Technical Project Guide Marine Application Part1 - General

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Technical Project GuideMarine Application

Part 1 - General


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TPG-General.doc 06.2003Rev. 1.0

MTU Friedrichshafen GmbH

Ship Systems Technology

Commercial

D-88040 Friedrichshafen

Germany

Phone +49 7541 90 - 0

www.mtu-friedrichshafen.com

Assistance:

MTG Marinetechnik GmbHD-22041 Hamburg

Germany

MTG Ref.: 679/335/2100 - 001

Phone +49 40 65 803 - 0

www.mtg-marinetechnik.de

Technical Project Guide

Marine Application

Part 1 - General

June 2003

Revision 1.0

The illustrations herein are presented with kind permission of the companies listed below.Rolls-Royce AB www.rolls-royce.com S-681 29 Kristinehamn SwedenSchottel GmbH & Co. KG www.schottel.de D-56322 Spay/Rhein GermanyVoith Schiffstechnik GmbH & Co. KG www.voith-schiffstechnik.de D-89522 Heidenheim GermanyZF Marine GmbH www.zf-marine.com

D-88039 Friedrichshafen Germany


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User Information

TPG-General.doc Page I 06.2003Rev. 1.0

USER INFORMATIONThis Technical Project Guide- is supposed to give the user general references for theplanning, design and the arrangement of propulsion plants and on-board power generationplants. Precise information on the different diesel engine series are to be taken from thespecific engine parts.

Following engine parts are planned/available:

Technical Projekt GuideMarine Application

Part 1 - General


Part 2 - Engine Series 2000


Part 3 - Engine Series 4000


Part 4 - Engine Series 8000(later on)

+

+

+


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Contents

CONTENTSChapter Title Page

TPG-General.doc Page III 06.2003Rev. 1.0

6.4 Propeller and Performance Diagram 6-26 6.4.1 Driving Mode 6-26 6.4.2 Fixed Pitch Propeller (FPP) 6-29 6.4.3 Controllable Pitch Propeller (CPP) 6-31

6.5 Waterjet and Performance Diagram 6-36 6.5.1 Geometry and Design Point 6-36 6.5.2 Estimation of Size and Shaft Speed 6-41

6.6 Fuel Consumption 6-42 6.6.1 General Assumptions 6-42

6.6.2 Operating Profile 6-44 6.6.3 Fuel Consumption at Design Condition 6-49 6.6.4 Cruising Range 6-50 6.6.5 Endurance at Sea 6-51 6.6.6 Calculating Examples 6-52 6.6.6.1 Example Data (Series 2000) 6-52 6.6.6.2 Fuel consumption at design condition 6-54 6.6.6.3 Fuel tank volume for a range of 500sm at 18kn 6-55 6.6.6.4 Theoretical cruising range at 12kn and fuel tank volume of 5m 3 6-56 6.6.6.5 Annual fuel consumption for an operating profile 6-57 6.6.6.6 Correcting the lower heating value 6-58

6.7 Generator Drive 6-59

7 APPLICATION AND INSTALLATION GUIDELINES 7-1

7.1 Foundation 7-1

7.2 Engine/Gearbox Arrangements 7-2 7.2.1 Engine with Flange-Mounted Gearbox (F-Drive) 7-2 7.2.2 Engine with Free-Standing Gearbox, V Drive Inclusive 7-3

7.3 Generator Set Arrangement 7-6 7.3.1 Engine with Free-Standing Generator 7-6 7.3.2 Engine with Flange-Mounted Generator 7-7

7.4 System Interfaces and System Integration 7-8 7.4.1 Flexible Connections 7-8 7.4.2 Combustion Air and Cooling/Ventilation Air Supply 7-11 7.4.2.1 Combustion-air intake from engine room 7-11 7.4.2.2 Combustion-air intake directly from outside 7-11 7.4.2.3 Cooling/ventilation air system 7-11 7.4.3 Exhaust System 7-12 7.4.3.1 Arrangements, support and connection for pipe and silencer 7-12 7.4.3.2 Underwater discharge (with exhaust flap) 7-13 7.4.3.3 Water-cooled exhaust system 7-14


