary irrigation times. It may be useful to group all the hydrants with a larger Tnec in a turn with a duration suited to this, or not to group the hydrants with a larger Tnec in the same turn, to leave some leeway and not reach the QNt during all the hours of the turn.

♦ Level (if there is a possibility of creating different pump levels). If there are areas with clearly differentiated levels, and the network is fed by direct pumping, the establishment of irrigation turns at different nominal heads is a strategy which would reduce the costs of pipes, if the flow rates are lower than with on-demand, and the cost of power, as pumping can be adapted to the pressure needs of each turn, avoiding wasting power on the hydrants that need less pressure.


260

The various ways to assign a turn in the GESTAR network to each of the hydrants making up a turn-based network are described below.

The toolbar includes the icon

TURNS

(p. ¡Error! Marcador no definido.). In the window shown in FIGURE 8. 23, the user can click the icon to generate the number of turns needed for the network being studied (according to the requirements of the designer), stipulating the number of hours of irrigation considered for each turn. Similarly, this tool will be very useful for assigning the same irrigation turn to several hydrants (known demand nodes; hybrid nodes). The operation for this window (FIGURE 8. 23) is described below.

FIGURE 8. 24 Turns window.

♦ Turns. Next to Turns, two icons are enabled, for adding new turns ( ), which will be available in the list on the left side of the window (FIGURE 5. 19) and will be named according to the correlative order, or eliminate turns ( ) after selecting them from the list. The changes to this list with these icons will always be saved when closing the window with the window close icon (upper right corner, FIGURE 5. 19).

♦ Turn. This option shows the number of the turn selected in the list, which can now be edited for configuration. The table (FIGURE 5. 19) specifies the components of this Turn.

♦ No. of hours. In the panel no. hours, the user can set the number of hours of irrigation the planner allocates to the selected Turn (decimals are accepted). This value will be taken into account if simulations are carried out in Evolution of Turns over Time (see p. 281).


261

♦ Total Q. In this cell GESTAR shows the sum of demand flows of the hydrants included in the Turn.

♦ Turn Components Through the Turns icon in the window shown in FIGURE 5. 19. Two icons are enabled, allowing new hydrants to be added to the turn ( ), or excluded ( ). To add them, you will need to do a Multiple Selection of the hydrant/hydrants to include in the Turn (rectangular, see p. 72, or irregular, see p. 74 ). To exclude a hydrant from the turn, just select it in the table and click the button .

♦ Apply turn. The specifications of the selected turn are saved and loaded to the network.

♦ Cancel. Closes the Turns window without applying the specifications for the selected turn to the network.

Individual allocation

FIGURE 8. 25. Known Demand Node. Turn option enabled.

When making an individual selection (see p. 72) of a Known Demand Node or a Hybrid Node, the user can make a particular allocation for that node of the turn, after enabling the Turn option in the Opening panel (FIGURE 8. 24). Be default, using the drop-down menu the user will have two turns available to assign to the hydrant. To generate a larger number of turns in the open network, the user must do


262

so beforehand using the icon Turns in the toolbar (FIGURE 8. 23), and they can then be selected from the drop-down menu.

On the top line of the toolbar, next to the icon

Opening Hydrants in an Irrigation Turn

, there is a drop-down menu similar to FIGURE 8. 25. .

FIGURE 8. 26. Drop-down menu, Opening Hydrants in a Turn

Select the corresponding turn from the drop-down menu, and only the hydrants assigned to that turn will remain open in the network, with a flow rate value equal to that of Demand. If the network contains Hydrants whose opening or closing has been declared Unconditionally (see p. 76), their status will not be changed after selecting Opening Hydrants in a Turn from the drop-down menu (FIGURE 8. 25). Next, the user can choose the option Calculate (see p. 66), obtaining an initial hydraulic analysis of the active turn, letting him review the flow rate values assigned to the Pipe Element at the Intake Node by the sizing assistant (FIGURE 8. 26), or after the sizing process, exhaustively checking the operating conditions (see p. 272). GESTAR also facilitates the analysis of the system using Evolution over Time tools for Turns (p. 281).

8.7 OPTIMISATION of the TURN-BASED NETWORK

The user accesses the process of optimisation of the turn-based network via the command Turn-based Network Optimisation from the GESTAR Sizing menu. The strictly-branched network to be sized must be created beforehand, as specified in section 8.1, PREVIOUSLY GENERATED TOPOGRAPHY. . In the same way, before opening the Turns sizing assistant, you must have assigned an Irrigation turn to each Hydrant (see section 8. 6).

The technique used to optimise Diameters identifies the critical sector or irrigation turn (the irrigation turn whose critical path is the one with the smallest hydraulic slope), sizing the main pipe to serve at least the entrance pressure needed in the sector or hydrant belonging to that path, considering this stretch to be prioritised.

CHARACTERISTICS OF TURN-BASED NETWORK OPTIMISATION

The process begins sizing each of the turns, as independent irrigation networks, with a design flow rate of the stretch in the turn equal to the sum of the maximum flow rates installed downstream, using the Improved Economical Series Sizing Method (Gonzalez and Aliod 2003, see Final Chapter REFERENCES). Next, the critical turn is selected, defined as the turn whose critical path has the smallest slope. The critical path


263

with the smallest slope of all the turns will be considered the priority path. For this priority path, the first solution will be the results of the sizing of the critical turn. In the remaining pipes, the diameters are unassigned, and will enter as unknown in the next turn by turn optimisations.

Next, all the turns will be sized, forcing the diameters of the stretches shared by the layout of the priority path discussed above, making it possible to adjust the diameters, given that the shared layouts will have larger diameters than needed to reach the required pressure on second-order critical layouts. The process is repeated until all the pipes have been configured.

This gives a sizing which ensures the irrigation sectors in a plot, or the hydrants in a turn-based network, work well, reaching at least the pressure required in the most critical stretch, and reducing as far as possible the other diameters to adjust the pressure in non-priority turns or sectors, using the “excess diameters” installed upstream in a stretch needed to feed other turns, making the installation more economical.

The assistant for Optimisation of a Turn-based Network deliberately omits STEP 1, so that the numbering of the other STEPS coincides with that used in the Optimisation of an On-Demand Network.

ASSISTANT FOR OPTIMISING DIAMETERS IN A TURN-BASED NETWORK

STEP 2: Review flow rates

FIGURE 8. 27. Assistant for the network optimisation process - Step 2: Review flow rates

The assistant gives the user a summary table (FIGURE 8. 26), with information on relevant parameters for each turn, obtained from the values previously defined in the network by the user, for review.

• Q. Flow rate circulating via the Pipe element of the Intake Node for this irrigation turn. This is the result of the accumulation of flow rate Demands for the hydrants included in the turn (FIGURE 8. 24).


264

• Sup. Sum of the Area Watered by the Hydrants (ha) contained in the turn.

• T max. Time the hydrant is open (in hours) (see APPENDIX PROBABILITY OF OPENING OF A HYDRANT, p. 469), for the hydrant included in en the turn with the greatest need for irrigation time (T maximum).

STEP 3 - STEP 10*

Operates as documented in Chapter 8. 4, OPTIMISATION of the ON-DEMAND NETWORK. pp. ¡Error! Marcador no definido. et seq.

*In the Turns Optimisation Assistant, STEP 5: RESTRICTIONS, the option of locking stretches of network so their diameter is not modified during optimisation (panel Installed Pipes, FIGURE 8. 13), is not accessible.


265

9 HYDRAULIC ANALYSIS

9.1 CONCEPTS AND RECOMMENDATIONS

The purpose of this section is to demonstrate the possibilities and working methodologies of stationary hydraulic analysis processes, in a series of scenarios and hypotheses which help to verify the design conditions and operational margins of the system.

The various utilities for network analysis provided in GESTAR offer the simulation of behaviour, both in mesh topology and in branched networks (see APPENDIX I p. 441). Random or deterministic demand scenarios can also be created, accepting the hydraulic simulation of the number of scenarios desired and considered meaningful by the user. In irrigation networks it is normal to find hundreds of hydrants. If you want to study the behaviour of the network during the design stage of the installation, with diverse hypothetical situations with different simultaneity conditions, specifying the open hydrants one at a time would be an extremely tedious process for the designer, especially if you want to see how the system behaves under multiple scenarios and combinations of demand. The possibility of creating scenarios in the programme which respect certain overall conditions is very useful, as this utility makes the implementation of scenarios in different operating conditions much quicker and more convenient.

It also provides a wide range of options for modelling demand by using different types of node (Known Consumption nodes, Hybrid nodes, Emitters and Sprinklers).

It should be pointed out that for the calculation process to be successful, nodes isolated from the reference pressure should not exist in any simulated situation, as for example, if a closed valve (see , p. 95) were implemented in a Pipe Element just before a node at the end of the line (see).

FIGURE 9.1 Example of node configured without reference pressure. NO CALCULATION


266

FIGURE 9.2 Example of configured node 227 open. CALCULATION

This situation should not be confused with the possibility of implementing closed Nodes in a scenario, which would be simulated with specific options for opening or closing (see FIGURE 9.3).

FIGURE 9.3 Example of configured node 227 closed. CALCULATION

Using the programme menu Calculations, you will find various options explained below in this chapter (Recalculate, Automatic), and which make it possible to save calculation time in the simulation.

9.2 CONFIGURING GENERAL CHARACTERISTICS

Before the hydraulic analysis, we advise you to review the configuration of a series of general characteristics, specifying the properties of the fluid, the formulation of lineal head losses to use, and general criteria for considering singular losses. You can find these under the Menu: Calculations/ Characteristics (FIGURE 9.4).


267

FIGURE 9.4 Preferences/ Characteristics.

Confirm that the physical properties of the circulating fluid loaded by default are correct, enabling their modification manually or through the Fluids database (see p. 157), and the type of formulation for continuous head losses.

If desired, the existence of singular losses distributed evenly throughout the pipelines can be considered, treating them as equivalent to an increase in length, of the percentage you think suitable. Thus, if this was a design criterion during the sizing phase (see p. 252) its consideration will be necessary in the phase of verifying optimisation results. Also, if considered desirable (in a network with many intersections, for example) you can include the automatic calculation of losses at bifurcations, where three pipes converge (see APPENDIX V LOSSES AT BIFURCATIONS, p. 471).

9.3 CONFIGURING THE NETWORK

Before running the simulation, you must review the correct configuration of a series of physical and topological parameters, to obtain results and bring these as close as possible to the real behaviour. If analysing the system in its temporal evolution, you should complement the information with the description of changes in demand time and the state of activation of the components. The aspects which must be given special care are described below.

Check that in no simulated state are there nodes cut off from the reference pressure.

See detailed explanation in section 9.1 CONCEPTS AND RECOMMENDATIONS, p. 265.


268

Adjusting data and reproduction of singular losses and set points in automatic regulating valves

In the case that you consider that the maximum flow rate of any hydrant does not agree with the real consumption (e.g., a series of later measurements show that consumption is less), there are tools for Consumption Nodes and Hybrid nodes which permit a precise calibration of demand (see , p. 82 and , p. 85).

Thus, from the Pipe Elements (see , p. 95), you can add Accessories, Singular losses or Valves with a given degree of closure, to reproduce the computation and location of singular losses in greater detail.

Pressure regulating, pressure sustaining and flow limiter valves (see , p. 115), can be implemented as independent hydraulic elements, bearing in mind several precautions for their use (see p. 118).

WARNING: The configuration of combinations, parallel or in series, of regulating valves cannot be arbitrary, as otherwise there may be convergence problems.

Configuring pump groups

The introduction of the points of the performance curves of the individual discharge equipment, working at a set rotational speed, can be done in tabular form or from a database (see , p. 110). .

The possibility of introducing performance curves arbitrarily is also a determinant for the very simple, although rigorous implementation of the behaviour of direct pumping stations with any type of regulation enabling a system curve to be followed, using one or more variable speed pumps (or the net pump head curve of the parallel association if all the groups are fixed speed). For this, it is sufficient to represent the pumping station as a whole using a pseudo-pump where the discharge height vs. flow curve is precisely the curve set point set on the pumping station robot, and the net power (or performance) vs. flow curve corresponds to the composition and type of regulation used. These curves can be set as tabular data by the user or obtained automatically using the tools which GESTAR 2008 provides under the menu Regulation of Pumping Station (see chapter 10.5. EVALUATION OF POWER COSTS AND OPTIMISATION OF PUMPING STATION REGULATION p. 314).

Enter the temporal and logical operating set points of the components

In the case of hydraulic analysis with temporal evolution, the patterns of opening/closing components over time must be established, as well as the modulation factors of consumption and the control set points of the regulated devices, if any. As it is also possible to calculate a series of instantaneous total energy parameters, if you want to use these resources, you will need to define the set points and working periods of the equipment (individual pumps or pumping stations) and the energy prices and power of the irrigation system.

When the components of the network, including the pump groups (whether individual pumps or pumping stations), have temporal programmes (open/close,


269

start/stop), these can be configured from the tables of Patterns specifying the open/closed status (start/stop for pump groups) for the time given. If there are also operations conditional on the state of other components, these will be reproduced using Logical set points created for this purpose (see p. 281).

In simulations with temporal evolution, fluctuation of demand over time at a point of consumption in relation to the consumption assigned to the hydrant, due to the shared use of a hydrant or the irrigation of different sectors, can be reproduced using the assigned modulation parameter.


270

9.4 SIMULATING RANDOM SCENARIOS

9.4.1 TOOLS FOR GENERATING RANDOM SCENARIOS

You can access the tool for creating random demand scenarios with random opening of consumption Nodes and Hybrid Nodes via the icon

Access to random scenario creation

, on the top row of the toolbar. Click this button to bring up the window in FIGURE 9.5. When creating and simulating these scenarios, the response of the network can be checked against different conditions of real demand, corresponding to a given percentage of opening of Known Consumption and Hybrid nodes, this percentage selected by the user according to the type of condition you want to analyse. This percentage represents the simultaneity of demand in the network in relation to the total potential of the installation.

Individual random scenarios can be created from the window in FIGURE 9.5 or you can use the Multiple Scenarios utility of the demand network. For the former, several tools are enabled which let you modify the conditions of each individual scenario according to your instructions. Access to the second option is via the associated button.

FIGURE 9.5 Dialogue for Random scenarios

♦ Type of Scenario.

• Homogeneous Probabilities. The option selected by default is the creation of scenarios with Homogeneous probabilities of opening for each Consumption or Hybrid Node (all the Nodes have the same probability of opening).


271

• Different Probabilities. For this option to be effective, you must have correctly defined the specific fields in the windows for all Consumption and Hybrid Nodes setting the probability of opening. Selecting the option Different Probabilities, the probability of opening for each node will be weighted in the creation of the random scenario. (Consult the methodology of calculating the probability of opening of each hydrant in Appendix IV, p. 469, and in the windows defining the Known Consumption Nodes, p. 82and the Hybrid Node, p. 85).

• Selection of Percentage Open When the In Number option is chosen, GESTAR will randomly open Consumption and Hybrid nodes up to a number, so that, in relation to the total installed nodes of both types, it reaches the percentage chosen using the scroll bar to the right of the window (FIGURE 9.5). If the option In Flow is enabled, GESTAR will randomly open Consumption and Hybrid nodes until the joint instantaneous demand reaches the percentage selected with the scrollbar, in relation to the sum of instantaneous demand of all nodes of both types (this option is not implemented in the current version of GESTAR). If the network has enough hydrants with similar consumption demands, the results of the In Number and In Flow options are the same.

♦ Criteria for Scenario. The user will have already defined a series of Nodes which are kept unconditionally open or closed, and are not affected by the random openings, using the button (see p. 76). When using the tool , from this quadrant, the number of Unconditionally Open Nodes and the number of Unconditionally Closed Nodes in the current network will be specified in the quadrants. Next, the number of Assignable nodes, those which are not subject to unconditional opening or closing, is specified. Next to the heading % Assignable Opening the selected percentage of opening in relation to the total assignable nodes is specified using the scrollbar. Finally, the number of total nodes in the network is obtained, and the Overall % opens (percentage of open nodes, including those unconditionally open, in relation to the number of total nodes).

♦ Results. From this quadrant the resultant sums are specified for the number of unconditionally open nodes in the network, unconditionally closed, Assignable open, Assignable closed, Total open and Total Closed.

9.4.2 CREATION AND ANALYSIS OF INDIVIDUAL RANDOM SCENARIOS

Initially, the use will use the scrollbar to set the percentage of active hydrants to be open in relation to the total number on the network. Each time a percentage is applied, (Create button in the window in

Creation of individual random scenarios

FIGURE 9.5) the open/closed hydrants created by GESTAR are shown, as well as the resulting percentage of the Random scenario creation routine. Hydrants disabled using the Restricting Random Scenarios button (p. 76) will not change state with the random action.


272

If you are not satisfied with the offered distribution and/or percentage, you can apply the percentage again. In the case of networks with very few active hydrants, slight deviations may appear in the results obtained compared to system values, due to the rounding applied to obtain a whole number of open hydrants.

After the creation of an individual scenario, you can resolve the hydraulic and energy state given by clicking the button

Simulation of the created scenario. Automatic calculation

on the toolbar, or via the Menu: Calculations/ Calculate. When this option is selected, as specified on p. 66, all the data will be communicated to the calculation module, which processes the information, and runs the solution of the scenario.

It is very useful, making it much quicker to obtain results, if before using the tool , you enable the Menu option: Calculation/ Automatic (see p. 154). In this case it is not necessary to give the order to Calculate; every time the Create button in this window is clicked, GESTAR will automatically run the calculation of the scenario. Click the Create button as often as desired to create new scenarios which will be immediately calculated.

When the desired distribution is reached, click the button Exit in the window in FIGURE 9.5.

Each time a scenario is calculated, the results are returned to the graphic module, and appear in the network schema on the screen with the specified variables (see Values in Nodes and Values in Elements, p.

Checking operating conditions

71) and colour codes (see Colour Codes, p. 66).

You can run checks immediately, as you will receive specific graphic information, if you have activated any of the available alarms (see Menu, Alarms/ Configuration (p. 162). It is especially clear if you select two special alarms called Negative Pressure and Pressure Below Set Point for Nodes with Regulation, which will indicate if Nodes of any kind have negative pressure, or calculated pressure below the set point. It will also be normal to require an analysis of velocity in the pipes to ensure that none of them exceeds the maximum design value considered, for which you can use the Alarms by Range of Values, which enable the study of this and other variables. For this type of alarms, as well as graphic markers, there are detailed reports in text format accessible via the Menu: Alarms/ Reports (see p. 165).

Remember that the numerical results obtained for the Nodes and Elements of the current calculated scenario can be viewed via the Menu: Results/ Numerical List or the icon on the toolbar (see p. 161).

RECOMMENDATION: After sizing a branched distribution network for operating to demand, you will need to check its behaviour at least for the design conditions, using the simulation of a sufficient number of random scenarios with a percentage of open hydrants equal to the simultaneity of the design. The simultaneity of the design is defined as the design flow rate at the intake line divided by the total installed flow rate, multiplied by 100.


273

9.4.3 CREATION AND ANALYSIS OF MULTIPLE RANDOM SCENARIOS

To automatically create and analyse numerous random scenarios, enable the option Multiple Scenarios in GESTAR by clicking the button in the window shown in

Automatic creation of multiple random scenarios

FIGURE 9.5. The dialogue in FIGURE 9.6 will appear (see p. 63).

This window lets you set the number of random scenarios to be automatically created and calculated, one after another, for each user-defined percentage of open Consumption and Hybrid Nodes or for each set consumption (option not available).

FIGURE 9.6 Multiple Scenarios

♦ Type of Scenario. From this quadrant the user can select the type of probability and parameter for application (detailed explanation on p, 270) to consider in obtaining the scenarios in series.

♦ Add. Each time you enter a Number of Scenarios-Percentage pair, filling the appropriate fields in with the values, click the Add button so that they become part of the list of Multiple Scenarios.

♦ Delete. To delete a pair of values from the list, select them by clicking on them with the mouse, then click on the Delete button.

Another way to enter a list is opening a Multiple Scenarios file (extension “.srt”)

using the button from the dialogue (FIGURE 9.6). These files must have been

previously saved with the button .

♦ Accept. Once a list of Multiple Scenarios has been set and the alarms configured if desired (button ), click the Accept button to create as many random scenarios as you have specified, with the general opening percentage set for each one. As the scenarios are generated, the corresponding hydraulic simulation will be run and the results filtered by the set alarms.


274

♦ Recalculate. Also, if you click Accept with the Recalculate option selected, in each scenario created after the first the calculation of the solution to the new scenario will begin with the results of the pervious random scenario. This option can save calculation time in large networks with many scenarios to calculate, although it is not recommended as a first option if regulating valves exist, as it can cause a lack of convergence.

♦ Calculate averages with open hydrant. The default option, so that when obtaining average results for the variable pressure in hydrant, only the values of scenarios where the hydrant was open will be taken into account.

When the sequence of scenarios has been created, calculated and filtered with the range of alarms, a brief report will appear at the bottom of the window (FIGURE 9.6) with the number of steps calculated (total scenarios proposed by the user), the number of successes (number of valid scenarios where the variables remained within the ranges defined in the configuration of the alarms) and the number of errors of calculation produced, if any.

Scenarios which do not trigger any alarm are called Valid scenarios. Scenarios which trigger one or more alarms are called Critical scenarios.

Next, if Critical scenarios have appeared in the range of cases, and the option Save Critical Scenario has been enabled in the Configuring Alarms window, (see p. 161) two small icons will appear (see FIGURE 9.7).

FIGURE 9.7 Managing Valid / Critical Scenarios.

The icon with the agreement symbol will give access to the visualisation and consultation of a summary of results of the scenarios classified as Valid Scenarios. This summary contains the maximum, average and minimum values found throughout the series of cases analysed for all variables.

The icon gives access to consultation of individual Critical Scenarios.

If no alarm was triggered in the automatically created and simulated cases, either because the variables did not trigger any activated controls or because there were no enabled alarms, these icons will not appear and the process concludes by giving direct access to the summary of results of Valid Scenarios.

Depending on the options implemented in Configuring Alarms, accessed via the button

Options for configuring alarms

(or the Menu: Alarms/ Configuration), the results of the created and


275

simulated scenarios will present a different structure and can be used for complementary purposes. (For more information about alarms, consult p. 161)

The options for configuring alarms are:

A) Random Creation and Multiple Scenarios WITHOUT active alarms: when all alarms are disabled, whatever the results of the scenario, all scenarios will be classified as valid. This option provides the maximum, minimum and mean values taking into account all the created scenarios, and is useful for estimating the extreme limits and average values of all parameters. It is useful for identifying synthetically the absolute extreme values of a certain degree of simultaneity in demand, but it does not identify how frequently these extremes occur, nor the occurrence, location, or frequency of conditions, which while not the least favourable, may be unsuitable.

B) Random Creation and Multiple Scenarios WITH active alarms: If the set of randomly generated scenarios does not breach any condition which triggers an alarm, this is case a). If Critical Scenarios appear, two sub-cases arise, depending on the option chosen for the checkbox Save Critical Scenarios.

B1) Option Save Critical Scenarios disabled: The summary of maximum, minimum and mean results will be shown, but only for scenarios classified as Valid, while the results for Critical Scenarios will be discarded. If there are no Valid Scenarios, a message will indicate this, and the process stops, returning the system to its initial condition.

B2) Option Save Critical Scenarios enabled: Scenarios generating alarms are saved to disc with all details for later consultation. The Valid Scenarios (if any) will be used to create a summary, as in A). This option is useful as a complementary analysis after a configuration of alarms of type A), as it lets you set:

♦ The frequency of appearance of extreme values

♦ The frequency of breaches of recommended ranges and set points

♦ The location of nodes, elements or entire areas showing dysfunctions

♦ The interaction, cause and effect relationship and phenomenology of unfavourable conditions.

All this enables you to judge the severity and probability of occurrence of the most unfavourable combinations, and facilitates the identification, diagnosis and if possible the preventive or corrective remedy of hydrodynamic and power problems.

For Valid Scenarios, the maximums, minimum and averaged values of all variables can be shown numerically, in tables, and graphically, on the network map.

Consulting average, absolute maximum and minimum values of Valid Scenarios.

From the toolbar icon Colour Code (button , see p. 66 ), or from the Table of Results, the values you want to view are selected using the fields Max., Min. and Med., respectively, in all types of visualisation (numerical values, colour code, table of Results) and data export. The default configuration of the colour code for each variable


276

uses equidistant ranges between the absolute minimum and maximum values found in all the created scenarios.

Another specific mode for consulting results is based on the use of the secondary mouse button, which now shows the maximum, average and minimum values of the most relevant variables of each component, obtained among the Valid Scenarios. Position the mouse over the node or element you want information about. The information viewed depends on the type of node. Thus, for a Consumption or Hybrid node, when you click the secondary mouse button, a window appears like that in FIGURE 9.8, also giving information on the average, maximum and minimum Pressure Margin, if the pressure set point is defined, depending on the visualisation option. If the node is a Junction Node the window will be smaller, without the Average Consumption value, as this is not relevant to the node type (see , p. 78).

FIGURE 9.8 Information on nodes in Multiple Scenarios with secondary mouse button.

Right-clicking over an Element brings up a window like that in FIGURE 9.9.

FIGURE 9.9 Information on elements from Valid Scenarios in Multiple Scenarios with secondary mouse

button.

To consult the numerical values as a list, for Valid Scenarios, use the toolbar

icon Result (button , see p 128 ). When calling up the list, it initially shows the average values of each variable in columns. Modifying the selection of maximum (Max) or minimum (Min) values, produces the chosen category in the List of Results.


277

FIGURE 9.10 Numerical List from Multiple Scenarios.

The same window lets you construct bar diagrams for comparing average, maximum and minimum values. Select the variable of the node(s) or element(s) you want to compare from the list. You can select the whole column (most of which can be sorted alphabetically first, in ascending or descending order) or a sub range of components. Next, from the quadrant Bar Graphs in the window in FIGURE 9.10, choose the categories to compare (maximum, average, minimum and set point, this last only enabled for pressures). Click on the button View Graph to bring up a new window (FIGURE 9.11) with a diagram with rectangular bars of heights proportional to the values they represent. The number of bars represented for each node or element will depend on the selected categories. The bars are shown vertically on the graph, so that the y axis corresponds to the chosen variable and the x axis shows the identifier(s) of the Node(s) or Element(s).


278

FIGURE 9.11 Bar graph

You can modify the visualisation of the Bar Graphs with the scrollbar at the bottom. Right-click to Print to .gif file and Copy to clipboard the whole graph.

If critical scenarios are obtained due to the configuration of alarms, and the checkbox Save Critical Scenarios is enabled in the Alarms window, another window will appear when clicking on the Critical Scenarios icon (

Navigation to consult results of critical scenarios.

FIGURE 9.12).

FIGURE 9.12 Selection window for critical scenarios.

This window offers data on the first variable to trigger the alarm. To see all the critical cases open the Alarms window and open the Report.

There are various ways to display the generated critical cases. The first is representing the results on the map, by colour code and with the numerical results on the drawing, and another is to see the numerical results via the icon Results (button

). The step from one scenario to another, for the map or the numerical results, can be done in two different ways using the navigation buttons (FIGURE 9.12). At the top right (buttons ) we have navigation buttons for visualising all cases, one by one, clicking the buttons manually each time you want to go to the next or previous case, with the possibility of going straight to the first or last (end buttons). There is also the video option (buttons ), offering the opportunity to see the complete sequence of all cases, with the options of pausing or stopping in the middle of the evolution.

In the Alarms window (button ), there is the possibility, using the Report button, of accessing the report on alarms corresponding to the critical scenario being


279

displayed. At the same time, the network layout will mark the nodes and elements which have set off the alarms set in the Configuring Alarms window.

If the Save Alarms in Database option is enabled (see p. 161) via the Alarms menu you can consult them by accessing the database where they are saved.

Detailed information on interpreting the graphic output is given on p. 178.

9.5 SIMULATING DETERMINISTIC SCENARIOS

In deterministic scenarios, the set of open hydrants at a given moment is specified by a series of tools. The deterministic scenarios include strictly stationary scenarios, without temporal evolution, and scenarios with quasi-stationary temporal evolution (simulation over extended period).

In scenarios without temporal evolution the only open/closed state of hydrants and activation/disabling of pumps which exists is shown on the network map, with no other earlier or later state being saved. The results of calculation are associated with the distribution of consumption and hydraulic devices which appear marked.

In deterministic scenarios with temporal evolution, having previously set the simulation time and the duration of the intervals, a table of patterns is set where, for each Known Consumption node, Hybrid node and Pump, the user sets the time intervals in which they are active.

After specifying the temporal pattern, the temporal simulation can be run. At each moment the SIMEXT.DLL calculation module resolves the hydraulic system in equilibrium 3 taking the consumption points and active pump groups those specified in the pattern table for each moment. Between one moment and the next, the consumption made on dams, pressure nodes and reservoirs will be assessed, and in the last case the changes in level, depending on the geometry entered for them, updating the last temporal step.

Once the hydraulic calculation of all the moments is finished, the results and data of the hydraulic simulation can be consulted, running the scenario forwards or backwards in time with the time arrows. The colour codes, numerical values displayed and drop-down windows for Nodes and Elements on the map, correspond to the results obtained for each moment. The tables and graphs of temporal evolution can then be called up. The following sections specify the procedures for using the available tools.

9.5.1 GENERATION AND ANALYSIS OF INDIVIDUAL DETERMINISTIC SCENARIOS

GESTAR offers various tools for creating deterministic stationary demand scenarios. Thus, you can determine which Nodes demand a flow rate in a concrete

Generation of individual deterministic scenarios


280

situation, for which you want to run a hydraulic analysis, using the icon , or the Menu: Options/ Open-Close Hydrants.

Selecting the button , as explained on p. 76, and clicking on a Consumption or Hybrid node nullifies the consumption of the Node (closed Node, icon in white), while if it is already closed it opens again (shown in blue) with the instantaneous demand it had before closing (previous demand) If there are unconditionally open or closed nodes (button , see p. 76), they must be modified beforehand with this tool, so that the button can be used to open or close them.

If you choose the option Menu: Options/ Open- Close hydrants (p. 143), you will go to the window in FIGURE 6.15. This lets you run the command to Open or Close a hydrant by entering its identifier in the corresponding field. This mode, of insertion of states, is very dynamic if you have a list of previously opened and closed hydrants. You can choose to be notified if the identifier entered does not exist. As in the previous option, Unconditionally open or closed nodes cannot be modified, and the situation of each Node will be shown on the graph.

FIGURE 9.13Menu Options/ Open-Close Hydrants.

As with the randomly created scenarios, you can resolve the hydraulic problem clicking the toolbar button

Simulation of the created scenario. Automatic calculation

or via the Menu: Calculations/ Calculate.

If the option in the Menu is previously activated: Calculation/ Automatic (see p. 154), each time you open or close a hydrant, or accept any change in the configuration of the network by editing the data of its components, the scenario will refresh the calculation directly, using the new configuration.

You can use the same tools for analysing and filtering results as for the randomly generated individual scenarios (see p.

Checking operating conditions

272).


281

9.5.2 GENERATING DETERMINISTIC SCENARIOS WITH TEMPORAL EVOLUTION

This tool lets you configure network analysis throughout a temporal sequence in which in each instant the network is in a quasi-stationary state. This methodology, called Extended Period Analysis in the literature, supposes that the conditions of consumption and operation of the pumping and control devices remain unaltered in a certain interval of time, and that the variation of level in the tanks in this interval occurs linearly. The change in conditions from one interval to another takes place depreciating the non-stationary terms of rapid transitories in the equations of behaviour of the components. Consequently, the system passes consecutively through a series of stationary states, in which the earlier instants influence the present exclusively through the process of loading/unloading the fluid accumulation points in the network. In the temporal evolution a set of deterministic scenarios are resolved sequentially, where each scenario calculated differs from the others in the state of openness of the hydrants and the operation of the pump groups (specified by the user), and the level of fluid in the accumulation points which can change level (if any), the evolution of which level is calculated by the programme.

Remember that the fluid storage points with a variable level over the length of the simulation (dams, reservoirs, tanks, etc.) are implemented using a specific node, the Reservoir node. The level in the Reservoir nodes is supplied by the calculation module according to the input/output of fluid in the interval of simulation, of the level at the initial instant of the interval, and the constructive characteristics of the reservoir (cubication curve or geometry). To run the simulation with Reservoir nodes, first load the construction data of the reservoir as explained on p. 79, in the section dedicated to this Node.

Results will be obtained for the interval calculated, for the following variables: Reservoir level, Total head, Flow rate consumed and Net Volume Supplied from the first instant of the simulation.

As will be documented below, you can also use the temporal evolution module to obtain a complete series of results referring to the energy parameters of the pumping stations. In this case, in the process before configuring the temporal simulation, you will need to define the type of Rates to use and the Characterization of the power supplied in the contract, with the tools described in detail below.

Using the icon

Access to creation of scenarios with temporal evolution

, at the top of the toolbar, enter the dialogue in FIGURE 9.14, where the designer will set the criteria needed to create deterministic scenarios with quasi-stationary temporal evolution (simulation in Extended Period)


282

FIGURE 9.14 Temporal Evolution configuration window

Configuration of time intervals and duration of the analysis From the window in FIGURE 9. 14, first the programming characteristics are determined, consisting of the length of the temporal interval and number of scenarios and the reference of the first instant of the simulation, using two alternative procedures:

♦ Total Time of the Simulation. If you choose this option, this value must be specified in the fields next to it, and the length of each interval in the next quadrant of the window, indirectly determining the total number of intervals or scenarios (to a maximum of 768, according to the default values).

♦ Number of intervals. Use this option to define the Number of Intervals moving the marker in the middle of the window. The default maximum number of intervals is 768. Together with the value specified as the length of each interval, this determines the total time of the simulation.

If desired, you can set the start time of the simulation in the fields for Starting time, so that GESTAR associates an absolute instant in time with each of the proposed scenarios, according to the length of the intervals. If these fields are not filled in, the times will be relative.

♦ Simulation data. The Simulation Interval will be set independently from this quadrant; i.e., the time between two successive resolutions of the hydrodynamic model (computational time step). This step must not be longer than the interval of the set pattern, nor more than a third of the minimum


283

time estimated for emptying and filling the Reservoirs of the system, so that the orders associated with their levels and the control devices can be run, and the results will be stable. The reduction of the Simulation Interval increases the stability of the results when there are control elements, but increases calculation time, and at its limits, can overload the files and databases with output results and alarms, so that good judgement is required.

♦ Determining run conditions with alarms In the window for configuring Evolution over Time (FIGURE 9. 14), a quadrant permits activation of the Alarms, which will be checked and taken into account in all the Simulation Intervals. To configure them click the Configure button in the same window or use the Alarms button (see p. 161), from this dialogue (FIGURE 9.14).

Also, if you activate the option Warn in this window, during the process of simulation with Evolution over Time, a warning will appear each time one of the scenarios proposed by the user exceeds the range or the faults set in the alarm configuration appear. This warning gives the option of cancelling the simulation, saving the results up to that instant, or continuing until the programmed pattern has been completed. The alarms are saved in the Alarms Report. In each scenario the alarms will be shown graphically as each scenario is viewed after the Evolution over Time is finished. If, however, the option Ignore is activated, no warning will appear if any alarm is triggered, but the alarm will be saved in the report and shown graphically at the end of the process.

♦ Hot Start. If an Evolution over Time is calculated with the Hot Start option selected, for each step in time after the first one, the calculations for the solution of the new step in time will begin using the results of the previous interval.


284

FIGURE 9. 15 Demand Patterns.

When the Patterns option is activated, the table in

Creating Temporal Programmes

FIGURE 9. 15 appears. For each of the hydrants in the current network (Known Consumption Nodes and Hybrid Nodes) and Pump Elements identified in the first column to the left, the table shows a row divided into a number of fields equivalent to the Pattern Intervals, deriving from the Evolution over Time configuration window (FIGURE 9.14). The first row of the table shows the number of the day of the Interval, and the second row specifies the time the Interval starts. If the field is blank this indicates that the associated Node or Element is closed or blocked for the corresponding time interval. If it is checked, the Node is open and the Element is enabled (e.g., pump running). The top of the Demand Patterns window (FIGURE 9.15) shows the functions for creating, retrieving and storing all data in the Temporal Programming window:

• Button . After requesting confirmation of the operation, this refreshes all Nodes information in the table in all the instants, leaving them inactive, i.e., it leaves all the fields associated with Nodes blank.

• Button . Opens an Evolution File (with extension “mdb”, “evt” or “xml”) with patterns, rates distribution and exiting settings wich can be recovered.

• Button . Lets you create and/or save the contents of current pattern, rates distribution and active settings in an Evolution File (extension “mdb” or “xml”).

You also have the option to enter the Sprinklers and Emitters defined in the network, and the Pipes which form it, activating the corresponding fields.


285

Click on a field to toggle between its open/closed state (when the field is blank it changes to marked, and vice versa). If fields are selected by dragging with the mouse while the button is held down, all the hydrants selected during the intervals marked will change state. Click with the mouse on the identifier (the start of each row) or the head of a column to toggle the state of all the fields in the row or column. Double-click on the upper left field of the table to toggle the state of all the fields. In the Modulation column of the table accessed from the Demand Pattern window (FIGURE 9.15), you can activate the Modulation option associated with each Node, which is effective for Known Consumption Nodes and Hybrid Nodes. Modulation multiplies the Modulation Coefficient for each Interval of the Pattern by the value of the Reference flow rate of the respective Node. The value of the Reference flow rate is shown in the Reference column of the table (FIGURE 9. 15 Demand Patterns. ), coinciding with the Demand flow rate for each Known Consumption Node and Hybrid Node, except if the hydrant is closed, where the value of the Reference flow rate will be the same as the Maximum flow rate. Thus instant Demand over time can be reduced or increased, being modulated according to the factors continually introduced. This option is useful for the implementation of operating conditions for shared hydrants, with different demand rates over time, to represent changes in demand when different sectors are watered from the same hydrant, or to implement any type of water consumption pattern. Once the Modular function of the corresponding Node is enabled, the user can define a Modulation Coefficient for each interval, with values from 0 to 9999999. Modulation not being enabled is equivalent to assigning a value of 1 in the active Pattern Intervals. To copy a row, whether or not it includes information on the Modulation Coefficient, click on the row to select is and use the command Control-C. Next, after de-selecting, enable the Modular option in the row where you want to paste the pattern. When the new row is selected, use the command Control-V to paste.

♦ Search. Use this quadrant to find Nodes and Elements in the table. Fill in the identifier field and click Search to show the node or element in the table.

♦ Continuous fictitious Q %. With this option, the user can modify the value of the Continuous Fictitious Flow Rate considered when calculating the opening time of the hydrant (see APPENDIX PROBABILITY OF OPENING OF A HYDRANT, p. 469).

♦ Generate Schedule. A daily pattern of random demand (on-demand irrigation) is generated in which each hydrant is assigned an irrigation schedule, in which all the enabled intervals (see p. 288) are equally probable for the start of the irrigation and where the time the hydrant is open (duration of the irrigation) is calculated (see APPENDIX PROBABILITY OF OPENING OF A HYDRANT, p. 469). . If the irrigation schedule of a hydrant reaches a blocked period (see p. 288), the irrigation stops and continues when it is enabled again. If the irrigation schedule cannot be completed by the end of the day, intervals will be taken from the start of the pattern (equivalent


286

to passing the irrigation on to the next day) until the required duration is completed.

♦ Generate Continuous Schedule. Equivalent to Generate Schedule, but the interval when irrigation starts is chosen at random, with the condition that the irrigation is not interrupted, i.e., no blocked periods are included in the irrigation schedule. In this case not all the enabled intervals are equally probable for starting the opening of a hydrant, as those which will not allow an uninterrupted irrigation period are not considered.

♦ Accept. Closes the Opening Pattern window, saving changes.

♦ Cancel. Closes the Opening Pattern window, without saving the changes.

Creating temporal patterns using turns The window in FIGURE 9. 16 (similar to FIGURE 9. 15, an example of the application of two irrigation turns in the Demand pattern) includes the field Turns, which enables the user to quickly create Demand patterns for turn-based networks.

FIGURE 9. 16. Demand pattern/ Application of Irrigation turn

• Choose Turn. From the corresponding drop-down menu the user can select the turn for which hydrants will be opened in the pattern. The number of turns available from the drop-down menu and the assigning of the hydrants to each turn will depend on the user’s previous definitions (see Chapter 8. 6 ESTABLISHING IRRIGATION TURNS, ¡Error! Marcador no definido.). As that chapter describes, the user has a descriptive, editable summary of the irrigation turns loaded in the network and accessible via the Turns icon (p. ¡Error! Marcador no definido.).


287

• Switch on from. The user will define the start time for opening hydrants for the selected turn. The start times of the intervals of the pattern as defined in the window of FIGURE 9. 14 are available from the drop-down menu.

• Apply. In the table in FIGURE 9. 16, click the option Apply to mark for the hydrants included in the turn, the number of intervals needed for the duration of the irrigation to match the user’s definition via the turns icon (p. ¡Error! Marcador no definido.), option No. hours.

Power Supply Use the button Power Supply in the bottom left corner of the window of the , to access the tool Consumption Modulation Pattern.

FIGURE 9. 17 Consumption Modulation Pattern.

From the window in FIGURE 9. 17, the user can assign the Power Supply for each Interval of the Pattern. Various Modulations of the Power Supply can be entered, in order to reproduce different supply contracts by day (different months, workdays and holidays, etc) or various negotiated alternative prices. The modulation of the power supply selected with the mouse will be used in the next Evolution over Time. If none is selected, by default GESTAR will use no. 1. The editing buttons Add, Modify and Delete are enabled so the preferred changes can be made. By default, the modulations called MaxPower are loaded, with the sum of the maximum power of all the pumps for each interval, and the modulation NullPower, with value 0 in all the intervals of the Pattern. If the special alarm for Power Supply is enabled in Configuring Alarms (see p. ¡Error! Marcador no definido.), during the Evolution over Time calculation process, scenarios where the power required by the pumping equipment exceeds the Power Supply supplied for the corresponding interval, according to the selected Power Supply Modulation, will trigger an alarm. For Alarm Configuration options for Evolution over Time see p. ¡Error! Marcador no definido.. Prices Click the button Prices in the window in FIGURE 9. 15 to go to the window in FIGURE 9. 18.


288

FIGURE 9. 18 Editing Prices in Evolution over Time

In the fields at the top of the window, assign the Reference Prices of the Power Supply (in €/kW and year) and Electric Power consumed (in €/Kwh). The variations of both prices depending on the time of day can be defined as a percentage of the Reference Price, or as absolute prices in cents (hundredths) of the currency unit used, taking the Reference Price equal to one. This second option is the that appears in the . , where prices have been entered in euro cents. The third table will define the distribution of blocked hours. Blocked hours are those when the hydrants cannot be used due to a circumstance such as, for example, high power prices. It will be populated with 0 if the hour is blocked and 1 if the hour is OK for irrigation. Each row of each table of the defines a Typical Day with a Price or Licence for a 24 hour period. You can Add, Modify and Delete the Typical Days in each table as desired, naming them as desired, using the editing buttons, in order to reproduce the price structure by months, period of supply, electricity company, etc. The process of simulating Evolution over Time uses the Typical Days shown in bold (with variations in the Price Rate and enabling of peak hours). To select a different Typical Day, choose from the corresponding row. The new selection will be bolded. The last table in the window of lets you use different Power Supply Prices and Energy during simulations of Evolution over time of more than one day’s duration. . After


289

setting the Start time during the simulation for each Price, from the Electricity Price and Power Price of the corresponding row, you can access a drop-down menu with the available Typical Days (depending on the previous definition via the first two tables in the window).

Creation of logical trigger settings for nodes and elements

Click the button Settings in the window in FIGURE 9.15 to go to another window (FIGURE 9.20) which allows you to set conditions for certain actions during Evolution over Time according to the value of various hydraulic variables for the system components. To do this, the use can create logical instructions using a simple language described in APPENDIX (p. ¡Error! Marcador no definido.) which, depending on the result of comparing the values of certain parameters with their thresholds, trigger opening-closing processes (on-off in the case of pumping equipment). APPENDIX (p. 547) shows the step-by-step process of deciding settings for an example case.

FIGURE 9. 19Viewing Settings in Evolution over Time

♦ Button . The fields of the window of FIGURE 9. 19 will be blank, for defining a new setting.

♦ Button . Use this option to edit settings which were previously saved to a text file (extension .txt).


290

♦ Button . Lets you save the current settings, visible in the second field of the window, as a text file (extension .txt).

♦ Add. Click this button to delete the information of any previous settings, and edit the upper fields, where you can add the name and orders of a new setting. To construct the new Logical Expression, you must use the programming language supported by GESTAR (see APPENDIX, p. ¡Error! Marcador no definido.).

♦ Modify. Lets you edit the setting selected in the list of settings in the bottom left field of the window (FIGURE 9. 19).

♦ Delete. Permanently deletes the selected setting from the list.

♦ Accept. If editing a setting, this accepts the changes. If not, this closes the window and takes you back to the patterns window, saving the changes.

♦ Cancel. If you are editing a setting, this stops all editing and does not save any changes. If not, it will take you back to the PATTERNS window (FIGURE 9. 15) without updating the settings.