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Contents


TPG-General.doc Page IV 06.2003Rev. 1.0

7.4.4 Cooling Water System 7-15 7.4.4.1 Cooling water system with engine-mounted heat exchanger 7-15 7.4.4.2 Cooling water system with separately-mounted heat exchanger 7-16 7.4.4.3 Central cooling water system 7-17 7.4.5 Fuel System 7-18 7.4.5.1 General notes 7-19 7.4.5.2 Design data 7-19 7.4.6 Lube Oil System 7-22 7.4.7 Starting System 7-23 7.4.7.1 Electric starter motor 7-23

7.4.7.2 Compressed-air starting, compressed-air starter motor 7-24 7.4.7.3 Compressed-air starting, air-in-cylinder 7-25 7.4.8 Electric Power Supply 7-28

7.5 Safety System 7-29

7.6 Emission 7-30 7.6.1 Exhaust Gas Emission, General Information 7-30 7.6.2 Acoustical Emission, General Information 7-32 7.6.2.1 Airborne noise level 7-32 7.6.2.2 Exhaust gas noise level 7-34 7.6.2.3 Structure-borne noise level 7-35

7.7 Mounting and Foundation 7-42 7.8 Acoustic Enclosure/Acoustic Case 7-43

7.9 Mechanical Power Transmission 7-44

7.10 Auxiliary Power Take-Off 7-47

7.11 Example Documents 7-48

8 STANDARD ACCEPTANCE TEST 8-1

8.1 Factory Acceptance Test 8-1

8.2 Acceptance Test According to a Classification Society 8-1 8.2.1 Main Engines for Direct Propeller Drive: 8-1 8.2.2 Main Engines for Indirect Propeller Drive 8-1 8.2.3 Auxiliary Driving Engines and Engines Driving Electric Generators 8-1

8.3 Example Documents 8-2

9 CONTROL, MONITORING AND DATA ACQUISITION (LOP) 9-1

9.1 Standard Monitoring and Control Engine Series 2000/4000 9-1

9.2 Engine Governing and Control Unit ECU-MDEC 9-2

9.3 Engine Monitoring Unit EMU-MDEC Separate Safety System 9-2

9.4 Local Operating Panel LOP-MDEC 9-2

9.5 Propulsion Plant Management System Version 9-3 9.5.1 Manufacturer Specification 9-3 9.5.2 Classification Society Regulation 9-4


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Contents


TPG-General.doc Page V 06.2003Rev. 1.0

10 MAINTENANCE CONCEPT / MAINTENANCE SCHEDULE 10-1

10.1 Reason for Information 10-1

10.2 Advantages of the New Maintenance Concept: 10-1

10.3 New Maintenance Schedule: 10-1 10.3.1 Cover Sheet 10-1 10.3.2 Maintenance Schedule Matrix 10-2 10.3.3 Task List 10-3

11 ASSEMBLING INSTRUCTIONS (LIFTING, TRANSPORTATION) 11-1

12 TRANSPORTATION, STORAGE, STARTING 12-1

13 PILOT INSTALLATION DESCRIPTION (PID) 13-1


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List of Figures

List of FiguresFigure Title Page

TPG-General.doc Page VI 06.2003Rev. 1.0

Figure 1.2.1: Engine designations (sides, cylinders, direction of rotation) 1-2

Figure 1.3.1: Structure of the MTU EXTRANET 1-3

Figure 3.3.1: Typical Standard Load Profiles 3-3

Figure 3.4.1: TBO definition of MTU 3-4

Figure 4.2.1: Fuel specification 4-1

Figure 4.2.1: Structure of the performance diagram 5-1

Figure 4.2.2: Engine performance diagram 5-3

Figure 4.2.3: Monohull 5-4

Figure 4.2.4: Semi-planing boat hull = high speed monohull with medium displacement 5-4