♦ Assistant. The assistant facilitates the creation of simple settings which modify the value of a hydraulic variable when a given condition is met, without the need to understand the coding of the instructions shown in the specific APPENDIX (p. ¡Error! Marcador no definido.). Clicking this option opens the window shown in FIGURE 9. 20. .


291

FIGURE 9. 20 Settings Assistant.

The different parts of the Settings Assistant window are summarised below.

♦ Action. Section for configuring the action executed by the setting. Only one action per setting can be included. Use the drop-down fields referring to Conditioned Action and Type of Node or Element to define the following Actions:

Start/Stop Pump Element.

Open/Close Pipe Element.

Open/Close Known Consumption node.

Open/Close Hybrid node.

Open/Close Emitter.

Open/Close Sprinkler.

To select the specific Node or Element associated with the Action, use the drop-down Identifier to access a list of all those in the network according to the Node or element type field.


292

♦ Condition. The Condition panel is used to establish the conditions which define the settings. The variables which can be used (via the drop-downs Type of condition and Variable) are:

Reservoir Node: water level.

Junction node: Pressure.

Known consumption node: pressure.

Hybrid Node: pressure.

Pipe element: flow rate.

Emitter element: flow rate.

Temporal Time: time

Temporal Enabling: Boolean

Depending on the chosen type, the Identifiers existing in the network will be

displayed. Select the one which you want to relate with the logical signal. From the Settings panel, you can modify the configuration so that the action will run when the value obtained for the variable is lower than the setting (the default option is for it to run if higher).

o Condition Value This field sets the value of the variable used to evaluate the condition. The units are specified in the Logical Expression, depending on the chosen variable.

Text fields are updated automatically as the Action and Condition are modified. ♦ Operator. Use the drop-down to enable the supported Boolean

and numerical operators.

After selecting the option Copy for each of the fields, the Action/Condition/Operation is accepted and appears in the lower text field showing the text of the equivalent setting, according to its Logical Expression.

♦ Setting name. Enter the name you choose for the setting in this field, which will be shown in the list of settings in the window of

♦ . Logical Expression. The lowest text field shows the logical structure of the setting, i.e., how the setting conditions are related. Choose the option Edit to modify it manually. This requires the use of a precise syntax for the programme to interpret it correctly ( see APPENDIX, p. ¡Error! Marcador no definido.).


293

♦ Condition List. Shows the conditions in the list. A limited number of conditions can be included for each setting.

o Logical ID: this field is for the logical identifier to be assigned to the first condition added to a setting. A unique identifier can be entered, with upper or lower case letters or any other character, to a maximum of 12 characters. For more information see APPENDIX (p ¡Error! Marcador no definido.)

o Add condition to setting: Add the selected condition to the setting condition list. The logical identifier specified in the Logical ID field will be assigned to it.

o Delete Condition from Setting: Deletes the selected condition from the Setting Conditions list.

Modify Condition List: Opens a new window for adding, changing and deleting conditions from the list. Once a list of settings has been configured and you have clicked Accept in the Settings window, they will be taken into account in calculating the Evolution over Time, so that when an instant meets any of the conditions of the settings, the corresponding action will take place in the next instant.

Scripting If using GESTAR at an advanced level, users sometimes deal with studies

requiring an analysis of recursive simulations, which can be tedious if done using the tools as implemented in the application.

The Scripting tool for custom simulations offers users the features of the GESTAR calculation engine, letting them tailor the analysis to the needs of the user, for example, with a very high number of simulations, saving only useful results, etc.

The Scripting option in the window shown in FIGURE 9. 14 lets the user open and execute a text file of commands (extension .txt), previously created by the user (FIGURE 9. 20)


294

FIGURE 9. 20 Selection of Scripts file

When the user generates the command file or Script, this must use the programming language supported by GESTAR (see APPENDIX, p. 545). When the selected command file is executed, by default the rest of the functions of the command files included in the Scripts folder are also executed.

If the execution of the Script changes a parameter, such as the Roughness of a Pipe element, the change will be saved in the network.

EXAMPLE SCRIPT

A script for a typical example is shown below. The objective was to find the

least favourable Known Consumption Node in 200 random scenarios for a fictitious continuous flow rate of 20%. .

Set ‘Iteraciones’ To 0 ;

Set 'MinimoMargen' To 10000 ;

Set 'NodoCritico' To "";

While ‘Iteraciones’ < 200 Then

[

RandomFlow( 0.2 , Null , Null , Null ) ;


295

CalculateHydraulicModel( );

Foreach hydrant in Hydrants Do

[

if hydrant IsOpen Then

[

if hydrant PressureMargin < 'MinimoMargen' Then

[

Set 'MinimoMargen' To hydrant PressureMargin ;

Set 'NodoCritico' To hydrant Tag ;

];

];

]

Loop ;

Set ‘Iteraciones’ To ‘Iteraciones’ + 1 ;

]

Loop;

9.5.3 ANALYSING DETERMINISTIC SCENARIOS WITH TEMPORAL EVOLUTION

When the Temporal programming table (

Browser for consulting results of temporal scenarios.

FIGURE 9.15 Temporal Programme) has been created, and the Temporal evolution simulation is run via the button Run, the progress of the calculation is shown in a progress bar in a new window. The set of warnings relating to the alarms must be accepted until the set of intervals has finished or the simulation is cancelled. When the simulation ends or is cancelled by the user de to


296

an alarm, the results of each e Simulation Interval can be seen in the window in FIGURE 9.21, the Temporal evolution browser, which appears automatically and gives access to the various Simulation Intervals.

FIGURE 9.21 Temporal Evolution browser.

To move from one interval to another, just click the buttons next to the numerical field (buttons ) or mouse-click directly on the field and enter the number of the interval you want to see (central number). There is also a video option to see the whole temporal sequence case by case, with options to pause or stop at any time in the evolution (buttons ). At the bottom left the moment is indicated corresponding to the scenario shown.

As well as visualising each interval on the map, there are other buttons in the window:

• Button If there were alarms in the temporal interval, the button Report in the window Alarms provides a list of the variables in Nodes and Elements which triggered alarms in the interval.

• Button Shows the window Tables for graphics , where the graphic visualization can be created of the temporal evolution of one of its variables. Its use is described below.

• Button Leads to the window Results, showing the values of the variables in Nodes and Elements in the currently displayed interval (see p. ). 67).

Button The button Save lets you save as Excel (“.xls”) or text (“.txt”) files all the values of the variables of the network in all the intervals of the Temporal evolution. It offers a possible limitation of exported simulation time to avoid overwhelming the capacity of the output files.

Tables and graphs of results in Evolution over Time. After running simulations with Evolution over Time, GESTAR lets you obtain tables and graphs which register or visualise the value over time of one or more variables selected by the user.

To access these resources, click the button on the Menu bar or in the Evolution over Time Cursor window (FIGURE 9. 21).


297

FIGURE 9. 22 Tables for Graphs. Reservoir Node.

The corresponding tables of FIGURE 9. 22 show the values of the different variables which can be shown in graphs, depending on the tab chosen from Nodes, Elements, Variable, Pumping Station. Each row of each table corresponds to each of the initial Instants of the Simulation Intervals, defined in the calculated Evolution over Time. ♦ Nodes. The type of Node must be defined in the first drop-down list, selecting the

Identifier of the Node in the next drop-down menu, depending on the type selected (among those existing in the network).

The hydraulic magnitudes which can be visualised for each Node are:

• Junction nodes: Pressure and Total Head.

• Reservoirs: Level, Total head, Consumption and Volume Supplied.

• Known Pressure Nodes: Pressure, Consumption and Total head, Pressure Margin and Set Point Pressure.

• Known consumption nodes: Pressure, Total head, Consumption, Pressure Margin and Set Point Pressure

• Emitters: Consumption.


298

FIGURE 9. 23Tables for Graphs. Known Demand Node.

♦ Elements. The magnitudes shown for each type of Element are:

• Pipes: instantaneous values for Velocity, Flow rate and Head loss.

• Valves: instantaneous values for Velocity, Flow rate and Head loss.

• Individual Pumps: instantaneous values for Flow rate, Head loss (- delivery head), Energy (consumed up to the instant), Power (absorbed), Performance, Velocity, for each Pump Element.

♦ Variable. Under the variables tab, after selecting a variable from the drop-down list from among the following, Pressure, Total Head, Consumption, Velocity, Flow rate, Level, Head Loss and Pressure margin, each column of the table establishes the values taken by the variable in each Node or Element, depending on the nature of the selected variable.

♦ Pumping station. The instantaneous values covering all Pump Elements are offered: Network power consumption, Power, Total Efficiency (of the set of Pump Elements, equivalent to instantaneous EEB, see definition on p. 319), instantaneous ESE (Power Supply Efficiency, in %), Cumulative Efficiency (of the set of Pump Elements from the starting point of the Evolution over Time to that instant, equivalent to EEB for the period), Cumulative ESE (%) (from the starting point of the Evolution over


299

Time to that instant), instantaneous Cost of Power, cumulative Total Cost, Cost by Volume and Unit of Power.

• Results. The Results field under the Pumping Station tab offers a summary of Power Costs, including: the Cost of the Power Supply, Cost of the Total Power Consumption and the Cost per Unit, according to the defined pricing.

♦ Represent.

The variable or variables to be represented in the graph can be selected with a mouse click at the head of the corresponding column of the table. The selected columns will then have a blue background. To cancel the selection of a previously selected column, just click on its heading.

Double click on the head of a column to sort the whole table according to the sequence of ascending values, instead of temporal, in the chosen column. To return to temporal order, double click on the first column, Instant.

When the Table for Graphs has been altered to suit your needs by the operations described above, you can continue to the graphic representation. The values of the Table for Graphs cannot be exported directly. They can be exported from the window of the Graph generated from them.

When you click the button Represent, GESTAR will show the graphic representation of the columns selected in the window Graph of Evolution over Time.


300

FIGURE 9. 24 Example Graphic Visualization

The graphs provided by GESTAR always have time as the variable associated with the horizontal axis, particularised in the Simulation Intervals defined in the Evolution over Time window. The vertical axis represents the values of the variables (one or more, of the same type or different) selected by the user.

Each variable will appear represented by a colour assigned by default by the programme. For greater clarity and better identification of the variables represented we recommend visualising simultaneously fewer than 10 parameters. Depending on the selection made in Tables for Graphs, a heading will appear for the graph identifying the variable (with its units), the Node or Element selected to be represented in the block Type of Table. At the bottom of the graph, under the horizontal axis, a legend associates each line of colour with the name of the Node or Element whose fixed variable is shown, or the different variables (with their units) which appear in the figure for a certain Element or Node, all as specified in the block Type of Table of the Table for Graphs. At the top of the window containing the graph (FIGURE 9.23) is a menu with various options: for configuring the appearance of the graph, for exporting the graph and optimising the presentation of data.

• Menu File/ Export. Here we have 2 options for exporting the graph: in *.gif format, including the graph as a drawing, or in text format, extracting the numerical data.

• Menu File/ Quit. Closes the graph window.


301

• Menu Edit/ Copy the image to the clipboard in Metfile Windows format. Pasting into any Office document (Paste special/ Metfile Windows) lets you include the image and edit it if necessary.

• Menu Graph/ Legend. Enables/disables the legend.

• Menu Graph/ Title. Lets you assign a name to the Graph.

• Menu Graph/ View data. To display numerical data over the lines of the graph.

• Menu Graph/ Optimise. As in the same graph different variables or the same variable with widely differing absolute values may be represented, this option makes an exponential type of presentation where the vertical scale shows the significand (from 0 to 10) while the legend indicates the power of 10 which the read values must be multiplied by to obtain the absolute values.

Clicking with the secondary mouse button on a node or element, as well as showing the information obtained in the other simulations (see p. 276), after a Temporal Evolution analysis, takes you directly to Evolution Graphs with several variables according to the type of node or element chosen.


302

10 EVALUATION OF POWER COSTS AND

OPTIMIZATION OF REGULATIONS IN

PUMPING STATIONS

10.1 UTILITIES

GESTAR introduces tools which are unique in their field, innovative and efficient, which let you evaluate rationally and in detail the performance of Pumping stations and their associated power costs, according to the composition of pumps, the type of regulation used and characteristics of the distribution network, with universal applicability. These resources are useful for better design in pumping stations, power management in pumping, and audits and rehabilitation of pumping systems.

Thanks to the tools offered by GESTAR you can optimise:

The selection of the number, type and regulation of pumping equipment in the design phase.

The most suitable regulation of the characteristics of an operational system for reducing power costs.

The definition and identification of the modifications needed in inefficient or obsolete operational systems.

The utilities needed are mostly associated with Temporal evolution tools, described in Chapter 9.5, as regards the calculation of power costs for deterministic irrigation programming, with pumping stations already configured. The rest are grouped under the Menu bar: Pump Regulation, enabling the following functions:

♦ System Curve (see p. 303).

♦ Selection of Pumps (see p.305).

♦ Probability Function of Pumped Flow Rate(see p.307).

♦ Pump Regulation(see p.309).

♦ Power costs (see p. 314).

The tools can be called up individually or integrated in the option “Pump regulation/ Power Costs”.


303

10.2 SYSTEM CURVE

The system curve in the network is defined as the relationship between the pressure supplied at intake, which must be enough for all the operational consumption nodes, and the flow rate demanded for each of the possible scenarios. The network must comply with a series of restrictions to obtain the system curve through the programme. Thus, in the current versions we must be dealing with a branched network, with a single point of total head (using inverse analysis techniques these restrictions can be avoided, currently in deployment) Dam node or Reservoir node. A Pump element cannot have been implemented at intake, and Total head at the intake point must be as low as possible. Losses from pumping equipment and filters must be modelled as singular losses in the first stretch of the network.

FIGURE 10.1 Example network topology for obtaining a System Curve

During the calculation process in GESTAR operational scenarios are randomly generated for different percentages of demand, within the range indicated and for each scenario, it determines the pump head required at intake to supply the set point pressure to the least favourable Node open in the scenario (see Appendix X, p. 519).

The user accesses the window in FIGURE 10.2.


304

FIGURE 10.2 Dialogue Calculate System Curve

• Flow rates. Filling in the field Analyse to Q, the calculation of the system curve will be bounded to the flow rate desired by the user (in m3

• Number of Scenarios. Indicates the number of scenarios to simulate for each percentage of flow rate, in relation to the total installed, passing through at intake; it is predefined with the value of 100 e., but we recommend a minimum number of Scenarios equal to 3 times the number of hydrants in the network.

/s). By default the design flow rate of the Pipe starting at the intake node is implemented. The labels for design Q and max Q show the design flow rate considered in the network and the maximum flow rate passing through the network when all Nodes are operational, respectively.

• Step. Percentage increase in relation to the cumulative flow rate, increasing the previous flow rate starting with Q=0 m3

• Calculate. Click this button to start the calculation process. The results obtained are exported to an spreadsheet (see p.

/s. To obtain simultaneity levels in the values the number of random scenarios set in the previous field will be run. The percentage is increased until it reaches the value given in Analyse to Q.

219), which will be saved where the user specifies (GESTAR will open the window Save System Curve). This document provides the points surrounding the maximums and minimums and the recommended system curve (reliability equal to the guaranteed supply at intake). The maximum system curve (surrounding the maximum absolute pressure requirements for each % of demand) favours safety as its reliability is nearly 100%, but it is not energy efficient. The minimum system curve (surrounding the absolute minimum pressure requirements for each % of demand) is unacceptable as it does not meet the pressure requirements for almost any consumption scenario (reliability tending to zero).

• Export Intermediate Cases. If this field is enabled before calculation, as well as the table with the values defining the system curve with a degree of reliability equal to the guaranteed supply at intake, the user will obtain detailed information in Excel format for each of the random scenarios generated for each value of flow rate passed through, obtaining the cloud


305

of points of the pressures demanded at intake in all the simulations. Based on these results, the user can establish system curves with any degree of reliability.

• Fit Curve. The results obtained follow a parabolic fit in the form:

H = Hmin+Ks Q

10.3 PUMP SELECTION

2

This menu provides resources for obtaining immediately Performance Curves for Pumps which meet certain operational conditions. There are two procedures for this. The first lets you synthesise hypothetical parabolic performance curves which pass through specified nominal pump head and flow rate points with a given maximum efficiency. The second lets you select the pump from the Pump Database, and retrieve its Performance Curves using the tools documented above on p. 110. The dialogue in FIGURE 10.3 is used.

FIGURE 10.3 Pump Selection.

• Synthetic Pump

The performance curves H-Q and R-Q are configured with the following requirements, leading to conditions illustrated in the FIGURE on p. 306.


306

The curve H-Q is approximated by a second degree polynomial with coefficients A, B, C.

The efficiency curve R-Q is approximated by a second degree polynomial with coefficients F, G and without independent term.

For the Nominal flow rate, design flow rate, Ad; to supply with the number of pumps indicated in the corresponding field, the curve generates the Nominal Head, design head, Hd

The curve H-Q has null slope (is horizontal) for Q=0.

, both values given by the user.

The curve H-Q, for null flow rate, supplies a pump head (Ho) given by Ho= (1+P/100) x Hd, where P is a parameter (increase in overpressure in relation to Hd

For the nominal flow rate the pump has its maximum efficiency, also given.

, in percentage, at zero flow rate) given by the user.

For the maximum flow rate, null pump head, efficiency must be null.

The first three conditions let you calculate the coefficients A, B and C. The last two, F and G (the third coefficient, independent term of the polynomial of the efficiency curve, is null, given that efficiency at null flow rate is also null).

FIGURE 10.4 Generation of the Synthetic Pump

In the window in FIGURE 10.3 enter the necessary values in the various fields.

The nominal H and nominal Q indicate the design point of the pump (or if applicable the pumping station, comprising pumps with identical performance curves), a point for which it is supposed efficiency will be highest.

The criteria for play P % indicate the increase of the head at zero flow rate in relation to the Nominal head for the Nominal Flow rate..

GENERATION OF THE SYNTHETIC PUMP

0

20

40

100

120

140

0 0,2 0,4 0,6 0,8 1 1,2 1,4 Pumping flow rate at intake

Manometric pressure heads

3

Q(m3/s)

Hd

B1

Hmin B2

H(mca)

B3

1 2

n

Bn.

(Qd ; Hd)

Qd

Hd (1+p)

p. Hd HCCk

ηmax

00

==QdQ

dH

nQ


307

Rend (%) indicates the maximum efficiency of the pump, produced for the design flow rate of each pump, this flow rate coinciding with the result of dividing the Nominal Flow rate by the Total Number of Pumps.

The Total Number of Pumps is defined as the number of identical pumps making up the parallel pumping station, also supposing that this is of variable velocity and the others are fixed velocity.

10.4 PROBABILITY DENSITY FUNCTION

The Probability Density Function (PDF) of the demanded flow rate enables the distribution of intake flow rates to be synthesised at a point of entry to the network, throughout a time period which can include the whole campaign or monthly periods The PDF of the demanded flow rate at an intake point is equivalent to knowing the distribution of relative frequencies of each flow rate at that point. This information is useful in the simulation of water consumption processes and, especially, in the prediction of power consumption throughout a long time period, if intake is by direct pumping.

In branching type on-demand irrigation networks, head flows correspond to a succession of different random scenarios, which are modified with the opening and closing of irrigation intakes Consequently, the flow rate at intake can be considered a continual random variable, whose PDF can be calculated (Esperanza, 2007) by the extension of the ideas contained in (Roldan et al., 2003). On the other hand, in networks for turn based irrigation, the PDF can be inferred from the de irrigation calendars programmes according to existing crops and established turns. Finally, in any type of operational network where there is a significant register of flow rates, the relative frequencies of each flow rate can be extracted from experimental data, which in turn will generate the PDF.

The calculation of the Probability Density Function of flow rates at intake of a branched demand network for a period comprising a certain number of months (FIGURE 10.5) is dealt with in GESTAR using a combination of monthly Probability Density Functions of Normal type, depending on the daily water needs of the month, the topological configuration, the maximum flow rates of the hydrants, and the plots and crops, leading to the probability density function supposed for the demands in the network. Appendix XI, , documents the significance and construction of the PDF of a given period.


308

FIGURE 10.5 Probability Density Function of demanded flow rates

Accessing this tool via the menu Pump Regulation/ Probability function of the Pumped Flow rate, the PDF of the flow rates is assessed, at the point of intake, for strictly branched networks running to demand. The user is offered the window shown in FIGURE 10.6.1. If the PDF is known, as the relative frequency of each flow rate consult section 10.6.1, p. 315

FIGURE 10.6 Probability Density Function of Flow Rate

• Daily Needs. When GESTAR calculates the Probability Density Function of the Flow rate, it can include the heterogeneity of demand for the different months of the campaign. This quadrant defines the Daily Water Needs for each month, expressed in mm. Using the icon the user can save in text format the daily needs defined for a given


309

supposition, letting them be reloaded in later calculations using the icon .

• Time brackets for electricity prices. This model, if required by the user, also takes into account the different price bands of time brackets (peak, off-peak and shoulder). The option Apply Time Bands must be enabled, showing in the corresponding cells the values of the number of hours predefined for each price shown in FIGURE 10.6. These can be modified as preferred by the designer.

• Effective Day of Irrigation. The number of hours of an effective day of irrigation must be set, assigning by default a value of 18 h. If time and price bands are applied, the EDI must be spread over the different time bands, where the predefined values are found in FIGURE 10.6 in each cell.

• Distributing Irrigation Times. The option is currently implemented for distributing the irrigation time among the different time bands, if the user has decided to take into account the different electivity prices, by % of known volumes, where the values given by default are shown in

• Limit Q and Step Q. In the bottom left of the (FIGURE 10.6) are two cells for defining the Limit Flow rate which the function will be built up to and the Flow rate step where the flow rate will be increased from the value 0 to obtain the different values for which the demand probability is calculated.

• Export Averages and Variances. When this field is enabled GESTAR will generate a spreadsheet with the monthly values of the averages (mathematical average of the observations) and the variance (measure of variability, this is the average square of the distances between each observation and the average of the set of observations) referring to the probabilities of opening.

• Export Annual and Monthly PDF. Exports to a spreadsheet the results of the probability function of monthly and annual demand for each of the required flow rate values.

10.5 PUMP REGULATION

This tool offers an agile and reliable solution to the definition of overall action curves for regulating fixed speed pumps, variable speed pumps, and composite regulations for a combination of pumps of both types. In any of these cases, an arbitrary number of pumps can be configured, of the same or different sizes.

In this way the Action Curves of a pumping station (Power-Flow rate, Head-Flow rate and Efficiency-Flow rate), given the composition of pump groups and the


310

type of regulation to be studied, can be obtained using this module, the configuration window for which is shown in FIGURE.

FIGURE 10.7 Pump Regulation Window.

• Fixed Velocity Pumps/ Variable Velocity Pumps. The two quadrants at the top of the dialogue shown in have a similar structure, so they will be explained jointly, below. FIGURE

Comment. In this field the identifier code of the pump can be entered. If nothing is entered, a number will be taken by default.

Rpm. In this field the rotational speed is entered of the nominal pump corresponding to the entered performance.

%. If the pump is variable speed, the % indicates the maximum percentage of rpm over the nominal, which lets the pump rotate without overlapping the next start point.

Sequential / simultaneous operation. For Variable Speed Pumps, the default supposition is that they work sequentially (option Sequential operation), i.e., one at a time. If there are various pumps (2 in this version) with variable speed working at the same time and the same rpm, choose the option Simultaneous Operation. This option can be enabled once the two pumps have been added to the editing list. al.

Performance Curve Table Discrete points of the Performance Curves of each pump in the composition are entered. The data to enter for each row are Flow rate (m3/s), Head (m) and one more, choosing between Power (kW) and Efficiency (%), with the missing value calculated with the other data. To fit the Performance Curves of the pumps more than two points must be entered in the table.


311

Accept Pump. To accept the entered pump click the button Accept

Pump, .

Editing list of Pumps. Once the pump is accepted, it will appear in the list to the right of the table, and can be edited ( button Edit Pump), deleted ( button Delete pump) and you can also view the graphs derived from the interpolation using splines of the curves H-Q, P-Q and R-Q ( button view graph of pump curves).

FIGURE 10.8 Curves of Pump head, Power consumption and Pump efficiency.

Database. The points defining the Performance Curves of the pumps can be retrieved from the Pumps Databases utility, .FIGURE 10.16


312

FIGURE 10.9 Choosing Pumps from a Database.

• Starting Sequence of the Pumps comprising the pumping station.

Calculate starting sequence. Once the pumps for the pumping station are defined, GESTAR offers the possibility of calculating their start sequence clicking this button. The sequence is shown by a table at the bottom left of this dialogue, representing the operational state of each pump making up the station, as the circulating flow rate increases. A “1” indicates that this pump is active and a “0” that it is stopped at a certain phase of the sequence. The starting flow rate is also shown of the next pump producing the phase change of the sequence, which by default corresponds to the maximum which each phase of the sequence can supply with the pumps working at nominal rpm (BVF)/maximum rpm (BVV), with a joint pump head equal to or more than that demanded by the System curve. (i.e., the cut of the parallel composition of the performance curves H-Q of the active pumps in this state at nominal/maximum rpm, with the System curve of the network). It also shows the pump working at variable speed in each state and the maximum percentage of its angular velocity in


313

relation to nominal. If recovery should not be possible between the start/stop points in a phase of the sequence, i.e., if the variable pump to link to the next phase should exceed the maximum acceptable rpm (over the limit in % indicated for the pump), the percentage of rpm, in relation to the nominal, needed for the variable speed pump to reach recovery will be marked in red and the situation will be noted.

Edit Sequence. If the sequence calculated is not the desired one, it ca be edited using this button. The list of start sequences will be accessible and can be modified by the user, recording or discarding these modifications using the buttons Accept changes / Cancel changes shown during the editing process at the bottom right of the window in FIGURE 10.16. Activating the option Edit modulation, the start flow rates can be modified manually, automatically calculating the % of r.p.m. the pump will reach when this start flow rate is supplied.

• Calculation of the Performance of the Pumping Station. When this button is clicked, GESTAR generates a synoptic Graph (see FIGURE 10.10) of the Power consumption of the pumping station and the Joint Efficiency and main Action Curves enabling a first evaluation of energy consumption and efficiency resulting from the entered composition and regulation. If you want full information on the case, click the corresponding button in the new window to generate a spreadsheet (see p. 223) with the features of the new pumping station, including results such as power consumed by each pump, efficiency, head supplied by the station, head demanded by the system, useful power and overall efficiency. All these results are calculated for the range of flow rates from null flow rate to the maxim entered in the network data tab.


314

FIGURE 10.10 Power Curves and Efficiency of Performance in Pumping Station

10.6 CALCULATING POWER USAGE

Finally, with the option Power Costs of the menu Pump Regulation, all the tools are available to analyse pumping stations and their power costs. This includes the set of functions which can be called up individually via the other options on the Regulation menu.

Access each tab following a logical sequence shown below, following their order.

FIGURE 10.11 Power Costs analysis sequence

Network Data

Station Regulation Power Data

Power results


315

Some stages, such as obtaining the System curve, can be run beforehand and their values loaded directly.

10.6.1 NETWORK DATA

The first window to appear after the Menu Pump Regulation / option Power Costs is shown in FIGURE 10.12, and requires a series of general data about the network.

FIGURE 10.12 Power calculations. Network data.

♦ General data for analysis.

• The sized Q and sized H indicate the flow rate and head derived from sizing the network. (see chapter 0, p. 225).

• Analyse to Q indicates the flow rate in m3

• Q intervals (l/s). Power costs are calculated from the value 0, for each of the values of Q, obtained by adding the flow rate before the interval defined in this field (in l/s), until arriving at the maximum flow rate to analyse (defined in the field Analyse to Q)

/s up to which the energy costs will be calculated.

♦ System Curve. The method for obtaining it is described on p. 303 et seq. GESTAR provides two ways for the user to define this curve in this module:

Manual entry of its coefficients, previously found or given externally, filling in the enabled fields for H min (minimum head) and K (dimensional coefficient)


316

Calculation of the system curve of the installation. The button System curve in the window starts the same process as that defined in the independent Menu module: Pumping regulation/ System Curve

♦ Probability Density Function (PDF). The last quadrant of the dialogue shown in FIGURE 10.12 is for implementing the Probability Density Function of the pumped flow rate. Appendix XI, refxxx , p, Xxx, describes the basic conceptual aspects of the properties and calculation of the Probability Density function. Two variants are offered:

Calculate Theoretical Function. To evaluate this function, in the case of branched networks in demand irrigation which fulfil Clement's hypothesis, click the button with the same name, also accessible via the menu Pump regulation / Probability function of pumped flow rate, as described in section 10.4, p. 307

Enter Frequencies Function. If the distribution is known of relative frequencies of each flow rate, according to experimental data or programming for turn irrigation, you can introduce this information to generate the corresponding probability density function. To do this, just click this button (FIGURE 10.12) and enter, in the dialogue shown in FIGURE 10.13, pairs of points in the cells for flow rate and relative frequency of each flow rate, and the Total Hours of the irrigation campaign (or for the period of the study). Appendix XI refxxx gives complementary information.

FIGURE 10.13 Dialogue Frequency of Flow rates.

10.6.2 STATION REGULATION

This tab groups data relating to obtaining the Action Curves of the Pumping Station.


317

FIGURE 10.14 Power calculations. Station regulation

You can choose two types of tools for obtaining the Action Curves:

Simplified Regulation:

Generic Regulation

Simplified Regulation: The station comprises fixed speed pumps except for one, which is variable speed. Also, all of them are identical with synthetic performance curves. The composition supplies for the nominal flow rate of the pumping station, the nominal head, and a specified maximum efficiency. The variable speed pump starts first, adapting its speed to the point in the system curve where the system is located. The first fixed speed pump (BVF) starts working when the point on the system curve coincides with the cut-off point of the curve H-Q of the BVF, and so on with all the fixed speed pumps comprising the station.

• Manual entry of the coefficients defining the curves H-Q and R-Q. From the window in FIGURE 10.8, the same fields are filled in as for selecting the synthetic pump

FIGURE 10.15 Configuration of Pumps.


318

• Calculate start Q. When the parameters are implemented defining the curve of the pumps, click the button Calculate Q cut to obtain the flow rate cut-off of the compositions parallel to the sequence of working pumps 1,2,?n. with the System curve of the network. These points serve as a reference in regulation to indicate the average stop/start flow rate of the groups.

Generic Regulation. To enter the data for this option click the button Edit. This opens a window (FIGURE 10.6) equivalent in content and operation to that described in section 10.5

FIGURE 10.16 Generic Regulation. Station data.


319

10.6.3 POWER DATA

FIGURE 10.17 Power Data

This tab lets you adapt the initial electricity and power parameters to each of the concrete cases of pumping where energy use is to be studied.

Electricity installation.

• Cos fi. In this field, enter the value of the power factor of the installation. The value assigned by default in GESTAR is 0.8997

• Efficiency Installation %. Set the efficiency of the pumping station as a percentage in this field. (By default a value of 100% is applied).

♦ Calculate power indicators. Using this quadrant the user can evaluate energy efficiency using the Energy Efficiency Indicators, which let you measure the power used to produce one unit of product.

• Pumping Energy Efficiency (EEB). If this option is enabled, GESTAR will calculate the indicator EEB, where this is the relationship between delivered energy and the energy invested in the pumping device (Efficiency of the pumping station as a whole). That is, it represents the quotient between the hydraulic power supplied by pumping and the electric power consumed.

• Efficiency of Electricity supply. If you want GESTAR to calculate the indicator ESE referring to the efficiency of supply, add in the adjacent field the value of the Available overall energy which will be accessible when this option is selected.


320

The indicator ESE represents the coefficient between the energy needed for the system and the real energy supplied, so that:

ICEE

ESE∆

= Yes 0⟨∆E

Where E∆ is the difference between the indicial energy of the water and the energy demanded by the supplied irrigation system and ICE is the Index of electrical load (m) representing the average manometric head supplied by pumping, including the supply points which do not need pumping.

Detailed formulations of both parameters are given below:

1000*36001*

iSuperficie

alVolumenTot*)g*cabeceraH*)iSuperficie(ponibleEnergíaDis∑∑

= ρ

Equation 10-1. Available Energy (according to the Institute for the Diversification and Saving of Energy)

alUtilEnergíaTot

1000*36001*

iSuperficie

alVolumenTot*)g*cabeceraH*)iSuperficie(())g*)ignaesionConsiPriCota(*iSupercifie((

(%)ESE ∑∑∑

−+

=

ρρ

Equation 10-2 Efficiency of Electricity Supply (according to IDAE)

♦ Power prices

Electricity prices. Select from the first drop-down list in the quadrant Power prices the type of contract arranged with the electricity company for the installation being analysed. Use the button prices to the right of the drop-down to go to the window where you can edit and load new prices. Also, choosing from the personalised list of rates, you can specify directly the data needed in the corresponding fields (Energy price (€/kWh.) and Electricity Supplied (€/kW month)).

10.6.4 POWER RESULTS

Finally, to calculate the power consumption of the station, the demanded power and other power results, click the button Calculate, to the left under any tab.

Calculation of the power consumed kWhCED in the irrigation campaign, of total duration T, uses integration of the distribution of density of the power consumed depending on flow rate.

∫ ⋅⋅⋅=max

0

)().(Q

kWh dqqFDPqPTCED


321

As can be seen in FIGURE 10.18, the last tab shows a summary of the results obtained, including the annual cost of pumping, energy consumption per year, etc It also shows a list of the cut-off flow rates of the start sequence of the station, a list of the flow rates and their corresponding power, and a last list corresponding to flow rates and efficiency.

FIGURE 10.18 Power results

This window lets you view the graphs P-Q and R-Q of the pumping station using the button of the same name. This produces two graphs like those in FIGURE 10.19. These graphs may present instabilities. This problem can be solved by reducing the value entered in the first tab with the name intervals of Q.


322

FIGURE 10.19 Graphs P-Q and R-Q.

Also, GESTAR lets you save all the results in a spreadsheet, so as many variables as you want can be manipulated and represented graphically. Thus, for example, the power consumption of the variable pump in relation to the total flow rate (FIGURE 10.20) can be represented, or the percentage of the angular velocity adapted at any time (FIGURE 10.21).

Potencia Absorbida bomba variable

0

5

10

15

20

25

0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16

Q (m3/s)

Pa (k

W)

FIGURE 10.20 Power consumption of the variable pump.


323

Alfa bomba

0

0,2

0,4

0,6

0,8

1

1,2

0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16

Q (m3/s)

Alfa

(%)

FIGURE 10.21 Percentage of the angular velocity of the pump.


324

11 IN-PLOT DESIGN

11.1 DEFINITION OF CONCEPTS

GESTAR incorporates tools for the In-Plot Design project which add robustness and agility to the techniques for the hydraulic design and simulation of sprinkler systems and localised in-plot irrigation systems.

The technical terms used for these solutions vary and can lead to confusion. For

this reason, before the hydraulic design of irrigation sprinkler networks, we will clarify and unify useful concepts to avoid possible conceptual problems.

♦ In-Plot Design: Defined as the part of the hydraulic design installed from the

intake node to the crop. GESTAR can generate two types of design: sprinkler networks and drip irrigation networks.

♦ Sprinkler irrigation network : An irrigation technique in which water is applied in the form of rain of varying intensity and uniformity, through sprinklers fed with pressurised water in the plot, where the water infiltrates where it falls. To distribute the water efficiently, sprinkler irrigation requires an infrastructure of pipes and sprinklers, called Coverage.

♦ Plot: The total surface which needs watering. In FIGURE 11. 1 it is bounded by the thickest black line, called the Outline or Plot Boundary.


325

FIGURE 11. 1 Diagram of the intake node of an irrigation plot.

♦ Intake node or Intake node hydrant: The intake node is the main hydrant supplying all the water needed to the plot. In FIGURE 11. 1 , it is symbolised by a blue square at the start of the network.

♦ Sector valves: The valves controlling the pressure at the entrance to the sectors and distributing the water to the secondary pipes. FIGURE 11. 1 shows them as two connected dark blue triangles at the entrance to the sectors.

♦ Primary pipes or Main pipes The pipes transporting the water from the intake node of the network to the sector hydrants, which are the water outlets in the plot. In FIGURE 11. 1 they are represented by thick orange polylines.


326

FIGURE 11. 2 Diagram of an irrigation sector.

♦ Irrigation sector: Defined as an area of the terrain watered by the same sector hydrant or sector water outlet. These hydrants can have a wide range of mechanisms, from a simple stopcock to complex devices with pressure limiters, pressure regulators, metres and so on. In FIGURE 11. 2 they are represented by pink dotted lines.

♦ Secondary pipes: The pipes taking the water from the sector hydrants of the network to the tertiary pipes. FIGURE 11. 2 shows them as medium-thick red lines.

♦ Tertiary pipes, irrigation branches or riser branches: These three terms describe the pipes distributing water around the plot from the secondary pipes to the irrigation emitters. FIGURE 11. 3 shows these pipes as thin blue lines.


327

FIGURE 11. 3 Example of a complete sprinkler irrigation network.

♦ Sprinklers: The devices which distribute the water in the form of rain.. Depending on their function, there are two types: circular sprinklers which water a circular area, and sector sprinklers which only water a predetermined sector. In general, all of them have an emitter element where the jet of water emerges, with a biasing spring that makes the sprinkler turn intermittently in a series of bursts. FIGURE 11. 4 shows the structure of a sprinkler.

♦ Sprinkler riser: A pipe of variable length which lets the water emerge at a sufficient height to reach the necessary area of crops.

♦ The Riser Height (Hc) is the known length in metres of the riser, coinciding with the parameter called emitter height, measured from the point of insertion to the sprinkler.

♦ Insertion point or Insertion Z: The exact place where the riser is inserted. Usually below ground level.


328

FIGURE 11. 4 Diagram of the structure of a sprinkler.

♦ Nominal Sprinkler Pressure: The interior pressure in the sprinkler before the water emerges. The flow rate emitted depends on this parameter, but once at the discharge point the pressure is atmospheric.

♦ Sprinkler reach: The length the water reaches during irrigation from the sprinklers, i.e., the circular area they can water.

♦ Drip irrigation network: an irrigation technique in which the water is applied via pipes with emitters at the location of the plant root More details on its use in the chapter on Drip Irrigation, pending incorporation.

♦ Drip irrigation emitters: The mechanisms which supply water to the crop root area. The flow rate discharged by an emitter relates to the hydraulic pressure at entry, via the equation: q = kd. hx

♦ Irrigation spacing: Irrigation spacing is the distance between two contiguous hose reel irrigators or two contiguous sprinklers on the same reel. This governs the layout of the sprinklers on the terrain, which is defined by its geometry and spacing. Layout Types can be rectangular or triangular.

. Where h is the hydraulic pressure at the entry of the water into the emitter. Kd is the characteristic discharge constant or coefficient of the emitter and equivalent to the flow rate provided at a pressure de 1 m. And finally, X is the emitter discharge exponent and is characterised by the flow regime inside the emitter, and its self-compensating devices.

The use of the computer application AutoCAD as a tool for plotting networks also involves a special technical drawing terminology, which we will explain here.

Válvula Pérdidas de carga singulares (Ks, N)

Caña porta-aspersor (Hc = Altura variable)

Punto deinserción (x,y,z)

Tubería terciaria

Aspersor N

sQKH =∆Na

saQKAlcance =

Cota del terreno


329

♦ Line: the simplest object in AutoCAD, corresponding to a segment or a series

of connected segments. This is the basic starting point of the pipe layout, particularly the tertiary pipes, consisting of lines. In (fig), the lines are the tertiary pipes, in dark blue.

♦ Polyline:: a sequence of segments created as a single object, which can create straight or curved line segments, or a combination. Irrigation plots, primary pipes, secondary pipes and sectors are drawn with polylines. An example polyline is the outline of the plot shown in FIGURE 11. 3.

♦ Block: Blocks consist of objects drawn in various layers with different colours, types and thicknesses of line. Although a block is always inserted over the current layer, the block reference keeps information on the original layer, colour and type of line of the objects contained in the block. It can monitor whether the objects in a block retain their original properties or inherit the properties of the current parameters of layer, colour, type or thickness of line. In FIGURE 11. 3, the sprinklers and intake node hydrant are blocks.

♦ Layers: Work in the AutoCAD environment takes the form of drawing in layers. The layers are used for grouping information about a drawing according to its function and for reinforcing the types of line, the colour and other parameters. Layers are the equivalent of the transparent papers used in design on paper, i.e., each layer corresponds to an object. Thus, in the previous example in Fig, we see several layers of work: the layer of the lines of tertiary pipes; the layer of the plot outline polylines, the primary pipes layer, the secondary pipes layer, and the layer of the sectors; and the block layer of the circular sprinklers, sector sprinklers and intake node. Because of all this, layers are the main organisational tool used in drawing. Layers are used for grouping information by function and for stipulating the type of line, colour and other standards. By creating layers, we can associate similar types of objects, assigning them to the same layer. For example, you can put auxiliary lines, text, levels and legends on different layers. This factor is important when using AutoCAD for GESTAR, because the different elements of the plot (outline, primary, secondary and tertiary pipes, sprinklers, level curves, etc) will be inserted into layers differentiated by colours, names and characteristics. The concept of the layer is especially significant, with its usefulness for grouping information, leading us to conclude that each object laid out in AutoCAD should be assigned to a layer according to its nature. Mixing layers may distort the entire result by applying the wrong functions to objects. For example, if we draw a line or segment on the layer assigned to the tertiary pipes, the programme will then work with the line as if it were a tertiary pipe, or if the secondary and primary pipe layouts are on the same layer, the programme will not be able to distinguish between them for its calculations.


330

11.2 UTILITIES

The functions implemented provide solutions ranging from generating GESTAR models of the plot based on AutoCAD cartography, to sizing the pipes forming the plot, the hydraulic analysis of the plot including all its elements, and generating plans, whether for plots with sprinkler irrigation or with drip irrigation.

For sizing and analysing in-plot systems, tools have been developed and

enhanced to handle the entire process. GESTAR software utilities for In-Plot Design include powerful resources for:

Generating coverage with circular sprinklers, sector sprinklers and drip

irrigation emitters with tertiary pipes and spacings assigned by the user, or coverage with drip feed lines at the separations chosen by the user using AutoCAD.

Optimal sizing of the components used in the design of in-plot irrigation, primary pipes, secondary pipes and tertiary pipes.

The hydraulic and energy analysis of the agricultural system and simulations of the scenario, obtaining operating parameters.

Generating detailed plans of the design and exporting them to AutoCAD format.

These methods make it possible to create economical designs and exact forecasts of all the hydraulic parameters, even in plots with very irregular shapes and topography.


331

11.3 SIZING AND ANALYSING IN-PLOT SYSTEMS

FIGURE 11. 5 shows a diagram of the subprocesses to be carried out for the process of sizing and analysing in-plot systems, which can handle tasks ranging from topological definition in complex systems to hydraulic testing of pressure and reach, including obtaining measurements.

FIGURE 11. 5Diagram of the process of sizing and analysing in-plot distribution networks.

This diagram shows a simplified version of the operations for completing optimum sizing and analysis of in-plot irrigation networks, whether for sprinkler irrigation networks or for drip irrigation networks, . ♦ Generating coverage.

GESTAR and AutoCAD are used in combination and communicate with each other to carry out this process.. In the AutoCAD environment, draw the plot outline or boundary with a polyline. Use GESTAR to define the characteristics of the network. Finally, GESTAR automatically draws a mesh of tertiary pipes with sprinklers or drip irrigation emitters, which with the specified irrigation spacing and type of distribution, covers the area inside the plot outline.

GENERACIÓN COBERTURA, a partir de los límites de parcela en dibujo AUTOCAD

SECTORIZAR Y DIBUJAR LA RED DE TUBERÍAS SECUNDARIAS Y TERCIARIAS

CONFIGURACIÓN DE LA RED PARA SU DIMENSIONADO

DIMENSIONADO DE LOS SECTORES

DIMENSIONADO TUBERÍA PRINCIPAL

ANÁLISIS HIDRÁULICO Y OBTENCIÓN DE PARÁMETROS DE FUNCIONAMIENTO

REDIMENSIONADO EN FUNCIÓN DEL ANÁLISIS HIDRÁULICO

EXPORTAR LA RED con los resultados del diseño a AUTOCAD, generación de planos.

AUTOCAD GESTAR C&L

GENERACIÓN DE CURVAS DE NIVEL Y SUPERFICIES

Modelo Digital del Terreno

IMPORTAR RED al entorno de diseño de GESTAR.

CORTES en la distribución de aspersores

ELEVACIÓN DE ENTIDADES


332

♦ Sectorising and drawing the network of secondary and tertiary pipes

In the AutoCAD environment, with the support of the generated coverage defining the tertiary pipes, draw the layout of the primary pipes, the secondary pipes and the sectors, in the case of sprinkler irrigation, generating the entire network of pipes of an In-Plot Design.

♦ Generating stretches and levels.

GESTAR needs a correct definition of the stretches making up the irrigation network, in order to establish correctly the connections of their elements, through a Cut-offs process in the Distribution de Sprinklers or Distribution of Drippers, as applicable. Also, the layout of the network in AutoCAD by default level has a null level. At this point the real levels of the plot should be assigned. These levels are defined by points or level curves, and therefore need a terrain modelling programme, such as MDT5, to set the elevation of entities which situates each element with its respective exact height.