Figure 4.2.5: Multihulls = catamarans, trimarans, 5-5

Figure 4.2.6: Semi-planing boat hull = high speed monohull with low displacement 5-5

Figure 6.1.1: Scheme of a propulsive unit (side view) 6-1

Figure 6.2.1: Scheme of propeller geometry (skew and rake) 6-10

Figure 6.2.2: Propeller clearance 6-12

Figure 6.3.1: Influence of change in resistance on effective power curve (example) 6-19

Figure 6.3.2: From effective to delivered power curve (example) 6-20

Figure 6.3.3: Effect of change in resistance on delivered power curve (example) 6-21

Figure 6.3.4: Effect of different propeller pitches on delivered power (example) 6-22

Figure 6.4.1: Change in delivered power due to weather, draught and fouling 6-26

Figure 6.4.2: Diesel engine failure in a two shaft arrangement 6-27

Figure 6.4.3: Choosing a design point for a fixed pitch propeller 6-29

Figure 6.4.4: CPP characteristic in a typical diesel engine performance diagram 6-31

Figure 6.4.5: Controllable pitch propeller design point 6-32

Figure 6.4.6: Example: Single shaft operation with CPP 6-34

Figure 6.4.7: Example: Constant speed generator in operation with CPP 6-35

Figure 6.5.1: Waterjet 6-36

Figure 6.5.2: Waterjet design point (Diagram has limited use for waterjet design) 6-37

Figure 6.5.3: Platform with pump 6-38

Figure 6.5.4: Waterjet performance diagram 6-39

Figure 6.5.5: Estimating the size of a waterjet (inlet duct diameter) 6-41

Figure 6.5.6: Estimating the design impeller speed of a waterjet 6-41


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List of Figures


TPG-General.doc Page VII 06.2003Rev. 1.0

Figure 6.6.1: Examples of operating profiles (freighter, fast ferry, OPV) 6-45

Figure 6.6.2: Examples of operating profiles (freighter, fast ferry, OPV) 6-46

Figure 6.7.1: Power definition 6-60

Figure 6.7.1: Engine room arrangement, minimum distance 7-1

Figure 7.2.1: Engine with flange-mounted gearbox 7-2

Figure 7.2.2: Engine with free-standing gearbox 7-3

Figure 7.2.3: Engine with free-standing gearbox and universal shaft, V drive arrangement 7-5

Figure 7.3.1: Engine with free-standing generator 7-6

Figure 7.3.2: Engine with flange-mounted generator 7-7

Figure 7.4.1: Connection of rubber bellows 7-10

Figure 7.4.2: Cooling water system with engine-mounted heat exchanger (Split-circuit coolingsystem) 7-15

Figure 7.4.3: Cooling water system with separately-mounted heat exchanger (e.g. keel cooling) 7-16

Figure 7.4.4: Central cooling water system 7-17

Figure 7.4.5: Fuel System 7-18 Figure 7.4.6: Evaluation value for max. fuel inlet temperature 7-20

Figure 7.4.7: Lube oil system 7-22

Figure 7.4.8: Starting system with pneumatic starter motor 7-25

Figure 7.4.9: Starting system with air-in-cylinder starting 7-26

Figure 7.4.10: Electric power supply 7-28

Figure 7.6.1: Limitation of NO x-emission (IMO) 7-30

Figure 7.6.2: Test cycle for Constant Speed Main Propulsion application (including diesel

electric drive and variable pitch propeller installation) 7-31

Figure 7.6.3: Test cycle for Propeller Law operated Main and Propeller Law operated AuxiliaryEngines application 7-31

Figure 7.6.4: Test cycle for Constant Speed Auxiliary Engine application 7-31

Figure 7.6.5: Test cycle for Variable Speed, Variable Load Auxiliary Engine application 7-31

Figure 7.6.6: Engine surface noise analysis (example) 7-33

Figure 7.6.7: Undamped exhaust gas noise analysis (example) 7-34

Figure 7.6.8: Single resilient mounting system with shock 7-37

Figure 7.6.9: Double resilient mounting system for extreme acoustic requirements 7-39


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List of Figures


TPG-General.doc Page VIII 06.2003Rev. 1.0

Figure 7.6.10: Examples for different Quiet Systems, structure-borne noise levels below theresilient mountings (e.g. diesel engine 20V 1163) 7-40

Figure 7.6.11: Structure borne noise analysis at engine feet, above rubber mounts (example) 7-41

Figure 7.9.1: Combined diesel engine and diesel engine 7-44

Figure 7.9.2: Combined diesel engine and diesel engine with separate gear compartment 7-44

Figure 7.9.3: Combined diesel engine or gas turbine 7-45

Figure 7.9.4: Combined diesel engine and gas turbine 7-45

Figure 7.10.1: Power take-off (PTO), gear driven 7-47

Figure 9.5.1: Propulsion Plant Management System version in accordance with manufacturerspecification 9-3

Figure 9.5.2: Propulsion Plant Management System version in compliance with classificationsociety regulations 9-4

Figure 10.3.1: Example of a maintenance schedule matrix 10-2

Figure 10.3.2: Example task list 10-4


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1 General

TPG-General.doc Page 1-1 06.2003Rev. 1.0

1 GENERAL1.1 Introduction

MTU Friedrichshafen in Germany and Detroit Diesel Corporation in the USA, twoDaimlerChrysler Group companies, have combined their off-highway operations. Withproduct ranges of MTU and DDC plus Mercedes-Benz engines under one roof, a world-leading supplier of engines and systems for the marine, rail, power generation, heavy-dutymilitary and commercial-vehicle as well as agricultural and construction-industrymachinery sectors has been created. All marine engines are under the brand MTU.

Especially within the shipping sector the company has established a long and successfulpartnership with hundred thousands of engines in operation around the globe on all seas.Based on its innovative capabilities, its reliability and system competence, MTU disposesof unique drive system know how and offers a large range of products of excellent quality.MTU develops, manufactures and sells diesel engines in the 200 to 9000 kW power range(for more information refer to publication SALES PROGRAM MARINE).

This publication has been compiled as a source of information only. It contains generallyapplicable notes for planning and installation of marine propulsion plants and electricpower plants.

Non-standard design requirements (i.e. applicable to the design of individual componentsor entire systems) such as may be specified by the operator or by classification societiesare not taken into consideration in the scope of this publication. Such requirementsnecessitate clarification on case-to-case basis.

Project-related or contract-related specifications take precedence over the generalinformation appearing in this publication, because the project-specific or contract-specificdata are of course applicable to the particular application and the overall propulsionconcept.


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1 General


1.2 DesignationsThe DIN 6265 respectively ISO 1204 designations are used to identify the sides andcylinders of MTU engines. Details are explained in Figure 1.2.1.

Figure 1.2.1: Engine designations (sides, cylinders, direction of rotation)

Driving end = KS ( Kupplungs s eite)

Free end = KGS ( Kupplungs gegen s eite)

Left-bank cylinders = A1, A2, A3, ..., A7, A8

Right-bank cylinders = B1, B2, B3, ..., B7, B8


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1 General


1.3 Special Documents PresentedSpecific information and documents are found in the MTU EXTRANET. The structure of theEXTRANET with its essential components is represented in the following diagram.

Figure 1.3.1: Structure of the MTU EXTRANET

Back to Start of Chapter Back to Contents


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3 Specification of Power and

Reference Condition


2 DEFINITION OF APPLICATION GROUPS2.1 General

In addition to general application by usage, e.g. marine vessel, the particular applicationmust be taken into account for selecting the correct engine.