♦ Importing the network to the GESTAR environment.

The hydraulic design of the irrigation networks is done with the calculation modules of the GESTAR software. The importing process transfers the layout, the lengths of the pipes and the levels of the nodes in the network from AutoCAD to the GESTAR environment. The objects to be converted are marked together with their working layers used in the AutoCAD environment, in order to convert the nodes and elements in separate steps, as necessary. The type of emitter, by default, is selected during this operation.

♦ Configuring the network for sizing.

The user reviews the type of pipes and their connections and installs the additional hydraulic components of the network. The sectors are laid out if they have not been imported. The intake node is modelled as an Known Pressure Node, the value of regulated pressure being the estimated value available downstream of the intake node hydrant. Also, the sector hydrants or water outlets are installed as Known Pressure Nodes, with the Sector Entry Point property activated.

♦ Sizing the sectors.

The next step is to size each of the irrigation sectors. The sizing of sectors takes into account the design criteria of maximum and minimum velocity, the nominal flow rate of the emitters and their working pressure, the materials involved, and the pressure on entry to the module. After this process, the Known Pressure Nodes installed as Sector Entry Points will show characteristics resulting from the sizing of the sector, necessary for sizing the main pipes, such as the working entry flow rate depending on the pressure in the sector, and the pressure required at entry, including the estimated losses in the valves.

♦ Sizing the main pipes.


333

The main pipes are sized taking into account the turn-based irrigation sectors. The irrigation turns are specified with the duration required and their corresponding characteristics. The programme identifies the critical irrigation sector (Sector Entry Point with the smallest hydraulic slope), sizing the main pipes to serve at least the entrance pressure taken into account in the previous process and considering the path to this sector as the priority. Next the rest of the pipes are sized, taking into account the pipes of the shared path to the critical sector, thus making it possible to adjust the diameters, as the shared paths will have larger diameters than needed for reaching the pressure of the non-critical modules. The process is performed recursively until it finds an optimal result.

♦ Hydraulic analysis.

The complete simulation of each of the irrigation turns in the plot is used to analyse its hydraulic functioning, detecting malfunctions and possible improvements to the design. In the hydraulic analysis, there are useful options for checking data, as well as the results: it shows the theoretical trajectory of the water, the real reach of the water with the data entered in the example, in the case of irrigation with total coverage by sprinklers.

♦ Exporting to AutoCAD:

Exporting the models of the plot to AutoCAD lets you generate detailed plans of the design in this format. The process for exporting from GESTAR to AutoCAD marks the objects to convert, both nodes and elements, with a configuration adapted to the needs of this type of project.

11.4 OBTAINING THE DIGITAL MODEL OF THE TERRAIN

Altimetrically irregular plots usually have level curves or points preset by the value of the variable ‘z’ which designates the level or altitude of the various points of the plot.

The programme MDT5 in AutoCAD includes a utility for creating a surface based on the level curves. Obtaining the digital model requires a prior process called triangulation. During this process the surface is tessellated as a series of triangular planes which adapt to the different levels, simulating the breaks or changes in the slope of the terrain which are defined by the breaklines. Breaklines are conventional AutoCAD polylines defined in certain layers. The vertices of these polylines may coincide, or not, with topographical points. If the ground level coincides, the triangulation process considers the level of the point. Naturally, if they do not coincide, the level of the vertex of the polyline is taken.

Triangulation can be obtained using different methods, most commonly by creating surfaces based on level curves or on a point cloud.


334

In MDT5, to create a surface based on level curves, just tick the checkbox corresponding to the command Create Surface. Vertices of the surfaces can also be added, changed or deleted with the corresponding commands in the menu Surfaces > Utilities. When selecting the option Create surface, a dialogue panel appears in which you must Save the file in the format . sup with a random name, which will prompt the window in

Level curves and creating the surface area

FIGURE 11.15.

FIGURE 11. 6Create surface window in the AutoCAD environment (MDT5)

♦ The table of options of Elements to Triangulate lets you specify the different

elements to use for the creation of the surface. You can triangulate Topographical Points, Breaklines and Level Curves at the same time. As each


335

option is enabled or disabled, at the right a button will be enabled or disabled which lets you specify which elements of the drawing are used.

• Points: enable this option if you want to triangulate the topographical points. By default, the programme triangulates all the points of the drawing, excluding those where the level is not triangulable. Click Select Points to specify a different set of points using the Selection window.

• Breaklines: this option lets you decide whether to use breaklines. Click the button Layers to select the layers where the breaklines are drawn, using the Select Layers window.

• Level curves: if the drawing includes a curve, polylines can be used to create vertices on the surface. These polylines behave like breaklines. Click the button Select to bring up the window shown in FIGURE 11.16.

FIGURE 11. 7Level curves window

The Select Curves button lets you select in graphic form the curves you want to use for triangulation.

The Select Layers option is used to specify the level curves to triangulate by selecting the layers they are in. The layers are selected in a window like the one in FIGURE11. 17. Select the layer and press the > key..


336

FIGURE 11. 8Layer selection window

Because in some cases, the polylines which define a curve have too many vertices, the MDT5 programme can apply a filter which disregards vertices which are very close together. This reduces the number of very closely grouped vertices. The parameter Distance between Vertices controls the distance below which the vertices are ignored.

The checkbox Eliminate Flat Triangles decides whether a post process will be used which avoids forming flat areas where the level curves are very pronounced, crests, etc.

Once the elements to triangulate have been decided, other options can be specified, which appear in FIGURE 11.15. For example, if an Outline will be used which surrounds the cloud of points to triangulate or of Islands will be considered in the triangulation. For both these cases you simply enable the corresponding options and specify the layer where the polylines are which represent these entities.

If no outline is specified, it is important to specify the Maximum Length of the sides of the outer triangles, to avoid forming areas with vertices too far apart.

Meanwhile, there is the option to Include Vertices of 3D Breaklines, which considers the coordinates of the vertices of the 3D polylines in the layers selected as triangulation vertices.

If the breaklines contain arcs, the parameter Discretise Breakline Arcs lets you specify the separation between the vertices that the programme will add to the surface along them.

Finally, the lower part of the dialogue controls how the surface is represented. There are different possibilities which are:

• Nothing: the surface is not drawn.


337

• Quick View: shows the surface on the screen, but without creating entities. The next time AutoCAD regenerates the drawing, the drawn elements will disappear. This has the advantage of not increasing the size of the drawing file.

• Outline: Represents only the outline of the surface. Useful if the surface has too many vertices and/or your computer is not very powerful.

• Window: lets you designate a rectangular area, for drawing just the parte of the surface inside it.

• Complete: draws all the lines making up the surface. If you create a surface with many vertices, the number of lines drawn is also very high, and this may increase the size of the drawing file so much that AutoCAD cannot handle it quickly. In this case it is advisable to use another representation option.

You can also select the layer where the surface will be drawn, clicking on Layer. Normally it is advisable to enable the checkbox Clean Layer, so the programme can delete the entities existing in the layer before drawing the surface. Additionally you can enable Zoom to the Surface so that the area of the drawing containing the surface is centred on the screen.

In the example below, a point-based surface will be generated using the application MDT6. The first step is to Convert the Drawing Entities so the Points included in the CAD drawing are defined as required by MDT6. On the AutoCAD toolbar in the MDT6 menu, click on Points/ Convert / Drawing Entities to reach the window in

Creating the Surface with Points

FIGURE 11-9.


338

FIGURE 11-9. MDT6. Option Points/ Convert / Drawing Entities.

From the panel Points Layer, click the button …to display the window in FIGURE 11-9.

FIGURE 11-10. MDT6. Points Layer. List of Layers.

From the List of Layers (FIGURE 11-10) select layer 7 and then click the Accept button in FIGURE 11-9.

From the AutoCAD toolbar in the MDT6 menu, choose the Surface menu, the option Create Surface and then Save the file in “.sup” format with a random name, which will bring up the first window in FIGURE 11-11. Mark the Maximum length and Points checkboxes. Enter a sufficient length, for example, 1550 metres. Next, choose


339

the option Select Points to bring up the Point Selection window. By default, all the Points will be selected.

FIGURE 11-11. MDT5 Create Surface/ Point Selection Windows.

Finally, accept the options, and the process will go ahead as seen in FIGURE 11-12.

FIGURE 11-12 Creating a surface in the AutoCAD (MDT5) environment


340

11.5 SPRINKLER IRRIGATION

11.5.1 GENERATING COVERAGE.

GESTAR is complemented by AutoCAD for laying out the network and capturing levels. In the AutoCAD environment, the line is a segment or a series of connected segments. Meanwhile, a polyline is a sequence of segments created as a single object. These two elements are the basic starting point for the layout of the irrigation networks.

The boundary of the irrigation plots is formed by a closed polyline, forming a

closed polygon which generates a boundary corresponding with the plot boundary. A reference line or segment should be found inside it which marks the location and direction of the line, matrix or mesh of sprinklers generated by the application. The image in FIGURE 11. 6 shows an example plot with a random shape, suitable for conversion to irrigation, with the plot outline or boundary drawn (polyline) in black and the reference line in blue (line or polyline).

FIGURE 11. 13 Outline of an irrigation plot and reference segment in the AutoCAD environment.

Based on an arbitrary plot outline, GESTAR can generate meshes of sprinklers

automatically in the AutoCAD environment (circular meshes inside and sectors at the edges) with spacings assigned by the user and the tertiary pipes. The generated meshes of coverage are made up of lines formed by the pipes connecting the sprinklers.


341

The GESTAR tool enabling the execution of this generation of coverages can be selected on the menu of the In-Plot Design toolbar, choosing the option Sprinkler Distribution, which will open the window of the same name, shown in FIGURE 11. 7, which will require a series of data for configuring the network.

FIGURE 11. 14Sprinkler distribution window

Sprinkler distribution requires choosing a series of characteristics to define the

final configuration of the coverage.

♦ Sprinkler Distribution Format lets the user choose the format of the distribution of the sprinklers, i.e., to give them different types of distribution, along a line, creating a matrix of sprinklers or in a plot.

• In a Line of Sprinklers you can choose:

The total Number of Sprinklers to be introduced in the line of sprinklers: the programme will space them equidistant over the reference segment already created in the AutoCAD environment, covering the entire area inside the plot perimeter.

The Sprinkler Spacing, letting you assign the distance between sprinklers on a reference segment in the AutoCAD environment. The programme will create a series of sprinklers placed at the distance selected by the user.

The application lets you use lines of tertiary pipes to join the sprinkler block objects using the option Creating an Associated Conduit.


342

• The Matrix of Sprinklers option can be used to create a template of sprinklers for laying out the irrigation network. This action will place a rectangular grid of lines defined according to its size and orientation to the right of a chosen point in the AutoCAD environment .

Dimensions gives the option of choosing, on the X or Y axis of the grid, the number of sprinklers to be installed and how far apart they should be.

Orientation defines the angles of the axes of the grid: 0 degrees for the X axis is a horizontal line, and for the Y axis a vertical line on the drawing plan in AutoCAD.

• The option Sprinklers in Plot will create a distribution of blocks representing the sprinklers which the programme will join to lines of tertiary pipes, creating a mesh. GESTAR lets you assign characteristics to the created mesh

Irrigation spacing assigns values of distance between sprinklers, distance between tertiary pipes and distance to the edge of the plot. The distance between sprinklers on the same tertiary pipe is introduced in the command with the letter (D); the distance between two parallel tertiary pipes is shown in metres in the field marked with the letter (H); and the irrigation margin, in metres, is the minimum distance the programme must respect when distributing in order to let machinery move around the edges of the plot. Whatever the value of the irrigation margin, no sprinkler will be further from the plot boundary than half parameter D of the irrigation spacing.

Type of Distribution lets you choose between a triangular or rectangular distribution of the sprinklers.

Irregular Outline. This option should be marked if the plots have very irregular perimeters, with angular edges, recesses or islands, i.e., spaces where the line of the mesh is broken into two or more sections. This option lets the programme consider only the areas within the perimeter of the plot and locate sector sprinklers on the difficult areas.

♦ Sprinklers Radius – Drawing Coverage Circles. This option lets you lay out reach circles around the sprinklers and the sector sprinklers according to the measurements entered in the field Sprinkler Radius. This action will create these circles in the AutoCAD environment, with the same layers as the sprinklers and the sector sprinklers.

♦ Sprinkler Layer Name: the name which will be assigned in the AutoCAD environment to the layer of blocks which the programme creates automatically for the circular sprinklers.


343

♦ Sector Sprinkler Layer Name: the name which will be assigned in the AutoCAD environment to the layer of blocks which the programme creates automatically for the sector sprinklers.

Once the desired characteristics have been chosen, click the button Create Distribution. This command will take the user to the AutoCAD environment, to select, with a mouse click, the commands according to the chosen type of distribution.

The option Sprinklers Distribution in a Plot is the most complex of the three format options. Its internal operations during the distribution are described in detail below:

The user chooses the previously defined characteristics Irrigation spacing and Type of Distribution, and then in the AutoCAD environment clicks on the plot boundary and the reference segment or base, both previously drawn.

At this point, the user waits for GESTAR to distribute the sprinklers in the selected plot with the parameters already defined. The first internal step is the definition of the Distribution Mesh: From the base segment parallel lines are drawn at the distance H defined in the irrigation spacing, first descending, i.e. from greater to smaller coordinates, and then ascending. This mesh will be used as a pattern for distributing the sprinklers and will look like FIGURE11. 8

FIGURE 11. 15Appearance of the mesh of Sprinkler Distribution in a plot

After creating the mesh, the programme lays out the distribution of sprinklers. This always begins at the top left corner of the mesh, i.e., the point where the mesh intersects with the plot boundary with the lowest X and highest Y coordinates. The distribution of sprinklers begins in this first line of the mesh,


344

placing the first sprinkler at a distance of D, and so on until reaching the plot boundary at the other end. At this end, the programme readjusts the distribution to let there always be a minimum distance between the last sprinkler of the distribution and the plot boundary. This minimum space is the Irrigation Margin and will allow machinery to pass along that edge of the plot.

The programme will send a probe in relation to the first sprinkler of the newly created distribution line with the right inclination for creating a rectangular or triangular spacing distribution. the first sprinkler of the new line of the mesh will be inserted at the point where the probe intersects with that new line. If the probe does not intersect that line of the mesh it will go on to the next sprinkler, and so on, until it finds a sprinkler from which the probe intersects the next line of the mesh, as seen in FIGURE 11. 9.

FIGURE 11. 16Diagram of the actions of the probe ordering the Sprinkler Distribution.

At the probe-mesh intersection of the next line of sprinklers the programme inserts a sprinkler and works from that point leftwards, going towards points with a lower X coordinate inserting sprinklers at a distance D successively, and when it reaches the plot boundary it starts the sprinkler distribution from the intersection point rightwards, towards a higher X coordinate.

Finally, it comes to the Sector Sprinkler Insertion. Some of the lines of the mesh may be shorter than the defined spacing structure, i.e., less than parameter D. The application will carry distribute sprinklers and sector sprinklers according to the following directives:

If the segment of the mesh is shorter than the radius of the sprinkler, GESTAR will place a single sector sprinkler at one of the ends.


345

If the line of the mesh is longer than the radius but shorter than the diameter of the sprinkler, GESTAR will place two sector sprinklers, one at each point where the mesh segment intersects the plot outline.

If the mesh segment is longer than the diameter of the sprinkler, GESTAR will begin inserting intermediate sprinklers, as described below: At the moment of distributing the sprinklers on the base segment of the mesh, the distance between the last sprinkler and the plot boundary must take into account the Margin established by the user. If this distance is less than the Margin, this last sprinkler will be moved to the middle of the last stretch.

Where

d – theoretical initial distance between last sprinkler and plot boundary

D – Irrigation spacing, distance between 2 sprinklers on the same tertiary pipe

If d < Margin, then distance d will be recalculated, and will become

2)( dDd NUEVA

+=

In this way we will have 2 extreme cases:

d = 0 the last sprinkler will be recalculated to be at a distance equal to half the irrigation spacing. If, for example, D = 18 metres, the last sprinkler would be 9 metres from the plot boundary.

d = Margin the last sprinkler will be at a distance equal to

2)Margen( +

=Dd NUEVA

If, for example, D = 18 metres, and the Margin is 12 metres, the last sprinkler would be 15 metres from the plot boundary.

FIGURE 11.10 shows that the distance of the last sprinkler from the plot

boundary “d” was less than the Margin, so instead of placing it at that point, it was placed in the middle of the last stretch “Dmg”


346

Dmg

dDmg/

2

Dmg/

2

FIGURE 11. 17Diagram of the Sprinkler Distribution

Therefore, the Sprinkler Distribution must be formed by the blocks, which are the sprinklers, and connected to them, the lines corresponding to the tertiary pipes.

11.5.2 SECTORISING AND DRAWING THE NETWORK OF SECONDARY AND PRIMARY PIPES.

A mesh of blocks of sprinklers joined by lines of tertiary pipes has been generated in the AutoCAD environment as a basis for the complete layout of the irrigation network. The mesh shown in FIGURE11.11 consists of:

♦ Circular sprinklers and sector sprinklers.

♦ Lines connecting sprinklers corresponding to the meshes of tertiary pipes.

♦ Coverage circles. If you choose the utility Sprinkler reach – draw coverage circles, the tool lays out the circles of the estimated sprinkler reach entered by the user.


347

FIGURE 11. 18 Mesh generated in a plot with the sprinkler distribution

The AutoCAD programme lets you count the number of sprinklers, whether circular or sector sprinklers, with the Quick Selection option in the Tools menu on the toolbar. First the objects to select are selected with the entry command ‘SELECT’ and then the dialogue window of the option Quick Selection opens, where you can choose the layer and the name of the layer you want to select. Accept and the command menu will show the number of objects selected in that layer. If the selected layer is ‘sprinklers’, the selected circular sprinklers will be counted, and if the selected layer is sector sprinklers, the selected sector sprinklers will be counted.

It is essential that the design and layout of the primary pipes and of the secondary pipes provides total connectivity of the networks to the project from the intake node hydrant to the sprinklers. The correct design and layout of the network in AutoCAD format is fundamental, as this will determine the optimal result of importing and the easy treatment of topography with the GESTAR software. An example is shown in FIGURE 11.12.

The primary pipes will be laid out with various polylines making stretches from the exit from a sector to the entrance of the next, and it will be essential to take into account the existing bifurcations.. Begin from the place where the hydrant is sited and click on the polyline drawing option with the layer assigned to this type of pipes open, and lay out the polyline until the entrance to the first sector or until the first bifurcation. After that the operation continues from one sector entrance to another, or from the start of a bifurcation to another, or to a sector entry point.

The secondary pipes will be delineated in a single stretch from the connection to the main pipes to the last branch of the tertiary pipes, with the layer assigned for this type of pipes selected. If the layout of the secondary pipes has vertices located at intersection points with the tertiary pipes this can cause problems in the distribution of later cut-offs, and therefore for these cases we recommend moving the vertex of the secondary pipe.


348

The tertiary pipes or irrigation branches have already been created by the software tool, and because of this, only the relevant changes will be made according to changes in the topology of the sprinklers, for the convenience of the user and for uniform irrigation. There may be points where secondary pipes and tertiary pipes cross in plots with a complex layout. The user must be aware of this, as the programme will automatically place an undesired cut-off between these pipes.

FIGURE 11. 19Sprinkler irrigation network

Another of the operations to be carried out to prepare the network will be the

sectorisation of the sprinklers, i.e., assigning sectors neatly, taking into account the future application of those sectors to a network of pressurised pipes and their use in the field with a series of irrigation turns. There are two possibilities for laying out the sectors: in AutoCAD and then marking the option to import the sectors or directly designed in GESTAR with the Assign Sector tool of the In-Plot Design menu, also accessible via the icon DrawSector on the toolbar (page 366).

The sectors are laid out in AutoCAD using polylines in a different layer to the rest of the pipes, in order to import it in a later process. One of the essential characteristics of the layout is that each sector must be closed and must always have one more vertex than sides. For example, if the number of sides is 4, as in this case, the sectors have 5 vertices, with the first and the last at the same point. The number of vertices and their location can be seen in the object properties panel in the AutoCAD environment, which is reached by selecting the object and clicking with the secondary mouse button on the option Properties.

Generating the coverage has created a continuous mesh of tertiary pipes, which must be sectorised for calculation and sizing, with a branched network. This means that


349

there are unneeded stretches of tertiary pipes between sectors. They can be eliminated in various ways:

♦ After importing to the GESTAR environment, patiently

eliminate the unneeded connections between tertiary pipes with the Delete tool (page 75) and draw the sectors with the Assign Sectors tool (page 366).

♦ In the AutoCAD environment, delete the unnecessary stretches of tertiary pipes using the entry command ‘DELETE’ which will delete the selected objects. A quick way to select objects for deletion is to type the command ‘f’, which is the option for selecting objects with a selection fence. You then have to specify various points to create a fence which goes through the objects you want to select and finally press the ‘Enter’ key to finalise the selection and deletion. In this process it is important to be careful with the layout of the selection fence, as if it comes too close to certain objects, such as the sprinklers, you may delete them by mistake.

♦ The process of Cut-offs in the Sprinkler Distribution (page 337) automates the process of deleting unnecessary tertiary pipes between sectors by laying the sectors out in AutoCAD format on top of the superfluous pipes and marking the option Calculate Cut-off with Sectors in the process.

Later, the location of the sprinklers, whether circular or sector sprinklers, must be fine-tuned, redistributing them in the cases where it appears necessary, so that the modification clearly helps an optimal implementation of the irrigation in the plot, producing a complete sprinkler irrigation network as shown in FIGURE 11.13, which used a similar method of laying out sectors with the tool automating the process.


350

FIGURE 11. 20Sprinkler irrigation network with the sectors laid out.

AutoCAD users must be aware of the working layers used to create this

network, as during the conversion of the elements (chapter 7. 5. 2, page ¡Error! Marcador no definido. and chapter 11. 3. 4 page 350) they will need to know them.

11.5.3 GENERATING STRETCHES AND CUT-OFFS

GESTAR requires the pipes to be divided precisely into stretches in order to establish an exact connection with the branched network and correctly locate the nodes and elements in the later import process. Also, irrigation plots usually have irregular topography. This is provided in various ways: it might be provided by points or level curves of the terrain in a topography programme, or if the plot has been levelled, by the elevation data or height loss in different irrigation areas or sectors, etc.

Level points or curves are usually available, so GESTAR lets entities be elevated with a specialised programme. The recommended programme is the topographical application MDT5, which is widely used, although this is not obligatory. Other applications can also be used for this purpose, with results consistent with the AutoCAD format and with the geometry of the lines and polylines, and their cut-offs.

The process of generating stretches and levels is determined by the actions which can be seen in the schema of FIGURE 11.14 and which are discussed individually below. If level curves are not available or there is no need to elevate entities, simply use the second tool in Sprinkler Distribution Cut-offs.


351

FIGURE 11. 21 Schema of the process of generating levels and stretches

The programme needs to execute a process which recognises the cut-off points between pipes so the connections between them will be exact and supply can reach the whole network. The tool for this action of breaking down the pipes is called Sprinkler Distribution Cut-offs, located in the In-Plot Design menu on the toolbar (

Sprinkler Distribution Cut-offs

FIGURE 11. 18).


352

FIGURE 11. 22 Sprinkler distribution cut-offs window

Sprinkler Distribution cut-offs are done by choosing the working layers of the AutoCAD environment. To do this, they are selected from the lists which can be used for the process, which are the following:

The Riser Layers list is used to choose the layer of the AutoCAD environment associated with the tertiary pipes or risers.

The Secondary Layers list is used for choosing the layer of the AutoCAD environment associated with the secondary pipes. There may be points where secondary pipes and tertiary pipes cross in plots with a complex layout. The user must be aware of this, as the programme will place a cut-off between these pipes.

The Primary Layers list is used for choosing the layer of the AutoCAD environment associated with the primary pipes.

The Layer Sectors list is used for choosing the layer of the AutoCAD environment associated with the sectors. This tool lets you delete the unnecessary parts of the tertiary pipes at the moment of sectorisation. To do this, the option Calculate Cut-off with Sectors is also ticked. This way, the unnecessary risers will be eliminated automatically.


353

The list of Objects to Transform is used to select the types of objects that are transformed in AutoCAD. Lines, 2D polylines and 3D polylines can be cut.

The option Eliminate Original Objects lets you eliminate the existing objects and must be ticked.

The recommended Tolerance is 0.01.

When an AutoCAD object is transformed into a Node in a GESTAR network, the programme checks that the Node was not created in an earlier transformation. The check consists of comparing the X, Y, and Z coordinates of the existing Node with the object being transformed.

If the difference between the three coordinates is below the Tolerance value, the application will consider it to be the same object, and will not create a new Node, but keep the single Node already created. This resource is useful for facilitating the connectivity of stretches and blocks of the network graphic, so that small drawing errors are automatically recovered from, where using the option Object Snap Mode (see p. 195) is not enough to connect the objects in points of insertion and ends of lines and polylines. Thus, all the ends and points of insertion found within tolerance will be considered as the same Node. This parameter must be set correctly, as a very small value would not have the connecting effect sought, and one that is too high would join nodes which should be separate. We recommend that tolerance be lower than the length of the shortest Pipe in the plan. Special care must be taken in the small stretches connecting the network to the hydrants; where these are very short, we recommend skipping these stretches and inserting the block representing the hydrant directly on the network conduit. If the end nodes of an element are joined into one by the Tolerance criteria alone, this element will not be created.

Elevating entities The elevation of entities lets you convert a flat cartography, with entities in 2D,

to a 3D cartography, in order to prepare it for obtaining profiles or to obtain a surface. The entities this command processes are lines, polylines and arcs.

This command is the last phase of the process of generating stretches and levels. It lets you locate the components of the plot in their original altimetry, so they can later be imported correctly and effectively. The tool used for this process is Elevating entities, in the drop-down menu of the option Utilities, in the MDT5 menu on the toolbar. The actions are carried out in the AutoCAD environment and consist of:

♦ Selecting the type of elevation desired. In our case we want to elevate a surface and therefore enter an ‘s’ in the space in the option. Once a set of entities has been selected, the programme assigns each of its vertices the level corresponding to them in the current surface. It also asks you to specify if you also want to process the polylines which are already in 3D, or only the two-dimensional ones. If the surface is not defined, the programme will try to assign the levels of each vertex according to the points in the drawing.


354

♦ Choosing objects through the option select objects, which lets you the objects to be elevated.

♦ The choice to elevate the polylines by entering the letter ‘s’ for yes or the letter ‘n’ for no in the option Also elevate the 3D polylines? <N>.

♦ The option of incorporating cut-offs at the points where the polylines cross the model by entering ‘s’ for yes or ‘n’ for no in the space given with the question Incorporate cut-offs with the model? <N>.

The phases of the process which permit the selection of various options for elevating entities are shown visually in FIGURE 11.19

FIGURE 11. 23 Options of the entity elevation tool in AutoCAD.

The entire procedure carried out in the AutoCAD programme is designed to handle and construct the topography of the irrigation network in a sophisticated and effective way, so that after importing into the GESTAR programme, it can calculate sizing with its energy module. For this reason a network methodically laid out with this programme can be handled easily and effectively in the GESTAR software, while a network which is poorly delineated and connected or with repetitive elements will lead to a tedious and probably unproductive session with the GESTAR software. Therefore, we strongly recommend paying close attention to the connections of the network between pipes, sprinklers and their respective cut-off points, for an easier and more agreeable use of the programme.


355

11.5.4 IMPORTING FROM AUTOCAD TO THE GESTAR ENVIRONMENT

The branched network is transferred from the AutoCAD application to the GESTAR environment through an importing process.

This process will be executed with the communication between AutoCAD and GESTAR correctly defined in chapter 7.5 page ¡Error! Marcador no definido.. Use the toolbar icon , or the menu File/ Import/ From AutoCAD, to reach the AutoCAD connection window. The elements and pipes are identified according to the drawing layer in AutoCAD as a riser branch, secondary or primary pipe automatically for later differentiated treatment. The importing process follows the sequence described in FIGURE 11. 21: first the nodes are identified and transformed, and after indicating the type of network, the pipes are identified and transformed, and finally a network file is generated in the Gestar format.

FIGURE 11. 24 Process of Importing from AutoCAD.

Transform nodes

The first step is to capture the entities of the AutoCAD drawing which will become Nodes generated from the drawing in *.dwg format. The different types of nodes (Known Consumption, Junction, etc.) will be created by successive transformations, taking into account the parameters listed below. Thus, the user can sequence the


356

transformations of the different types of Nodes modifying these variables, gradually accumulating the results of the transformations to create the new network.

FIGURE 11. 25Transforming AutoCAD nodes to GESTAR.

♦ Objects to Transform. GESTAR lets you transform AutoCAD

objects of the Block and Point type to Elements and Nodes. When the user opens the first window in FIGURE 11. 20, GESTAR will have captured the collection of Points and Blocks from the open and active AutoCAD drawing, presenting it as a drop-down list in the first panel. The type of objects to be transformed into Nodes can be selected, as many as desired, from this list. The geometric property of elevation of each objet to be transformed will be captured and associated with the Node created in GESTAR.


♦ Tolerance. When an AutoCAD object is transformed into a Node in a GESTAR network, the programme checks that the Node was not created in an earlier transformation. The check consists of comparing the X, Y and Z coordinates of the existing Node with the object being transformed.


357

.

If the difference between the three coordinates is below the Tolerance value, the application will consider it to be the same object, and will not create a new Node, but keep the single Node already created. This resource is useful for facilitating the connectivity of stretches and blocks of the network graphic, so that small drawing errors are automatically recovered from, where using the option Object Reference (see p. 195) is not enough to connect the objects in points of insertion and ends of lines and polylines. Thus, all the ends and points of insertion found within tolerance will be considered as the same Node. This parameter must be set correctly, as a very small value would not have the connecting effect sought, and one that is too high would join nodes which should be separate. We recommend that tolerance be lower than the length of the shortest Pipe in the plan. Special care must be taken in the small stretches connecting the network to the hydrants; where these are very short, we recommend skipping these stretches and inserting the block representing the hydrant directly on the network conduit. If the end nodes of an element are joined into one by the Tolerance criteria alone, this element will not be created.

♦ FIGURE 11. 21 shows a set of variables which can be defined by the user. These starting points are the following: water supply (m3/s), surface (ha), set point pressure (mca) and hydrant diameter (inches). For the example, no water supply needs to be applied, as this will be introduced in the sprinkler window. However, a surface of 1 ha, a set point pressure of 42 mca, a hydrant diameter of 2" and a tolerance of 0 will be introduced.

The options offered by the GESTAR software during transformation are wide-ranging and include a very powerful feature in the case of In-Plot Design with sprinkler irrigation, as the drop-down list in the Type of Node section gives the possibility of choosing the type of Node to be created, in this case, Sprinkler Node. In this way, the nodes whose layers corresponding to sprinklers and the sprinkler sector can be transformed directly into sprinklers. The Sprinkler Configuration window (see icon , p. ¡Error! Marcador no definido.) lets you configure the sprinklers according to the needs of the user.


358

CONFIGURATION OF THE EMITTER

FIGURE 11. 26 Sprinkler configuration window

The sprinklers to be introduced into the irrigation network will be chosen and configured in the Sprinkler Configuration window, FIGURE 11.22. Two fields are recognised: the upper where the emitter is configured, and the lower where the riser is configured.

Configuration of the emitter

In the top left of the window in FIGURE 11. 22 the elevation of the emitter is entered, which is the height of the point of emission over the point of insertion, in this case 1.5.

In the top right the sprinkler is chosen from those available in the GESTAR database. If none of these meets the needs of the user, the data can be entered manually. For this example, the manufacturer Rain Bird was chosen with the emitter type T 40 RC -6. This action populates the sprinkler characteristics, defined below the table, except the reach and the nominal flow rate. The pressure which will finally reach the emitter is not known, so the user must choose according to the reach required and the type of sprinkler.


359

Configuration of the riser

♦ At the bottom the type of pipe needed for the riser is chosen according to the database. Its interior diameter (20 millimetres), length (1.5 metros) and roughness (0.000007) are entered.

Click the button Transform in FIGURE 11.21 to begin the transformation of Nodes. When the lower part of the window reaches 100%, click Next. This opens the window in FIGURE 11.23 where you must select the option IN-PLOT DISTRIBUTION, which then goes to the window in FIGURE 11. 24.

FIGURE 11. 27 Selection of the type of network to Transform.

In the same way as the nodes, the elements to transform must first be captured in the AutoCAD environment. In the case of sizing for in-plot irrigation, a specific application is the transformation of the sectors if they have previously been laid out in AutoCAD, as in this way you can obtain the imported sectors in GESTAR for the later treatment of the network.

Transform elements


360

FIGURE 11. 28 Transforming AutoCAD elements to GESTAR.

♦ Objects to Transform. The application can transform AutoCAD objects of the Line, (2D)Polyline and 3D Polyline types into Pipe or Sector Elements. The user can select various types of object for transforming simultaneously. In the case of transforming entities of the 3D Polyline type, the levels of the end vertices will be automatically captured. When there is a transformed Node on a vertex, the elevation associated with the node in transformation will have precedence over the level of the 3D Polyline. The lengths imported for the Pipes and the Sectors correspond with those of the Lines, (2D) Polyline and 3D Polyline.


361

♦ Work Layers. As with the Nodes, GESTAR lets you filter the layers which you want to form part of the transformation. One or various layers can be selected, which will be taken into account by the programme, and if none is selected (as set by default), no type of filter by layer will be taken into account. It is very important that in the selected layers, all the types of line existing in the selected rectangle really correspond to conduits, and not to any other layout element.

♦ Transform Free Ends into. On this drop-down list, where all the types of Node defined in GESTAR appear (Junction, Reservoir, Dam, Known Pressure, Known Consumption, Hybrid, Free and Double Condition nodes), select the type of Node to be created at the ends of the transformed lines or polylines when the ends do not coincide with the points of insertion of Blocks or Points already transformed through the Nodes Panel.

♦ Default Variables. Two variables can be set for GESTAR to assign to the created Pipes: the values of Internal diameter (mm) and Roughness.

♦ In the field ELEMENTS TO TRANSFORM - DISTRIBUTION OF SPRINKLERS/EMITTERS each of the work layers in AutoCAD must be associated with each type of pipe. In this way, in the list transforming the secondary pipes, their work layer, SECONDARY PIPES must be selected; the list transforming the primary pipes is the second list and its work layer, GENERAL, is selected. In the case study the outline of the sectors was drawn in the AutoCAD environment and imported by selecting its work layer in the last list. This step is fairly useful, as it saves having to select sectors later. If you have decided to import the sectors, as well as selecting them in the corresponding layer, you must select the option Import sectors.

The tolerance value assigned in the Nodes Panel also controls the transformation of Pipes. Thus, if the difference in coordinates of an end vertex and another Node is closer than the value set for Tolerance, GESTAR will generate a single Node in its place. We advise the user to analyse the proximity of the different hydrants and Junction Nodes on the AutoCAD plan before setting the tolerance value. It will also be vitally important to delineate the network correctly in AutoCAD. We recommend activating Object Snap Mode (command REFENT) to connect stretches and objects correctly, avoiding connectivity problems, as if they exceed the Tolerance value this will lead to duplicate Nodes in the network. In the case of plans combining Lines, Polylines, 3D Polylines and Blocks, end vertices may appear which coincide in floor but not in level, so that the objects will not be connected. Given that the tolerance criteria are checked in all three coordinates, this will produce independent superimposed Nodes in the GESTAR model, with different levels, and isolated stretches in the network.


362

The transformation of an AutoCAD plan generated according to the recommendations on the definition of each group of pipes (primary, secondary and tertiary pipes) in a different layer (p. 329) will generate a network in GESTAR in which each Pipe Element making it up will be associated with its Type of pipe (Type 1 for the primary pipes, Type 2 for the secondary and Type 3 for the tertiary pipes). The correct definition of the Type of pipe will be essential during the sizing process; after the creation of the Network, it can be modified via the drop-down menu of the Pipe element (p. 95).

As indicated in the chapter on importing,

Create Network

7. 5. 2 on page ¡Error! Marcador no definido., both nodes and elements can be transformed in a sequence, i.e., in several steps, if desired. In this way, the transformation ends when the user stops sequencing transformations and thus, during the process, the cursor at the lower right shows the message Transformation of Elements Finalised or Transformation of Nodes Finalised. After the transformation sequence is finished, the Create Network button (FIGURE 11. 20) must be pressed for the import process to finalise. The programme will ask for the name and location for saving the new network in *.network format.


In any sizing process, the GESTAR optimisation algorithm requires the network to be sized to be strictly branched. To make sure of this, the menu has In-Plot Design / Tools/ Direction of circulation enabled.

When you select this command, the assignation of the Start Node and End Node in the Pipe Elements (see p. 95) making up the network is reviewed and modified if necessary, so its definition will be consistent with the direction the water circulates in.

11.5.5 SIZING THE SECTORS.

The sizing of the sprinkler irrigation networks begins in the conduits which make up the irrigation sectors. GESTAR has solutions adapted to this process, letting you optimise the diameters of the secondary pipes, and rationally select tertiary branches quickly and for general application.

The essential first step is the configuration of the network. In this way, the intake node is modelled as a Regulated Pressure Node, assigning the pressure available at the output of the hydrant feeding the plot as the regulated pressure value. The entrance to the sectors is also represented by a Regulated Pressure Node, but in this case, with the property “ Plot Sector Entrance”, with the regulated pressure value being that estimated as the value on entrance to the sector. Q of Sector, Pressure Required and Turn are data needed for the later process of sizing the main pipes. These data will be assigned automatically at the end of sizing the sector with the values obtained.


363

FIGURE 11. 29 Known Pressure Node at Intake

Considering the configuration of the network, it will be taken into account that two secondary pipes cannot fork directly from a Known Pressure Node. To avoid this layout problem in GESTAR, a collar will be designed in the cases where this occurs (FIGURE11. 26). A length of 1 metre will be assigned to the pipe corresponding to the collar.

FIGURE 11. 30 Introducing a collar.


364

More specifically, the collar will be delineated in GESTAR using first the split pipe tool (p. ¡Error! Marcador no definido.), which lets you choose two points where the secondary pipes will be split, generating junction nodes. The Pipe element tool (p. 95) lets you delineate the layout of the collar, and it will be necessary to select the type of secondary pipes and a length of 1 metre in the pipe element characteristics window. Finally, the stretch from the Known Pressure Node to one of the junction nodes generated when splitting the pipes will be eliminated using the tool Eliminate Node/Element (p. 75). These tools let you configure the network, which in the example will be as shown in FIGURE11. 27.

FIGURE 11. 31 Network configured for sizing in the GESTAR environment.

Next, check the network is strictly branched (the configuration of the Start and End Nodes of the elements coincides with the direction of flow). The pressure height at the intake node must be modified, setting a high enough value for the tool Circulation Direction to work correctly. Click the button (or via the menu Calculations/ Calculate) and check that the arrows showing the direction of circulation of the water are as desired. To see the circulation arrows, go to the menu Results/Legend and change the Manual option to Auto for elements. Now you can use the tool Circulation Direction, enabled via the In-Plot Design menu/ Tools/Circulation Direction, to define the start and end nodes of the pipes, following the Circulation Direction viewed with the arrows. (The tool inverts the Start Node-End Node of a pipe element, if it finds a negative velocity).


365

The next step will be the calculation of the Design flow rates (see Chapter 8. 3 DESIGN FLOW RATES ON-DEMAND); in the case of In-Plot Design and turn-based functioning, the Cumulative Flow Rates will be calculated and applied to the network. When the process of determining Design flow rates is running (menu item Sizing/On-Demand Design Flow Rate), the window in FIGURE 11. 28 will appear.

FIGURE 11. 32 Design flow rates window.

Cumulative flow rates. In In-Plot Design select the option Cumulative flow rates. GESTAR calculates the Design flow rates which will circulate in each of the Pipes using the hypothesis that all the sprinklers are working at the same time (except those configured as closed or unconditionally closed at the time of launching the Design flow rates function, as explained in section 8. 3).

♦ Start Node Label. Indicates the Start Node where the programme begins calculating the design flow rates. This label must coincide with the name of the Known Pressure Node located at the network intake.


366

FIGURE 11. 33 Design flow rates table.

This action is followed by the Design flow rates table, which can be Saved,

Printed and Edited from its window. You will have to click Apply to the network to continue with the procedure.

The need to calculate by sectors means the sectors must be defined. If they have not been imported, they can be laid out via the In-Plot Design menu on the toolbar, in the option Assign Sector, or click the icon to assign the sectors using the same method as for an irregular selection (p. 74), i.e., defining a polygon around each sector, clicking on the map to define its vertices. To close the polygon when the sector has been assigned, click with the secondary mouse button.


367

FIGURE 11. 34Select sector

The laid out and assigned sector must be active for sizing to go ahead; select it by clicking inside the assigned polygon with the secondary mouse button. This will bring up a context menu where you can Select the Sector and size it individually using the option Sector sizing of the In-Plot Design toolbar menu, or clicking the icon . This will open a window for sizing the sector as shown in FIGURE11. 31. We recommend checking that the Selected Sector is correct and includes all the elements and nodes required for sizing.

Sectors are sized taking into account the design criteria: maximum and minimum velocity, the nominal flow rate and working pressure of the sprinklers, the materials involved, and the pressure on entry to the module. In this way, the Sector Sizing window is divided into four parts according to these parameters: Sector, Criteria, Riser branch and Secondary pipes.


368


♦ Sector. Reports the important characteristic of pressure at the entry valve for each sector for calculating sizing.

♦ Valve Pressure or available pressure is the fundamental parameter in sizing and reports the initial pressure of the valve at the entrance to the sector. GESTAR lets you enter this information manually, or calculating it according to a physical estimate linking the pressure needed by the sprinkler, the height of the sprinkler riser, the maximum change in level, the level of the valve, the maximum head loss and the estimated hydraulic slope (Equation 11-1). In order for the programme to perform the estimated calculation, mark the option Calculated Entrance Pressure by clicking on the checkbox and then the button Apply to estimate the entrance pressure. The application also lets the user enter three physical data from the expression calculating the pressure of the valve (Pressure in Sprinkler, Riser height and Estimated hydraulic slope).

ZvPsprzHcpteHgPv −+∆++= )(

Equation 11-1 Formula for calculating the sector entrance pressure, Pressure in Valve.

Where Pv is the valve pressure at the entrance to the sector (mca); Hg the maximum head loss (m/m); Hc is the riser height (m); z∆ is the maximum change of level (m); Pspr is the pressure needed by the least


369

favourable sprinkler (mca) and Zv is the level of the valve. FIGURE11. 32 shows the factors of the calculation.

FIGURE 11. 36The components of the formula for sizing the sector.

♦ Level of the Valve: Factor Zv of Equation 11-1 indicating the level of the

valve.

♦ Maximum level difference: Shows the maximum difference between the height of the entrance valve and the sprinkler with the least favourable level at the point of insertion, i.e., with the greatest difference between the level of insertion of the riser and the level of the valve.

♦ Maximum Head Loss: Indicates the head loss between the valve and the sprinkler with the greatest head loss.

♦ Pressure in Sprinkler: In this field, enter the pressure needed at the point before the sprinkler nozzle for the water to reach all the surface indicated as its reach.

♦ Riser height: The height in metres of the riser indicated by the letters Hc in Equation 11-1.

♦ Estimated hydraulic slope: The application does not know the diameters of the pipes before sizing, so this figure expresses an estimation of the hydraulic slope.

♦ Criteria. The calculation of the sector sizing will also depend on the criteria of the designer, while respecting the accepted Pressures and Velocities.

♦ Static Pressure Increments for Pressure rating. The static pressure increments for the Pressure Rating of the Pipes can be established for the whole system in this field.

Maximum Velocity. The maximum acceptable velocity is set to avoid problems of erosion, cavitation and transitories in the pipes. The overall


370

costs of the network will be sensitive to this parameter, and will be reduced as the maximum velocity increases.

♦ Minimum Velocity. Expresses a minimum speed limit of the water when carried through the pipes to be sized. In this field the minimum acceptable velocity must be set, in m/s, to serve as an alarm for indicating situations where the acceptable head loss (relating to velocity) is too low..

♦ Margin of Uniformity of Pressures. In this field the designer can define the acceptable range of pressures in the sprinklers, around the value of Pressure in Sprinkler defined in the Sector field. The minimum pressure required in the sprinkler for sizing the Sector will be equal to the Pressure in Sprinkler – Margin of Uniformity of Pressures/2. Similarly, the maximum pressure will be equal to the Pressure in Sprinkler +Margin of Uniformity of Pressures/2. If the maximum pressure requirements cannot be met, GESTAR will launch a warning message. To make it easier to designate the Margin of Uniformity, enable the Tool Difference of Levels in the Sector from the In-Plot Design menu. This tool can be used to obtain the value of the difference in levels between the highest and the lowest sprinkler included in the selected sector.

♦ Riser Branch. Sector sizing needs some characteristics to be specified in the set of mechanisms making up the irrigation network, including the riser branch. In this case, the application lets users choose a material and diameter, and provides the option to force the selected material if you want the chosen material and diameter to be the only ones used for all Riser branches.

♦ Material. A drop-down menu lets you select the material of the tertiary pipes depending on the materials in the application databases.

♦ Roughness. Expresses the roughness of the selected material, which can be modified if necessary.

♦ Pressure rating. Indicates the pressure rating of the pipes for each material via a drop-down menu for selecting the most usual pressure ratings.

♦ Maximum Pressure. Shows the maximum pressure the selected pipes can withstand.

♦ Nominal diameter (DN). The Nominal Diameter of the riser branch can be selected in a drop-down menu, and the next field shows its internal diameter.

♦ Price. Indicates the price of the selected pipes according to the database, although this value can be modified by the user.


371

♦ Secondary pipes. Creating recommendations for defining the materials of the secondary pipes in the economic optimisation process will be a key point for obtaining the optimum sizing of the sector.

♦ Available Materials. All the Materials defined in the database associated with the network appear in the selection list.

♦ Material to Use. User will include in this list the Materials they want to be considered in the optimisation based on the list of available Materials, clicking the arrow on the right to add and the cross to eliminate the material, if any are wrongly selected

♦ Range of Internal Diameters. This option lets you restrict the size of the Pipes considered when optimising for each material.


♦ Nominal Flow Rate at Sector Entrance. If this option is chosen, after sizing the sector, a set point pressure is applied to the entrance node equal to the pressure at the entrance to the sector, and a maximum flow rate equal to the flow rate at the entrance to the sector, which will equal the sum of nominal flow rates of the installed sprinklers.

♦ Flow Rate at the Entrance to the Sector Simulated after Sizing. The nominal flow rate can be used as the entrance flow rate, which will be the sum of nominal flow rates of the installed sprinklers, or the simulated emitted flow rate of these sprinklers. After sizing the sector, if you have marked this option, a hydraulic simulation is run internally with the diameters obtained, starting from the indicated entrance pressure, and taking into account the operating curves of the sprinklers. The resulting flow rate will be used as the sector flow rate for sizing the main pipe.

♦ Head Loss in the Valve. Designation of the head losses considered in the sector entrance valve (in m).

At the end of the process of sizing each sector, GESTAR generates a PDF document with the entrance data and list of results after optimisation, and the economic breakdown of the pipes.


372

FIGURE 11. 37 Regulated Pressure Node after Sector Sizing.

After sizing the Sector, its Regulated Pressure Node intake node will be saved with determining information (FIGURE 11. 33) to be used in the next step of sizing the main pipes. The value represented as Pressure Head is modified automatically, becoming equal to the Required Entrance Pressure calculated in the sizing of the Sector (Equation 11-1). In the same way, the sector flow rate value (Q Sector) will be loaded automatically, with the Sector Entrance Flow Rate Simulated after Sizing (according to the option chosen in the window of FIGURE11. 31). This flow rate is equal to the sum of the emitted flows depending on the pressure of the installed sprinklers in each sector (obtained by simulating the scenario).

11.5.6 SIZING THE MAIN PIPES

The main pipes are sized taking into account the turns of the irrigation sectors in the plot.

GESTAR includes tools for defining turns: specification of the number of turns,

the duration and definition of sprinklers or hydrants belonging to turns, planning and simulation of the turns, etc. These tools are applicable both to the irrigation turns in the plot, and to general distribution networks (see p. ¡Error! Marcador no definido.) which use turns.

In this way, the correct resolution of the sizing will be done by establishing turns for the sectors which permit an optimum and economical sizing of the installations.


373

FIGURE 11. 38 Regulated Pressure Node. Establishing the turn

To do this, go to each of the Regulated Pressure nodes at the intake of the sector, and set the turn with the corresponding drop-down menu. By default, two turns are enabled. To define a greater number of turns, click the icon , available in the toolbar, to bring up the Turns Assignment window. From this window, click the button

in the option Turns to add new turns to the list.

FIGURE 11. 39 Turn assignment window. Example in-Plot Irrigation Network.


374

♦ Turns. An in-plot irrigation network functions by applying irrigation turns which permit an optimum and economical sizing of the installations. In this way, by enabling the turns

icon (FIGURE11. 35) on the toolbar, the turns must be applied which will organise the irrigation of the sectors making up the plot. In the top left part of this window, you can add and delete turns by clicking on the “+” to add and the “x” delete. The list of all the turns will appear in the menu on the left.

♦ Turn Components. The components belonging to the irrigation network included in each turn. To add these components you must first select them and then click “+” to add and “x” to delete them. After assigning all the components which will define the turns, click on the button Apply turn.

♦ Number of Turn. Indicates the number of the turn selected at that moment in the window in FIGURE11. 35.

♦ Number of Hours. Lets you select the number of hours the turn will be functioning in cases of simulations with evolution over time and for simulations with patterns. This does not influence the sizing calculation.

♦ Total Flow Rate. Defined as the total flow rate required by all the components of the turn.

Although not essential at this stage of the sizing, each sprinkler will be assigned a turn. This will enable later simulations of each turn in operation.

After the window in FIGURE 11. 35 opens, click the icon , and first select the turn in the list to which you want to add sprinklers. Next click the secondary mouse button on the outline of the sector to enable the option Select Sector. Then click button

, next to the heading Turn Components in the window in FIGURE 11. 35 to include the sprinklers of the sector in the table immediately below. Finalise the operation with the option Apply Turn. (The sprinklers can also be selected using the multiple selection button .)

Alternatively, after generating all the necessary turns with the option Turns , you can assign them individually by double-clicking on the Sprinkler and going to the Sprinkler Configuration window (see detailed information for the icon , p. ¡Error! Marcador no definido.).

The general conduit is optimised based on the pressure coming out of the intake node and guaranteeing the entrance pressure in the irrigation sectors which were used to size them, for a flow rate equal to the sum of the emitted flows depending on the pressure of the installed sprinklers in each sector (obtained by simulation of the scenario).


375

For the sizing, click on the icon on the toolbar or the option Size Main Pipes in the In-Plot Design menu. You can access the assistant for Optimisation of the Main Pipes (FIGURE11. 36), which is identical to the one for sizing Turn-Based Distribution Networks (see chapter 8. 7, OPTIMISATION of the TURN-BASED NETWORK). .


To size the Main Pipes of a sprinkler irrigation system, you need only review the Flow Rate (column Q in table FIGURE11. 36) which will go through the intake node of the system, depending on the correct assignment of turns to the sprinklers, done earlier. .


376

FIGURE 11. 41 Optimisation Assistant. Step 3: Intake node data. Regulated pressure.

♦ Intake node data. One of the options shown below will be enabled, according to the topology of the network being analysed.

• Known Pressure. For the case of networks without a Pump Element at the intake node (the pressure available in the intake node of the sprinkler irrigation system is known). GESTAR loads the values defined at the intake Node referring to the Identifier, Level, Known Pressure and Total Head. Selecting the Edit button, you can access each cell and modify the data.


♦ Slopes. Advanced users can assess the value of these parameters required for sizing, following the detailed recommendations on page 241 et seq.


377

FIGURE 11. 42 Optimisation Assistant. Step 4: Minimum pressures

Select the default option, Set Point Pressure in open Hydrants with Regulation,

for the optimisation to take into account the entrance pressures of the required sectors, previously enabled by the user in each Known Pressure Node at the sector intake, using the property “Plot Sector Entrance”. The other options, which cannot be used with the above one and are less likely to be used, are documented for the optimisation assistant of on-demand networks (see p. ¡Error! Marcador no definido. et seq.).

FIGURE 11. 43 Optimisation Assistant. Step 5: Restrictions

The designer can specify in the window shown in FIGURE 11. 39 the acceptable values of maximum and minimum velocity, time to break even on the investment and


378

the expected interest rate on repayments. (Detailed explanation on p. ¡Error! Marcador no definido. et seq.). The option of blocking stretches of the network so their diameter will not be modified during optimisation (the field Installed Pipes, FIGURE8. 13), is not accessible for sizing the main pipes of in-plot irrigation.

If the pressure at intake node is unknown, steps 6 and 7 (Pumping Stations and Electricity Prices) will be accessible. See p. ¡Error! Marcador no definido..

FIGURE 11. 44 Optimisation Assistant. Step 8: Unfavourable Predictions.

This dialogue gives the designer the possibility of defining a series of safety margins in budgets where there is uncertainty about the real situation or if they have not been defined in the previously created network. The sizing assistant lets you set generic criteria at the same time for an upper bound, applied to all stretches of the network, and stretch by stretch for specific Pipes. (See p. ¡Error! Marcador no definido.). GESTAR uses the database of Materials associated with the network, in Microsoft ACCESS 97 format.


379

FIGURE 11. 45. Optimisation Assistant. Step 9: Materials


♦ Material to Use. Include in the list the Materials you want to be considered when optimising, from the list of available materials.



As explained in the dialogue in the last step of the assistant (STEP 10), when sizing a network with a Pump Element at intake, GESTAR will transform the Junction Node downstream of the Pump Element into a Known Pressure Node. This Node will function as an intake node, disabling the real Intake Node and Pump element. From the new Known Pressure node, the user will receive information about the nominal pressure required from the pumping station to meet the requirements defined with the obtained diameter results.

Once the optimisation process has finalised successfully, the results obtained will be loaded into the network.

GESTAR identifies the critical irrigation sector (the intake node with the lowest

hydraulic slope), sizing the main pipes to serve at least the entrance pressure taken into account in the previous process and considering the path to this sector as a priority. Next the rest of the pipes are sized, taking into account the pipes of the shared path to


380

the critical sector, thus making it possible to adjust the diameters, as the shared paths will have larger diameters than needed for reaching the pressure of the non-critical modules.

The general conduit is optimised based on the exit pressure from the intake node and guaranteeing the entrance pressure in the irrigation sectors which was used to size them, for a flow rate equal to the sum of the emitted flows depending on the pressure of the installed sprinklers in each sector (obtained by simulation of the scenario).

With the primary pipes defined, the pressure which will finally reach the irrigation modules can be simulated, and recursively optimised, if we have more power in any of them than was considered in the first sizing of the sector.

11.5.7 HYDRAULIC ANALYSIS AND OBTAINING THE OPERATING PARAMETERS.

At the end of the sector sizing process, the intake node of the sector modelled as a Regulated Pressure Node will be directly transformed into a Reducing Valve using the Tool / TRANSFORM SECTOR ENTRANCE INTO REDUCING VALVE on the In-Plot Design menu. The only previous requirement is to have selected the sector for the transformation (secondary mouse button click on the outline of the sector).


381

FIGURE 11. 46 Reducing Valve after Transformation.

As shown in FIGURE 11. 42, the Pressure head value of the transformed Regulated Pressure Node will be assigned automatically as the Set Point Pressure of the reducing valve.

If not working with a Reducing Valve at the intake of the Sector, the corresponding Regulated Pressure Node should be transformed into a Junction Node, so the hydraulic analysis can be carried out.

The configuration and sizing of the entire plot with all its parameters, characteristics of the sprinklers, materials, diameters, regulating elements, etc, make it possible to completely simulate each of the irrigation turns in the plot, analysing their hydraulic operation, detecting malfunctions and possible improvements in the design.

The last drop-down menu in the top row of the toolbar associated with the icon

enables the user to open the hydrants or sprinklers included in the irrigation turn.


382

After opening the sprinklers in the sector for hydraulic analysis, on calculating

Nominal and Calculated Reach

, if the Sprinkler reach icon on the toolbar was previously enabled (or using the option in the Plot Design menu, Show Nominal Reach) GESTAR shows the nominal reach of the sprinklers, which is the theoretical trajectory of the water from the sprinklers, creating a blue circle around each sprinkler indicating the reach of the water if the sprinklers receive exactly the required pressure; and at the same time, it draws the real trajectory or Calculated reach of the Sprinklers, forming a red circle which shows the real reach of the water with the data entered in the example. These reach circles can be turned on and off using the options Show Nominal Reach and Show Calculated Reach in the In-Plot Design menu on the toolbar. This tool lets you view irrigation overlaps and thus analyse the layout’s quality or faults (FIGURE11. 43).

FIGURE 11. 47Sprinkler reach in a sprinkler irrigation network.

The Uniformity Coefficient option in the In-Plot Design menu shows the user a statistical representation of the uniformity of the flow rates calculated for the open sprinklers.

Uniformity coefficient


383

FIGURE 11. 48. Uniformity Coefficient results.

Open the sprinklers which you want to analyse (usually included in an Irrigation turn) and select the command Uniformity Coefficient to bring up a window like that in FIGURE 6. 38, with the value of the Uniformity Coefficient calculated, resulting from the application of Equation 11.2.


Where M is the mean value of the calculated flow rates emitted by the open sprinklers, n is the total number of sprinklers and S|d| is the sum of the absolute values of the deviations from the mean of the flow rate calculated in the sprinkler.

From the icon

Measurements

(p. 60), and from the In-Plot Design menu/ Measurements, the user is offered detailed information of the Measurements of the Pipe Elements and Sprinklers (for this case, only from the In-Plot Design menu/ Measurements/ Summary of Sprinklers). This information will be very useful for the designer who wants to draw up a detailed budget for the sizing after checking it with a simulation.

11.5.8 EXPORTING RESULTS TO AUTOCAD.

GESTAR includes tools for exporting the models of the plot to AutoCAD, making it possible to generate detailed plans of the design in this format, as described in chapter 7. 5, page ¡Error! Marcador no definido. and summarised below:

When GESTAR finds an open network, using the icon , a new dialogue appears (FIGURE 11. 45). This tool enables the network drawing to be created automatically in AutoCAD with the information you choose about its Nodes and Pipes. The AutoCAD programme should already be open before exporting, with a blank drawing open, where GESTAR will add the topology of the network with the variables required by the user.

1 100d

CUM n

∑= −

⋅


384

FIGURE 11. 49Export network from AutoCAD

The following parameters referring to appearance can also be modified:


♦ Text height. This value usually needs adjusting.

♦ Precision. Lets you choose the numerical precision for the data which will appear (from 0 to 4 decimal points).

♦ Scale. Depending on the size of the network, a scale factor will have to be applied when drawing node icons. This scale factor appears automatically in the export window (FIGURE11. 45). However, the user can set the preferred scale value manually.

GESTAR implements options to improve visualisation of the information:

♦ Show information in pipes based on a minimum length. Activating this option, information will appear associated with pipes over the length defined in the adjacent field.

♦ Text size proportional to pipe length. When this option is enabled, text size will vary according to the length of the pipe, up to a maximum text size set in the corresponding field.


385

♦ Polytubes. If there are pipelines formed by various stretches with different orientations, you can choose between presenting the associated text centred and aligned relative to the longest stretch of the polytube, or relative to the central stretch of the polytube.


11.6 DRIP IRRIGATION

11.6.1 GENERATING COVERAGE

When modernising irrigated plots, energy efficiency and the irregular levels of the terrain in many areas become very important, and therefore in-plot design projects are available for changing to drip irrigation. Nowadays these projects are designed graphically with drawing and topography software such as AutoCAD, which is in widespread use.

In the AutoCAD environment, the line is a segment or a series of connected segments. Meanwhile, a polyline is a sequence of segments created as a single object. These two elements are the basic starting point for the layout of the irrigation networks.

As with sprinkler irrigation, the boundary of the irrigation plots is formed by a closed polyline, forming a closed polygon which generates a boundary corresponding with the plot boundary. A reference line or segment should be found inside it which marks the location and direction of the line, matrix or mesh of sprinklers generated by the application. GESTAR can generate a mesh of drip irrigation lines situated at a Distance between Drip lines assigned by the user in order to deploy the rest of the pipes and to size the plan.

The image in FIGURE 11-50 shows an example plot with a random shape, suitable for conversion to irrigation, with the plot outline or boundary drawn (polyline) in black and the reference line in blue (line or polyline).


386

FIGURE 11-50 Drip irrigation plot being transformed in the AutoCAD environment.

The AutoCAD programme permits delineation with layers. The layers are used for grouping information about a drawing according to its function and for reinforcing the types of line, the colour and other parameters. Layers are the equivalent of the transparent papers used in design on paper, i.e., each layer corresponds to an object. Thus, in the previous example in FIGURE 11-50, we see two layers of work: the layer of the polyline outlining the plot, and the layer of the reference segment. All of this means that layers are the main organisational tool used in the drawing. Layers are used to group information by function and to set the type of line, the colour and other rules. By creating layers, we can associate similar types of objects, assigning them to the same layer. For example, you can put auxiliary lines, text, levels and legends on different layers. This factor is important when using AutoCAD for GESTAR, because the different entities in the plot (outlines, primary, secondary and tertiary pipes, sprinklers; level curves, etc.) will be distinguished by layers with different colours, names and characteristics.

FIGURE 11-51 Drip line distribution window.

Once the territory boundary is known, GESTAR will automatically generate the coverages in the AutoCAD environment with drip lines with specifications assigned by the designer in random plots. The GESTAR tool which enables coverages of lines of emitters to be generated can be seen in FIGURE 11-51. This utility lets you distribute a line of emitters in a plot in the AutoCAD environment according to your preferred characteristics. To select them, click the option Distribute Line of Emitters in the In-Plot Design menu in the toolbar.


387

The distribution of the lines of emitters requires characteristics to be selected for

defining the final configuration of the network.

• Distance between Drip Lines lets the user choose how far apart the drip lines should be.

• Duplicate Line of Emitters. If this option is enabled, for each line or polyline detected in the Cad plan for transformation, Gestar will create two parallel Drip feed lines, separated by the distance set in the field Distance Duplicate Line of Emitters (m).

♦ Name of the Drip Feed Layer. The name decided by the user for use in the AutoCAD environment for the automatically delineated drip feed line.

Once the required characteristics of distance and names have been assigned, press the button Create Distribution. This command will take the user to the AutoCAD environment, where you can click on a plot outline to choose the boundaries of the plot for installing the irrigation coverage, and then choose the location of the previously drawn reference segment by clicking on it.

Next, as shown in FIGURE 11-51, the Drip Distribution Angle will display the angle of distribution of the drip feed line in the AutoCAD environment, and the field Number of Drip Branches will show the number of drip lines arranged in the drawing after the automatic distribution.

11.6.2 DRAWING THE NETWORK OF SECONDARY AND TERTIARY PIPES

The AutoCAD environment has generated a mesh of drip feed lines for creating the final design of the irrigation network. This mesh, which can be seen in FIGURE 11-52 is made up of lines which correspond to the tertiary pipes or drip feed lines.

FIGURE 11-52 Drip irrigation plot being transformed in the AutoCAD environment.


388

After this action the rest of the network design configuration must be finished. Thus, the designer must design and lay out the primary and secondary pipes which will provide total connectivity for the networks in the project in the AutoCAD environment, with the same methodology as when designing sprinkler networks.

The correct design and layout of the network in AutoCAD format is fundamental, as this will determine the optimal result of importing and the easy treatment of topography with the GESTAR software.

The primary pipes will be laid out with various polylines making stretches from the exit from a sector to the entrance of the next. Begin from the place where the hydrant is sited and click on the polyline drawing option with the layer assigned to this type of pipes open, and lay out the polyline until the entrance to the first sector. After that the operation continues from one sector entrance to another.

The secondary pipes will be delineated in a single stretch and with just two vertices from the connection with the main tube to the last branch of the tertiary pipes. Also, if the layout of the secondary pipe has vertices on points where it crosses drip line branches, this can lead to problems in the distribution of later cut-offs. In these cases we recommend moving the vertex of the secondary pipe.

The drip feed lines or emitters branches have already been created using the tool in the software. There may be points where secondary pipes and lines of drippers cross over in plots with a complex layout. Users should be aware of these, as the programme will place a cut-off between them.

Therefore, the AutoCAD user should be aware of the work layers used to create the network, as you will need to be familiar with them during the transformation of the elements (chapter 7.5.2, page ¡Error! Marcador no definido.)

Next, adjust the location of the lines of emitters where necessary, looking out for likely changes in the terrain, ending up with a complete plot as seen in FIGURE 11-53, where the black polylines represent the primary pipe and the red ones represent the secondary pipes.

FIGURE 11-53 Complete Drip irrigation plot being transformed in the AutoCAD environment.


389

11.6.3 GENERATING STRETCHES AND LEVELS

Drip irrigation is the most efficient form of automatic irrigation in terrain with slopes and irregular levels, so to install sprinkler irrigation in places with variable levels you will need to set the elevation of entities with the help of a specific specialist programme, such as the topography application MDT5/MDT6, which is very widely used, although not obligatory. For this reason other software can be used to do this, if their results are compatible with the AutoCAD format and have a similar geometry of lines, polylines, layers and cut-offs.

The process of generating stretches and pipes uses the same plotting method as for in-plot sprinkler irrigation, but with minor modifications to adapt it to drip irrigation.. Thus, the schema in FIGURE 11-54 must be followed, which is similar to the one for sprinkler irrigation.

The surface will be created when the designer chooses, but always before the other actions. Section 11.4, page ¡Error! Marcador no definido., explains alternative procedures for creating surfaces using the application MDT5/ MDT6. However, the second and third actions are explained again individually to make it easier to use the manual, and because there are subtle but significant differences. If no level curves are available or there is no need to elevate entities, simply use the second tool in Drip Feed Distribution Cut-offs.

FIGURE 11-54 Schema of the process of generating stretches and levels

The programme needs to run a process which can recognise cut-offs between pipes and emitter lines so the connections between them will be exact and to be able to

Drip Feed Distribution Cut-offs


390

supply the whole network. The tool for this pipe cutting is called Drip Feed Distribution Cut-offs, located in the In-Plot Design menu on the toolbar.

This tool, Drip Feed Distribution Cut-offs, can be used to cut Drip feed lines with Curves or by Length at the same time. This option is useful for irregular plots, with steep slopes in the drip feed line. GESTAR can divide the Drip feed lines generated in AutoCAD into sub-sections with particular information. This process will convert the lines representing the Drip feed lines into polylines with different vertices, which after being imported will indicate the sub-sections, i.e., different stretches with different levels in each Drip feed line.

FIGURE 11-55 Drip line distribution cut-offs window

♦ The list of Drip Feed Layers is used to choose the layer of the

AutoCAD environment associated with the drip feed lines or emitter branches.

♦ The Secondary Layers list is used for choosing the layer of the AutoCAD environment associated with the secondary pipes.


391

♦ The Primary Layer list is used to choose the layer of the AutoCAD environment associated with primary pipes. In this case it is disabled as it is not useful.

♦ The Curves Layer list is used to choose the layer of the AutoCAD environment associated with curves. This tool lets the application create sub-sections in the emitter lines in the exact location of the cut-off with the level curves, so the emitters can have different characteristics depending on the height of the terrain. To do this, also tick the option Calculate Cut-off with Curves.

♦ Calculate Drip Feed Cut-offs with Secondary pipes. When this option is enabled, divisions are generated in the lines/ polylines included in the Secondary Pipes Layer, in the cut-off points of the secondary pipe with the emitter lines.

♦ Another way to divide drip feed lines into sub-sections is by the length of the pipe. This option, Calculate Cut-off by Length, lets the user enter different characteristics of the drip feeds for the length which will be entered in the appropriate field.

♦ The list of Objects to Transform is used to select the types of objects that are transformed in AutoCAD. Lines, 2D polylines and 3D polylines can be cut.

♦ The option Eliminate Original Objects lets you eliminate the existing objects , and is therefore ticked in most cases.

The recommended Tolerance is 0.01. The tolerance value assigned in the Nodes Panel also controls the transformation of Pipes. Thus, if the difference in coordinates of an end vertex and another Node is closer than the value set for Tolerance, GESTAR will generate a single Node in its place. We advise the user to analyse the proximity of the different hydrants and Junction Nodes on the AutoCAD plan before setting the tolerance value. It will also be vitally important to delineate the network correctly in AutoCAD. We recommend activating Object Snap Mode (command REFENT) to connect stretches and objects correctly, avoiding connectivity problems, as if they exceed the Tolerance value this will lead to duplicate Nodes in the network. In the case of plans combining Lines, Polylines, 3D Polylines and Blocks, end vertices may appear which coincide in floor but not in level, so that the objects will not be connected. Given that the tolerance criteria are checked in all three coordinates, this will produce independent superimposed nodes in the GESTAR model, with different levels, and stretches isolated in the network.

♦ Elevation of entities


392

The elevation of entities lets you convert a flat cartography, with entities in 2D, to a 3D cartography, in order to prepare it for obtaining profiles or to obtain a surface. The entities this command processes are lines, polylines and arcs. The result will be to add topographical information to the elements constituting the network in the AutoCAD file.

This command is the last phase of the process of generating stretches and levels. It lets you locate the components of the plot in their original altimetry, so they can later be imported correctly and effectively. The tool used for this process is Elevating entities, in the drop-down menu of the option Utilities, in the MDT5 menu on the toolbar. The actions are carried out in the AutoCAD environment and consist of:

♦ Selecting the type of elevation desired. In our case we want to elevate a surface and therefore enter an ‘s’ in the space in the option. Once a set of entities has been selected, the programme assigns each of its vertices the level corresponding to them in the current surface. It also asks you to specify if you also want to process the polylines which are already in 3D, or only the two-dimensional ones. If the surface is not defined, the programme will try to assign the levels of each vertex according to the points in the drawing.

♦ Choosing objects through the option select objects, which lets you the objects to be elevated.

♦ The choice to elevate the polylines by entering the letter ‘s’ for yes or the letter ‘n’ for no in the option Also elevate the 3D polylines? <N>.

♦ The option of incorporating cut-offs at the points where the polylines cross the model by entering ‘s’ for yes or ‘n’ for no in the space given with the question Incorporate cut-offs with the model? <N>.

♦ The phases of the process which permit the selection of various options for elevating entities are shown visually in FIGURE 11.56.

FIGURE 11-56 Options of the Elevation of Entities tool in AutoCAD.


393

11.6.4 IMPORTING FROM AUTOCAD TO THE GESTAR ENVIRONMENT CONFIGURING DRIP FEEDS.

The branched network is transferred from the AutoCAD application to the GESTAR environment through an importing process, in a very similar way to the sprinkler irrigation process. However, there are differences in the configuration of the emitters.

This process will be executed with the communication between AutoCAD and GESTAR correctly defined in chapter 7.5 page 209. Use the toolbar icon , or the menu File/ Import/ From AutoCAD, to reach the AutoCAD connection window. First, the Points or blocks defined in AutoCAD will be converted to nodes as used in the GESTAR system. Next in the transformation of elements, they will be identified according to the drawing layer in AutoCAD as drip feed line, secondary pipe or primary pipe, for differentiated treatment in GESTAR. When the necessary transformations have finished, choose the option Create Network to finalise the importing process successfully.

FIGURE 11-57 Communication between AutoCAD and GESTAR. Transforming Nodes.

Objects to Transform. GESTAR permits the transformation of AutoCAD Block and Point objects into Nodes.


394

♦ When the user goes to the menu File/ Import/ From AutoCAD and sees the window shown in Error! Reference source not found., GESTAR will have captured the collection of Points and Blocks from the open and active AutoCAD drawing, presenting it as a drop-down list in the first panel. The type of objects to be transformed into Nodes can be selected, as many as desired, from this list. The geometric property of elevation of each object to be transformed will be captured and associated with the Node created in GESTAR.


♦ Tolerance. When an AutoCAD object is transformed into a Node in a GESTAR network, the programme checks that the Node was not created in an earlier transformation. The check consists of comparing the X, Y and Z coordinates of the existing Node with the object being transformed.

Click the Transform button to start the transformation of Nodes. When the bottom of the window reaches 100%, if you do not want to transform more objects, choose the option Next. This opens the window in FIGURE 11-57. Select the option IN-PLOT DISTRIBUTION to go to the window in FIGURE 11-58 .

Click the button Transform in FIGURE 11-57 to begin the transformation of Nodes. When the lower part of the window reaches 100%, click Next. This opens the window in FIGURE 11-58 where you must select the option IN-PLOT DISTRIBUTION, which then goes to the window in FIGURE 11-59.

FIGURE 11-58 Selecting the type of network to Transform.


395

Transforming elements

FIGURE 11-59 Window for transforming AutoCAD elements to GESTAR.

♦ Objects to Transform. The application can transform AutoCAD objects of the Line, (2D)Polyline and 3D Polyline types

♦ Work Layers. In this section, for drip irrigation systems, one or more layers must be selected which contain the objects to be transformed to drip feed lines. The selected layers will be those taken into account by the programme, and if none is selected (as set by default), no type of filter by layer will be taken into account.

The transformation of drip feed lines is the main specific requirement for In-Plot Design of drip irrigation in the AutoCAD communication window. This specific requirement enables the selection of different characteristics for the drip feed line.

♦ Elements to be created. To import drip irrigation systems to Gestar, enable the Drip Feed option in the top right of the


396

window in FIGURE 11-59, which will then open the window in FIGURE 11-60.

♦ Transform Free Ends. On this drop-down list, where all the types of Node defined in GESTAR appear (Junction, Reservoir, Dam, Known Pressure, Known Consumption, Hybrid, Free and Double Condition nodes), select the type of Node to be created at the ends of the transformed lines or polylines when the ends do not coincide with the points of insertion of Blocks or Points already transformed through the Nodes Panel.

♦ In the second field, each AutoCAD work layer must be associated with each type of pipe. In this way, in the list transforming the secondary pipes, their work layer, SECONDARY PIPES must be selected; the list transforming the primary pipes is the second list and its work layer, GENERAL, is selected. In the case study the outline of the sectors was drawn in the AutoCAD environment and imported by selecting its work layer in the last list

♦ Import Sectors. If you have decided to import sectors, as well as selecting the appropriate layer, you must enable the option Import sectors.

♦ Transform. The process of transforming Line, Polyline 2D and Polyline 3D objects into Drip Feed type Elements, and transforming primary pipes and secondary pipes into Pipes, is similar to the transformation of Nodes, clicking the Transform button in the first field, but only after the requirements have been properly defined in the first and second field (FIGURE 11-59).


397

FIGURE 11-60 Selecting the Emitter to Transform.

♦ No. of Emitters per Grouping. Use this field to change the number of drip feeds located in each emission point on the line. The default value is 1.

♦ Function. Use the drop-down tab to select whether the Drip Feed will be Turbulent or Self-compensating.

♦ Tipo Inserción. Desde la ventana desplegable Tipo Inserción, deberá discernirse la forma de inserción del gotero en la línea, Integrado o Insertado.

♦ Manufacturer. The user can choose from a drop-down list of different drip feed line Manufacturers which were previously defined in the Database (see Section 13.2 DRIP FEED DATABASES, page ¡Error! No se le ha dado un nombre al marcador.¡Error! Marcador no definido.).

♦ Model. After choosing the Manufacturer, the different types of Drip Feed lines associated with the chosen manufacturer in the database (see p. ¡Error! Marcador no definido.), will be accessible in the drop-down list Model. When you select a model the following parameters will appear automatically in the window in FIGURE 5.39:

Internal Diameter (mm) in millimetres of the active line of emitters.

Nominal Flow Rate of the drip feed, in l/h.


398

Minimum Operating Pressure in m.

Discharge Curve. Tabulated values of pressure and flow rate.

Characteristic equations of the Drip Feed (see page ¡Error! Marcador no definido.).

♦ Line.

Distance between Emitters (m). Use the drop-down tab to define the distance between the drip feeds on the line.

Coef M. Coefficient of head losses on the drip feed line.

Length (m). The field shows the length in metres of the sub-section to be created, depending on its graphic representation. This can be changed manually by the user.

Create network

As indicated in the chapter on importing, 7. 5. 2 on page ¡Error! Marcador no definido., both nodes and elements can be transformed in a sequence, i.e., in several steps, if desired. In this way, the transformation ends when the user stops sequencing transformations and thus, during the process, the cursor at the lower right shows the message Transformation of Elements Finalised or Transformation of Nodes Finalised. After the transformation sequence is finished, the Create Network button (FIGURE 11. 20) must be pressed for the import process to finalise. The programme will ask for the name and location for saving the new network in *.network format.


11.6.5 SIZING DRIP FEED SECTORS

Sizing irrigation networks begins with the conduits which form the irrigation sectors. GESTAR has solutions adapted to this process, enabling the optimisation of the diameters of secondary pipes supplying the drip feed lines.

The essential first step is the configuration of the network. After importing from AutoCAD, the menu View/Scale (see p. 61) lets the user configure the origin of


399

coordinates, the exact maximum coordinates for the graphic window, and the visible area.

FIGURE 11-61 Network imported from AutoCAD in the GESTAR environment.

The head of the system must be modelled as a Regulated Pressure Node (FIGURE 11-62), assigning the pressure available at the output of the hydrant feeding the plot as the regulated pressure value. The entrance to the sectors is also represented by a Regulated Pressure Node, but in this case with the property “Plot Sector Entrance” enabled, with the estimated pressure at the entrance to the sector set as the regulated pressure value. Q Sector and Pressure Required are the data needed for the later process of sizing the main pipe. These data are assigned automatically after the sector has been sized with the values obtained.

FIGURE 11-62 Known Pressure Node at Intake

Considering the configuration of the network, it will be taken into account that two secondary pipes cannot fork directly from a known pressure node. To avoid this layout


400

problem in GESTAR, a collar will be designed in the cases where this arises. A length of 1 metre will be assigned to the stretch of pipe fitted with this collar (see page ¡Error! Marcador no definido. et seq.).

Optionally, the polylines defining the Irrigation Sectors can be captured from the AutoCAD file for importing the network. If they have not been added in the import process, they must be defined using the tool Assign Sector, from the In-Plot Design menu (see page ¡Error! Marcador no definido.).

Definition of the Irrigation Sectors

FIGURE 11-63 Network configured for sizing in the GESTAR environment.

Right-click in the central area of the sector to be sized to being up the Select Sector dialogue. When this is enabled, sizing can begin, using the Size Drip Feed Sector option from the In-Plot Design menu.

Sizing Drip Feed Sector


401

FIGURE 11-64 Size Drip Feed Sector Window.

♦ Intake Valve.

Level. Position in height (m) of the intake valve.

Pressure. Pressure in the valve (m). The data will be loaded as previously defined in the Regulated pressure node used for modelling, but will be accessible for modification by the user from this window.

Head Loss in the Valve. Designation of the head losses considered in the sector intake valve (in m).

♦ Drip Feed.


402

Operation. Field to select whether the Drip Feed is Turbulent or Self-compensating.

Sizing Requirements. The Sizing Requirements field offers two procedures for setting the minimum pressure values at the least favourable emission point of the drip feed lines making up the sector. These procedures are mutually exclusive.

11.6.6 Nominal data of the configured Drip Feed. The pressure and flow rate values required for sizing at the least favourable point will be those assigned to the drip feed line in the Drip Feed database (see page ¡Error! Marcador no definido.) as Qn (nominal flow rate (l/h)) and Pt (Working Pressure (m)).

11.6.7 Defined Flow Rates and Pressures. If this option is selected, the flow rate desired by the user and the minimum pressure value permitted at the least favourable point must be defined. The pairs of values are not related to each other; the subsequent simulation processes (see page 409) will estimate the real value of the flow rate for the unfavourable point associated with the minimum pressure, and its variance from the desired flow rate.

♦ Calculating Valve Pressure and Minimum Drip Feed Line Pressure according to the Uniformity Coefficient. This field is enabled only if the option Defined Flow Rates and Pressures is selected in the Sizing Requirements panel. It lets you use a theoretical formula to estimate the pressure needed in the sector intake Valve. The following parameters must be defined:

CU: Uniformity coefficient

Mean Q (l/h): mean flow rate.

CV: manufacturing coefficient of variation of the emitter.

e: number of emitters each plant receives water from.

M: relationship of the difference between maximum and minimum pressures in the irrigation sub-unit and the difference between the mean and the minimum of the same sub-unit. *Recommended value: 2.5.


403

N/Ks: adjustment coefficients of the Drip Feed discharge curve.

Click the option Apply to set the resulting theoretical necessary pressure in the Intake Valve panel. The user will also receive information on the theoretical value of the Minimum Flow Rate at the least favourable point for the minimum pressure defined in the corresponding field of the Sizing Requirements panel. The minimum required pressure value can be modified interactively, giving a new Necessary Pressure value at the valve intake. Finally, the theoretical Mean Pressure value for the Sector as a whole is estimated.

♦ Secondary pipes. Creating recommendations for defining the materials of the secondary pipes in the economic optimisation process will be a key point for obtaining the optimum sizing of the sector.


♦ Material to Use. User will include in this list the Materials they want to be considered in the optimisation based on the list of available Materials, clicking the arrow on the right to add and the cross to eliminate the material, if any are wrongly selected



♦ Nominal Flow Rate at Sector Entrance. If this option is chosen, after sizing the sector, a set point pressure is applied to the entrance node equal to the pressure at the entrance to the sector, and a maximum flow rate equal to the flow rate at the entrance to the sector, which will equal the sum of nominal flow rates of the installed drip feed lines.

♦ Simulated Sector Entrance Flow Rate after Sizing. After sizing the sector, if this option is selected, GESTAR performs an internal hydraulic simulation with the diameters obtained, based on the indicated intake pressure, and taking the Drip Feed discharge curves into account. The resulting flow rate will be used as the sector flow rate for sizing the main pipe.


404

11.6.8 SIZING THE MAIN PIPE

After all the sectors in the system have been sized, the values of Entrance Flow Rate and Required Entrance Pressure will be defined at the entrance to each sector (FIGURE 11-65).

FIGURE 11-65 Regulated Pressure Node after Sizing the Sector.

To begin the process of sizing the main pipe, turns must be assigned to each of the Drip Feed Lines and sector entrance valves (modelled as Regulated Pressure Node) if this was not done earlier.

Using the icon

Definition of turns.

on the toolbar, drip feed lines can be added to a turn in a multiple selection (see page ¡Error! Marcador no definido.), or an individual drip feed line can be selected (see page 106) to modify the assigned turn. The designer can choose to associate Drip Feed Lines from one or more sectors with a turn.

For the sizing, click on the icon

Main Pipe Optimisation Assistant

on the toolbar or the option Size Main Pipes in the In-Plot Design menu. You can access the assistant for Optimisation of the Main Pipes (FIGURE 11-66), which is identical to the one for sizing Turn-Based Distribution Networks (see chapter 8. 7, OPTIMISATION of the TURN-BASED NETWORK). .


405

FIGURE11-66Asistente Optimisation. Step 2: Revise Flow Rates

To size the Main Pipes of a drip irrigation system, you need only review the Flow Rate (column Q in table FIGURE11. 36) which will go through the intake node of the system, depending on the previous correct assignment of turns to the drip feed lines.

FIGURE 11-67 Optimisation Assistant. Step 3: Intake node data. Regulated pressure.

♦ Intake node data. One of the options shown below will be enabled, according to the topology of the network being analysed.

• Known Pressure. For the case of networks without a Pump Element at the intake node (the pressure available in the intake node of the sprinkler irrigation system is known). GESTAR loads the values defined at the intake Node referring to the Identifier, Level, Known Pressure and Total Head. Selecting the Edit button, you can access each cell and modify the data.


406


♦ Slopes. Advanced users can assess the value of these parameters required for sizing, following the detailed recommendations on page 241 et seq.

FIGURE 11-68 Optimisation Assistant. Step 4: Minimum Pressure

Select the default option, Set Point Pressure in open Hydrants with Regulation,

for the optimisation to take into account the entrance pressures of the required sectors, previously enabled by the user in each Known Pressure Node at the sector intake, using the property “Plot Sector Entrance”. The other options, which cannot be used with the above one and are less likely to be used, are documented for the optimisation assistant of on-demand networks (see p. ¡Error! Marcador no definido. et seq.).

FIGURE 11-69 Optimisation Assistant. Step 5: Restrictions


407

The designer can specify in the window shown in FIGURE 11-69the acceptable values of maximum and minimum velocity, time to break even on the investment and the expected interest rate on repayments. (Detailed explanation on p. ¡Error! Marcador no definido. et seq.). The option of blocking stretches of the network so their diameter will not be modified during optimisation (the field Installed Pipes, FIGURE 11-69), is not accessible for sizing the main pipes of in-plot irrigation.

If the pressure at intake node is unknown, steps 6 and 7 (Pumping Stations and Electricity Prices) will be accessible. See p. ¡Error! Marcador no definido..

FIGURE 11-70 Optimisation Assistant. Step 8: Unfavourable Forecasts

This dialogue gives the designer the possibility of defining a series of safety margins in budgets where there is uncertainty about the real situation or if they have not been defined in the previously created network. The sizing assistant lets you set generic criteria at the same time for an upper bound, applied to all stretches of the network, and stretch by stretch for specific Pipes. (See p. ¡Error! Marcador no definido.). GESTAR uses the database of Materials associated with the network, in Microsoft ACCESS 97 format.

FIGURE 11-71. Optimisation Assistant. Step 9: Materials


408


♦ Material to Use. Include in the list the Materials you want to be considered when optimising, from the list of available materials.



As explained in the dialogue in the last step of the assistant (STEP 10), when sizing a network with a Pump Element at intake, GESTAR will transform the Junction Node downstream of the Pump Element into a Known Pressure Node. This Node will function as an intake node, disabling the real Intake Node and Pump element. From the new Known Pressure node, the user will receive information about the nominal pressure required from the pumping station to meet the requirements defined with the obtained diameter results.

Once the optimisation process has finalised successfully, the results obtained will be loaded into the network.

GESTAR identifies the critical irrigation sector (the intake node with the lowest

hydraulic slope), sizing the main pipes to serve at least the entrance pressure taken into account in the previous process and considering the path to this sector as a priority. Next the rest of the pipes are sized, taking into account the pipes of the shared path to the critical sector, thus making it possible to adjust the diameters, as the shared paths will have larger diameters than needed for reaching the pressure of the non-critical modules.

The general conduit is optimised based on the exit pressure from the intake node and guaranteeing the entrance pressure in the irrigation sectors which was used to size them, for a flow rate equal to the sum of the emitted flows depending on the pressure of the installed sprinklers in each sector (obtained by simulation of the scenario).

With the primary pipes defined, the pressure which will finally reach the irrigation modules can be simulated, and recursively optimised, if we have more power in any of them than was considered in the first sizing of the sector.


409

11.6.9 HYDRAULIC ANALYSIS AND OBTAINING OPERATING PARAMETERS

At the end of the sector sizing process, the intake node of the sector modelled as a Regulated Pressure Node will be directly transformed into a Reducing Valve using the Tool / TRANSFORM SECTOR ENTRANCE INTO REDUCING VALVE on the In-Plot Design menu. The only previous requirement is to have selected the sector for the transformation (secondary mouse button click on the outline of the sector).

FIGURE 11-72 Reducing Valve after Transformation.

As shown in FIGURE 11-72, the Pressure head value of the transformed Regulated Pressure Node will be assigned automatically as the Set Point Pressure of the reducing valve.

If not working with a Reducing Valve at the intake of the Sector, the corresponding Regulated Pressure Node should be transformed into a Junction Node, so the hydraulic analysis can be carried out.

The configuration and sizing of the entire plot with all its parameters, characteristics of the sprinklers, materials, diameters, regulating elements, etc, make it possible to completely simulate each of the irrigation turns in the plot, analysing their hydraulic operation, detecting malfunctions and possible improvements in the design.

The last drop-down menu in the top row of the toolbar associated with the icon

, lets the user open the drip feed lines included in an irrigation turn.


410

Before the simulation, using the associated icons and drop-downs (see values in nodes

Viewing results after the simulation

page , and values in elements page ), choose the values you are interested in analysing after the simulation, such as viewing the velocities in pipe elements, or pressure values at the start and end of the drip feed line sub-sections. After clicking the calculation icon , as well as the parameters chosen for direct viewing in the graphic window, you can access extensive information associated with each line of drip feeds by right-clicking on the drip feed line to analyse (FIGURE 11-73).

FIGURE 11-73 Information associated with the drip feed line accessible via right-click.

This offers a summary of relevant results (head loss, flow rates, velocities, etc.) and graphs showing the values of flow rate emitted and pressure (FIGURE 11-74), and velocity and pressure, for each position in the drip feed line.


411

FIGURE 11-74. Graph of Flow Rate Emitted-Pressure.

The Uniformity Coefficient option in the In-Plot Design menu shows the user a statistical representation of the uniformity of the flow rates calculated for the open drippers.

Uniformity Coefficient

FIGURE 11-75. Results window of the Uniformity Coefficient.

Open the drip feed lines you want to analyse (usually included in an irrigation Turn) and select Uniformity Coefficient to open a window like FIGURE 11-75, with the calculated Uniformity Coefficient value resulting from applying Equation 11-3.


1 100d

CUM n

∑= −

⋅


412

Where M is the mean value of the calculated flow rates emitted by the open drip feeds, n is the total number of drip feeds and S|d| is the sum of the absolute values of the deviations from the mean in

the calculated emitter flow rate.

Use the icon

Measurements

(page ) or the menu In-Plot Design/Measurements to see detailed information on the Measurements of the Pipe Elements and Drip Feeds (for this case, only via the menu In-Plot Design/ Measurements/ Summary of Drip Feeds). This information will be very useful for the designer who wants to draw up a detailed budget for the sizing after checking it with a simulation.