The choice of the application group determines the maximum possible engine power andthe anticipated time between major overhauls (TBO). Load varies during operation, withthe result that the TBO is dependent on the actual load profile and varies from differentapplications.

For an optimum selection of the engine taking into account the maximum power availablethe following information should be obtained from the operator:

Application, e.g. yacht, patrol boat, ferry, fishing vessel, freighter etc. Load profile (engine power versus operating time)

Anticipated operating hours per year

Preferred time between overhauls (TBO, for special cases only)

The terms load profile and TBO and the relationship between them are explained indetail in chapter

3 Specification of Power and Reference Condition- and

10 Maintenance Concept / Maintenance Schedule-.

If no specific load profile information is available from the operator, the selection of theengine is performed on the basis of the standard load profile determined by MTU by meansof typical application. The MTU Sales Program distinguishes for the marine applicationpropulsion engines and marine auxiliary engines and engines for the on-board supply ofelectricity. The following application groups are subdivided into in detail.


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Reference Condition


2.2 Marine Main Propulsion and Auxiliary Propulsion Plants1A Vessels for heavy-duty service with unlimited operating range and/or

unrestricted continuous operationAverage load : 70 90 % of rated power

Annual usage : unlimited

Examples : Freighters, Tug Boats, Fishing Vessels,Ferries, Sailing Yachts, Displacement Yachtswith high load profile and/or annual usage

1B Vessels for medium-duty service with high load factors

Average load : 60 to 80 % of rated power

Annual usage : up to 5000 hours (as a guideline)Examples : Commercial Vessels, including Fast Ferries,

Crew Boats, Offshore Supply & ServiceVessels, Coastal Freighters, MultipurposeVessels, Patrol Boats, Displacement Yachts,fan drive for Surface Effect Ships

1DS Vessels for light-duty service with low load factors

Average load : Less than 60 % of rated power

Annual usage : Up to 3000 hours (as a guideline)

(Series 2000 & lower power engines approx. 1000 hours)

Examples : High speed Yachts, Fast Patrol Boats, Fire-Fighting Vessels, Fishing Trawlers, Corvettes,Frigates

Significant deviations from the above application groups should be discussed with theresponsible application engineering group.

2.3 On-Board Electric Power Generation/Auxiliary Power

3A Electric power generation, continuous duty (no time restriction), e.g. diesel-

electric drive, diesel-hydraulic drive or drive for fire fighting pumps

3C Electric power generation for onboard standby power generation, e.g.emergency power supply or drive for emergency fire fighting pumps



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Reference Condition


3 SPECIFICATION OF POWER AND REFERENCE CONDITION3.1 Definition of Terms

The available power for a specific engine type and application group is listed in the SalesProgram.

3.1.1 ISO Standard Fuel-Stop Power (ICFN)The rated power of marine main propulsion engines of application group 1A, 1B and 1DS isstated as ISO standard fuel-stop power, ICFN, in accordance with DIN ISO 3046.Measurement unit is kW.

I = ISO power

C = Continuous powerF = Fuel stop power

N = Net brake power

The fuel-stop power rating represents the power that an engine can produce unlimitedduring a period of time appropriate to the application, while operating at an associatedspeed and under defined ambient conditions (reference conditions), assumingperformance of the maintenance as specified in the manufacturers maintenanceschedule.

Power specifications always express net brake power, i.e. power required for on-engine

auxiliaries such as engine oil pump, coolant pump and raw water pump is alreadydeducted. The figure therefore expresses the power available at the engine output flange.

The engines of application group 1A and 1B can demonstrate 10 % overload in excess ofrated fuel-stop power for the purposes of performance approval by classification societies.

Fuel stop power of the engines in application group 1DS cannot generally beclassified.

Some classification societies accept the certification of engines of application group 1DSfor special service vessels with specific load profiles. In case of such a request, therespective application engineering group should be contacted.