413

12 OPTIMISING IRRIGATION SCHEDULES

The TELEGESTAR system is a platform which can integrate various GESTAR functionalities simply and transparently into telecontrol and telemanagement systems, providing resources for modelling, energy management, supervision, detecting functionalities, regulating pumping equipment, etc., for the SCADA systems and working environments of third-party management applications. It does this with a Web Service architecture which permits secure integration. One of the most important tools created in the TELEGESTAR environment for managing pressurised irrigation systems is the PRO-IRRIGATION function. The PRO-IRRIGATION function automatically distributes single or periodical irrigation requests within the available interval (usually between one day and one week), optimising the distribution so that when the irrigation takes place, sufficient pressure to the hydrant is ensured, and if power costs exist they will be as low as possible.

In the case of directly pumped networks, the PRO-IRRIGATION Decision Support System concentrates as much as possible of the irrigation in the periods when power costs are lowest until the pumping station is saturated, and relocate the smallest proportion in the most expensive periods, as long as there is enough pressure at all times in all the open hydrants, good performance in the pump stations, and ensuring the lowest possible power costs. This saves money in two ways: because the most energy is consumed in the cheapest periods, and the minimum voltage can safely be contracted for the other periods. PRO-IRRIGATION is a powerful tool for organising demand, offering the manager the optimum solution in terms of the cost of the power consumed, ensuring that the power supply is not overloaded, and guaranteeing the quality of the service in terms of pressure requirements.

The PRO-IRRIGATION function uses cutting-edge calculation techniques but is user-friendly and intuitive for irrigation managers, offering multiple options and alternatives for flexibly and realistically adapting to all types of irrigation request, thanks to having been configured and tested to meet the needs of any irrigation collective.

In order to provide a graphic interface for the PRO-IRRIGATION function, in cases where:

• There is no remote control system installed and operational (while this makes it easier to use PRO-IRRIGATION, it is not essential).

• Communication via gateway is desired between the remote control and TELEGESTAR, as an option or as the first step towards integration.

• There will be demonstrations of the technology, training sessions or adaptation of systems


414

the GESTAR package can be operated as a graphic interface for using the PRO-IRRIGATION function,

This tool is enabled only as part of a contract to implement custom services in installations for Irrigation Collectives, and in TELEGESTAR demonstration sessions.

The service provided for implementation of the GESTAR/TELEGESTAR functions in the management of pressurised networks, and in particular PRO-IRRIGATION, includes the following processes:

- Analysis of specifications, uses and preferences of the collective. Recommendations and decision on the level of integration and functionalities included.

- Implementation of the telecommunications architecture.

- Generation of a model and databases for the whole system: construction components, settings, pumping equipment, regulation, controllers, prices, etc.

- Customisation and pre-configuration parameters

- Calibration of the model.

- User training. Advice and configuration of the first schedules.

- Monitoring irrigation campaigns, support and updates.

If the system is at the project stage, under construction or being renovated, a preliminary stage will consist of recommending improvements, identifying the need for remodelling and eliminating limiting factors in the infrastructure in order to make subsequent operational strategies for saving by managing demand as effective as possible.

For this reason, the operation of the graphic interface which GESTAR provides for the PRO-IRRIGATION function is summarised below, without entering into exhaustive detail, as the expert handling of these resources requires personalised training, included in the implementation contract.

12.1 DATA CONFIGURATION

For irrigation requests to be optimised, the network must include only Known

demand nodes , Pipe Elements and Pump Elements . The label of each component (Node or Element) must be unique.


415

Baseline data of the pattern of demand

*

9. 5. 2A detailed explanation of the windows associated with the process of Evolution over

Time can be found in chapter .

FIGURE 12. 1 Evolution over Time Window*.

First, the scheduling characteristics are determined from the window in FIGURE 12. 1. This step must be carried out correctly according to the optimisation requirements, as the calculation template will be created according to these parameters. The length of the time interval, the number of scenarios and the reference of the instant the simulation begins must all be specified. The value corresponding to the section Simulation Interval will match the value assigned in Interval length (FIGURE 12. 1).


416

FIGURE 12. 2. Patterns of Demand Window*.

The process of Optimisation of the irrigation requests, accessible from the Optimisation option in FIGURE 12. 2, will take into account the values previously defined in the Power Supply and Prices options in the same window (FIGURE 12. 2).

FIGURE 12. 3 Power Supply Window*.

From the window in FIGURE 12. 3, the user can assign the Power Supply for each Interval of the Pattern. The modulation of the power supply selected with the mouse will be used in the next Optimisation. If none is selected, by default GESTAR will use no. 1.


417

FIGURE 12. 4 Prices Window*.

In the fields at the top of the window in FIGURE 12. 4, assign the Reference Prices of the Contracted Power (in €/kW and year) and Electric Power consumed (in €/Kwh). The variations of both prices depending on the time of day can be defined as a percentage of the Reference Price, or as absolute prices in cents (hundredths) of the currency unit used, taking the Reference Price equal to one.

In the section Enabling Peak Hours, the values taken from the window in FIGURE 12. 4 will not be taken into account during the optimisation process, as they must be defined via the Optimisation assistant and cannot be changed. This means changes can be made to these values without permanent effect.

Click the Optimisation option in the window in

Optimisation Input Data

FIGURE 12. 2. Patterns of Demand Window*.

to go to the window in FIGURE 12. 5 Optimisation Input Data

.


418

FIGURE 12. 5 Optimisation Input Data

SIMULATION DATA

♦ Temporal Data

This section gathers the values of Start Time and duration of the Temporal Step, as defined from the window in FIGURE 12. 1. If you want to change any of these parameters, we advise closing the Optimisation Input Data (FIGURE 12. 5) and Patterns of Demand (FIGURE 12. 2) windows, and making the changes from the Evolution over time window (FIGURE 12. 1). This way you can be sure that the grid of patterns generated when you click the Patterns option again (FIGURE 12. 1) is suitable for use in the Optimisation process.

The End Time field specifies in absolute values the final instant of the simulation for analysis, depending on its duration and the Start Time. The Base Day or day the simulation starts can be specified. If it is not specified, by default the programme takes the date of running the simulation as the Base Day.

The mode of viewing the unit of time (HH:MM, minutes, hours) can be modified from the drop-down menu Unit of Time.

♦ Time Restrictions

If you want to programme time restrictions, you must use the GESTAR programming language, which is described in the appendix GESTAR Programming Language, p. ¡Error! Marcador no definido..

♦ Irrigation Restriction. This will determine the hours of the day in which irrigation is possible.

♦ Start Time Restriction This specifies if there is a time interval in which irrigation should begin.


419

♦ Sun Exposure Restriction. This means a small penalty for the optimisation of the number of hours indicated. These periods are less favourable for irrigation due to sun exposure, wind, etc. (The penalty value programmed in the algorithm is 2.5 cents, less than the cost of the power. )

♦ Settings. The opening and closing of pumps will be specified according to the restrictions. The settings of various Pump Elements can be specified. This means that, for example, a pump can be scheduled to open during a given turn with a higher operating head, and in a different turn with a lower operating head.

ELECTRICITY PRICE

The window in FIGURE 12. 5, in the field Electricity Prices, shows a table summarising the pricing data to be taken into account in the Optimisation process. The values of Power Cost (kWh/€) and Power Supply (kW) will be analysed from the simulation Start Time. Any change in these pairs of values will be reflected in the table, specifying the time interval of application (in absolute values, via the Minimum Time and Maximum Time).

Penalty in KWh (€/kWh). An equivalent power cost is established for excess voltage.

By default, the table is read-only; if you need to change any of the values shown, choose the option Edit. Next, use the options Accept/ Cancel to accept or reject your changes.

EDITING OPTIMISATION INPUT DATA

From the window in FIGURE 12. 5, enable the editing options: Clean data, option which loads the data as defined in the Evolution over Time windows (p. 415 et seq.); Load data, which lets you populate the fields with previously configured input data; or the option Save data , which lets you save the optimisation input data for use in later processes. The files will be recognised in the formats *txt and *xml.

From the window in

Day Pattern

FIGURE 12. 5, enable the Day Pattern options. This brings you to the window Select Nodes for Pattern, which gives an estimate of the hours of use and flow rates to be supplied to hydrants for creating the pattern, based on theoretical design data. This is an intermediate step which can be omitted if you know what the irrigation requests will be.


420

FIGURE 12. 6 Select Nodes for Pattern

The list on the left (FIGURE 12. 6) shows the Known demand nodes which can be selected and added to the pattern. If the Node is Unconditionally open, it will not appear in the list. If the Node is Unconditionally closed it will be greyed out and cannot be selected. (See Restrictions on random scenarios , p. 76).

From the field % Fictitious continuous flow rate this value can be modified as a percentage, varying the irrigation requirements and thus the time needed.

From the field % flow rate, the instantaneous flow rate can be modified in a hydrant or hydrants to be added.

Tick the checkbox for Demand for the value of Demand to be taken (see Known Demand Node , p. 82). If left unchecked the value of Supply will be taken into account.

When you press the button Add, the selected Known demand nodes and the flow rate (demand or supply) will be added to the list on the right (FIGURE 12. 6). The


421

instantaneous flow rate to apply will be specified next to each Node (reflecting any changes made with the tools described above).

Click Next in the window in FIGURE 12. 6 to go to the window in FIGURE 12. 7. From this window the user can modify active requests for the nodes subject to irrigation, with the requirements specified from the window in FIGURE 12. 6, and the previously defined restrictions (FIGURE 12. 5).

Click Next in the window in

Custom requests

FIGURE 12. 6, or select the option Custom requests from the window in FIGURE 12. 5, if the requests are known, to go to the window in FIGURE 12. 7.

FIGURE 12. 7. Requests Window.

First, enable the editing icons to be able to Open the files of existing requests or Save the files of created requests. The archives used will be in the formats *. xml or *. txt.

LIST OF HYDRANTS

The nodes which can be used for irrigation and are not unconditionally open are listed in blue. If a node is unconditionally closed, it will be listed in black.

The list is in tree form. Thus, click on the identifier of a node to see an expanded list of active requests. Select the Identifier to enable the option Add request for that node. Select a Request from the expanded list to access the options Modify request / Delete request.


422

SELECT A HYDRANT TO SEE DETAILED INFORMATION ON THE IDENTIFIER AND ITS WATER SUPPLY. FROM THE FIELD % FLOW RATE, YOU CAN MODIFY ITS INSTANTANEOUS FLOW RATE. (FIGURE 12. 8) TICK THE CHECKBOX FOR DEMAND FOR THE VALUE OF DEMAND TO BE TAKEN (SEE KNOWN DEMAND NODE , P. 82). IF LEFT UNCHECKED THE VALUE OF SUPPLY WILL BE TAKEN INTO ACCOUNT.

STATISTICAL SUMMARY TABLE

The lower middle of FIGURE 12. 7 shows a table summarising the total duration of the simulation, broken down into 24-hour time intervals. The interval is specified by the starting instant (Min Time) and the end instant (Max Time) in absolute values, and their duration (Irrigation time). The Average power cost, Average statistical volume (the volume of the requests is distributed among all the hours available) and Average flow rate are specified for each interval.

This information will be useful to the user when deciding whether to add or modify irrigation requests.

MODIFY AN EXISTING REQUEST

FIGURE 12. 8 Requests Window. Modify Request.

Click on the option Modify Request to enable the Minimum and Maximum Times which limit the period in which irrigation is requested. As these values are changed, the Hours Available for irrigation will change (read-only option).

Mouse over the last field of the table of pairs of values, Consumption / Duration, and press the Enter key to make the table editable. This will be very useful when working with shared hydrants, if you want to distribute a request considering intermediate closures, which may be different in each sub-period, etc.


423

Check the fixed period option to disable the possibility of editing the maximum time. Irrigation will begin at the time specified in the Minimum Time field, with no values allowed which would prevent irrigation throughout its duration. This irrigation request cannot be modified by the algorithm but it will be calculated.

ADD REQUEST

If this option is chosen the column furthest to the right of the window in FIGURE 12. 8 becomes accessible.

Use the Label of the new period to name the new request. The Fixed Period option is offered (see the option Modify Request, p. 422

Adding a Reference Irrigation Period

This field must be filled in the same way as the option Modify Request, p. 422.

Three types of request can be added:

♦ Single Request. A once-only request. This must be used for the optimisation of an irrigation session lasting one day

♦ Periodical Request. This lets the request be repeated regularly. The drop-down menus Periodicity (the options available will depend on the loaded pattern) and Number of times will be enabled for configuration.

♦ Custom Request. A repeated request, with a custom definition of the gaps between each request.


424

Finish

FIGURE 12. 9 Optimisation Parameters

♦ Output folder. By default, the documents of results will be saved in the GESTAR installation folder, C:/Program files/GESTAR2014. From this field, the user can specify another Path to the Output File, where the files from the optimisation will be saved.

♦ Checking Properties. Table summarising the penalty values preferred and acceptable for the calculation algorithm.

♦ Optimisation Parameters.

o Initialisation. This drop-down menu offers several initialisation options which can define the search range at the start of optimisation, to improve the initial solutions found by the algorithm. The suitability of one or another option will depend on the characteristics of the case being analysed. The default option, Random, will consider all the events to be equally probable. If the option Shifted is chosen, the start and end moments of the period will be evaluated as more probable for irrigation to start. If the option Centred is chosen, the most probable irrigation instants will be the central instants. The option Mixed is similar to the option Shifted, but with less loss of probability in the central area.

o Speed. Setting a lower speed will enable better results, but more time will be needed for calculation.


425

o Calculation Time. This option is used to define the preferred maximum calculation time, after which the optimisation process will end automatically.

FIGURE 12. 1 Progress of the Optimisation

Durante the optimisation process, the user receives information in real time with the stages reached, Status, and Optimisation Time Elapsed (Optimisation Data). Separate graphs show the evolution of the Value of the Objective Function and the Power Cost. The viewing scale of both graphs can be adjusted (fields at the bottom of the graph), or can be selected automatically (Auto). Finally, a graph is presented with the flow rate values at the intake node for each instant of the simulation, for the Current optimisation result.

To conclude the process before finalisation, choose the option Request Stop (FIGURE 12. 10).

12.2 CONCLUSION OF THE PROCESS

After various messages from the GESTAR software, the user will see the following alert:


426

FIGURE 12. 2 Optimised Pattern

The window in FIGURE 12. 2, Patterns of Demand, will show the optimal pattern, which can be analysed using Evolution over Time, etc.

The final documents will be saved to the path specified in the window in

Generated documents

FIGURE 12. 9.

♦ flowFINAL.xml. Optimised pattern file.

♦ flow.csv. Flow rate values provided in each instant for each Hydrant.

♦ time.csv. The result of the optimised pattern for each hydrant with the following parameters tabulated: Minimum date, Maximum date, Start date, End date, Minimum time, Maximum time, Start time, End time, Duration, Minimum hour, Maximum hour, Start hour, End hour, Duration hour, Flow rate, nPeriod, Tag.

♦ result.csv. Results for each period of the values of voltage, flow rate and height in Pump Elements, and of pressure supplied in Hydrants.


427

13 HANDLING DATABASES

GESTAR lets you maintain the whole system of databases in the programme.

To modify these databases externally, remember they have been created using ACCESS 97. They can be edited in later versions of ACCESS, but without converting the original structure to the new version of ACCESS..

GESTAR provides a series of databases which are automatically copied during the installation of the programme. In the installation route they can be found in the folder SEG-BdD.

In the menu File on the GESTAR menu bar, select the option Modify Databases to bring up the screen shown in FIGURE 12.1.

FIGURE 12.1 Modify Databases

This window enables the creation, maintenance, extension or modification of each of the databases in GESTAR. Depending on which database you want to access, click one button or the other.


428

13.1 PIPE DATABASES

Click on the Pipes button in the window FIGURE 12.1 to get a start screen like the one in FIGURE 12.2.

FIGURE 12.2 Pipes Database.

From the drop-down menu on the left of the window, go to the Database of Pipes which can be edited in GESTAR. Double click on the chosen database to display the different materials in the file, double click again to hide them. Double click on a material to show information on the different pressure ratings for it. Depending on the active category, different options will be accessible on the toolbar at the top of the window (FIGURE 12.2).

♦ New... click this button to open a field with the following options:

• Database. Lets you create a database with the information you save. To keep this accessible, select the first category from the drop-down menu (Gestar).

• Material. After selecting the database you want to modify, add a new Material with this option. In a window similar to FIGURE 12.3, you can specify the manufacturer, type of material and roughness coefficient in mm.


429

FIGURE 12.3 Creating a new Material.

• Pressure rating. Lets you add new Pressure ratings for the chosen material. First fill in the window in FIGURE 12.4. In the field for the name of the Pressure rating, you can use alphanumerical characters, and numerical values are required for the definition of the maximum pressure the Pipe can take (in m.c.a), and its possible play (in mm).

FIGURE 12.4 Creating a new Pressure rating.

♦ Add Existing DB. Databases can be edited in GESTAR only if they are saved to the folder SEG-BdD. With this button, you can add existing databases saved elsewhere to this folder. For this these files must not change their original structure during any possible changes.

♦ Duplicate Database. Lets you create a database based on an existing one. After selecting the original database, click this button and enter the name of the new file. When this action is validated, the new database will be accessible from the drop-down menu.

♦ Delete. With this tool you can delete the data relating to a complete database or with a material or pressure rating.

♦ Edit. This button will be usable when a material or pressure rating is selected with the mouse from the drop-down menu. In the first case, it lets you modify the name of the manufacturer and the material, and the value of the coefficient of roughness. the second lets you change the name of the pressure rating, the maximum acceptable pressure and the play value.

♦ Edit Pipes Table. This tool accesses the table at the right of the window in FIGURE 12.2, enabling the storage or modification of various values for a given pressure rating. Three fields are required for a new entry: Reference, Internal


430

Diameter and Price. Optionally, from the table you can include the values of Thickness, Exterior Diameter, Length of the Pipe, Weight per linear metre and celerity.

♦ Associate with Active Network. This can be used only if there is a network open before the user enters the menu Modify databases. It will associate the edited Pipes Database with the current network.

IMPORTANT: If modifying a Pipes database externally, be sure to respect the structure of the file. In this type of database, only the tables Material, Pressure rating and Tub_Comerc contain information on Pipes. Be especially careful:

♦ Not to enter blank spaces in each cell of these tables.

♦ In the field Reference in the table Tub_Comerc, the first characters must be numerical to indicate the Nominal Diameter of the Pipes, separated from the rest by an underline, e.g. 110_PVC or 110_[PVC-10]. Two identical References cannot exist anywhere in the table.

♦ Respect the following limitations to the maximum number of characters in certain fields. Table Material, field Manufacturer, 15 characters, field Description: 15 characters; Table Pressure ratings, field Description: 8 characters.

A failure to observe these considerations may lead to malfunctions in the programme, especially the sizing module.

13.2 DRIPPER PIPE DATABASES

After selecting the Drippers in the window in FIGURE 12.1, the dialogue in FIGURE 12.5 opens..

FIGURE 12.5 Database of Drip Pipes.

The information is stored in tables under the name of the manufacturer. Data can be gathered on Material, Pressure rating, Nominal D, Internal D, Thickness, External D, Roughness, Max length, Weight and RRP of the pipe, with the essential data being the


431

definition of the Material and Nominal D. From the drop-down list at top, select the table from among the stored manufacturers.

♦ Modify table. This button lets you modify the selected table. Click it to bring up the table. The difference between this table and the earlier one is that the one in FIGURE 12.6 is totally editable, while the earlier one FIGURE 12.5 is read-only and cannot be modified.

FIGURE 12.6 Modification of Tables of Drip Pipes.

The button Delete Table also allows the contents of the selected table to be deleted, after checking.

♦ Add Table. Enables the user to add a new table with data from a new manufacturer.

13.3 ACCESSORY DATABASES

On the main screen of the Database management system (FIGURE 12.1) choose the option Accessories to show the screen in FIGURE 12.7.

FIGURE 12.7 Accessories Database.


432

This window lists the accessories available in the GESTAR database. This list includes the name of the table with the hydraulic data for each accessory.

If you want to add a new Element to the list, click the button Add/ Modify Acc. The list will stop being read-only and new data can be entered.

In the upper left corner of the Accessories Database window (FIGURE 12.7) you can choose the name of a table, which can be modified clicking the button View/ Modify Table The window shown in FIGURE 12.8 will appear.

FIGURE 12.8 Modification of Tables of Accessories

Use this window to edit the chosen table using the button Modify Table, or create a New Table, with the corresponding button.

13.4 VALVE DATABASES

On the main screen of the Database management system choose the option Valves to show the dialogue in FIGURE 12.9.

FIGURE 12.9 Valves Database.


433

♦ Manufacturers. Clicking this button to bring up the window in FIGURE 12.10, where you can register or modify the contact information of the manufacturer selected in the enabled list, or add contact data for a new manufacturer.

FIGURE 12.10 Modify Manufacturer Data

♦ Operation/Protection. Select this option from the window in FIGURE 12.9 to open the database of valves in pipe, i.e., sectioning, one-way or throttle valves which may be linked as a singular element to a Pipe (see , p. 102). The window consists of four quadrants, where you can Add, Edit or Delete Elements using the buttons.

FIGURE 12.11 Modify Database: OPERATION / PROTECTION VALVES

♦ Manufacturer. At the top of the window a drop-down field lets you modify the selected manufacturer for editing.

♦ Types. The different types of operation or protection valves loaded by default in the database are: free-flowing, free-flowing with small diameter, one-way


434

flap, one-way ball, butterfly, guillotine, globe, Saunders-type diaphragm. When adding or editing a type of valve you can specify if this is a one-way valve in the corresponding field. Select the button Edit Coefficients Cd to bring up a window similar to FIGURE 12.12.

FIGURE 12.12 Modify Type of Valve

This opens the table assigning values of Cd and N to obtain the performance curve of the type of valve to modify or add. The arrows let you navigate through the different rows of definitions of coefficients, for different percentages of closing.

♦ Sub-types. To make them easier to find, valves are grouped in sub-types according to their constructive characteristics.

♦ Series. Each group of valves of different diameters with identical characteristics is identified by the manufacturer with a series number. When you edit or add a Series, you go to the next window:


435

FIGURE 12.13 Modify Series of Valve.

As well as the series number and the description of the valve, the user can associate the series with a .pdf file with the spec sheet.

♦ Code. In the last quadrant, after the series has been selected, a table appears with the codes registered in it with the nominal diameters associated with each code.

FIGURE 12.14 Modify Valve Code.

Click the button Add or Edit to open a window like the one in FIGURE 12.14 where you can edit the chosen code, of the Nominal Diameter (in mm), of the nominal pressure (in atm), and the price.

♦ Automatic Control. This option, available in the window in FIGURE 12.9, leads to

the database of single function regulating valves (see , p. 115).


436

FIGURE 12.15 Modify Database: AUTOMATIC CONTROL VALVES

The structure of the dialogue is similar to the window for editing the database of operation and protection valves (see p. ). In this case, only two quadrants are implemented (for 433 Series and Codes), and a new drop-down field appears at the top, to select the type of valve (Pressure reducing, Pressure sustaining, Flow limiter).

FIGURE 12.16 Modify Code of Automatic Control Valve.

Once the code is selected, as well as the options described in the section above, the coefficients of the open valve can be edited (value of Ks or if absent, Kv), as seen in FIGURE 12.16.

13.5 EMITTER DATABASES

Click on the button Emitters in the window in FIGURE 12.1 to bring up the window in FIGURE 12.17.


437

FIGURE 12.17 Emitter Database.

This window has two keys for access. One refers to the manufacturer of the emitter and the other to the table with the data for a given emitter.

The manufacturer is selected from the list at the top left of the screen, and the data table in the adjacent panel. Both concepts are internally connected but are independent when modified or viewed. In view of FIGURE 12.17, you can modify an existing manufacturer or data table, or add a new manufacturer or table.

The values available for entry in the Data Table are: P (Atm), Q (l/sec), Scope (m), Pluv-C (mm/h), Pluv-T (mm/h), Position-C (m) Position-T (mm). If the emitter is a drip feed it will be defined specifying exclusively the values of pressure and flow rate.

13.6 PUMP DATABASES

In the initial window for modification of databases select the option Pumps (FIGURE 12.1) to get the next dialogue:


438

FIGURE 12.18 Pumps Database.

Via the upper left tab, choose the database to be modified from the folder SEG-BdD, sub-folder Pumps. The Pumps registered in the database appear in the central table of the window, ordered by code. You can navigate by the scrollbar to the right. Select the pump to edit, specifying the model and number of pump runner in the enabled fields. The possibilities for editing are:

♦ View. Click this button to open a window similar to that in FIGURE 12.19, but which allows only the consultation of a set of general data about the pump, (position, series, price, r.p.m, max r.p.m.) and the data of the performance curves for each type of runner stored.

♦ Modify. Click the button Modify to edit the set of data. Use the button Add runner to store the performance curve of a new runner defining at least two pairs of data of flow rate (m3/h) / head (m). Include the power needed in kW and the value of the NPSH for each service point.


439

FIGURE 12.19 Modify Pump.

♦ Delete. Lets you delete the selected pump and all data associated with it from the database.

Two more options are enabled from the window in FIGURE 12.18:

♦ Search. Lets you search based on the specification of the pump model. If found in the database, the first pump model coinciding with the search string will be selected in the list.

♦ Add pump. Click this option to bring up a window with the same fields as in FIGURE 12.19, but in this case empty, so you can define in them the characteristics of the new pump you want to add.

13.7 ELECTRICITY PRICE DATABASES

Finally, activate the cell Electricity Prices in the window in FIGURE 12.1 to bring up the next dialogue. You can also reach it via the menu Pump Regulation, section Power Costs, tab Power Calculations, and button Prices.


440

FIGURE 12.20 Databases of Electricity Prices.

Base Prices

Electricity Prices Field where you can choose a title for later identification.

Base Price of Contracted Power Supply: (€/kW month and period) Reference base price of the Power supply contract.

Base Price per kWh (€/kWh). Base price of the kWh consumed in the reference period.

Editing Time and Price Brackets.

The second table of the window in FIGURE 12.20 shows the codes and types of the saved time and price brackets. Use the buttons Add, Modify or Delete to update the stored configurations. The definition parameters are:

Code. A code will be assigned to each time band. The programme does not allow codes to be repeated.

Type: In this field you can add a comment for each price rate for later identification.

Surcharge %. Specifies as a percentage the variation in electricity prices for each time (coefficients iIkW iIkWh ) in relation to the regular rate. Positive values mean extra charges at that time of day, and negative ones mean discounts.


441

APPENDIX I. CONSTRUCTIONAL AND

OPERATIONAL CHARACTERISTICS OF

DISTRIBUTION NETWORKS FOR PRESSURISED

IRRIGATION.

AI.1 DEFINITIONS.

GRAPH.

The graph of a distribution network is defined as the single line graphic representation of the network, made up of significant points, called Nodes, and Elements connecting the Nodes.

BRANCHED TOPOLOGY

A network has a branched topology if in its associated graph the connection between any two Nodes can only be made by a single route (case a). Otherwise, the topology is defined as meshed (case b).

(a) (b)

FIGURE AI. 1 Branched graph (a) and meshed graph (b).

CONSTRUCTIONAL TOPOLOGY.

The constructive topology of a network is the combination of:

-Its graph.

-The description of levels of all Nodes.


442

-The description of the diameters, roughness, lengths and material of all conduits.

-The specification of devices and special pieces installed (pumps, valves, reductions, filters, elbows, etc.).

BOUNDARY CONDITIONS.

The boundary conditions of a network in a given instant mean the combination existing at that time:

-of consumption in the Nodes where the demand for fluid is known.

-of energy levels in the points where pressure, level and kinetic energy are known.

CONFIGURATION OF CONTROL DEVICES.

The configuration of control devices in a network at a given instant is defined as the concrete set of states of activation, regulation and set points of the different internal elements (pumping groups, valves, regulators, etc.) of the network a that moment.

SCENARIO.

A scenario in a distribution system is defined as a combination of:

-the constructive topology of the network.

-some determined boundary conditions.

-a concrete configuration of the control devices.

STRICTLY BRANCHED SCENARIO.

A scenario of a fluid distribution network is called strictly branched (FIGURE AI. 2) if:

-it has a branched topology.

-boundary conditions dare such that:

• There is only one point with a set energy head, normally at intake,

• The rest of the nodes in the network are similar to points of known consumption, i.e., bifurcation, with null consumption, or supply points with demand independent of pressure.


443

FIGURE AI. 2 Strictly branched scenario.

STRICTLY BRANCHED NETWORK.

A network is strictly branched if all its scenarios are strictly branched.

AI.2 THE PARADIGM OF STRICTLY BRANCHED NETWORKS.

AI.2.1 SIZING STRICTLY BRANCHED NETWORKS.

Exclusively in networks where the topology and boundary conditions are implemented configuring a strictly branched network, is it possible to determine a priori the Design Flow Rates, unconnected to hydraulic equations and the characteristics of the pipe itself, making it possible, among other things, to establish direct methodologies for sizing the diameters of the conduits, methodologies which can be classified

AI.2.2 CALCULATION OF PRESSURES IN EACH SCENARIO.

in two types: functional sizing, i.e., determination of a combination of diameters and materials which satisfies certain restrictions regarding values of pressure in Nodes and velocity in pipelines, and economic optimum sizing, seeking the same goal, while also looking for the combination of diameters and material in the network which would minimise the theoretical costs of the pipes. Each of the above methodologies allows for various approaches which share conceptual or practical advantages and limitations.

However, only in strictly branched scenarios is it possible to calculate explicitly the pressure in all the points in the system for any combination of demands, once the internal diameters and material of the pipes have been determined, needing only to subtract - or add - the corresponding head losses, calculated immediately, to the only known total head, given that the flows of all the conduits are given as the sum of the flow rates demanded downstream in the concrete demand scenario.

However, the scope of this methodology of hydraulic analysis, applicable only to strictly branched networks, is very limited, and it is increasingly necessary to have general and flexible methods which allow us to find solutions to the configurations


444

found in practice. FIGURE AI. 3 shows the schema of a typical demand irrigation network illustrating some of the usual aspects.

Although the structure is essentially branched two redundant pipes can be seen at intake, asymmetrically connected, and an interconnection between two branches to correct a problem of insufficient pressure, resulting in meshes. There are also two Reservoirs, which can supply the network simultaneously, and a pair of points discharging to the open air, pouring water into two irrigation ditches, through a partly open butterfly valve. Consequently, there are four points of set total head (the two reservoirs and the two emissions). It also shows the presence of automatic regulation devices, such as the pressure reducing valves, pressure sustaining valves and flow rate limiter valves, increasingly found on all types of networks.

FIGURE AI. 3 Schema of collective irrigation network

When a network presents a mesh or more than one point of known total head, alternative routes to the supply or flow rates emitted according to local pressure appear, so that the distribution of flow rates in all or part of the network cannot be known without resolving the complete system of equations reproducing the hydraulic behaviour of the distribution system. This system contains many non-linear equations whose solution unavoidably requires the help of the techniques used in the hydraulic calculation of general networks, even when the network maintains a branched appearance.

Depending on the simplifications offered by the model of a strictly branched network it is not surprising that in systems dedicated to irrigation, where the topology most often fund is branched, pressurised distribution networks normally fit a strictly branched paradigm, with a main intake point and flow rate demands generally regulated by the hydrants in their normal operation.

This fact, together with the lack until now of sufficiently robust and easy to use simulation tools, means that there has been little systematic use of hydraulic simulation


445

programmes in irrigation, although they are widely used in other contexts (mains supply, cooling and heating, hydroelectricity and regulation, fire prevention networks, etc.). In contrast, irrigation network projects use optimum sizing techniques (especially productive in branched networks, given design flow rates known beforehand, as mentioned above) to the point that a design is normally considered complete when the economic diameters of the pipes has been established.

However, we can affirm, depending on the situation found as a result of numerous experiences analysing pressurised irrigation, that while for the purpose of sizing pipes, the paradigm of the strictly branched network can be considered as essentially correct, as far as concerns the simulation and reproduction of the instantaneous, local real behaviour of these networks, the operation of the system according to the model of the strictly branched network is the exception rather than the rule. If seeking to improve the efficiency of the design and of network operation, this requires the introduction of techniques of prediction and general hydraulic analysis, which are also ideal, and even more precise and productive, in irrigation networks.

Fortunately the greater availability and cheapness of computer power in the last decade and the development of new, more powerful, robust and efficient numerical techniques have closed the gap between computer applications for hydraulic calculation and those available in other areas of engineering, bringing together a growing number of different professional circles and making them more aware of the advantages offered by the simulation of systems compared to conventional techniques of design by trial and error. The use of this type of tool is also spreading among the bodies which manage hydraulic systems, as it makes it possible to evaluate and anticipate, at low cost, their response to a great variety of practical situations, for planning, prevention or regulation.

Therefore it is essential in the design and exploitation of modern irrigation systems to have absolutely general calculation techniques, which can realistically accommodate any constructive topology, combination of boundary conditions and configuration of control devices, in other words: any scenario.

In the sections below we revise the most significant hydraulic characteristics of networks for pressurised irrigation, taking as the comparative element the intake systems. This will give further justification for the need for and reliability of hydraulic analysis tools in the context of irrigation networks for their better design and management.

AI.3 HYDRAULIC CHARACTERISTICS OF PRESSURISED IRRIGATION NETWORKS.

Pressurised water distribution systems for irrigation and general supply share many characteristics while presenting notable differentiations. The most relevant aspects of irrigation systems are:

♦ Topology predominantly, although not exclusively, branched.

♦ Low density of the network and high intensity of demand.


446

♦ Discontinuous and controlled demand structure.

♦ Presence of combined boundary conditions where various points of set total head coexist with demands dependent on and independent of pressure.

These characteristics will be a common thread in the systematic review of the hydraulic aspects of these networks.

AI.3.1 TOPOLOGY.

In the supply of drinking water the major arteries are usually interconnected, forming a mesh structure which ensures the water can reach every residential block following more than one route from the intake points of the network, even when this means greater costs in e pipe layout than the strictly necessary minimum. This redundancy, as well as homogenising pressures, attempts to ensure supply by alternative circuits when there is an interruption in the circulation of any of the pipes supplying a sector.

In demand irrigation networks, the large surface areas to be covered, the dispersion of consumption points, the high costs of pipes with the large diameter needed to take the large volumes of water served and the greater tolerance of crops to occasional water shortages lead to the adoption of a branched morphology where each supply point is supplied through a single series of pipes, given that it has been shown to be generally more economical than any other mesh providing an equivalent service.

However, it must be remembered that meshed layouts in irrigation networks can be recommendable in certain contexts, some of which are:

Special situations.

Guaranteed supply.

Scaling investments.

Correction of insufficient pressures.

Gardening applications.

SPECIAL SITUATIONS.

In particular situations due to restrictions in the layout (geographical features, rocky or mobile terrain, excluded areas, etc) or the availability of diameters, a redundant interconnection at some point can be more economical than a purely branched solution.

GUARANTEED SUPPLY.

On other occasions, the aspects of guaranteed supply can be relevant, for example in the stretches near intake of the network, those of greater diameter and cost,


447

where repairs or maintenance paralyse the whole sector, it may not be advisable to install a single large diameter pipe given its vulnerability, and may be more prudent to install two or more parallel pipes of a smaller diameter which will form some type of mesh in their connection. On other occasions, the proximity of hydraulically independent sectors can make a meshed interconnection advisable to reduce the vulnerability of each of them to cutting off the supply, especially in crops with high added value or precise irrigation requirements.

SCALING INVESTMENTS.

The supposed greater cost of parallel pipes at intake, compared to a single large diameter pipe, can be compensated by savings in financing the stoppages caused by staggered installation of parallel conduits, as the sector change and requires greater flow rates. The alternative of installing a single large diameter pipe with a carrying capacity which may be underused for many years may not be more advantageous.

CORRECTION OF INSUFFICIENT PRESSURES.

Situations which can make local meshing in the network advisable appear when problems of insufficient pressure in already built branches need correcting, especially if they are in use. The circumstances in which a given hydrant presents a deficit in pressure are more often found than one might think (aging infrastructure, changes in crops or maximum flow rates, design errors, etc). On these occasions, if a nearby branch has sufficient total head, the interconnection of the branches, forming a mesh, can increase the pressure in the problem area significantly, without the branch contributing flow suffering an excessive decrease in its respective pressure. The diameter and cost of the conduit needed to remedy this situation can be much less than the cost of replacing already installed pipes in the problematic branch wit newer or larger diameter pipes.

GARDENING APPLICATIONS.

Finally, in gardening applications it is normal to find distribution pipes forming rings around the periphery of the plot, connecting to the irrigation devices. This is because the meshing of the system tends to even out the total heads of all points, and thus the pressures, with total flexibility for later changes and readjustments of the points of insertion of lateral pipes, which are very frequent in these applications. Given that in gardening small diameters and limited extensions are used, the cost differential compared to the branched solution is not significant, especially if compared to other investments associated with the residential areas where they are installed.

Meanwhile, by assigning a common diameter to the whole mesh, the designer avoids complicated assembly and design problems, as this avoids the tedious calculation of pipes in decreasing diameters, needed in branched networks, to ensure the homogeneity of pressures, a solution which, as well as being rigid and not easily accepting later changes, requires a collection of diameters and special pieces which must be gathered, stored and assembled, meaning higher costs than those saved in pipes compared to a mesh with a constant intermediate diameter.


448

AI.3.2 NETWORK DENSITY AND INTENSITY OF CONSUMPTION.

DENSITY IN LAYOUTS.

In demand irrigation systems we find distribution networks highly dispersed in the layout, with a low concentration of outlets, compared to drinking water systems. Sectors of irrigation dominated by a single catchments or regulation reservoir can range from 200 ha. to several thousand ha. While in an irrigation system we find an outlet or hydrant for each 1-10 ha, and the hydrants are separated on average by 300 m. to 600 m., in a domestic supply system there are just a few metres between one building and the next, and the next independent outlet. In a mid-sized city (pop. 500,000) there are usually as many metres of pipe laid as there are inhabitants, forming a dense, profusely interconnected web.

DENSITY OF USERS.

The number of users making decisions in an irrigation system ranges from a few dozen to several hundred, in the most extreme cases, with the most frequent being sectors with 200 to 400 irrigation outlets. In any case, there is a difference of three orders of magnitude between the number of independent users in one type of system or another.

Given the relative topological simplicity of the network and the small number of outlets, in pressurised irrigation systems it is completely possible to reproduce the complete network of pipes, including singular elements and individual outlets, with no need to schematise the topology of the network before analysis.

INTENSITY OF DEMAND.

Despite the dispersion of users over the area and the comparatively low number of them in a hydraulic irrigation sector, their flow rate demands are significantly higher than individual urban consumption. If the consumption made by a citizen opening a tap for a short period can be estimated at around 0.1 l/s, an open irrigation hydrant can easily use dozens of l/s for most of a day.

In drinking water supply, as in any distribution system where there are many thousands of consumers with random behaviour patterns, it is impossible and irrelevant to try to trace individual demand behaviour or isolated effects, which are diluted and have little impact on the whole. Thus, in urban networks the consumption decisions of users do not affect the system except cumulatively, and are quantifiable only from a statistical viewpoint.

However, in irrigation systems, the high instant flow rates demanded by each irrigator, in a group of users which is already comparatively small, mean that the rest of the network is affected by his individual actions.


449

MOST UNFAVOURABLE CONDITIONS.

Finally, it should be remarked that while the design criteria of irrigation networks are focused on ensuring sufficient pressures for peak water demands in the months of most need, in drinking water supply peak demand is set by fire prevention conditions usually much higher than maximum consumption.

AI.3.3 STRUCTURE AND CONTROL OF DEMAND.

Another substantial difference between irrigation networks and drinking water supply is the type of demand behaviour and the type of intervention which the managing body uses for its control and supervision.

The essential features described below are grouped under the headings:

Seasonal and daily variations.

Discontinuous patterns of demand.

Control of open outlets.

Control and registry of consumed volumes.

Constant and regulated instantaneous demand.

SEASONAL AND DAILY VARIATIONS

In the structure of demand, we find large seasonal variations in irrigation systems, and a lesser daily variation, en relation to drinking water supply. While domestic, industrial, sanitation, etc consumption in centres of population have a larger base over the year, affected in some months by slight increases in demand, in irrigation systems demand is concentrated in certain periods, with dormant periods in the seasons when there is no need to apply water, and the network is completely inactive. The opposite is true of variations throughout the day: urban demand is reduced at night, to as low as 25% of daytime peaks, while the flow rates demanded over 24 h. by irrigation systems must be more uniform, especially in automated networks and peak seasons, when all the hours of the day must be used.

DISCONTINUOUS PATTERNS OF DEMAND.

The variations in the flow rate circulating in irrigation networks come essentially from variations in the number of outlets open at the same time, as the flow rate extracted in each hydrant is practically uniform once the hydrant is in use. In irrigation networks the pattern of demand of each Node is therefore markedly discontinuous: if the hydrant is open it will use all the maximum flow rate constantly while it remains open; when the application of the dose of water is finished the hydrant will remain closed, with a strictly null flow rate, for a period of varying length. Thus,, there are often situations in which no flow is circulating in most of the branches, and even the whole network (except for leaks), which is unthinkable in a drinking water supply.


450

In drinking water supply systems, variation in demand can be due to an increased number of users or greater intensity of flow rate demanded, depending on the type of use. This modulation will affect the outlets and nodes of the system gradually, as it represents the integration of many individual, small demands.

CONTROL OF OPEN OUTLETS.

Unlike drinking water supply networks which contain numerous outlets, in irrigation networks it is possible to some extent to supervise the flow rates supplied in real time, with the possibility of notable control, both of outlets in use and of flow rates supplied instantaneously.

Thanks to the spread of telecommunications, the consumption status of outlets can be known at any time through the irrigation notification protocols transmitted to the managers of the plot, or by automatic procedures based on flow rate sensors installed in the hydrants. A synchronization of greater use than allowed for in the design, a change in socio-economic conditions or unsuitable manipulation of the hydrants will lead to over-exploitation of the network, reflected in malfunctions or inefficiency in the application of water and energy.

CONTROL AND REGISTRY OF CONSUMED VOLUMES

The strict accounting for water consumed in pressurised irrigation systems is practically universal, given that accurate invoicing is an essential goal of modern irrigation systems. In drinking water supply systems it is still very frequent to find outlets for private individuals, communities, public centres, services, etc., where there is no meter, so the determination of consumption with precision is impossible.

CONSTANT AND REGULATED INSTANTANEOUS DEMAND

Another factor favouring hydraulic management of pressurised networks is based on the constancy of flow rates demanded by hydrants, once open, and the possibility of integrating the behaviour of users’ hydraulic devices in extreme cases into the model of the network. This is an essential difference to drinking water supply systems, as although in the latter the basic demand on flow rates is relatively constant (given the regulating action of users on taps counterbalancing the variations in pressure in the network) the flow extracted from the network, at any given moment, cannot be precisely known; far less can the mathematical analysis of the system include the hydraulic behaviour of the internal installations of users.

When in irrigation systems the consumption of open hydrants is similar to nodes where demand is known and independent of pressure – as well as constant while open – an approximation will be essentially correct, as long as there are control devices interposed between the shared distribution network and the plot, and these are working correctly. These basic devices consist of a pressure reducer and a flow limiter.

Even when these devices are not supplied with enough pressures, it is possible to predict instantaneous consumption (see Appendix II, p. 457).


451

AI.3.4 TYPE OF BOUNDARY CONDITIONS.

In the case of hydraulic systems, the points where the total energy head is known can be regarded as equivalent, for all purposes, to the points where total head is known (given pressure and level) as long as the kinetic energy is negligible. This condition is satisfied, first, by the systems supplying the network (dams, reservoirs, tanks), as in the reference points, pressure and level are set, while kinetic energy is insignificant.

However, the points where the flow is discharged to atmosphere (emission through open valves without regulators interposed, hydrants with regulator not operating, breakage points, sprinklers, drippers, drip tape, etc) also represent nodes where the total head is known, as the pressure at the discharge point is exactly atmospheric and the level corresponds to the point of emission of the flow rate. In these cases, although the kinetic energy in the emission section, Se, can be important for some of the above types of emission, as long as the loss of kinetic energy is considered as another energy loss, forming part of the dissipation of the emitter element, all the emission points can be regarded as equivalent to total energy points equal to the total head 465(see Appendix III, p. ), so that the equation modelling these devices in the general case will be:

NS QK

SQk

DL

gH +

+=∆ ∑ 2

2

21 λ

(AI.1)

Where:

L:= length of the conduit associated with the emitter

D:= hydraulic diameter of the conduit associated with the emitter

S:= section of the conduit associated with the emitter

λ := friction factor of the conduit associated with the emitter

k := dimensionless coefficients of singular losses

Ks

N = exponent characteristic of the emitter

= dimensional coefficient characteristic of the emitter

In the irrigation emitters, Ks and N in (AI.1) are determined experimentally by testing the pressure/flow rate response of the emitter, which fits to a curve of the type ∆H = Ks Q N. If the emission is characterised by another type of device, with dimensional coefficients of known losses K´ , and happens in a section of area SE

2;1121 2

222 =

−+′= NQ

SSgQKK

eS

(Appendix III) then:

(AI.2)


452

In distribution systems, Nodes regarded as points of consumption are usually treated like Nodes where demand is determined and independent of pressure, a condition which, as it has already been studied, will be verified both in drinking water supply systems and in irrigation distribution networks, as long as demand is regulated by variable opening valves interposed between the network and the consumer, regulated manually or automatically, counterbalancing the possible variations in pressure of the network through changes in its degree of opening.

In drinking water supply and irrigation systems there is normally a main feed tank for each sector, taken as a point of known total head. However, in operating irrigation systems one often finds more than one point of total head in the network. Some of the situations where this can happen are:

Multiple intake points.

Pumping to reservoirs with two-way pipes.

Irrigation emitters.

Unregulated discharges.

Localised leaks and breaks.

MULTIPLE INTAKE POINTS.

When a network has two different sources of supply, intermediate accumulation tanks, tail tanks, etc, each of the tanks or reservoirs becomes a point of known total head.

PUMPING TO RESERVOIRS WITH TWO-WAY PIPES.

While the conditions with multiple tanks appear exceptionally in irrigation systems, there are very many situations where to pressurise the network it is necessary to pump, supplying the area, if the geography permits, not directly from the pump groups but via a raised regulation/accumulation reservoir where the water is pumped in off-peak hours from the lower reservoir (FIGURE AI. 4 a). Normally the conduit used for this discharge coincides for part of the route with the

intake conduits of the network (FIGURE AI. 4 b).

(a) (b)


453

FIGURE AI. 4 Pumping with intermediate regulation tank.

Although in the sizing phase we suppose the whole network will be supplied from the intake reservoir, depending on the hydraulic conditions set by the scenarios arising in practice, four types of combinations of flow can be found (FIGURE AI. 5). While cases a) and b) in FIGURE AI. 5 still fit the paradigm of the strictly branched scenario, the other two cases c) and d) suppose the existence of two points of known total head.

(a) (b) (c) (d)

FIGURE AI. 5 Elevations with two-way pipes.

IRRIGATION EMITTERS.

While demand distribution networks are not usually directly connected to devices for pressurised application of water (cannons, sprinkler networks, branches with drippers or micro sprinklers, misters, drip tapes, etc.), the distribution networks inside the plot present a profusion of emitters, so that it can be desirable to enter this area to complete the design aspects in the plot.

Conventional approaches establish models for Emitter Lines where the emission devices are inserted using behaviour equations of losses in the branch deduced under the proximate hypothesis of supposing a continuous supply of flow per emitter or per unit of length. This description is inexact insofar as in construction, the emitters are fixed beforehand, so that the flow rate provided depends on local pressure and the performance curve of the pressure/flow rate response of each type of emitter, this pressure in turn being strongly dependent on earlier emissions and especially on variations in level, which can be very significant in pressurised irrigation systems.


454

The irregularity and variation of this pressure leads to emissions with a non-homogeneous flow rate, which needs to be known and marked with elevations in order to avoid unacceptable losses of uniformity. For this, traditional formulations revise the homogeneity of pressures a posteriori, establishing the threshold of non-homogeneity which may be presented between the least favourable points, and a maximum tolerance depending on the hydraulic characteristics of the emitter (Christiansen's criterion). These approaches are widely accepted, as they make manual calculations much easier. Their disadvantages are:

♦ Uncertain intuitive detection of the least favourable points, especially in conditions of very irregular planimetrics and altimetrics, a fairly frequent situation in these installations.

♦ The need to use hypotheses which are not always fulfilled closely enough: the identity of emitters, the regular distribution of emitters or groups of emitters, trapezoidal plots, uniform slopes for each Emitter Line, etc.

♦ The need for successive trial-and-error tests if the final results contradict the initial hypothesis.

Using computational models in this context allows for more detailed approximations than would be viable for manual calculation, making it possible to overcome these limitations. To do this, the boundary conditions of the emitters must be properly configured and not taken merely as points supplying known flow rates independent of pressure.

The invariable parameter which can be known a priori in all devices emitting flow, and which constitute a correct boundary condition for hydraulic analysis, is the total head at the discharge point, which in turn can identify the level, as the pressure head is cancelled out at the point of emission when taking pressures referenced to atmospheric pressure. The flow rate really extracted from each emitter will depend on the pressure which feeds it locally and its response curve to the pressure ∆H = Ks QN

465,

which must be specified (Appendix III p. ).

The response curves of the emitted flow rate in relation to the feed pressure head are characterised by the manufacturers and can be implemented in the GESTAR simulation pack.

UNREGULATED DISCHARGES.

All the discharges of flow to the exterior without automatic control elements for regulating pressure and/or flow rate should be catalogued under this heading. For example, discharges to drinking troughs, isolated reservoirs, canals and irrigation ditches, or gravity-watered plots in practice use a conduit with a sectioning valve at the end, in most cases operated manually, which opens, completely or partially, when the supply is needed. The extracted flow rate, for a given degree of openness of the valve, will fluctuate depending on the pressure in the network (which in turn depends on the extracted flow rate). The boundary condition which correctly reproduces the hydraulic behaviour of these points of emission is not desired extracted flow rate, as this cannot


455

be specified without adjusting the opening of the discharge valve, but rather the value of the total head at the point of discharge.

In the general behaviour equation of the emitter (AI.1) Ks465

is evaluated against the expression (AI.2) (see Appendix III, p. ).

2;1121 2

222 =

−+′= NQ

SSgQKK

eS

where K´ is the dimensional coefficient of head losses corresponding to the singular element the discharge runs through, given by its geometry and degree of openness. The need to retain lineal losses in (AI.1) and kinetic energies in (AI.2) will be examined according to the concrete conditions of the discharge.

LOCALISED LEAKS AND BREAKS.

A local leak can be interpreted as a discharge to the exterior through a fictitious conduit of a diameter, D, which can be made equivalent to the hydraulic diameter of the crack and with a length, L, equal to the thickness of the conduit wall, e. however, this first contribution in the expression (AI.1) is negligible, except for a very small D (cracks). If we also take to be negligible in (AI.2) the kinetic energy in the conduit and the localised energy losses which occur in the process (deviation of the leaked current, hydraulic resistance of the surrounding terrain) the total head in the conduit will be entirely transformed into kinetic energy in the perforated or cracked section (a conservative criterion which will over-value the leaked flow rate) so that the pressure/flow rate relationship (AI.1) characteristic of the leak will be reduced to the contribution of the kinetic energy in the escape section, SE

∆H = 1/(2g S

:

E 2) Q 2 ; Ks = 1/(2g SE

2) , N = 2

If trying to represent the effect of a larger break, the same process is followed, taking as the limit case of the section with the leak, S

(AI.3)

E, in (AI.3) the complete transversal section of the conduit completely broken, but taking the precaution of cancelling out demands downstream from the point of complete breakage, as there is now no continuity in the branch enabling it to by fed.


457

APPENDIX II. MODELLING HYDRANTS

This appendix reviews the hydraulic behaviour of hydrants and modelling their connection to the network and the plot in order to simulate them correctly in GESTAR.

AII.1 OPERATION OF THE PRESSURE REGULATOR.

♦ Reduce the feed pressure of the equipment of the plot to protect it from excessive pressures if these exceed the recommendable values.

♦ Supply the right pressure for the specifications of the plot installations.

♦ Maintain the pressure constant in the supply to the equipment of the plot, independently of the variations of pressure existing in the network.

To carry out this action the pressure regulator/reducer will control pressure downstream from the hydrant (see FIGURE AII. 1). If increased pressure is detected, provoked by any cause, (e.g., increased pressure in the collective network transmitted through the open hydrant), using an automatic mechanism the regulator will close the hydraulic valve of the hydrant, increasing the head losses until the downstream pressure is reduced to the set point level. Thus, in FIGURE AII. 1 whether the pressure is pA (47 mca) in case A or pB (42 mca) in case B, the various levels of openness of the valve of the hydrant will provoke head losses of de 7 mca and 2 mca respectively to maintain the set point pressure (40 mca) invariable at point P supplying the plot.


458

pB= 42 m, B

NETWORK INSIDE THE PLOT

FIGURE AII. 1 Operation of a pressure reducing valve.

The opposite happens if the pressure regulator detects a pressure drop downstream from the hydrant: it will open the hydraulic valve of the hydrant so that the lower head losses provoked in this case, in relation to the initial situation, compensate for the decreased pressure in the network. However, the process described cannot continue indefinitely, so that, when the valve corresponding to the hydrant is completely open, new pressure drops in the network cannot be compensated for by the regulator by further opening a valve which is already completely open, as shown in FIGURE AII. 1 for case C, with feed pressure in the collective network of 38 mca. The local pressure of the network will then be transmitted directly to the plot (minus, of course, the head losses of the hydrant when the regulating valve is completely open). In short: to maintain the pressure constant and at the set point, the pressure regulator needs the network pressure to be higher than the set point value plus the value of the head losses in the completely open hydrant.

AII.2 OPERATION OF THE FLOW RATE LIMITER.

The flow rate limiter is designed to avoid a higher instantaneous flow rate being extracted from a hydrant than the maximum allotted to the irrigator (maximum flow rate), and usually coincides with the instantaneous demand of the hydrant when open (although not always, as will be shown later).

If for any reason (low hydraulic resistance in the internal network, breakage in the network, direct discharge to atmosphere, alteration, intentional or not, of the parameters of the pressure regulator, etc.), the flow rate should exceed the value of the maximum flow rate allotted to the irrigator, the flow limiter device will cancel out the action of the pressure regulator, throttling the flow itself (introducing supplementary head losses) as much as necessary to reduce the flow rate to the value of maximum flow allotted. In this case, the feed pressure to the equipment will not be the set point

pA=47 m, A

pC= 38 m, C p= 40 m, A and B

QA =QB QC < QA

pp

Qp P

COLLECTIVE DISTRIBUTION NETWORK


459

pressure; this pressure, set by the flow limiter, will be the value needed for the hydraulic installations of the working irrigation sector to emit the right maximum flow.

AII.3 HYDRAULIC RESPONSE OF HYDRANTS..

The constant rate of pressure downstream from the hydrant is reflected in the constant flow rate emitted by the set of irrigation devices connected to the hydrant. In fact, while the distribution of conduits and emitters in the plot is unchanged, for the same feed pressure at the shared intake (cases A and B of FIGURE AI. 4) the emitted flow rate will be the same (QA = QB). Logically, if the connection with the irrigation sectors is altered, or the regulators interposed inside the plot between the hydrant and the emitters is modified, the net flow rate circulating towards the equipment, Qp

So, for the purposes of hydraulic analysis, the collective network and the hydraulic installations of the plot can be considered as completely independent, as long as the collective network has enough pressure to guarantee the action of the pressure reducer, and, in this case, when analysing the collective distribution network, the condition which must be set as known in the node where the hydrant is installed is the constancy of the extracted flow rate, independently of network pressure.

, will be changed, but this will remain constant as long as the placement of the hydraulic installations for applying water is maintained.

This instantaneous demand, always the same as or less than the maximum flow rate allotted, can be found out by experiment, once the plot is equipped, using in situ measurement of the volumes provided by the time unit, which are easy to determine thanks to the volumetric counters which are now usually installed for all hydrants, or by portable flow meters (volumetric, ultrasound) which can be connected provisionally for this purpose. As the number of outlets in a collective network is moderate, applying this procedure is simple.

While on the subject of this analysis we can ask two questions of great relevance to the correct modelling of the system under all conditions:

1) How to anticipate the value of demand in a hydrant when there is enough pressure in the network and the pressure reducer is operational?

2) How to anticipate the value of demand in a hydrant when there is not enough pressure in the network and the pressure reducer is completely open?

These questions are dealt with in some detail below.

VALUE OF DEMAND WHEN THE PRESSURE REDUCER OF THE HYDRANT IS WORKING.

The network designer must make sure that, for the set point pressure established, the flow rate emitted by the irrigation equipment fits the maximum flow authorised for the irrigator, as if it is lower (e.g., because the network has too much hydraulic resistance) the irrigation time will be too long. If the hydraulic resistance of the internal network as a whole is too low, or if the set value of the pressure regulator is increased,


460

the extracted flow rate could be higher than the maximum allotted rate. To avoid this, a second regulating device should be installed in the hydrant: the flow rate limiter. A good project for the internal network should therefore use all the authorised flow of the hydrant, without exceeding it, when the plot is supplied with the set point pressure.

However, if a plot has very different irrigation sectors and/or is in the process of implementing irrigation installations or crops, there may be situations where the projected instantaneous consumption is deliberately lower than the maximum flow rate.

The value of this consumption can be anticipated according to the design and hydraulic behaviour of the interior of the plot. When the pressure in the collective network is above the set point of the pressure regulator, the interior network can be independent of the collective network, and the condition which must be set in the feed to the internal network is, in fact, the rated pressure of the regulator, so that the known information at the intake of the plot is the total head downstream from the hydrant. With this feed pressure for the internal distribution network, and given the placement of the additional emitters, pipes and regulators, a projection can be made of the flow rate to the exterior. Using the estimates of the installation project, or carrying out a hydraulic simulation of the internal irrigation system using GESTAR, the flow rate really demanded for the irrigation sector given the set point pressure can be deduced.

We can conclude that given:

-The existence and correct operation of the flow limiter in the hydrant.

-The existence of a correct project for the plot, which attempts to use the full authorised flow of the hydrant in each application of water.

-The existence in the collective network of pressure levels higher than the set point pressure of the hydrant.

The flow rate extracted from the network through a hydrant in a consolidated irrigated area will very probably be constant and equal to the authorised flow.

In any case, although the hydraulic system of the plot does not use all the authorised flow, the flow rate extracted from the hydrant will be constant (and lower than the maximum authorised) as long as the network pressure is higher than the set point value of the corresponding pressure reducer and the hydraulic installations of the plot are not altered.

BEHAVIOUR OF THE SYSTEM WHEN THERE IS NOT ENOUGH PRESSURE FOR THE OPERATION OF THE PRESSURE REDUCER.

When there is not enough pressure upstream from the pressure reducer to maintain the set point pressure downstream. the reducer will remain open and inactive, transmitting the pressure of the collective network directly to the plot intake with all its fluctuations (unless the hydraulic resistance of the internal network of the plot is so low that the flow rate is still higher than the maximum authorised flow value and the flow rate limiter system still has to intervene).


461

In this case, the hydraulic behaviour of the collective network and of the plot network are no longer independent, both being intrinsically linked, as, depending on the type and number of emitters, their placement, the installed pipes, etc, the internal network will permit a greater or lesser flow rate to pass through to the crops in response to the pressure coming from the network, which will now not be constant or known a priori, as it was when the pressure reducer was able to work.

In principle, to deal with these circumstances the scenario of the collective network will need to include the configuration of all the internal hydraulic devices connected to the network, jointly analysing the behaviour of the system as a whole.

However, this detailed description, while it can be tackled as a last resort, would be excessively verbose and not very practical for managing the collective network.

The problem can be avoided by using an alternative technique describing the hydraulic behaviour of the plot using a curve which synthesises the response of the total flow rate emitted by the set of equipment installed on the plot in relation to the feed pressure of the primary pipe. Given that with different feed pressures a given internal network will emit different flow rates, if there is a relationship Hp = Hp ( Qp ) linking the pressure head downstream from the plot intake, Hp with the total flow rate circulating to the plot equipment when fed by this pressure, Qp

H

, expressed for example by a potential function of the type:

p = Hp ( Qp ) = Ks QpN

this may involve a whole system hanging from a hydrant as an emitter (Appendix III, p.

(AII.1)

465) with equivalent hydraulic behaviour and the same pressure/flow rate response curve (FIGURE AII. 2).

FIGURE AII. 2 Example of potential fit Hp = Ks QpN of the function linking the feed pressure of

the plot installations with the net flow rate served.


462

The coefficients KsFIGURE AII. 2

and N of the above response function (AII.1) can be determined ( ) using potential fit techniques by least squares of a set of pairs of values: feed pressure/total circulating flow rate, found by analysis or experiment.

If using an analytical method, with the help of a suitable hydraulic calculation package, such as GESTAR, the complete distribution network in the plot will be simulated with all its emitters and control devices (FIGURE AII. 3), feeding it in successive simulations with different pressures, Hp, and calculating the corresponding flow rate circulating through the primary pipe to the irrigation system, Qp. This technique lets you predict the pressure/flow rate response curve, Hp = Hp ( Qp

If the internal installations have already been made and are operational, the function H

), whether the system is already installed or at the project stage.

p = Hp ( QpFIGURE AII. 3

) of the entire plot can be found empirically, gradually throttling a valve located after the hydrant ( ) and simultaneously measuring, for each degree of closure of the valve, the pressure in the manometer, Hp, and the

corresponding flow rate circulating through the intake, Qp

FIGURE AII. 3 Field test for measuring the response function of the plot Hp = Hp ( Qp )

.

Either of the two methods is simple enough to be implemented in practice, especially if the network for the plot is designed with the help of GESTAR, requiring in any case minimal time and resources compared to other project or management tasks normally taken on in irrigation engineering.

AII.4 MODELLING HYDRANTS IN GESTAR.

The described behaviour of the hydrants is implemented in a compact form in the NETCAL calculation module. The values of Ks

85 and N of the behaviour curve of the

plot are introduced in GESTAR in the hydrants definition window (see p. )1. At the

NETWORK INSIDE THE PLOT

COLLECTIVE DISTRIBUTION

Hydrant with volumétric meter. Measurement of flow rate Qp

Throttle Valve

Manómet Measurement

of pressure Hp

PLOT OUTLET/INTAKE


463

same time the value is entered of the dimensional coefficient of singular losses in the hydrant, KsH

∆H = K

, when this is completely open, corresponding to the expression:

sH Q 2

which can be made null if these losses are negligible.

(AII.2)

The combined behaviour of the pressure regulator and flow rate of the hydrant, integrated with the plot response, can be modelled compactly combining the pressure/flow rate response curve and the set point value of the flow rate limiter. The description of the implemented strategy is supported by FIGURE AII. 4, where, to simplify the reasoning, we suppose the instantaneous demand established in the hydrant window coincides with the maximum flow authorised. The set point pressure of the pressure reducer is Hc and the demand of the plot when the intake opens is Qdot

The potential approximation of the pressure/flow rate response of the plot must correspond to the curves of type A or B, as type C is not compatible with the set feed conditions. In curve C of

.

FIGURE AII. 4 we see that if the network is fed with pressures higher than the set point, the regulator will reduce the pressure to the set point level, but the network of the plot, fed with this pressure, will evacuate a lower flow rate than the supposed demand, which in this case equals the maximum authorised flow. To avoid this contradictory situation the definition window of hybrid nodes will check the values entered and exclude this possibility.

In FIGURE AII. 4 the pressure/flow rate response curve A indicates that the value of the maximum authorised flow is just enough for the set point pressure. Curve A goes through point (Hc , Qdot), consistent with the data provided, without the intervention of the flow rate limiter. The plot will be optimally designed when it uses all the allotted flow rate, Qdot, when fed with the set point pressure, Hc

If the plot has a type B feed curve, a feed with set point pressure H

.

c involves a supplied flow rate to the plot Qmax of a higher value than the configured allotted maximum before opening the hydrant. Here the flow rate limiter must intervene, producing an additional fall in pressure, Hc - Hlimit , preventing its going over the value of Qdot. The plot, which has a lower net hydraulic resistance than in case A, will be fed with a pressure below the set point, Hlimit, which is just as much as needed for evacuating the value of the limited maximum, Qdot. The value of Hlimit is known depending on the values of Ks

FIGURE AII. 4, N and the maximum allotted flow specified in the

hydrant (see ).

The calculation module in each iteration checks the pressure level which will exist after the hydrant with the regulation Elements completely open, Hcal (calculated network pressure less the losses from the valve(s) corresponding to the completely open hydrant(s)), and modifies the modelling of the hydrant, according to the relative values of Hcal and Hlimit

H

, as follows:

cal > H


limit

cal , is the same as or more than Hlimit (cases A and B), the hydrant is configured as a Known Consumption Node with consumption the same as maximum flow rate. In case B network pressure can even go below the set


464

point value, Hc, without modifying the flow extracted from the hydrant, as long as Hcal remains above Hlimit

H

.

cal > H


limit

cal, is lower than Hlimit, the hydrant will be configured as an emitter with the response curve Hp = Ks Qp

N, with the values Ks

Finally, we must remember that the reasoning above is based on the supposition that the instantaneous demand is equivalent to the maximum flow rate allotted to the plot. However, this may not be the case. In this event, using the procedure described above, the algorithm is implemented in practice using the value of instantaneous demand established in the definition window of the hydrant, and which is the same or less than the maximum allowed flow of the hydrant, instead of using the value of the maximum flow. this means that the set point of the flow rate limiter of the hydrant is

always regulated to the same level established in the instantaneous demand window.

and N specified in the definition window.

FIGURE AII. 4 Modelling hybrid nodes

Q consumo < Q dot

H límite = Ks Qdot N ≤ Hconsigna

Hcal

H consigna (Hc)

Q max= (Hc/Ks)1/N

H = Ks Q N

Operating margen of the

C

B A

Q

Qmax flow rate (Q )


465

APPENDIX III MODELLING EMITTERS

FIGURE AIII. 1 Definition of variables in emitter.

Let P, Z and V be pressure, level and velocity of a point of the pipe, respectively. The hydraulic jump between the ends of an emitter beginning at C (

FIGURE AIII. 1) and discharging to atmosphere at point E through a section SE

( ) 2,22

QPReyKg

VZg

Pg

VZg

PC

EC

′=

++−

++

ρρ

a liquid of density ρ, is

(AIII.1)

where the right side of (AIII.1) is associated with head losses in the emitter itself (dissipation in the emitter of mechanical energy in the unit of time by unit of circulating weight). Coefficient K´ in (AIII.1) depends on the geometry, Reynolds number (and consequently on the flow rate) and also on the feed pressure, Pc, if it has deformable elements (self-compensating emitters).

Intake pointA

Internal emitter devices

Singular

Intake conduit. Diameter: D Length: L Área of the section: S

Section of emitter start C

Emitter section E, Área of the


466

Reordering the expression (AIII.1) and given that the pressure in the discharge section, SE, is the atmospheric, (PE=Patm

222

2 1121 Q

SSgQKZ

gPZ

gPHH

CEECCE

−+′=

+−

+=−

ρρ

), (AIII.1) equivalent to:

(AIII.2)

In (AIII.2) the second term to the right can be interpreted as the loss of all the kinetic energy projecting the fluid in the emission section, where the pressure is atmospheric.

The last term of (AIII.2) corresponds to the kinetic energy of the flow at the entrance to the emitter, usually negligible.

Given that the sections of flow projection are not usually well defined in practice, the three contributions to the right of (AIII.2), all dependent on the flow rate, will accept a joint approximation, at least for a certain range of flow rates, of the potential type:

222

2 1121: Q

SSgQKQK

CE

NS

−+′=

(AIII.3)

Logically, the coefficient Ks and exponent N in (AIII.3) are different from those in (AIII.2) and their values can easily be determined by adjusting a potential function to the experimental data documented by the manufacturers, which reflect the flow rate emitted according to the feed pressure in relation to the atmosphere.

In the emitters for drip irrigation the contribution of kinetic energy in discharge is negligible, but K´ depends on the flow rate, inducing values of N greater than 2. This is not the case for other devices (sprinklers, hoses, leaks, etc.) with high kinetic energy at output, where K´ tends to be a constant value, implying a value of N equal to 2.

The difference in levels between C and E can be systematically regarded as negligible, so that the jump in total head between the ends of the emitter, ∆H=Hc-Hatm

∆H=H

, is systematically identified in practice with the manometric pressure head feeding the emitter:

C-Hatm=( PC- Patm

Consequently, the behaviour of the emitter device is modelled according to:

)/ρ g (AIII.4)

∆H= Ks Q N

As the emitters are connected to the feed points by conduits, which in turn include singular and lineal losses, it is advisable to join the emitter and its associated conduit in a single element using a suitable expression for the jump in total head.

(AIII.5)

Supposing that the emitter is at the end of a stretch of length L, of a pipe of hydraulic diameter D, constant section S and contains singular losses given by


467

dimensionless coefficients k, the difference in total head between the initial end of Element A (

FIGURE AIII. 1) and the start of emitter C will be evaluated as follows:

2

2

21

SQk

DL

gHH CA

+=− ∑λ

(AIII.6)

using the Darcy-Weisbach formulation for calculating lineal losses, where λ is the friction coefficient.

Clearing the value of the total head in C by means of the expression (AIII.2) and introducing it in (AIII.6), we obtain the equation which models the emitter group:

NSEA QK

SQk

DL

gHHH +

+=−=∆ ∑ 2

2

21 λ

(AIII.7)

When emission is through open valves, free discharge, cracks and leaks, the contribution Ks Q N of (AIII.7) must be replaced by its initial expression (AIII.3) as then S, SE

In sprinkler irrigation systems, including total coverage, the computational tools now provided by GESTAR permit the individual consideration of each sprinkler as a specific emitter, although the graphic environment must be strengthened to deal easily with systems of hundreds or thousands of sprinklers.

will be set and K´ will be deduced from the dimensionless coefficient of losses of the singularity through which the flow is evacuated.

However, in local irrigation many consecutive emitters appear, which in the most extreme case, Emitter lines in drip irrigation, can contain hundreds of emission points in each Emitter line. Drip tapes with permeable walls, which provide a continuously distributed flow rate, can be considered a limit case of this group. In these cases the treatment of each point of emission as a specific node of the network is not practical or viable with the individualised approximations described, given the enormous graphic and computational load this would add to the system, and it is useful to introduce new approximations suitable for computational treatment, which exceed the classic simplifying hypotheses which suppose the flow rate to be supplied independently of pressure, but which do not require behaviour equation for each emitter. Preliminary formulations have been made in this area, which are awaiting verification and so have not been included in GESTAR 1.2. Advanced modelling of the functioning of these devices requires the adaptation of recent 5,6 formulations obtaining analytical behaviour equations which are considered and solved together with the rest of the system to determine, as an integral part of the results, the flow rate effectively supplied for each group of emitters.


469

APPENDIX IV. PROBABILITY OF OPEN STATE OF

A HYDRANT

When calculating the probability of a hydrant being open the following parameters must be known:

qfc

S

= Fictitious Continuous Flow rate (l/S.ha)

p

Q

= Watered Area of the plot (ha)

dot = Maximum authorised flow rate for the Plot (m3

r = Operational efficiency

/s)

TTrr /= (AIV.1)

r measures the proportion of the time in which irrigation is effectively applied, Tr, discounting repair or maintenance downtime, days unsuitable for irrigation, start and end hours, etc. in relation to the total time of the campaign, T. This factor must be considered for determining the time of use of each hydrant, as in the calculation of the fictitious continuous flow rate, qfc

The time of use associated with an outlet, t, is equivalent to the time needed to receive the volume of water the plot requires, according to the needs of the crops, given by q

, an uninterrupted supply of water 24 hours a day is supposed.

fc

TSqtQ pfcdot ⋅⋅=⋅⋅310

, i.e.:

(AIV.2)

Clearing t from (AIV.2) we obtain the irrigation time of the plot for the installed hydrant:

TQSq

tdot

pfc ⋅⋅

⋅= 310 . (AIV.3)

The probability of the open state of a hydrant is defined as the quotient between the time the hydrant must be open, t, in relation to the time in fact available for irrigating, Tr

rQSq

Tt

rTtp

dot

pfc

r

110

13 ⋅

⋅

⋅=⋅==

. Taking into account (AIV.1) and (AIV.3) this probability is evaluated:

(AIV.4)


470

The Degree of Freedom, DF, of the hydrant is defined as the inverse of the probability and represents the number of times the time which is really available, Tr

pfc

dotr

SqrQ

tT

pGL

⋅⋅⋅

===3101

, contains the time needed for irrigation, t, and is expressed as:

(AIV.5)

If, given qfc , Sp and r the maximum authorised flow is set, Qdot

If, alternatively, the degree of freedom, DF, or to put it another way, the probability of use of a hydrant is fixed, from (AIV.5) we deduce the maximum flow which has to be assigned to each hydrant:

, using (AIV.4), we determine the probability of the hydrant being open, from which we can also deduce the degree of freedom.

GLr

SqQ pfc

dot ⋅⋅

⋅= 310 (AIV.6)

When the maximum flows assigned to the hydrants are reduced to scaled values, the designer defines the appropriate range of assigned flow according to the size of the plot. In this case the maximum flow will be a datum and the probability of opening will differ from one plot to the next, calculated by (AIV.4).

At present it is also possible to establish arbitrary set points in the flow limiters of hydrants, permitting any value within the range of the respective size, which can be set in the factory and/or modified in the field. In this case it can be useful to specify a homogenous degree of freedom for a set of the plots, or for all of them, so that irrigations are carried out with similar flexibility, calculating the maximum flow according to (AIV.6).

In the definition window of known consumption nodes (see p. 82) and Hybrid nodes (see p. 85) there are options for entering the maximum allotted flow (default option) or the degree of freedom as basic parameters in the definition of the Node. The default option does not require the values of qfc , Sp and r unless you want the probabilities of opening of each hydrant to intervene, while if you choose to specify the degree of freedom you will necessarily have to also supply these values to set the maximum allotted flow.


471

APPENDIX V. LOSSES AT BIFURCATIONS

The calculation package includes an option for automatically calculating singular losses in bifurcations and junctions. Only links of three conduits will be considered. The links will be detected from the network graphi and by default will suppose a 90º junction. According to the direction of flow, the stretches of the junction and the relative magnitude of the bifurcating or joined flow rates, the corresponding coefficients of lossesii

Case 1:

will be established. A default quotient is supposed between the rounding radius, r, and the diameter of the pipe, D, of the value r/D=0,1. The Elements are ordered from larger to smaller diameter following an ascending index extending the formulations in reference to the case in which the areas or velocities are not equal. As the Node at the intersection of the T is not included in the reference formulation, as only two energy equations appear in it, the transformation must be done which permits reassigning the losses of the T to the three energy equations the programme works with. The next procedure is to assign the loss associated in the reference with the velocity of the main branch to the other branch which appears in the energy equation. The term of velocity of the first will also be assigned to the second. The different cases will be as follows:

1 2

3

4 Q2Q1

Q3

−

⋅⋅

⋅−⋅⋅

⋅+⋅⋅

⋅⋅⋅

=

⋅=∆

41

2

232

223

232

223

42

21

22

21

2112

1723.09.0045.12

16

1

DDQDQ

DQDQ

DQQ

gK

QKH

S

ST

π

(AV.1)

where ∆HT12

refers only to the singular losses between 1 and 2 due to the T and does not include the other losses occurring in pipes 14 and 42.

ii Blevins, R. D. (1984). Applied Fluid Dynamics Handbook, pp 91. Van Nostrand Reinhold Company Inc.


472

−

⋅⋅

⋅−⋅⋅

⋅−⋅⋅

⋅⋅⋅

=

⋅=∆

43

2

212

221

212

221

42

23

22

23

2332

1939.0746.0837.12

16

3

DDQDQ

DQDQ

DQQ

gK

QKH

S

ST

π

(AV.2)

Case 2:

1 2

3

4 Q2Q1

Q3

≤<

+

−

−

⋅⋅

⋅⋅⋅

⋅⋅⋅

≤≤

+

−

⋅⋅

−⋅⋅⋅

⋅⋅⋅

=

⋅=∆

122.0;103.122.065.02

16

22.00;103.122.055.12

16

1

342

2

231

213

41

22

21

2

1

342

2

231

213

41

22

21

2

2

2212 2

VV

DDQDQ

DQQ

g

VV

DDQDQ

DQQ

gK

QKH

S

ST

π

π

(AV.3)

where the V terms denote velocities.

+

⋅⋅

⋅+⋅⋅

⋅−−⋅⋅

⋅⋅⋅

=

⋅=∆

43

2

231

213

231

213

41

23

21

23

2313

1894.0942.0083.02

16

3

DDQDQ

DQDQ

DQQ

gK

QKH

S

ST

π

(AV.4)

Case 3:

1 2

3

4 Q2Q1

Q3


473

+

⋅⋅

⋅−⋅⋅

⋅+−⋅⋅

⋅⋅⋅

=

⋅=∆

41

2

213

231

213

231

43

21

23

21

2131

1467.0714.041.02

16

1

DDQDQ

DQDQ

DQQ

gK

QKH

S

ST

π(AV.5)

The calculation of ∆HT32

Case 4:

is carried out in a similar way, replacing sub indices 1 with sub indices 2.

1 2

3

4 Q2Q1

Q3

−

⋅⋅

⋅+⋅⋅

⋅−⋅⋅

⋅⋅⋅

=

⋅=∆

41

2

223

232

223

232

43

21

23

21

2113

1171.1557.1869.12

16

1

DDQDQ

DQDQ

DQQ

gK

QKH

S

ST

π (AV.6)

The calculation of ∆HT23 is carried out in a similar way, replacing sub indices 1 with sub indices 2.


475

APPENDIX VI. PARAMETERS WINDOW

The Parameters option in the Calculation menu permits the modification of a series of parameters controlling the system start, convergence, relaxation and the conditioned factor of the low resistance elements. The dialogue which appears when this option is selected, as commented regarding the Calculations menu in section 5.6 (p. 155), is the one in FIGURE AVI 1.

FIGURE AVI 1 Parameters Window

This block of parameters is configured by default. To change it, if necessary, it is advisable to have a certain degree of experience in the use of the programme, and in calculating networks, in order to modify it safely and make efficient use of it. Possibly, after the definitive optimization of the relevant values of the marked parameters, this section will not appear in future versions. The required parameters are:

♦ Maximum number of iterations.

♦ Type of dynamic error.

♦ Dynamic error.

♦ Dimensionless residue tolerance.


476

♦ Type of start.

♦ Value of start.

♦ Relaxation coefficient.

♦ Conditioned coefficient.

♦ Possibility of creating file of iterations

AVI.1 MAXIMUM NUMBER OF ITERATIONS.

This parameter indicates the maximum number of iterations which the programme permits in order to reach convergence.

This should not be high, to avoid long calculation times without finally reaching convergence. Neither should it be too low, which might not let the solution be found in networks with slow convergence. Normally convergence is reached with a number of iterations lower than 10. Even in very large networks with pathological elements, convergence can be reached below 20 iterations. If this margin is not reached, it is very probable that the process would still not converge with a higher number of iterations, and if it did, it would raise suspicions of the existence of an error in the definition of the network.

AVI.2 TYPE OF CONTROL OF CONVERGENCE

The convergence of calculations towards the solution is controlled by two metrics of error: when the calculated errors are less than those provided by the user, the programme considers convergence to have been reached. These two errors are:

♦ A. Static error: Defined as the quotient between the average residue of the equations forming the nodal system of calculation and the average flow rate in the elements.

♦ B. Dynamic error. b1) of head in nodes or b2) of relative flow rate in elements: It is established according to the maximum difference between the value of the head in the Nodes, or the relative flow rate in Elements, between two consecutive iterations. It is sized in metres in case b1 and is dimensionless in b2.

A faulty selection of the accepted thresholds of error for convergence can lead to false conclusions, either ending the process before reaching enough precision, when the margin is very wide, or inducing a false lack of convergence due to having established excessively restrictive values.

Tracking the errors shown by the programme in each iteration, such as the activation of the options showing partial results in Elements, can help to judge if the criteria for error have been set correctly


477

There are two options for the type of control of convergence, and the errors which will control convergence according to the selection are:

AVI.3 TYPE OF START

This parameter refers to the form of starting the system of equations. There are three types of start to select from the list Type of start:

1. Reynolds number: All the Elements will start which have the Reynolds number required by the starting value (only recommendable if there are no pumps in the network).

2. Velocity (except pumps): All the elements will initialise with a requested estimated velocity of circulation, except the pumps, which will initialise in their average operating point (recommended option).

3. Reynolds number (except pumps): All the elements will initialise with a requested Reynolds number, except the pumps, which will initialise in their average operating point.

AVI.4 START VALUE

Represents the value which the Elements will start with. Depending on the type of start selected, this will be the Reynolds number or the velocity (in m/s).

RECOMMENDED VALUES:

Reynolds = 1000.

Velocity = 1.0 m/s

In most cases the type of start does not influence the final convergence of the process, but does influence the number of iterations needed to finalise calculations, with option 2 usually presenting better behaviour in this regard.

AVI.5 RELAXATION COEFFICIENT

This coefficient is used to relax the oscillations in the Newton-Raphson method used in the resolution of the non-linear system. Its theoretical value can be between 0 and 1, although we recommend not using values below 0.5. To prevent instability associated with a start which is very distant from the final state, during the first three iterations, GESTAR relaxes unconditionally with a factor 0.5. In a first pass we recommend not relaxing. If the system solution does not converge it is advisable to


478

relax the method for the next passes. When the programme detects a good convergence rate, it deletes the defined relaxation factors.

AVI.6 CONDITIONED PARAMETER

This parameter establishes the threshold of the conductivity coefficient

KC=1/ (Ks Q)

of the network conduits above which the Elements must be taken as low resistance, separating them from the nodal equations, as other wise the conductivity coefficient, of a different order of magnitude from the rest, will wrongly condition the matrices used in the calculation process, compromising or preventing network convergence.

When an Element has low resistance or carries a low flow rate, so that KC is above the established threshold, the behaviour equation of the Element in question is separated from the system of nodal equations and its equation is added to the overall system.

As this parameter is reduced, the number of Elements considered as low condition increases, and consequently, so does the calculation time of each iteration, as it resolves a larger system of equations. To begin with a value of the order of 1 to 0.1 m2 s-1 is recommended. If a null value is established for the conditioned parameter, all the Elements in the network rill appear separated.


479

APPENDIX VII. THE STRUCTURE OF GESTAR

NETWORK DATABASES

AVII.1. INTRODUCTION

GESTAR offers the possibility of storing networks in ACCESS database format. In section 7.4 p.185 information is given on the creation and possibilities for use of networks saved in this format. This appendix describes the structure of the databases generated by GESTAR and gives a brief description of the tables and fields where information on the networks is stored.

To store a network in database format, use the command File/ Export/ Access Database, in the GESTAR main menu. The creation of this file. with the extension “mdb”, lets you use all the power of ACCESS for manipulating, managing and analysing the data and results of a network.

Networks in database format can be opened by the GESTAR application using the command File/ Import/ ACCESS Database.

AVII.2. DESCRIPTION OF TABLES IN NETWORK DATABASES.

Each database of networks created in GESTAR contains a total of 16 tables, containing all the information of the network and the results of hydraulic simulations, if any. The tables are:

♦ Accessories. Information on the accessories associated with Pipe elements or the stretches associated with Emitters.

♦ Reservoirs. Information on Reservoir Nodes referring to location and head (x, and level), levels (Max. Level, Min. Level, Initial Level, Present Level) and if modelling assimilates the reservoir to a truncated conical tank, Section and Slope.

♦ Reservoir Splines Information on Reservoir Nodes referring to the H/V table defining the Volume curve.

♦ Pumps. General information on Pump Elements, and if a single parabolic fit is chosen for the whole range of flow rates, on the parameters referring to this formulation.


480

♦ Pump Splines. Information on Pump Elements referring to the definition table for fitting using Splines.

♦ Pipes. Information on Pipe Elements. This table is usually the largest, as Pipes are the basic element of any irrigation network. As GESTAR can take Pipes data from a complete database, the list of Pipes in the network is very large and useful.

♦ Known Consumption. Information on Known Demand nodes.

♦ Polytube Detail. Information on the intermediate vertices of the Pipes.

♦ Double condition. Information on Double Condition Nodes.

♦ Elesk. Information on Free Elements.

♦ Dams. Information on Dam Nodes.

♦ Emitters. Information on Emitter Nodes.

♦ Hydrants. Information on Hybrid Nodes.

♦ Junction nodes. Information on Junction nodes.

♦ Losses. List of all the singular losses existing in the network.

♦ Regulated Pressure. Information on Known Pressure nodes.

♦ No condition. Information on Free Nodes.

♦ Valves. Information on Valve Elements.

♦ Vis (Display). Information on the display/visualisation parameters of the network: map size and visible part of map.

AVII.3 DESCRIPTION OF FIELDS IN NETWORK DATABASES.

A brief description of each field in the 19 tables of GESTAR networks in database format.

AVII.3.1. ACCESORIOS (ACCESSORIES) TABLE.

♦ Tipo (Type). Type of accessory ("Angular elbow", "Large radius elbow", "Medium radius elbow", "Small radius elbow", "Rapid entry", "Straight entry", "Reductions", "One-way Valve")

♦ Parámetro (Parameter). Parameter characteristic of the type of existing accessory.


481

♦ Valor (Value). Value of the parameter in the field Parameter.

♦ Num. Number of existing accessories.

♦ Ks. Parameter k of the expression of losses H=k·(v2

♦ Elemento (Element). Identifier of the Element the accessory is associated with.

/2·g) of the accessory.

AVII.3.2. BALSAS (RESERVOIRS) TABLE.

♦ Id. Alphanumerical identifier (maximum 6 characters).

♦ X. Coordinate X in relation to origin (metres).

♦ Y. Coordinate Y in relation to origin (metres).

♦ Cota (Level or elevation). Level in relation to a common reference of height (metres).

♦ Sección (Section). Free laminar area of the reservoir at its maximum level (m2

♦ Pendiente (Slope). Angle formed by the walls of the reservoir with the horizontal (degrees; greater than 0º and less than 90º)

).

♦ NivMax (Max. level). Maximum acceptable level of fluid in the reservoir (m).

♦ NivMin (Min level). Minimum acceptable level of fluid in the reservoir (m).

♦ NivInicial (Initial level). Initial level of fluid in the reservoir at the start of a long period simulation (m).

♦ NivActual (Current level). Current level of fluid in the reservoir at the present instant of a long period simulation (m).

♦ Comentario (Comment). Alphanumerical string for additional information (maximum 20 characters).

♦ ConsumCalc. Value of consumption of the hydraulic simulation of the network (m3

AVII.3.3. BALSASPLINES (RESERVOIR SPLINES) TABLE.

/s).

This table gathers information referring to the H/V definition table of the volume curve of the reservoirs.

♦ IBa. Reservoir identifier: Correlative number assigned to each reservoir according to its order, as shown in the above table (Reservoirs table).


482

♦ H. Height (m). Height of full reservoir.

♦ V. Volume (m3

AVII.3.4. BOMBAS (PUMPS) TABLE.

). Storage capacity of the reservoir for the full height defined in the same row in the relevant column.


♦ Nodo inicial (Start Node) Identifier of the start node.

♦ Nodo final (End Node) Identifier of the end node.

♦ Diámetro (Diameter). Diameter of the intake flange (m).

♦ A. Constant A of the behaviour equation of the pump H(Q)=A·Q2+B·Q+C (A must be less than zero; Q in m3

♦ B. Constant B of the behaviour equation of the pump H(Q)=A·Q

/s; H in m).

2+B·Q+C (B must be less than or equal to zero; Q in m3

♦ C. Constant B of the behaviour equation of the pump H(Q)=A·Q

/s; H in m).

2+B·Q+C (C must be greater than zero; Q in m3


/s; H in m).

♦ Caudal (Flow rate). Value of flow rate of the hydraulic simulation of the network (m3

♦ Velocidad (Velocity). Value of velocity of the hydraulic simulation of the network (m/s).

/s).

♦ PérdidaCarga (HeadLoss). Value of head loss of the hydraulic simulation (m).

♦ Coefnpsh1. Independent coefficient of the parabolic curve modelling the NSPH.

♦ Coefnpsh2. Linear coefficient of the parabolic curve modelling the NSPH.

♦ Coefnpsh3. Quadratic coefficient of the parabolic curve modelling the NSPH.

♦ Coefrend1. Independent coefficient of the parabolic curve modelling Efficiency.

♦ Coefrend2. Linear coefficient of the parabolic curve modelling Efficiency.

♦ Coefrend3. Quadratic coefficient of the parabolic curve modelling Efficiency.

♦ Coefpot1. Independent coefficient of the parabolic curve modelling Power.


483

♦ Coefpot2. Linear coefficient of the parabolic curve modelling Power.

♦ Coefpot3. Quadratic coefficient of the parabolic curve modelling Power.

♦ Rpm1. Angular velocity of the pump.

♦ Maxgraf. Positive root of the parabolic equation fitting the pumped head from the pump in relation to the flow rate.

AVII.3.5. BOMBASPLINES (PUMP SPLINES) TABLE.

The table gathers definition data for the performance curves of the pumps.

♦ IB. Pump identifier: Correlative number assigned to each pump according to its order, as shown in the above table (Pump table).

♦ Q. Flow rate. (m3

♦ H. Height. (m).

/s).

♦ P. Power. (kW).

♦ R. Efficiency. (%).

♦ NPSH. NPSH required (m).

AVII.3.6. TUBERÍAS (PIPES) TABLE.


♦ Nodo inicial (Start Node). Identifier of the start node.

♦ Nodo final (End Node). Identifier of the end node.

♦ Longitud (Length): Length of the Pipe (m).

♦ Diámetro interior (Internal diameter). Internal diameter (m).

♦ Diámetro nominal (Nominal diameter). Nominal diameter (m; -1 if not available)

♦ Fabricante (Manufacturer). Name of Manufacturer of the Pipe (“<None>” if not available).

♦ Material. Material of the Pipe (“<None>” if not available).

♦ Timbraje (Pressure rating). Pressure rating of the Pipe (“<None>” if not available).


484

♦ Rugosidad (Roughness). Internal roughness of the Pipe (units depend on the formulation of losses).

♦ Cerrado (Closed). Value indicating if the Pipe is closed (1) or open (0).

♦ ValvAntirretorno (One way Valve). Value indicating the existence of a one-way valve (1: exists; 0: does not exist).

♦ TipoVálvula (Valve Type). Type of valve present in the Pipe (options: "<None>", "Seat", "Ball", "Gate" and "Butterfly").

♦ PorcentajeCierre (Percentage Closed). Percentage of closure of the valve specified in the field ValveType (must be less than 100).

♦ KsVálvula (KsValve). Coefficient Ks associated with the valve specified in the field ValveType with the percentage of closure specified in the field PercentageClosed. Corresponds to the coefficient of the expression of losses H(Q)=Ks·Q2

♦ NumAccesorios (Num Accessories). Total number of accessories associated with the Pipe. The type and characteristics of the accessories are specified in the table Accessories.

.

♦ NumPérdidas (Num Losses). Total number of losses associated with the Pipe. The type and characteristics of the losses are specified in the table Losses.

♦ GrupoDiseñoInverso (Inverse Design Group). Value indicating the Pipe belongs to Free Pipe Sets (0: does not belong; n: belongs to the group n of unknown diameter; -n: belongs to the group n of unknown Roughness).


♦ CaudalCalc (Flowrate Calc). Value of flow rate of the hydraulic simulation of the network (m3


/s).

♦ PérdidaCarga (Head Loss). Value of head loss of the hydraulic simulation (m).

♦ NumeroPuntos (Number of Points). Number of intermediate vertices in the Pipe.

♦ CaudalDiseño (Design Flow rate). Design flow rate assigned to the Element (m3

♦ Celeridad (Celerity). Celerity of the Pipe (m/s) (“0” if not available).

/s).


485

AVII.3.7. CONSUMO CONOCIDO (KNOWN CONSUMPTION) TABLE.





♦ Dotación (Maximum flow rate). Value of the maximum allotted flow rate (m3

♦ Demanda (Demand). Value of the real flow rate demand (m

/s).

3

♦ DemandaAnterior (Previous Demand). Value of flow rate demand when a closed consumption node is opened (m

/s; must be less than or equal to the value of the Maximum flow rate field). When demand is null, the Node is closed.

3

♦ SuperfRegada (Irrigated area). Surface area of the plot supplied by the hydrant (ha).

/s).

♦ CaudalFicticio (Fictitious Flow rate). Continuous fictitious flow rate supposing an uninterrupted supply of flow to the plot all day long (litres/(s·ha)).

♦ Rendimiento (Efficiency). Operational efficiency. Quotient between the real and theoretical durations of the irrigation campaign (between 0 and 1; dimensionless).

♦ GradosLibertad (Degrees of Freedom). Inverse of the probability that the outlet is open.

♦ TipoSorteo (Type assignment). Value indicating the type of information caracterising the hydrant (0: maximum flow; 1: degrees of freedom).

♦ TipoProb (Type probability). Value indicating the state of the hydrant (1: unconditionally open; -1 unconditionally closed; 0: subject to random scenario generation).

♦ Probabilidad (Probability). Probability of the hydrant being open.

♦ Regulación (Regulation). Value indicating the existence of a pressure regulator in the hydrant (0: does not exist; 1: exists).

♦ PresionConsigna (Set point pressure). Set point pressure of the pressure regulator (m).



486

♦ AltPiezCalc (Total head height). Value of total head from the hydraulic simulation (m).

♦ Diámetro (Diameter). Diameter of the hydrant in inches ("empty" if not available).

♦ Turno (Turn). Number of irrigation turn assigned to the hydrant (“0” if not available).

AVII.3.8. DETALLEPOLITUBOS (DETAIL OF POLYTUBES) TABLE.

♦ IdTramo (Stetch id). Number identifying the intermediate vertex.

♦ IdTubo (Pipe Id). Alphanumerical identifier of the Pipe the vertex belongs to.

♦ X. Coordinate X of the vertex.

♦ Y. Y coordinate of the vertex.

♦ Z. Coordinate Z of the vertex.

AVII.3.9. DOBLE CONDICIÓN (DOUBLE CONDITION) TABLE.







/s).

3

♦ Altura de Presión (Pressure head). Value of the pressure in the Node (m).

/s; must be less than or equal to the value of the Maximum flow rate field).


AVII.3.10. ELESK TABLE.



487



♦ Tipo (Type). Type of Element without Passive Characteristic (1: Ks

♦ Diámetro (Diameter). Internal diameter (m).

unknown; 2: diameter unknown; 3: length unknown; 4: roughness unknown).

♦ Longitud (Length): Length of Element without Passive Characteristic (m).

♦ Rugosidad (Roughness). Internal roughness of Element without Passive Characteristic (units depend on the formulation of losses).




/s).


♦ Estado (State). Value from the hydraulic simulation indicating if the Element without Passive Characteristic acts like an active (1) or passive Element (0).

AVII.3.11. EMBALSES (RESERVOIRS) TABLE.




♦ Lámina (Free surface). Level of the free surface of the water in relation to a common height reference (metres).


♦ ConsumCalc. Value of consumption of the hydraulic simulation of the network (m3/s).


488

AVII.3.12. EMISORES (EMITTERS) TABLE.





♦ Fab Emisor (Emitter maker). Name of Manufacturer of the emitter (leave blank if not available).

♦ Tipo Emisor (Emitter type). Model of the emitter (leave blank if not available).

♦ Ks Emisor (Ks Emitter). Coefficient Ks of the expression of losses of the emitter H(Q)=Ks·QN

♦ N Emisor (N Emitter). Coefficient N of the expression of losses of the emitter H(Q)=K

.

s·QN

♦ Nodo Origen (Nodo Origen). Identifier of the Node the emitter starts from.

.

♦ Longitud (Length): Length of the Pipe associated with the emitter (m).

♦ Diámetro Nominal (Nominal diameter). Nominal diameter of the Pipe associated with the emitter (m; -1 if not available).

♦ Diámetro Interior (Internal diameter). Internal diameter of the Pipe associated with the emitter (m).

♦ Fab Tubo (Pipe maker). Name of Manufacturer of the Pipe associated with the emitter (“<None>” if not available).

♦ Material Tubo (Pipe material). Material of the Pipe associated with the emitter (“<None>” if not available).

♦ Timbraje Tubo (Pipe pressure rating). Pressure rating of the Pipe associated with the emitter (“<None>” if not available).

♦ Rugosidad Tubo (Pipe roughness). Internal roughness of the Pipe associated with the emitter (units depend on the formulation of losses).

♦ Cerrado (Closed). Value indicating if the Pipe associated with the emitter is closed (1) or open (0).

♦ Valv Antirretorno (One-way valve). Value indicatig the existence of a one-way valve (1: exists; 0: does not exist).


489

♦ Tipo Válvula (Valve Type). Type of valve present in the Pipe associated with the emitter (options: "<None>", "Seat", "Ball", "Gate" and "Butterfly").

♦ Porcentaje Cierre (Percentage Closed). Percentage of closure of the valve specified in the field Valve Type (must be less than 100).

♦ Ks Válvula (Ks Valve). Coefficient Ks associated with the valve specified in the field ValveType with the percentage of closure specified in the field PercentageClosed. Corresponds to the coefficient of the expression of losses H(Q)=Ks·Q2

♦ Num Accesorios (Number Accessories). Total number of accessories in the Pipe associated with the emitter. The type and characteristics of the accessories are specified in the table Accessories.

.

♦ Num Pérdidas (Num Losses). Total number of losses in the Pipe associated with the emitter. The type and characteristics of the losses are specified in the table Losses.



/s).

♦ Pérdida Carga (Head Loss). Value of head loss of the hydraulic simulation (m).

♦ Consumo Calc (Calculated consumption). Value of consumption of the hydraulic simulation of the network (m3


/s).

♦ Turno (Turn). Number of irrigation turn assigned to the hydrant (“0” if not available).

♦ QNominal. Nominal flow rate in l/s (“0” if not available).

♦ Aspersor (Sprinkler).

AVII.3.13. HIDRANTES (HYDRANTS) TABLE.




♦ Cota (Level). Level in relation to a common reference of height (metres).


490



/s).

3

♦ DemandaAnterior (Previous Demand). Value of flow rate demand when a closed consumption node is opened (m

/s; must be less than or equal to the value of the Maximum flow rate field). When demand is null, the Node is closed.

3

♦ ÁreaRegada (Irrigated area). Surface area of the plot supplied by the hydrant (ha).

/s).

♦ CaudalFicticio (Fictitious Flowrate). Continuous fictitious flow rate supposing an uninterrupted supply of flow to the plot all day long (litres/(s·ha)).

♦ Rendimiento (Efficiency). Operational efficiency. Quotient between the real and theoretical durations of the irrigation campaign (between 0 and 1; dimensionless).

♦ GradosLibertad (Degrees of Freedom). Inverse of the probability that the outlet is open.

♦ TipoSorteo (Type sorting). Value indicating the type of information caracterising the hydrant (0: maximum flow; 1: degrees of freedom).

♦ TipoProb (Type of probability). Value indicating the state of the hydrant (1: unconditionally open; -1 unconditionally closed; 0: subject to random scenario generation).

♦ Probabilidad (Probability). Probability of the hydrant being open.

♦ Regulación (Regulation). Value indicating the existence of a pressure regulator in the hydrant (0: does not exist; 1: exists).

♦ PresionConsigna (Set point pressure). Set point pressure of the pressure regulator (m).

♦ Ks. Coefficient Ks of the equation of losses H(Q)=Ks·Q2 corresponding to the hydrant when completely open (s2/m5

♦ N. Parameter N of the equation of losses H(Q)=K

).

s·QN

♦ KsParc. Parameter K

of the plot network (dimensionless).

s of the equation of losses H(Q)=Ks·QN of the plot network (s2/m5


).

♦ ConsumCalc (Calculated consumption). Value of consumption of the hydraulic simulation of the network (m3/s).


491

♦ AltPiezCalc (Calculated total head). Value of total head from the hydraulic simulation (m).

♦ Diámetro (Diameter). Diameter of the hydrant in inches ("empty" if not available).

♦ Turno (Turn). Number of irrigation turn assigned to the hydrant (“0” if not available)

AVII.3.14. NODOS DE UNIÓN (JUNCTION NODES) TABLE.






♦ AlturaPiezomCalc (Calculated total head). Value of total head from the hydraulic simulation (m).

AVII.3.15. PÉRDIDAS (LOSSES) TABLE.

♦ Num. Number of existing losses.

♦ Ks. Parameter Ks of the equation of losses H(Q)=Ks·QN

♦ Nexp. Parameter N of the equation of losses H(Q)=K

.

s·QN

♦ Elemento (Element). Identifier of the Pipe associated with the loss.

.

AVII.3.16. PRESIÓN CONOCIDA (KNOWN PRESSURE) TABLE.






492

♦ AlturaPresion (Pressure head). Value of the pressure in the Node (m).


♦ ConsumCalc (Calculated consumption). Value of consumption of the hydraulic simulation of the network (m3

AVII.3.17. SIN CONDICIÓN (NO CONDITION) TABLE.

/s).






♦ ConsumCalc (Calculated consumption). Value of consumption of the hydraulic simulation of the network (m3

♦ AltPiezCalc (Calculated total head). Value of total head from the hydraulic simulation (m).

/s).

AVII.3.18. VÁLVULAS (VALVES) TABLE.




♦ Tipo (Type). Value indicating the type of valve (0: pressure reducing; 1: pressure sustaining; 2: flow limiter)

♦ Diámetro (Diameter). Diameter of the valve (m).

♦ Presión consigna (Set point pressure). Set point pressure of reducing and sustaining valves (m).

♦ Caudal límite (Limit Flow rate). Set point flow rate of the flow limiter valve (m3

♦ Ks. Value of the coefficient Ks of the equation of losses H(Q)=K

/s)

s·Q2 of the valve when completely open (s2/m).


493




/s).


♦ Estado (State). State of the valve (1: regulating; 2: passive; 3: closed).

AVII.3.19. VIS (DISPLAY) TABLE.

♦ MapXMax. Maximum value of the X coordinate on the map of the network (m).

♦ MapYMax. Maximum value of the Y coordinate on the map of the network (m).

♦ Xvis. Value of the X coordinate of the portion of the network map displayed (m).

♦ Yvis. Value of the Y coordinate of the portion of the network map displayed (m).

♦ Scr. Percentage displayed of the map in relation to the maximum size of the map (between 1% and 100%)

♦ A. Y coordinate of the map in relation to the main form (m).

♦ B. Length of the X coordinate of the map (m).

♦ C. X coordinate of the map in relation to the main form (m).

♦ D. Length of the X coordinate of the map (m).

♦ E. Value of the vertical scroll of the map.

♦ G. Value of the horizontal scroll of the map.

♦ TUBOS. Name of the Database of pipes associated with the network.

♦ XOrigen. Value of X at the origin of coordinates.

♦ YOrigen. Value of Y at the origin of coordinates.


494

APPENDIX VIII. OBSOLETE COMPONENTS

GESTAR is constantly being updated and improved, so some modellings have been changed, making earlier versions obsolete. To make it possible to calculate networks generated in earlier versions and let the user select the type of model used in the simulation, both calculation options are available. Via the menu Options/ Preferences (see p. 136 ) the default selection of the corrected models can be changed.

We again underline that two types of formulation for the same component cannot exist on the same network at the same time.. GESTAR 2008 automatically detects the type of definition in the *.red file and the application opens with the appropriate option. If you want to modify the type of modelling, you must first delete the components defined with another formulation.

AVIII.1. LEGACY MODELLING RESERVOIR NODE

The Reservoir node (see p. 79) is a feed node used for a simulation of network behaviour over time (see Temporal Evolution, p. 64).

If, via the menu Options/ Default values/ Nodes the option Splines is disabled in the quadrant Reservoirs (see FIGURE 6.12, p. 137), the Reservoir node will be treated as a truncated conical tank. To run the simulation in this case, the following data are needed (FIGURE AVIII. 1).

FIGURE AVIII. 1 Reservoir node treated as truncated conical tank.

♦ Initial Level: Value of the initial level of the reservoir. To dissipate the influence of this value on network behaviour, a long simulation time must be used.


495

♦ Max Level, Min. Level and Initial Level: Acceptable maximum and minimum levels of fluid in the reservoir, and the initial level.

♦ Section: Section of the reservoir (m2

♦ Slope: Angle formed by its walls in relation to the vertical (in degrees); this angle must be greater than or equal to 0º and less than 90º.

) at its maximum level.

During the option of Temporal Evolution (p. 64) the data supplied will be taken into account; all other instant calculation options take the initial level as their value

AVIII.2. LEGACY MODELLING PUMP ELEMENT

The earlier formulation of the Pump Element enables a single parabolic fit for the whole range of flow rates. To access this type of model, go to the menu Options/Preferences/Elements and disable the option Splines in the quadrant Pumps (see FIGURE 6.13, p. 142). The Pump Element will then be declared via the polynomic equation which reproduces its performance curve H QB ( ) (always expressed in International System units).

The procedure for creating a Pump Element (see p. 110) coincides with the other formulation (you will need to click on the start node and the end node). The window which opens automatically will look like the one shown in FIGURE AVIII. 2. The form consists of four pages, accessed by clicking on the relevant tab.


496

FIGURE AVIII. 2 Pump Element definition window.

The top of the window shows which is the start node (intake) and end node (discharge) of the pump, which can be swapped with the button next to them, and the fields for entering or modifying the following data:

♦ Intake Diameter: the diameter of the intake flange, which may be the same as the free element before it. Used for computing the velocity of the intake flange, needed in order to determine the NPSHA.

♦ Identifier and Comment.

Under the tab Q-H the following data are entered:

♦ A, B and C: the coefficients of the second degree polynomial fitted to the performance curve of the pump supplied by the manufacturer, representing the behaviour of the Element H QB ( ) thus:

− = = + +∆H H Q AQ BQ CB ( ) 2

The coefficients are obtained by an interpolation by least squares to a minimum of three points (or two if B = 0 ).


497

Help is available in GESTAR to carry out the polynomial fit entering a set of pairs of points of the performance curve clicking the Fit button. The function of the fitting utility is described on p. 105.

So that the operation of the pump does not cause instability in the network, A must be negative and it is much preferable for B to also be negative. If A > 0 the entered pump element will not be accepted and calculation will not continue. If B > 0 the programme will warn that the calculations might not converge, but it will accept the data.

As you can see there are also tabs for NPSHR, Efficiency and Power. It is not obligatory to fill in these pages for the construction and simulation of the pump, but providing this data can give us valuable information when designing the installation or gathering the results of a calculation.

All the tabs are configured similarly to tab Q-H (FIGURE AVIII. 2). They comprise:

♦ two text boxes for giving pairs of points (at least three) which will be used to plot a parabola fitted by the least squares method for constructing the different performance curves of efficiency, power or NPSHR.

♦ a set of buttons for accepting, deleting or adjusting these pairs of points.

♦ a space reserved for the presentation of the graph when the relevant calculations have concluded.

The NPSHR page asks for the points for constructing the curve. This curve is normally supplied by the manufacturer. This curve will be taken into account when testing to see if the pump cavitates. The cavitation check will be carried out during computation. Check the Cavitation option on the Alarms screen beforehand if you want to be notified. When the programme finds a pump during calculation, it will check to see if the cavitation alarm button was enabled, and if so will calculate the available NPSH now and for the calculated flow rate, and will take the value of NPSHR of the curve entered by the user. If it finds that the value of available NPSH is lower than required, it will show a warning about the situation. This warning will vary according to the type of calculation carried out.

The other two pages, on efficiency and power, are closely interrelated. Based on one of these curves (power/ efficiency) and the curve H-Q of the pump, the other (efficiency/ power) will be totally defined. Thus, once the power curve is drawn, the efficiency curve will automatically be drawn. Once this is done, if for any reason a new performance curve is drawn, the power curve will be redrawn according to the new data.

If we fill in these two pages, GESTAR will take these data into account when showing results, and will take the data needed to reflect the power and energy consumed by the pump.

The Pump Element by default has a one-way valve which stops the flow circulating against the direction of discharge. Similarly, if the circulating flow rate is higher than the maximum value allowed for the pump, i.e., if the total head at discharge


498

is less at the output than the intake of the pump, and the pump behaves like a power sink, a Pump Overflow warning will appear. For computing the operating point of the pump in this circumstance, the same polynomic fit of the pump performance curve is extrapolated for the region of peak negative impulsion (loss of positive head).

In the case of calculations with Temporal Evolution, if a pump overflows in a given instant, the warning appears at that instant. If the warning is ignored, the programme continues the calculation routine, and so for later instants, if the network is reconfigured according to the specified scenarios, the same pump may return to normal working or may overflow again. It should be clear that this warning simply notifies the user that the network situation may be different than expected, as GESTAR understands that this state, where there is a higher head at intake than discharge, is not normal.


499

APPENDIX IX. REGULATING PUMPING

AIX.1. INTRODUCTION

In distribution networks where use of a pumping station is unavoidable for supplying the required pressure, it is very important to adapt the pressure pumped out by the station to the pressure needed and demanded throughout the supply, which is normally variable over time, depending on the flow rate required at intake. This can be done by using regulation incorporating frequency variators which adapt the angular velocity of the pumps at all times and so reduce the pumped head to what is strictly required. This minimises energy losses, which is increasingly important as fuel costs rise and the energy market is liberalised.

For a given pressurised distribution network, a plethora of dispositions can be found for the pumping station, depending on the model and number of pumps chosen, and the included regulation. As described in chapter 5, Gestar offers a tool which analyses, in a generally applicable way, different compositions of pumping stations with different types of regulation. Various pumping regulation alternatives can be compared and studied for network design or for possible improvements in operating stations which increase energy efficiency. Thus, for various types of regulation, the operational parameters of the installation are studied depending on the circulating flow rate, such as power consumption, overall efficiency, and energy losses, making it possible to calculate costs of yearly power consumption for each variant in regulation, and the total costs of the system itself.

This appendix will give an extensive description of the concept of regulation of pumping stations in general; and its application and operation in Gestar, in particular.

AIX.2. TYPES OF REGULATION

There are various types of regulation, which are chosen depending on the characteristics of the network and the environment. To choose the one which best fits the particular needs of the network in question, different pump installations can be simulated, each incorporating variants of regulation with the same or different numbers and sizes of pumps, and the energy use results studied to choose the best alternative.

Two types of pumping can be installed. Direct pumping injects water from the pumping station directly into the distribution network, without any reservoir or regulation in either. Indirect pumping pumps the water constantly, first to the regulation tank or reservoir at a high level, and only then will the water reach the distribution network by natural pressure or small pumps downstream from these regulating devices.


500

This is the most frequent type, both in pressurised irrigation systems and in urban supply networks.

Depending on the characteristics of the terrain it will be possible to use one type of pump or another; for example, flat areas limit the possibility of incorporating regulation elements where the terrain cannot be raised high enough for a tank to give the pressure needed. In these cases direct pumping must be used, as indirect is not viable. In other cases, and with the newly existing problem of new price bands and rising prices of energy, the indirect pumping option can be considered, as it permits pumping water in less expensive time bands, and not as required by demand, as with direct pumping.

Also, each type of pumping includes different variants in regulation; each one is defined depending on the pumps used, the number of units installed and active in each percentage of demand of the system, its operations or set points at start and finish according to the evolution of demand, but especially on whether the pumps are fixed speed (FS) or variable speed (VS), and whether they are the same or different sizes.

Figure Appendix IX. 1 shows a schema of the possible variants in regulation which can be configured for each type of pumping.

Figure Appendix IX. 1. Schema of variants in regulation

In direct pumping several variants can be studied, which according to type, can be classified in three groups: regulation with fixed speed pumps, regulation with variable speed pumps, and mixed regulation. With indirect pumping regulation is done with a regulating element (reservoir, tank or dam) and fixed speed pumps. In this description of regulation methods only direct pumping will be explained.

Before explaining the procedures to follow for each regulation, a series of concepts will be defined which will be used throughout this chapter and which it is therefore necessary to know.

♦ The system curve indicates the head which should be discharged from the pumping station so that the required pressure reaches all the nodes in the network. This


501

curve normally increases with the demanded flow rate and can be modelled with an exponential curve (Hmin+Ks Q2

♦ The operating curve of the pumps is defined by the pumped head, efficiency and power consumption in relation to the flow rate passing through each one and the nominal angular speed.

).

♦ The operating curve of the pumping station is the pumped head, efficiency and power consumption by the total pumps comprising the station. These curves will be different depending on the regulation adopted, thus, for example, if regulation is by variable speed pumps, the operating curve of the total pumped head will coincide with the system curve.

♦ The cut-off flow rate is defined as the cut-off point obtained by calculating the intersection between the system curve and the operating curve of the pumps, together or individually. It can be said that, starting from this flow rate, the pump(s) in question cannot supply all the pressure required at intake to meet the needs, so that at his time, or even a little earlier, the next pump should be started. Therefore. these cut-off flow rates can be used to estimate the starting point of the pumps.

AIX.3. DIRECT PUMPING. REGULATION OF FIXED SPEED PUMPS

In irrigation systems and urban networks, regulation is usually with fixed speed pumps (FS), especially with indirect pumping via a reservoir and regulation tanks built downstream from a total head level higher than that of the pumping station itself.

In this second variant of regulation (FS) analysed, the energy behaviour will be studied of generic hydraulic equipment in a pressurised irrigation system where direct pumping is applied to the distribution network but regulating the station in steps using FS pumping.

This type of regulation is applied to pumping stations consisting only of fixed speed pumps. The purpose of this regulation is the sequential starting of the different pumps as the demanded flow rate increases. Thus, when demand is low, a single pump will operate, until the demanded flow rate increases and reaches the flow rate which starts the next pump. Normally this flow rate is near the cut-off flow rate of the operating curve of the pumping station with the system curve. Once both pumps are running, the next starting point can be calculated using the obtained crossing point between the system curve and the operating curve relative to the two pumps acting in parallel. Figure Appendix IX. 2 shows as a graph the different cut-off points, based on which the next pump should start sequentially.


502

Figure Appendix IX. 2. Cut-off flow rates

With this type of regulation a large amount of energy is wasted, as at all times the pumping station is discharging more head than is needed. Figure Appendix IX. 3 shows the energy use in a station consisting of five fixed speed pumps, where the losses mentioned are marked by the striped area. To eliminate this extra energy consumption, another type of regulation can be used, such as for example, regulation using frequency variators, as commented in the next sub-section.

Figure Appendix IX. 3. Energy losses in FS pump regulation


503

As already mentioned, this is the most traditional type of regulation, and easy to find in various types of system. The regulation is stepped and can be based on flow rate, total head, or both.

Here the pumps start or stop working depending on demand (Figure Appendix IX. 3), and based on set points of cut-off flow rates. The features of this regulation can be summarised as:

♦ The pumps constituting these pumping stations must operate at their nominal speed at all times, so no mechanism for varying their speed of rotation will exist, so that the variation in the power curve will be based on certain set points for starting and stopping each pumping unit.

♦ The pumping units installed in the pumping station with this type of regulation can be identical in technical characteristics, or can be of different sizes, characteristics and pumping capacities.

♦ The regulation carried out to adapt to the necessary conditions will be the establishment of set points for starting and stopping, based on the required flow rate or based on the head needed at intake.

AIX.3.1. CONFIGURING FIXED PUMP REGULATED STATIONS IN GESTAR

This type of regulation can be configured simply in Gestar thanks to the "Energy Costs" module. This tool enables the calculation of the operating curves of the analysed station, which will later be very useful for calculating the power consumed over a specified period. Among these curves we can find the head discharged by the pumping, power consumed and energy efficiency in relation to the flow rate demanded at intake, among other things.

This module can include all types of fixed speed pumps, whether the same or different, without any limit to the number of pumps incorporated.

Once the desired pumps are loaded, either manually, entering the points which best describe the head, power and efficiency curves, or using the databases offered by the software, the cut-off flow rates are calculated of the head discharged by the pumps with the system curve of the network being studied, and based on those cut-off flow rates a launch sequence of these units is proposed, which is optional and can be modified by the user if preferred.

To explain the internal mechanism which Gestar uses to calculate the proposed sequence we will use an example comprising two different fixed speed pumps. The performance curves of each of them are shown in Figure Appendix IX. 4 and Figure.


504

Figure Appendix IX. 4. Performance curves of the pump-1


505

Figure Appendix IX. 5. Performance curves of the pump-2

In Figure Appendix IX. 6 we can see the complete window referring to the configuration of the pumping station. The left side shows the area for entering data relating to the fixed speed pumps, and on the right, the data entry relating to the variable speed pumps. The lower part indicates the sequence of the FS pumps, where the pumps are ordered according to their cut-off flow rates, from smaller to greater. In the case shown, pump-1 has a cut-off flow rate (0.068 m3/s) less than the cut-off flow rate of pump-2 (0.077 m3

It also represents the sequence proposed by the application for starting the FS pumps with the help of a table. In this table, the rows identify the different pumps and the columns are the different states, or in other words, the points where the next unit starts sequentially.

/s), which is why pump-1 appears first.


506

Figure Appendix IX. 6. Configuration window for pumping stations with FS pump

The basis for the calculation engine for proposing one or another sequence is the ordering of the pumps from lower to higher cut-off flow rate; first, one by one; second, two by two, and so on to the total number of pumps. Thus, the sequence calculated by Gestar comprises three states. In the first, the working pump is pump-1, as there is a 1 in its row and zero for the other pumps, which are not running. Pump-1 will be operational until the cut-off flow rate (0.068 m3/s), after which this pump will stop and, instead, pump-2 will start until its cut-off flow rate (0.077 m3/s). In the third and last state, both pumps will be working. The last cut-off flow rate (0.13 m3

With this sequence proposed by Gestar we have a logical sequence which informs us at what exact point the working pump cannot supply the required head, and a new pump should start.

/s) is basically for information, as it will not determine any stop, but indicates at what point the pumping station can no longer supply the pressure needed by the network.

The explanation of why the pumps are ordered from smaller to greater, and thus the reason for this sequence, is because we suppose the smaller pumps to have lower energy costs, and thus less waste. Although this is not necessarily true, as the consumed power curve may be larger in a pump with a lower cut-off flow rate, and thus, the pumps would not be selected in the ideal way to reduce wasted energy as much as possible.


507

To test the calculated results and the power consumption and efficiency curves of the station according to the specified sequence, use the graphs produced by the application. For the example analysed, these graphs can be observed in Figure Appendix IX. 7, where we deduce that each pronounced peak in the curves defines a new state, or in other words, the start of a new pump. For this sequence, the calculated power consumption is about 97.160 kWh.

Figure Appendix IX. 7. Operating curves of the example pumping station.

As described above, Gestar proposes a starting sequence according to the criteria mentioned, but as there are many ways of configuring a pumping sequence (starting flow rates, number of states, etc.) this tool has been provided with a sequence editor enabling modification, addition or elimination of states. Thus, the application enables the simulation and analysis of all types of pumping alternatives in order to reach a totally precise and absolutely reliable decision.

To test if any sequence exists which optimises the power consumption more, the proposed sequence can be edited and the different states modified, and the power consumed calculated to observe if power use is increased or reduced in relation to the first one. Thus, for example, we can experiment with the states, and eliminating the second state we obtain the graph shown in Figure Appendix IX. 8. With this sequence, the energy use is around 99,000 kWh, a little higher than the consumption obtained with the proposed sequence.


508

Figure Appendix IX. 8. Operating curves eliminating state 1.

The "Power Costs" module also offers the possibility of calculating the optimum sequence for a given flow rate and data entered in the pumping station. In this way we can determine the cut-off flow rate which optimises energy use, among other things.

If we test the effectiveness of the proposed sequence with this tool, we obtain, in this case, that the proposed sequence is the optimum one, as the cut-off flow rates coincide with the starting flow rates, as we can extract from Figure Appendix IX. 6.

AIX.4. DIRECT PUMPING. VS PUMP REGULATION

Implementation of the regulation variant with all variable speed (VS) pumps has been carried out mainly for experimentation and theoretical analysis within the possibilities associated with the subject of pumping regulation and optimization of power consumption in pressurised irrigation systems or other systems. In practice this type of regulation is not frequent, given the cost of the regulation equipment, nor even strictly applicable throughout the range of flow rates, given the low efficiency found in the area of reduced flow rates. However, this variant can also be configured in Gestar, although it should be remarked that when the number of VS pumps is higher than two, the sequence must be entered by the user from the beginning, as this is the only restriction adopted by the calculation of the sequence.

Therefore this regulation variant consists of a speed variators acting permanently on each of the pumps installed and throughout the range of required flow rates of the system curve.


509

This type of configuration makes the head discharged by the station, throughout the total range of demanded flow rates, equal to the head required by the network, and so the power consumed is used more efficiently than with FS pump regulation, and thus, power consumption is lower.

The starting sequence of the different VS pumps will be similar to the one seen above. That is, for low flow rates only one pump will operate. This situation will persist until the flow rate demanded at intake is higher than the cut-off (or start) flow rate of the operating curve of the VS pump at its nominal speed with the system curve. In this instant, the operational pump will give way to the next VS pump until the cut-off flow rate. From this flow rate, both pumps will operate until the cut-off flow rate of the operating curve of the sum of the two pumps with the system curve, and so on, if the pumping station comprises more than two pumps.

To explain in detail the operation of this type of variant we will use the same example as in FS pump regulation, but, in this case, both pumps will have a frequency variators attached.

AIX.4.1. CONFIGURING VS PUMP REGULATED STATIONS IN GESTAR

This type of configuration can easily be included in the module of "Power Costs". In this case of VS pump regulation only variable speed pumps will be used, so their data will have to be incorporated in the table referring to this type of pump. As explained for FS pump regulation, the data for the pumps can be added manually or using the databases corresponding to pump manufacturers.


510

Figure Appendix IX. 9. Configuration window for pumping stations with VS pump

As can be seen in Figure Appendix IX. 9, the data needed to calculate the power use of the VS pumps is slightly different to the data for FS pumps. These differences include the necessary data referring to the nominal angular velocity of the VS pumps and the percentage of the nominal angular velocity which indicates the maximum velocity each pump can support. Thus, this percentage will mark a transition in the starting sequence, as from this point, the VS pump cannot supply the pressure needed at intake.

Another notable characteristic is the option which permits the analysis of a sequential or simultaneous operation. This type of option is only considered when the configuration has two VS pumps and when we are at the states in the starting sequence where both VS pumps are running.

Sequential operation considers one VS pump as if it were fixed speed, working at maximum revolutions, and the other VS pump adapts its angular speed at all times in order to provide the required pressure. Thus, the state in which both pumps are operational is similar to the situation in which the pump which maintains its rpm constant is fixed speed and the other pump is variable speed.

The sequence offered by the programme is based, as explained for FS pump regulation, on cut-off flow rates. Thus, the first VS pump to start working will be the one with the lowest cut-off flow rate, second will be the next VS pump, and in third


511

place, both pumps will work together. In this last state, the pump which maintains constant revolutions will be the one with the higher cut-off flow rate. This option can be modified, as can the sequence itself.

Figure Appendix IX. 10. Operating curves of VS pump regulation with sequential operation

For the given example, the operating graphs are shown in Figure Appendix IX. 10. With this regulation, energy use is obtained of 83.081 kWh, much lower than the consumption obtained with VS pump regulation (99.000 kWh).

Simultaneous operation, like sequential, will take into account when there are two VS pumps and both are operating at the same time. In this situation there will be two pumps with the same alpha, i.e., the same percentage of the nominal angular speed of each pump. To calculate alpha, the application uses the Newton-Raphson method to solve the system of equations obtained, which is based on the discharged head from both pumps being identical to each other and to the head of the system curve corresponding to the analysed flow rate at intake, and that the flow rate of each pump adds to the total flow rate at intake.

The proposed system of equations is based on the modelling of head curves discharged by the pumps in relation to the flow rate passing through them. This modelling was done using splines, or in other words, using third degree polynomials for each range situated between two consecutive flow rates.


512

When the VS pumps adapt their revolutions to discharge the demanded head at all times, the operating curve is modified as the revolutions of the pump decrease.

Finally, two last equations could be added to the proposed system, as for a given and known point (Hi, Qi

This system of equations can be solved iterating by the Newton-Raphson method, where the unknowns we want to be calculated are alpha (α) and the flow rates passing through each pump.

), the heads are the same as each other and the flow rate of each pump adds to the total.

For the example analysed in this section with the different types of regulation, but applying in this case simultaneous operation, a flatter energy efficiency curve is obtained which is slightly higher than the one obtained by sequential operation, as extracted from Figure Appendix IX. 11.

Figure Appendix IX. 11. Operating curves of VS pump regulation with simultaneous operation

This simultaneous operation gives better energy results, as in this case the power consumption is 79.789 kWh compared with 83.081 kWh obtained in sequential operation. The explanation of this saving is that the efficiency of the station when both pumps are fully operational is improved, as for small flow rates both pumps are working with a variators, and so there are no points where the pumps have to greatly reduce their angular speed, which often leads to much lower efficiency values than desired.


513

AIX.5. DIRECT PUMPING. MIXED REGULATION

In the mixed regulation variant, the regulation most used in installations with direct pumping, we can find different configurations according to the number of fixed and variable speed pumps, depending on the pumps being of equal size, with and without overlap.

This section describes two representative cases of mixed regulation reflecting the most characteristic aspects of the different variants which can be found. First we describe regulation with FS and VS pumps of the same size with overlap; and second, regulation with different FS and VS pumps; consisting of:

The mixed variant with overlap is regulated with units of equal size with a frequency variators acting periodically on one of them, simulated in the model by the conversion parameter of the speed of rotation (α). The frequency variators will act on a pumping unit which will be responsible for regulation in the installation, delaying the start of new units in a margin of ±10% of their design flow rate or cut-off flow rate.

From this point the VS pump will stop regulating and the first fixed speed pump will start as a normal fixed speed unit at 100% of its nominal pumping capacity. From this point and until the next cut-off point, the FS and VS pumps will operate. If demand increases the rest of the installed pumps will start successively in the same order.

Figure Appendix IX. 12 shows the operating curves of a pumping station consisting of three pumps of equal size, two fixed speed and one variable speed. In this case, the frequency variators will reach 100% and the different starting points of the successive FS pumps are reflected in the peaks of the power consumption and efficiency curves. In this variant energy consumption of 80.2091 kWh is obtained.

Gestar offers the possibility of simulating these regulations with general applicability. For example, it can run simulations with different operating percentages of the variators other than the nominal. This information can be entered as a complement to the inherent data of the variable speed pumps, and will be set for all the states making up the sequence, i.e., the variable speed pump will operate until the limit marked in the percentage field in relation to the nominal angular speed. Another way to mark the maximum angular speed of the pump is to indicate the different cut-off flow rates of each state in the table of the sequence, so that the limit angular speed the VS pump must take for each state will be automatically calculated. In this last case, different states can be analysed, and for each of them, the maximum speed the variable speed pump operates at will be different.


514

Figure Appendix IX. 12. Mixed Regulation operating curves with identical pumps

Figure Appendix IX. 13 shows a mixed regulation with overlap where an increase of 10% has been applied over the nominal speed of the variable speed pump. As can be seen in this graph, the cut-off points have increased considerably, and for this case, a flattening has been obtained in the efficiency curve, and the power curve has been smoothed out, giving slight savings in power consumption (79430 kWh).

But could this mixed regulation, where a percentage of the constant maximum angular speed has been chosen, be improved? The answer is yes.

If we use the tool included in Gestar for calculating the optimal sequence for each flow rate analysed, we study various "strategic" flow rates close to the earlier cut-off flow rates, we can find that the optimal cut-off flow rates marking the change from one state to another are not those calculated by the calculation engine when the invariable overlap is 110%. These cut-off flow rates are 0.08 m3/s, 0.135 m3/s and 0.172 m3

Figure Appendix IX. 14/s, where the percentage adopted in each one is 6.8%, 8% and 10%, respectively.

With this new regulation, which can be seen in , we obtain a slight savings, reducing energy consumption to 79.188 kWh.


515

Figure Appendix IX. 13. Mixed Regulation operating curves with identical overlap

Figure Appendix IX. 14. Mixed Regulation operating curves with different overlap


516

The variant of mixed regulation with pumps of different sizes, as its name indicates, consists of working with units of different sizes, where the smallest one covers the lowest demands in a range which can vary from 45 to 50% of the maximum pumping capacity of the largest unit. From this point the frequency variators (α) commutes its action to the next largest pump, and so on. This, in this type of regulation, there must be at least two units with frequency variators, which can operate sequentially or simultaneously, as explained above. To demonstrate its operation and possible configurations, we will use an example consisting of three pumps, two of variable speed and one of fixed speed.

First, we will study the case in which the fixed speed pump is identical to the variable speed pump with greater range, and this in turn is the same as the pump with the behaviour curve shown in Figure Appendix IX. 4. We will give this pump the name “Pump-1”. Meanwhile, the smaller variable speed pump (“Pump-3”) will be ruled by the behaviour curve shown in Figure Appendix IX. 15.

Figure Appendix IX. 15. Operating curves of Pump-3.

With this regulation, whose starting sequence is shown in Figure Appendix IX. 16, we obtain an energy consumption of 75.370 kWh, slightly lower than the consumption of the other regulation variants seen above. With this configuration, the calculated curves of power consumption and total efficiency of the pumping station are represented in Figure Appendix IX. 17.


517

Figure Appendix IX. 16. Starting sequence

Figure Appendix IX. 17. Curves of the pumping station with the mixed regulation variant with pumps of different sizes and sequential operation

If now, instead of taking into account the sequential operation of the variable speed pumps, we consider a simultaneous operation, we obtain an energy consumption of 74.220 kWh and slightly smoothed operating curves, as seen in Figure Appendix IX. 18.


518

Figure Appendix IX. 18. Curves of the pumping station with the mixed regulation variant with pumps of different sizes and simultaneous operation


519

APPENDIX X. SYSTEM CURVE

The pressure requirements to be supplied by the pumping station in conventional regulation systems are formulated in terms of the system curve of the pumping station, i.e., the pair of values demanded flow rate-output pressure of the pumping station. The output pressure of the pumping station, for demanded flow rate, is established as the pressure needed to supply sufficient pressure to all the hydrants in the network with the following conditions:

♦ The demanded flow rate must be lower than an acceptable maximum, normally the design flow rate of the system, above which meeting pressure requirements cannot be guaranteed.

♦ The open hydrants generating demand are distributed randomly, so that there are no singular concentrations of demand which increase local head losses and thus there are no singular increases in pressure requirements at intake.

Calculation of P (q) begins by establishing the system curve. This depends on the pressure needs in the different possible scenarios for each possible flow rate, i.e., for the same demand of flow rate in the network, we find different scenarios of open/closed hydrants producing it, and thus, different pressure needs. This situation, characteristic of demand irrigation networks where there are no patterns of opening, means that for the same flow rate there is a "cloud" of pressure needs. Sometimes, pressure requirements at intake can oscillate considerably, due to the existence of more demanding hydrants. The value of pressure needed can vary for the same flow rate depending on whether these hydrants are open or not.

To explore the different situations of pressure needs, the methodology presented by GESTAR proposes generating and simulating a series of consumption scenarios with different outlets opened at random, sweeping the possible ranges at intake, calculating the manometric pressure required at intake to have enough pressure available in the critical hydrants of each scenario.

The table shows the example scenarios generated for 10% open hydrants in a typical network. For each scenario the critical demanded pressure is registered, and the demanded flow rate as the sum of the maximum allotted flow of the open hydrants.


520

FIGURE AX. 1 Simulation of consumption scenarios with 10% open (example studied: network at Valdega)

For a given % opening, we have the set or cloud of pairs of points flow rate – critical pressure. If we repeat this simulation of scenarios for the different percentages of opening of the network, we obtain the clouds of points of pressures needed for each flow rate:

16 142 95 49 48 146 Q (m3/s) Critical demanded P scenario 1 X X X X X X 0,15999682 65,48 scenario 2 X X X X X X 0,16000068 60,3 scenario 3 37,31 X X 64,54 X X 0,15998919 64,54 scenario 4 X 34,15 X X X X 0,16000491 57,3 scenario 5 X X X X X X 0,16001245 61,6 scenario 6 X X X X X X 0,1599936 68,19 scenario 7 37,54 34,18 X X X X 0,1599995 62,1 scenario 8 X 34,15 X X X X 0,16000953 64,79 scenario 9 X X 47,31 X X 59,81 0,15999545 68,56 scenario 10 X X X X X X 0,15998788 59,13 scenario 11 X X X X X X 0,16000131 64,46 scenario 12 X X X X X X 0,1600035 61,14 scenario 13 X X X X X 63,4 0,15998723 63,4 scenario 14 37,37 X X X X X 0,16000061 60,29 scenario 15 X X X X X X 0,16000077 60,37 scenario 16 X X X X X X 0,16000022 61,73 scenario 17 X 34,14 X 63,85 X X 0,16002032 63,85 scenario 18 X X 47,75 X X X 0,16000745 57,97 scenario 19 X X X X 62,67 X 0,16000234 65,19 scenario 20 X X X X X X 0,16000627 61,76 scenario 21 X X X X X X 0,15999237 60,11 scenario 22 X 34,16 X 64,93 X X 0,15999983 64,93 scenario 23 X X X X X X 0,16000436 68,85 scenario 24 X X X X X X 0,16000339 59,93 scenario 25 X X X X X X 0,15999079 62,71 scenario 26 X X X X X X 0,15999638 60,12 scenario 27 X X X X 59,31 X 0,15999997 63,95 scenario 28 X 34,16 X X X X 0,15999471 59,55 scenario 29 X 34,16 X X X X 0,15998885 60,68 scenario 30 X X 47,34 X X 59,75 0,15999827 64,95 scenario 31 X 34,15 X X 60,8 X 0,16001911 62,75 scenario 32 X X X X X X 0,16000223 68,4 scenario 33 X X X X X X 0,15999734 62,39 scenario 34 X X X X X 59,67 0,15999968 68,49 scenario 35 X X X X X X 0,16000448 62,11 scenario 36 X X X 69,08 64,4 X 0,15999724 69,08 scenario 37 X X X X X X 0,15999992 59,69 scenario 38 X 34,15 X X X X 0,16000092 62,03 scenario 39 X X X X X X 0,15999426 59,75 scenario 40 X X X X X 59,57 0,15999621 63,13 scenario 41 X X X X X X 0,16000247 60,77 scenario 42 X X X X X X 0,159997 62,71 scenario 43 X X X X X X 0,15999624 62,71 scenario 44 X X X X X X 0,16000322 64,54 scenario 45 X X X X X X 0,16000359 61,42 scenario 46 X X X X X X 0,16000076 62,87 scenario 47 X X X X 59,17 X 0,16000265 66,3 scenario 48 X X X X X X 0,16000506 62,25 scenario 49 X X X X X X 0,15999991 61,72 scenario 50 X 34,15 X X X X 0,16000205 60,28 scenario 51 X X 55,26 X X X 0,1600053 57,12 scenario 52 X X X X X X 0,15999644 59,93 scenario 53 X X X X 59,38 X 0,15998818 62,68 scenario 54 X X X X X X 0,1599967 60,23 scenario 55 X X 48,05 X X X 0,15999533 59,88 scenario 56 X X X X X X 0,1600025 59,92 scenario 57 X 34,15 X X X X 0,16001168 64 scenario 58 X X X 64,17 X X 0,15998824 64,17 scenario 59 X X X 64,47 X X 0,15998398 64,47 scenario 60 X X X X X X 0,16000959 61,73 scenario 61 X 34,15 X X X X 0,16000055 59,77 scenario 62 X X X X X X 0,15999091 61,27 scenario 63 X X X X X X 0,15999264 66,61 scenario 64 X X X 65,28 X X 0,16001502 65,28 scenario 65 X X X X X X 0,16 68,49 scenario 66 X X X X X X 0,15999681 63,23 scenario 67 X X X 64,27 X X 0,16000272 64,27 scenario 68 37,37 X X X X X 0,16000019 63,14 scenario 69 X X 55,14 X X X 0,1599943 67,47 scenario 70 X X X X 60,15 X 0,16000028 65,33 scenario 71 X X X X X X 0,16000344 64,98 scenario 72 X X X X X X 0,15999442 59,12 scenario 73 X X X X X X 0,16000594 59,36 scenario 74 37,31 X X X X 59,25 0,1600024 59,25 scenario 75 X X X X X X 0,16000783 63,39 scenario 76 X X X X X X 0,16000493 59,6 scenario 77 X X X X X 59,76 0,16000313 59,88 scenario 78 X X X X X X 0,15999821 61,09 scenario 79 X X X 66,28 X X 0,15999185 69,4 scenario 80 X X X X X 59,98 0,1600025 63,11 scenario 81 X X 55,12 63,84 X X 0,15999617 63,84 scenario 82 X 34,15 X X X X 0,16000628 59,82 scenario 83 X X X X X X 0,16000773 60,69 scenario 84 X 34,15 X 65,12 60,45 X 0,16001835 65,12 scenario 85 37,32 34,15 X X X X 0,16000186 60,41 scenario 86 X X X X X X 0,1599943 58,94 scenario 87 X X X X X X 0,16001213 65,55 scenario 88 X 34,17 X X X X 0,16001005 65,32

X X X X X X 0,16000946 64,16


521

FIGURE AX. 2 Set of pressures needed in simulation of random scenarios for different degrees of open hydrants (typical network).

If we take as the set point the maximum envelope of these sets of pairs, we guarantee that in all the possible scenarios, the pressure provided will be sufficient, and that no hydrant will be working below its set point pressure. Establishing the system curve as the maximum envelope may be excessively conservative (and contradicts the probabilistic design criteria associated with calculating the Clement Design Flow Rates).

It is observed that for high flow rates, the maximum requirement is due to a flow rate-pressure pair located far from the bulk of the data, produced by a situation which is critical but very improbable. If we adopt this value as the set point for this flow rate, we will be supplying a pressure well above what is needed for most cases. This leads to high power consumption and poor energy efficiency.

The minimum system curve (the envelope of the absolute minimum pressure requirements for each % of demand) is unacceptable as it does not meet the pressure requirements for almost any consumption scenario.


522

FIGURE AX. 3 System Curve: maximum envelope, effective curve and minimum envelope

We consider the effective system curve or recommended system curve (RSC) to be that which corresponds to a degree of reliability (probability that the pressure requirements will not be exceeded) similar to and consistent with the guarantee of Design Flow Rates at intake using the Clement formulation.

To obtain it we take as the value of the pressure requirement at intake the maximum value of the pressures required on average by each hydrant for each % of demand.

The effective system curve Hc(q), fit to a quadratic expression is

2min QKHHC ⋅+=

and has a degree of reliability equivalent to the operation quality at intake for design conditions.

With the registry of pairs of points obtained in all the simulations, system curves can be established with any degree of reliability.

0 10 20 30 40 50 60 70 80 90

100

0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 Q (m3/s)

H m

H MED(m) H MAX H MIN Q clement Polinomic (H MED(m)) Polinomic (H MAX) Polinomic (H MIN)


523

APPENDIX XI. PROPERTIES OF AND OBTAINING

DF FLOW RATES

The distribution of head flow rates corresponds to a succession of different random demand scenarios, which are modified by opening and closing irrigation intakes. Consequently, the head flow rate of a continuous random variable can be considered, whose Probability Density Function (PDF1

) for a flow rate q is defined as the expected time relative to the existence of a flow rate between q and q + dq:

dqqdt

Tdqdt

TqFDP

)(11)( == (AXI.1)

Where T, in seconds, is the total duration of the flow rate observation period, and

dt is the time of presence of flow rates between q and q + dq. Namely:

dqdqqyqentreoscomprendidcaudalesderelativaFrecuencia

dqTdqqyqentreocomprendidcaudaldeexistenciadepromedioTiempo

dqdt

TqFDP

+

=⋅

+==

________

__________1)(

The relative frequency during the period T of a flow rate between q and q + dq

is:

T

qdtdqqFDP

)()( =⋅ (AXI.2)

Thus the relative frequencies classified for each range of flow rates and the PDF

are directly related, but do not take the same values or dimensions (the dimensions of the PDF are s-1/m3

).

In the case of irrigation systems, time T of flow rate observation contains only the hours of the Irrigation Session, as the hours when irrigation is excluded should not be taken into account when calculating relative frequency. While null flow rates have no impact on the PDF, as they do not generate volume demand or energy consumption, for the data to be consistent for the data, the relative frequency of null flow rates is taken into account when they occur during the Irrigation Day. By definition, any PDF is normalised and satisfies:

5 Also called Density.


524

1)(max

0

=⋅∫Q

dqqFDP (AXI.3)

Integrating the head flow rate for the irrigation session determines the total

volume supplied in the network, which can be calculated as the integral for the whole domain of flow rates of the product of PDF (q) and q.

dqqqFDPTdqqdqdt

TTdttqV

QQT

⋅⋅=⋅⋅⋅⋅=⋅= ∫∫∫max

0

max

00

).(1)( (AXI.4)

To evaluate the PDF at the project stage, GESTAR estimates a theoretical PDF (García, 2009), (Esperanza, 2007) obtained by extending the ideas of (Roldan et al., 2003), consisting of adding together the contributions of the monthly PDFs, which statistic can be assimilated to a Normal distribution, the average and typical deviation of which can be calculated according to the probabilities of opening of each hydrant for each month (depending in turn on the module, surface area and monthly irrigation needs) and for the time bracket.

If flow rate records exist, the PDF can be inferred from these measurements, obtaining an experimental PDF, which may come from: a) Pre-existing networks in use, with a similar behaviour, and where demand relative to maximum flow rate is thought to be similar. b) The network itself once in use and having recorded a “sufficiently representative” spread of flow rates for the sample to be statistically significant. c) A formulation of turns (forecast or implemented) enabling the relative frequency of each flow rate to be known.


525

PDF evaluated according to monthly demand. Theoretical or synthetic PDF

PDF evaluated according to monthly demand is constructed according to the probabilities of opening of the hydrants, probabilities which depend on the irrigation requirements of the crops, the time needed to irrigate, and the allocation assigned to each outlet. This evaluation method is applied for existing irrigation networks and new ones where demand is stochastic, unknown or unmetered. A characterisation of the spread of flow rate frequencies in systems is not always available, whether because they are at the project stage or because devices are not available to measure and store data over time.

This model evaluates a demand distribution curve combining the monthly Gaussian type probability density functions depending on the daily irrigation needs of the month, the topology, the maximum flow of the hydrants, and the plots and crops served, to lead to an assumed probability density function (PDF) for network demand. The strategy followed in the model incorporates heterogeneity in demand for different months ( j ) and discrimination by prices for time brackets. Different functional probabilities for each hydrant are considered, with different maximum flow rates, surface areas, and irrigation times; it is also assumed that

The maximum flow rate ( id ) and surface area ( iS ) are specific to each hydrant.

Monthly needs ( jN ) (measured in mm/day) will be uniform for the entire network, as will the Effective Day of Irrigation (EDI), related to network performance.

In this way irrigation times will be different for each outlet or hydrant ( i ). Each hydrant ( i ) will have its own time each day as needed to apply irrigation each month ( j ) according to the needs of the month ( jN ) and its maximum flow rate ( id ), so that:

i

ijij d

SNt

⋅=' Where: 'ijt - daily open time needed by the hydrant ( i ) in

the month ( j ) to meet the irrigation requirements of the month ( jN ) with the maximum flow rate ( id ).

Each hydrant or outlet ( i ) in each month ( j ) and each time bracket or pricing bracket (bracket’) will have its own opening probability ( ijfranjaP ), according to the time ( 'ijt ) of application in one day of each month ( j ) and the spread of this time over the

time brackets ( 'ijfranjat ).


526

The probability of opening of each hydrant ( i ) in each time bracket will be determined as the quotient between the time needed for applying irrigation in each hydrant ( i ) in a time bracket for any day of the month ( j ) among the times available for irrigation in each bracket.

To calculate the probability of opening of the hydrant, the average flow rate per time bracket and each month will be:

ijfranja

nt

iijfranja Pd ⋅= ∑

=1µ (AXI.5)

Where:

jfranjaµ - average flow rate in each time bracket (‘) of the month (j).

id - maximum flow rate for each hydrant ( i ).

ijfranjaP - probability of opening of the hydrant ( i ) for a typical day of each month ( j ) and respective time bracket (‘).

In the same order the variance is determined of the average head flow rate demanded for each time bracket and month ( j ) using the expression:

( ) [ ]ijfranjaiiijfranja

nt

iijfranja PddPd ⋅−⋅⋅= ∑

=1

2σ (AXI.6)

Assuming that the statistical distribution of flow rates each month follows a normal type of law, consistent with the Clément hypotheses used for defining design flow rates and maximum demand, for all the hours of the effective day of irrigation (EDI), the probability density function (PDF) for the network head flow rate is calculated for each month and each time bracket, as a normal distribution evaluated with the values of mean and variance.

The probability density functions ( ( )ijfranja Qfdp ) of each month ( j ) and the density function corresponding to the irrigation campaign ( ( )ifranjaaño Qfdp _ ) are represented graphically by the data in FIGURE AXI.1 for a specific price rate period, for example in a generic irrigation network.


527

FIGURE AXI.1 Curves of monthly and annual Probability Density Functions

The curves of the monthly probability density function (FIGURE AXI.1 ) reflect the behaviour of the distribution of consumption for each month ( j ), giving us an idea of the frequency of certain head flow rates in the system.

However the annual curve is not the normal type, i.e., is not a Gaussian bell curve, because it is the result of multiplying the monthly density function curves ( jfranjafdp ) by the useful time ( jt ) of duration of each period or month ( j ), giving a curve of frequencies and annual distribution of head flow rates.

If the probability density functions are multiplied ( ( )Qfdp jfranja ) or ( ( )Qfdp franjaaño− ) by the powers absorbed in the pumping station according to the flow rate, it generates the power distribution absorbed according to the circulating flow, so that an integration can be made in the range of flows required to evaluate the cost of the energy consumed during the hours of pumping per year in the different time brackets in a more realistic way.

EXAMPLES:

Obtaining the PDF in the first example is based on the monthly water needs of an irrigation sector corresponding to the projected values.

MONTH 1 2 3 4 5 6 7 8 9 10 11 12 Needs (mm/day)

0,00 0,02 0,66 0,80 1,88 2,65 4,50 4,09 1,40 0,00 0,00 0,00

TABLE AXI.1 Monthly volumes served

These values, gathered from the project, are entered in the window “Probability density function of flow rate” and applied to the modelling in Gestar of the irrigation sector being studied (it has information on surfaces, maximum flow, etc, for the hydrants)


528

FIGURE AXI. 2 shows the result found for the PDF of the demanded flow rates throughout the irrigation campaign, showing, as usual, a less frequent appearance of flow rates near the design rate, and a greater presence of flow rates in the medium to low area, indicating the advisability of also having high performance available in intermediate flow rate ranges.

FIGURE AXI. 2 Estimate of probability density function of flow rates

Another case using the theoretical PDF is evaluating it based exclusively on the month to month water needs (mm/day) obtained from the volumes served at the head according to the accumulated records of the flow meter (monthly consumption), and the hours of the effective irrigation campaign. The PDF is obtained by processing the measurements of the flow meter and calculating the volume served month by month, and this is transposed to needs in mm/day. As total hours of the campaign, the estimated hours of the EDI x number of days where there are records (days when the pump station was running).

Month Total m3 mm/day MAY 97607,00 1,66630285 JUNE 155765,00 2,6591501 JULY 394746,00 6,73892637 AUGUST 314688,00 5,37221216 SEPTEMBER 38916,00 0,66435647 TOTAL 1001722,00

TABLE AXI.2 Monthly volumes served


529

PDF evaluated according to the distribution of frequency of demanded flow rates. Experimental PDF If the demand structure of a network is known or can be estimated, either because it is operational and there are reliable records, or because demand in the network is considered to be similar to that in an equivalent which has been characterised, the PDF can be evaluated directly in the form of the relative frequency of presence in each flow. In the case of energy analysis for already installed, operational networks, if we have records of flow rates throughout the campaign (a flow meter with a data storage system), we can build the experimental PDF grouping the frequencies in intervals of flow rate. To build the PDF in this way, we need a representative sample of network demand, either because it is already operational and there are records, or because network demand is considered to be similar to that in an equivalent which has already been characterised. In this section a first approach is made to the analysis and possible treatment to be applied to pumping systems where demand is previously known through the data gathered over time, or through direct measurements of circulating flow in a useful time period ( t∆ ). Calculating the number of records whose flow value falls in the defined flow intervals (Q1 and Q2), the relative frequencies of occurrence of the flow rates are obtained. These records change in the time that the system has been operational in the flow intervals considered. The times when the system has not recorded any activity are assigned a flow rate of 0 until the total hours of the irrigation campaign are completed (Effective day of irrigation x days of the campaign).

0

2

4

6

8

10

12

14

5 20 35 50 65 80 95 110

125

140

155

170

185

200

215

230

245

260

275

290

305

320

335

350

365

380

395

410

425

440

455

470

%

Q (l/s)

Frecuencia

FIGURE AXI.3 Relative frequencies of occurrence of flow rates (5 l/s intervals)


530

Grouping the frequencies in flow rate intervals (5 l/s), (FIGURE AXI.3 ), we

construct the Probability density function PDF (FIGURE AXI.4 ).

Thus, the probability that the demanded flow rate Q(i) is found in the range (Q1, Q2) will be the area below the curve.

0

2

4

6

8

10

12

14

16

18

20

22

0,01

0,02

0,03

0,04

0,05

0,06

0,07

0,08

0,09 0,1

0,11

0,12

0,13

0,14

0,15

0,16

0,17

0,18

0,19 0,2

0,21

0,22

0,23

0,24

0,25

0,26

0,27

0,28

0,29 0,3

0,31

0,32

0,33

0,34

0,35

0,36

0,37

0,38

0,39 0,4

PD

F

Caudal (m3/s)

Curva PDF experimental

FIGURE AXI.4 Probability density function

EXAMPLE: In this example the PDF is evaluated experimentally based on the data recorded from measuring the flow rate every 15 minutes, which the pumping station has stored throughout the campaign, grouping the frequencies in intervals of 5 l/s.

The experimental or evaluated PDF according to the frequencies is constructed by calculating the records where the flow rate is in a certain interval, in this case of 5 l/s. Once we know the number of records of each flow rate interval, and the time covered by the records, we relate it with the total number of records and obtain the relative frequency. The time for days where there is a record that the pump was running is assigned a flow rate of 0 until the hours of the EDI are complete.

To obtain the frequencies we need to extract the following data from the flow meter:

Days of campaign: days on which there were records of flow

Total hours of campaign: Days of the campaign x 24

Efficiency: Efficiency of the network (EDI/Total hours of the campaign)

Annual EDI or theoretical campaign hours: Physical campaign hours x Efficiency (or EDI x Days of campaign)


531

Recorded hours: Number of hours recorded with the pump station running

(including hours recorded with flow rate 0)

Needed to make up theoretical hours and considering flow rate 0: Theoretical hours of campaign – Recorded hours

Amount of data recorded: Total number of flow meter readings

Amount of data to complete q=0: Needed to make up theoretical hours and considering flow rate 0:

TOTAL AMOUNT OF DATA: Number of records of data + Number of records to complete q=0:

Thus the relative frequency of a flow rate interval will be the relationship between the number of records whose q value falls in the interval and the total number of recorded data (including data considered to be flow rate 0 in theoretical hours).

sTotalesNúmeroDatoregistrosnqFrecuencia º)( =∆

GESTAR2010 processes these frequencies and transforms them into the experimental PDF.

The theoretical campaign hours obtained will be used for calculating energy consumption.

TABLE AXI.3 and TABLE AXI.4 show the results of calculating flow meter records for obtaining total data for relative frequencies. TABLE AXI.5 shows an example of data processing for obtaining relative frequencies and the experimental PDF, using the total number of data obtained in TABLE AXI.4 for relating frequencies: 13.968.


532

Days of campaign 153

Physical hours of campaign 3672

Efficiency 0,75

Annual EDI or theoretical campaign hours: 2754

Recorded hours 2418

Needed to make up theoretical hours and considering flow rate 0

336

TABLE AXI.3 Hours of operation of the Arguedas station for processing frequencies

Amount of data recorded 13632

Amount of data to complete q=0 336

TOTAL NUMBER OF DATA 13968

TABLE AXI.4 Number of frequency measurements processed


533

TABLE AXI.5 Processing data to obtain Experimental PDF


534

FIGURE AXI.5 shows the experimental PDF through head flow rate data recorded automatically by the pumping station every 15 minutes, together with the synthetic variant PDF generated by GESTAR, based exclusively on monthly volumes (example in above section).

The qualitative similarity of these PDFs can be observed. The area below each part of the curve represents the relative frequency of occurrence of the respective flow rate, so that it can be concluded that all the variants predict a high presence of small and medium flow rates, and a very low probability of concurrence close to the design flow rate, 0.3 m3/s, a fact linked to water consumption clearly lower than predicted.

Arguedas FDP 2003

0

2

4

6

8

10

12

14

0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 0,18 0,20 0,22 0,24 0,26 0,28 0,30 0,32 0,34Q m3/s

VOLUMENES MENSUALES EXPERIMENTAL

FIGURE AXI.5 Synthetic (monthly consumption) and experimental Density Functions for the example network.


535

APPENDIX XII. GESTAR PROGRAMMING

LANGUAGE

GESTAR has some advanced functions which can be run from a script. For a script written by the user to be understood by GESTAR, it must have a set of characteristics set out in this appendix.

These words are used by the scripting language and cannot be used to name variables. The reserved words have specific meanings in the internal language of GESTAR, as they form part of its syntax.

Reserved Words

SYNTAX OF THE LANGUAGE

If, Then, else, While, Do, Loop, Foreach, in, break, Set, To, Function, EndFunction, return, true, false, Null, Random, Debug

TEMPORAL DATA

IsPeakHour, Time, TotalTime

HYDRAULICS DATA

Open, Close, IsOpen, IsClose, Pressure, PressureMargin, Height, Demand, Duty, Flow, Velocity, HeadLosses, Power

FIGURE 13.21

Supported Symbols

is a summary of the symbols supported by GESTAR’s internal programming language. Their meaning and use are described in the following sections of the APPENDIX.

+ -- * / ^ & | = != , { } [ ] ; ( ) >>= <<= .

FIGURE 13.21. Summary of Supported Symbols


536

Data types

Data types refers to the type of information being dealt with, where the minimum unit of information is the datum. It can also be considered as the range of values which a variable may take during execution. The GESTAR language accepts five different data types.

NULL

Special marker to indicate there is a value does not exist in a database, or in other words, null value, empty, no value assigned.

Data type: Null

NUMERIC

The numeric data type contains double precision numbers, i.e., it can accurately store numbers with more than 6 digits. The point (.) must be used to separate decimals.

Example: 1.2345, -1.2345

BOOLEAN

The logical or Boolean data type can represent binary logic values, i.e., 2 values, which in GESTAR programming represent True or False.

Possible values: True / False

STRING

A String is a sequence of characters such as letters, numbers and punctuation marks. It is represented with the characters in quotes.

Data type: “String”

There may be a programming fault if the string contains a reserved word or symbol. Two examples are described below:

“Different” Contains if. Avoid using it.

“;” In this case use “\$”


537

ARRAY

The array is a data structure of 1 to N components of any data type, with a whole number as the index, from 0 to N-1 (corresponding to the last element).

An array is created by placing a series of comma (,) separated values between curly brackets ({ }).

Example Array:

Notation: { 1 , “2” , True , { 1 , 2 , 3 } , Null }

Meaning:

Value 1: 1 Value 2: “2” Value 3: True

Value 4: {1 , 2 , 3} Value 5: Null

Variables

The GESTAR Programming Language supports the use, assignment and reading of variables at the local level (only accessible from a single child process) and at the global level (accessible from application routines or macros and in all its procedures and functions). Names of variables must contain alphanumerical characters, between single quotes ( ‘ ).

Examples of Variables:: ‘Variable’ , ‘Contador’

Local variables do not need to be declared, i.e., they are created automatically, and it is enough to assign them a value. Global variables must be declared, as described in the next section.

DECLARING GLOBAL VARIABLES

The command “Create” must be used, which assigns a null value by default.

Example: Create ‘NewGlobalVariable’.

ASSIGNMENT TO VARIABLE

Done using the instruction Set / To (Set Variable To Value).

Example of assignment: Set ‘Contador’ To 0.


538

The set of data inserted in a structured or specific sequence is called an instruction, which is interpreted and executed. Instructions may be simple or compound.

Instructions

COMPOUND INSTRUCTIONS

Compound instructions must be written between square bracket ([ ]), separated by a semicolon (;).

Schema:

[

Instrucción 1;

Instrucción 2;

….

Instrucción Final;

]

If you want to execute several simple instructions they must be included in a compound instruction.

Incorrect example: Correct example:

If ‘A’ > 0 Then if ‘A’> 0 Then

Set ‘A’ To ‘A’+ 1 [

Set ‘A’ To ‘A’+ 2 Set ‘A’ To ‘A’ + 1

Set ‘A’ To ‘A’ + 2

]

CONDITIONAL INSTRUCTIONS IF/THEN/ELSE

An instruction or group of instructions which can be executed or not, depending on the value of a condition. The reserved words If / Then / Else are used.

Schema:

If Expresión Boleana Then

Instruccion

Else if Expresión Boleana Then


539

Instruccion

Else

Instruccion

The operands for obtaining the result of the Boolean Expression may be a variable, an operator, or a function.

ITERATIVE INSTRUCTION WHILE/DO/LOOP

Iterative instructions let you create loops. In a loop, the internal instructions are executed a certain number of times, according to the criterion for ending the loop. The reserved words While /Do/ Loop are used and it repeats until the Boolean condition is met.

Schema:

While ExpresiónBoleana Do

Instrucción

Loop

Example:

Set ‘Contador’ To 0;

While ‘Contador’ < 10 Do

[

Set ‘Contador’ To ‘Contador’ + 1 ;

Instrucción ;

]

Loop

Instructions and Boolean Expressions can operate with variable, operator or function.

ENUMERATION INSTRUCTION FOREACH/ IN/ DO/ LOOP

The following enumeration instruction in GESTAR scripting cycles through the elements of an array. This cycle traverses the collection and the variable receives an element of the collection in each iteration. It uses the reserved words: Foreach/ In/ Do/Loop.

Schema::


540

Foreach ElementoSimpleVector in ExpresiónVector Do

Instrucción

Loop

Where

ElementoSimpleVector: in each instant returns the active element of the array.

ExpresiónVector: may be an array, or a function/variable which returns an array.

Example:

Set ‘Vector’ To { 1 , 2 , 3 };

Set ‘SumaVector’ To 0 ;

Foreach numero in ‘Vector’ Do

[

Set ‘SumaVector’ To ‘SumaVector’ + numero ;

]

Loop;

FUNCTION CALL INSTRUCTION.

The function call instruction executes a function with the indicated parameters. The output data are obtained as an array if more than one, or as a single value. If there are no output data, it returns Null.

To execute a function, write the name of the function and add the different input parameters between brackets (()) and separated by commas (,).

Schema: NombreFunción( ArgIn_1 , … , ArgIn_N )

Example:

[

Set ‘Numero’ To 0 ;

Set ‘String’ To ToString( ‘Numero’ );

]


541

Result: The variable ‘String’ has the assigned value “0”

FUNCTION DECLARATION FUNCTION - RETURN - END FUNCTION

Generates a function which can be used based on that point in the code. GESTAR programming functions must fulfil a set of special characteristics:

• Functions are always declared globally.

• A function cannot be recursive, i.e., it cannot call itself.

• If a value is returned, the instruction RETURN will be used, followed by the values separated by commas ( , ).

Schema:

Function NombreFuncion( ArgIn1, … , ArgInN )

Instruccion

EndFunction

Example: FUNCTION CALCULATING THE ABSOLUTE VALUE OF A GIVEN NUMBER.

Function ValorAbsoluto( Numero )

[

If Numero < 0 Then

[

return 0 -- Numero;

]

Else

[

return Numero;

]

]

EndFunction;

Set ‘NumeroOriginal’ To -1.35;


542

Set ‘NumeroFinal’ To ValorAbsoluto( ‘NumeroOriginal’ );

Result:: The value of the variable ‘NumeroFinal’ will be 1.35.

DEBUG Instruction

A debugging procedure which lets you identify and correct programming errors. When this instruction is executed, a window will pop up with the message which has been defined as a parameter. If you click Yes it runs the script; if you choose No, Gestar will close.

Esquema: Debug Cadena_de_Caracteres

An expression is a combination of constants, variables or functions, denoting a calculation process which results in a value. In GESTAR programming, an expression will return a value belonging to one of the five accepted data types:

Expressions

Null, Boolean, Numeric, String or Array

MATHEMATICAL EXPRESSIONS

Supports the following binary mathematical operators:

Add (+), Subtract (--), Multiply (*), Divide (/), Exponentiation (^), Remainder of a Division (%)

Reserved words and specific functions:

• Random: returns a random number between 0 and 1.

• ToNumber( inputString ): converts a numeric string into a double precision number.

• ToInt( inputNumber ): converts a double precision number into the nearest whole number.

RELATIONAL EXPRESSIONS

Equality (==), Inequality (!=), strictly greater than (>), strictly less than (<), greater than or equal to (>=) , less than or equal to (<= ).

BOOLEAN EXPRESSIONS

Supports the following binary Boolean operators:

AND ( & ) , OR ( | ) , XOR( ^ ) , Division () ,


543

OTHER EXPRESSIONS

Concatenation (+) : returns a String composed of all the indicated items.

Example: “A” + “B” + “C” + “1” + “2”: returns “ABC12”

Lets you read and modify data from the hydraulic model and temporal data in evolutions over time. This is done with a series of special instructions described in the sections below.

Access to GESTAR data

READING HYDRAULIC VARIABLES

To read a hydraulic variable, indicate with a String the component label and then the variable you want to know. The variables you can see depend on the characteristics of the type of component (Pipe, Pump, etc. ).

Example:

Etiqueta “BAL1“ Level Propiedad (Nivel)

Nivel de la Balsa de etiqueta “BAL1”

ASSIGNING HYDRAULIC VARIABLES

Using the command Set/To. To indicate the name of the variable, write a String with the Label of the component and then the Property to which you want to assign the value (see Table AXII 1 and Table AXII 2).

Schema:

Set Etiqueta Propiedad To Nuevo Valor

Example:

Set“BOM2” IsOpenToTrue

Name Applicable

To Property Data type

Tag Nodes Tag String Height Nodes Height Numeric Pressure Nodes Pressure Numeric Level Reservoir Level Numeric Duty CC / HID Max flow Numeric Demand CC / HID Demand Numeric PressureMargin CC / HID Pressure margin Numeric Probability CC / HID Probability Numeric IsOpen CC / HID Open Boolean


544

IsClose CC / HID Closed Boolean

Tabla AXII 1. Properties of Nodes

Name Applicable To Property Data type

Tag Elements Tag String Flow Elements Flow rate Numeric Velocity Elements Velocity Numeric HeadLosses Elements Head losses Numeric IsOpen Elements Open Boolean IsClose Elements Closed Boolean Diameter Elements Diameter Numeric Roughness Pipes Roughness Numeric Power Pump Power Numeric

Table AXII 2. Properties of Elements

ITERATION OVER HYDRAULIC COMPONENTS

Includes reserved words which return an array with all the labels of the components of a given type, depending on the reserved word (Table AXII 3). This permits iteration using the expression Foreach/ In/ Do / Loop over different components of the same type.

Reserved word Component type Hydrants Known Consumption Pumps Pump Pipes Pipes

Valves Valves Tanks Tanks Tanks Tanks

Table AXII 3. Reserved Word according to Type of Component

Example: CLOSING ALL THE PUMPS AND HYDRANTS IN THE NETWORK

[

Foreach bomba in Pumps Do


545

[

Set bomba IsOpen To False ;

]

Loop;

Foreach nodoCC in Hydrants Do

[

Set nodoCC IsOpen To False ;

]

Loop;

]

ACCESS TO TEMPORAL PROPERTIES IN EVOLUTION OVER TIME

A series of reserved words is defined:

• Time: returns the value of the time in a day (00:00 to 24:00)

• TotalTime: returns the current value of time (00:00 - …. )

• IsPeakHour: returns information on whether the time of day is blocked.

Time is written in the format HH:MM (00:15).

CALCULATEHYDRAULICMODEL( );

Pre-Installed Functions

Carries out a hydraulic calculation of the model, with the data as they are found. Updates the values of calculated pressure, pressure margin, flow rate, velocity, etc.

STOREHYDRAULICRESULT( )

Stores the current the result of Gestar as if it were an instant of an evolution over time. This lets you apply alarms and see all the hydraulic properties of the network when the execution of the script finishes.


546

RANDOMFLOW (FLOW, %FLOW, ALWAYSOPENARRAY, ALWAYSCLOSEARRAY )

This function randomly sorts homogeneous probabilities depending on the input parameters.

FLOW: indicates the numeric value of the desired flow rate. If Null, %Flow must be numeric.

%FLOW: percentage of desired flow rate, in relation to the installed rate. If Null, Flow must be numeric.

ALWAYSOPENARRAY: labels of the unconditionally Open hydrants. A Null value means there are none.

ALWAYSCLOSEARRAY: labels of the unconditionally Closed hydrants. A Null value means there are none.

RANDOMOPENING (OPENING, %OPENING,ALWAYSOPENARRAY ,ALWAYSCLOSEARRAY )

This function randomly sorts homogeneous probabilities depending on the input parameters.

OPENING: indicates the numeric value of the number of open hydrants. If Null, %Opening must be numeric.

%OPENING: percentage of the number of open hydrants compared to the desired total. If Null, Flow must be numeric.

ALWAYSOPENARRAY: labels of the unconditionally Open hydrants. A Null value means there are none.

ALWAYSCLOSEARRAY: labels of the unconditionally Closed hydrants. A Null value means there are none.

TEXTFILE (COMMAND , ARGUMENT )

This function lets you create and write Strings in text files.

COMMAND: String indicating the action to be taken.

“Create” : creates a text file with the name of the string traversed by the variable Argument.

“WriteLine”: writes a line in the text file with the string traversed in the variable Argument.

“Close”: closes the text file.


547

APPENDIX XIII. HELP IN CREATING SETTINGS

Creating settings is a useful tool for conditioning certain actions during a simulation with evolution over time. This would be the case of opening and closing pumps over time in a system. In order to help users to understand how settings work in GESTAR and to enable the programme to create them autonomously, this appendix offers an example of creating a setting. There is an irrigation reservoir with a water level of 4.5 metres, fitted with a water raising pump. The contracted time-of-use electricity prices establish two time brackets: peak hours (from 08:00 to 14:00) and cheap hours (from 14:00 to 08:00). The aim is to generate a deterministic scenario with evolution over time (p. 304). Results will be obtained for the interval calculated, for the following variables: Reservoir Level, Total Head, Consumed Flow Rate and Net Volume Supplied from the starting instant of the simulation, and results referring to the power parameters of the pump stations.

FIG. AXIII. 1. Basic Components of the Practical Example.

We want the water in the reservoir to maintain a high level, specifically, between 3.5 metres and 4.2 metres. In order to keep the water at this level, the pump will start when the reservoir level is lower than 3.5 metres and will stop working when it is over 4.2 metres.

However, during peak times (between 08:00 and 14:00) we want to reduce water transfers as much as possible, so during this period the reservoir level will be allowed to fall below 3.5 metres, to a set minimum of 2 metres. Once at this level, the pump will


548

start again, maintaining the water level between 2 metres and 2.5 metres during this time bracket, when consumption is more expensive. Thus, after 14:00, when consumption is cheaper, the pump will again raise the water level. FIGURE AXIII.2 gives a visual rendering of what reservoir levels under these conditions would look like.

FIG. AXIII. 2 Visual schema of required reservoir levels

For this case, GESTAR has a set of examples called Worked examples. They can be

accessed via toolbar through the icon Open network . Select this option to start the search for the route of these files. By default, the programme installs them on the hard disc in the installation folder, in a folder called Worked example. The current example uses the file Worked _example_step7_complete_system_Tevolution( edu-premium).red.

Once the network is open it will be analysed in a sequence over time. In the example case, the simulation over time was previously configured, and a Pattern of Demand was generated considering the type of Electricity Price contracted, called Time_evolution_Worked_example. mdb. (saved by default to the folder C:/Program Files/ Gestar 2012/Worked Example).

The Evolution over Time tool can be accessed from the toolbar via this icon . Once this window is open (FIGURA9.14 Ventana de Configuración de la Evolución

Temporal.), choose the enabled option Patterns. Via the Open pattern icon , FIG. AXIII. 3, you can load the pattern Time_evolution_Worked_example.mdb.,


549

FIG. AXIII. 3. Patterns of Demand Window with the Example Pattern loaded.

You can now define a series of commands which affect the course of the simulation, in order to fulfil the required conditions. To do this, choose the option Settings, at the top of the Patterns of Demand window (FIG. AXIII. 3

).

FIG. AXIII. 4 Settings Window.

Two methods are established for defining the Settings (FIG. AXIII. 4): programming them using the GESTAR internal programming language, or using the Assistant.

• The pump will start with a reservoir level between 3.5 metros and 4.2 metros from 14:00 to 08:00 (cheap hours), in order to maintain a high reservoir level which will be used in peak hours.

The conditions requested for the settings in the example case can be summarised thus:

• The pump will start working, if needed, with a reservoir level of 2 metros to 2.5 metros from 08:00 to 14:00, trying to keep electricity use to a minimum during these hours.

The user must be familiar with the characteristics of GESTAR’s programming language (described in detail in APPENDIX XII; p ¡Error! Marcador no definido.). The script or command file of the settings in the example case will look like the text transcribed below, so it can be interpreted by GESTAR.

Adding Settings with the GESTAR Programming Language


550

13.7.1 EXAMPLE CASE SETTINGS COMMAND FILE

if "0" Level > 4.2 Then [ Close "BOM2" ; ] else if "0" Level < 2 Then [ Open "BOM2" ; ] else [ if Time>07:59 & Time<14:00 Then [ if "0" Level > 2.5 Then [ Close "BOM2" ; ] else [ Set "BOM2" IsOpen To "BOM2" IsOpen ; ] ] else [ if "0" Level < 3.5 Then [ Open "BOM2" ; ] else [ Set "BOM2" IsOpen To "BOM2" IsOpen ; ] ] ] Using the Add option, the settings script can be written directly in the window in FIG. AXIII. 4, or can be saved in a text file and opened using the option Load (see GENERATING DETERMINISTIC SCENARIOS WITH TEMPORAL EVOLUTION, p. 281).


551

Adding Settings with the Assistant

FIG. AXIII. 5 Assistant Settings Window.

The user must give a Name to each setting, which will identify it in the list of settings (FIG. AXIII. 4), once the setting has been defined and the option Accept has been selected in the Assistant (FIG. AXIII. 5). The example simulation requires two settings, one for each Action needed in these conditions: Open pump and Close pump. (The result would create four settings, one per necessary Condition). NOTE: ONLY ONE ACTION CAN BE EXECUTED PER SETTING. In the Action field the text will appear of the action executed by the setting depending on what was selected in the drop-down menus Conditioned Action, Type of Node or Element and Identifier. This operation coincides with the setting field Condition.

As mentioned above, the example case requires the pump to start working when the reservoir level goes below 2 metres in any case, and below 3.5 metres in the cheap hours. To do this, a setting is created as follows: An action must be created, which will be: Open Pump BOM1 yes. The user can simply choose options from the drop-down tabs as needed for each case and click the Copy button. In this case, as shown in FIG. AXIII. 5, for this action the words to be chosen are Open, corresponding to the action we want, Pump, affecting the node where the action will happen, and BOM1, the name identifying the node where the action will happen. Conditions are created in a similar way. In the example we want to create a condition: the level in reservoir 0 is less than 2


552

metres. Thus, we choose Level, the variable to be modified, Reservoir, the element the variable modifies, 0, the number identifying the element, Less than, which is the chosen setting or condition, and 2, the value of the setting. Next, as in the Actions, click the Copy button. It is possible that the user can make a mistake while entering the actions and conditions, so the same window gives the option of changing the Logical Expression of the setting and deleting the action or conditions; by clicking the option Edit, which will be accessible in the last field of FIG. AXIII. 5. However, we not only need to turn on the pump when the reservoir water level is lower than 2 metres, but also when it is lower than 3.5 metres, in hours outside the 08:00 - 14:00 bracket. Therefore we will add another condition to the list: the level in reservoir 0 is less than 3.5 metres, as long as the time is no greater than 8:00 or less than 14:00. From the field Operators you can Copy the logical operators needed to relate the conditions correctly. Similarly, we must generate a new setting, as we want to avoid the pump running above 4.2 metres, and during peak times, above 2.5 metres. Therefore we add the action Close Pump BOM1 yes; and the remaining necessary conditions: the level in reservoir 0 is greater than 4.2 metros and the level in reservoir 0 is greater than 2.5 metres when the time is no greater than 8:00 and the time is less than 14:00. Once a list of settings has been configured and you have clicked Accept in the Settings window, they will be taken into account in calculating the Evolution over Time, so that when an instant meets any of the conditions of the settings, the corresponding action will take place in the next instant. .

Results

Finally, once the settings are created, the button Accept is clicked in the Settings window and the Pattern window, and the Run button in the first temporal evolution window. This will give the result in an evolution over time window as seen in FIGURE AXII.9 . Thus, each interval of the simulation can be analysed.

FIGURE AXII.9 Results window, evolution over time.

GESTAR also offers the possibility of obtaining graphs of temporal evolution in the components acting in the simulation. To obtain this graph, right-click on the element for which you want to see the graph. A pop-up menu will appear (FIGURE AXII.10 ) giving the option to choose the desired temporal evolution graphs.


553

FIGURE AXII.10 Contextual menu of the reservoir in the example. .

In the example shown here, the reservoir level appears as a determining factor in the system and as such the graph representing the level is shown in FIGURE AXII.11.

FIGURE AXII.11 Temporal evolution graph of reservoir 0 level.


554

REFERENCES

ALIOD, R.; EIZAGUERRI, A.; ESTRADA, C.; PERNA, E. (1997): “Métodos convencionales y avanzados para el diseño y análisis hidráulico de redes de distribución a presión en riego a la remanda” Riegos y Drenajes Siglo XXI, nº 22, Enero 1997.

ALIOD, R., EIZAGUERRI, A.; ESTRADA, C. (1998). “Development and validation of hydraulic modelling tools for pressurised irrigation networks”. Hydroinformatics ’98. Vladan Babovic & Lars Christian Larsen, Danish Hydraulic Institute, Horsholm, Denmark, 545-552.

ALIOD, R & GONZÁLEZ, C. (2007): “A computer model for pipe flow irrigation problems”. Numerical modelling of hydrodynamics for water resources – García-Navarro & Playán (eds). Taylor & Francis Group, London, ISBN 978-0-415-44056-1.

ALIOD, R.; ESPERANÇA, M; GONZÁLEZ, C.; MARZAL, A.; VAQUERO, V. (2007): “Comparativa de los Resultados de diversos algoritmos de dimensionado óptimo de redes ramificadas en redes colectivas de riego a presión”. Actas del XXV Congreso Nacional de Riegos. Pamplona (Navarra)

DUFF, I. F.; ERISSMAN, A. M.; REID, J. K. (1986): “Direct methods for sparse matrices.” Oxford Science, Oxford, United.Kingdom.

ESPERANÇA .M. (2007). “Procedimientos de optimización del diseño y regulación del

bombeo con inyección directa en sistemas de riego a presión”. Tesis Doctoral del Departamento de Ciencia y Tecnología de Materiales y Fluidos. Área de Mecánica de Fluidos. Universidad de Zaragoza.

ESTRADA, C.; GONZÁLEZ, C.; ALIOD, R.; PAÑO J. (2009): “Improved Pressurized

Pipe Network Hydraulic Solver for Applications in Irrigation Systems” J. of Irrigation and Drainage Engng, Vol. 135, No. 4, August 1, 2009

GARCÍA S.; ALIOD R.; PAÑO J.; MARZAL A.; PRAT R.; LÓPEZ-CORTIJO I., ESQUIROZ J.C., EDERRA, I.; (2008): “Aplicación de las nuevas herramientas implementadas en gestar 2008 para la evaluación fiable de la regulación y los costes energéticos en estaciones de bombeo directo”. XXVI Congreso Nacional de Riegos. Huesca (Huesca).

GARCÍA S. (2009): “Herramientas y metodologías avanzadas en Gestar 2008 para el diseño hidráulico integral de redes de riego a presión con bombeo directo” Proyecto Fin de Carrera. EPS Huesca.


555

GONZÁLEZ, C. & ALIOD, R. (2003). “Mejoras en el método de la serie económica para el dimensionado de redes ramificadas”. Actas del XXI Congreso Nacional de Riegos. Mérida (Badajoz).

GONZÁLEZ, C. & ALIOD, R. (2005): “Modelización integrodiferencial de la hidráulica de un elemento con consumo en ruta dependiente de la presión y alimentado por los dos extremos”. Actas del XXIII Congreso Nacional de Riegos Elche (Alicante).

GONZÁLEZ, C., M. ESPERANÇA, A, ALIOD, R., MARTÍNEZ, I, GARCÍA, S. (2005) “Resultados de la Generalización y Mejora de las Rutinas de Dimensionado Óptimo, Mediante el Método de la Serie Económica, Implementadas en GESTAR”. Actas del XXIII Congreso Nacional de Riegos. Elche (Alicante).

GUILLÉN, J; BESCOS, M.; DOZ, J.M.; MARZAL, A., ALIOD, R. (1998): “Metodologías y resultados para la validación y calibración de modelos hidráulicos de redes de distribución a la demanda”. Riegos y Drenajes Siglo XXI, nº 102, Septiembre 1998

IDAE. (2008). “Protocolo de auditoria energética para las comunidades de regantes”. Ministerio de Industria.

LABYE, Y., OLSON, M.A., GALAND, A., TSIOURTIS, N. (1988): “Design and optimization of irrigation distribution networks”. FAO Irrigation and Drainage paper. Food and Agriculture Organization of the United Nations.

LÓPEZ-CORTIJO, I.; ESQUIROZ, J.C.; ALIOD, R.; GARCÍA, S. ( 2007): “Determinación de los costes energéticos en el cálculo de redes a presión con bombeo directo”. XXV Congreso Nacional de Riegos. Pamplona (Navarra).

PAÑO, J.,

RAO, H.; BREE, D. (1977): “Extendend Period Simulation of Water Systems Part A” ASCE, Journal of the Hydraulics Division, Vol 103, nº HY2, Proc. Paper, pp. 97-108.

GARCÍA, S., ALIOD, R., GONZÁLEZ, C. (2009). “Evaluación y optimización de costes energéticos en regadíos a presión mediante Gestar 2009”. Riegos y Drenajes XXI. Nº 167. Mayo Junio 2009

ROLDÁN, J.; PULIDO-CALVO, I.; LÓPEZ-LUQUE, R.; ESTRADA, J.C.G.;. (2003) Water Delivery System Planning, considering irrigation simultaneity. ASCE, Journal of Irrigation and Drainage Engineering, Vol 129, nº4, pp 247-255

.UPV (1993): “Curso de diseño hidráulico de redes de riego. Unidad Docente Mecánica Fluidos”. Unidad Docente Mecánica de Fluidos. Universidad Politécnica de Valencia.

UPV (1999): “DIOPCAL, descripción y uso de la aplicación”. Grupo de Investigación y Desarrollo de Modelos Hidráulicos. Departamento de Ingeniería Hidráulica. Universidad Politécnica Valencia.


556

WARRICK, A.W. & YITAYEW, M. (1988): “Trickle lateral hydraulics I; analytical solution”. J. Irrigation and Drainage Engng 114 (2) pp. 281 - 288.

0

ManualGESTAR2014 English

Documents

Transcript of ManualGESTAR2014 English