Before delivery, all engines will be factory tested on the dynamometer at standard ISOreference conditions (intake air and raw water temperature 25C).

Acceptance test procedures at MTU:

MTU works acceptance test Acceptance test in accordance with classification society regulations under supervision

of the customer

As a rule, marine main propulsion engines are supplied with power limited to fuel-stoppower as specified in the Sales Program.


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Reference Condition


3.1.2 ISO Standard Power Exceedable by 10 % (ICXN)The rated power of marine onboard power generation of application group 3A and 3C isstated as ISO standard power exceedable by 10 %, ICXN, in accordance withDIN ISO 3046. Measurement unit is kW.

I = ISO power

C = Continuous power

X = Service standard power, exceedable by 10 %

N = Net brake power

3.2 Reference ConditionsThe reference conditions define all ambient factors of relevance for determining enginepower. The reference conditions are specified in the Sales Program and on the applicableengine performance diagram.

ISO 3046-1 standard reference conditions:

Total barometric pressure : 1000 mbar or (hPa)

Air temperature : 25 C (298 K)

Relative humidity : 30 %

Charge air coolant temperature : 25 C (298 K)


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Reference Condition


3.3 Load ProfileThe load profile is a projection of the engine operating routine. The following standard loadprofiles have been established in the past, based on accumulated field experience withspecific vessels and a huge number of recorded load profiles.

Standard Load ProfileApplication Group

applied powerin % of rated power

operating time in %

100 10

80 50

60 20

1A

(all engines except 4000 M60R)

< 15 20

100 20

90 701A

for V4000M60R only< 15 10

100 751B

up to and incl. Series 4000 < 15 25

100 3

85 82

1B

above Series 4000< 15 15

100 10

70 701DS

< 10 20

Figure 3.3.1: Typical Standard Load Profiles

If there is a significant difference between the actual and standard load profiles, MTUcalculates the TBO on the basis of the load profile submitted by the customer.

All MTU engines can be operated at fuel-stop power as long as required by the customer.Of course, extensive operation at fuel stop power (higher load profile) will shorten the timebetween maintenance intervals.


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Reference Condition


3.4 Time Between Major Overhauls (TBO)Up to now, the TBO for diesel engines is not specified in any international standard.Therefore each engine manufacturer uses his own definition for TBO.

Figure 3.4.1: TBO definition of MTU

According to MTU, the TBO is defined to be the time span in which operation withoutmajor failure is ensured, i.e. it precludes wear-related damage requiring a major overhaul

or engine replacement.This time span is theoretically reached, if a probability of wear-out failures exceeds 1% (so-called B1 definition). This means that an MTU engine can still provide full and unlimitedservice until the last operating hour before the scheduled overhaul.

The major criterion for a ship is availability and thus the reliability of the propulsion. Basedon this, MTU decided to limit the statistical wear-out failure rate to 1 % only.

TBO definition from other engine manufacturersIn contrast to MTUs TBO definition, some other manufacturers define a scheduled TBO ata wear-out failure rate of 10% or up to 50% (B10 or B50 definition). This means, thatstatistically up to 50% of all engines do not reach the pre-defined TBO without majorfailure.

F a

i l u r e

r a

t e

Operating time

TBO MT UMaintenance Echelon W6

Early failures 1 Random failures Wearout failures

1 Probable start-up failures


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Reference Condition


Load Profile RecorderMost engines in the MTU Sales Program do include a load profile recorder as an integralpart of the Electronic Engine Management System.

This device continuously records the operating time spent at certain power levels andspeeds, together with several other important engine parameters.

The load profile could be downloaded from the Electronic Engine Management System andanalysed. In case of significant deviations between the recorded load profile and theassumed load profile, the TBO could be revised.

The finally applicable TBO will also take into account the actual engine condition as aresult of installation conditions, quality of fluids and lubricants and service.



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4 Fluids and Lubricants

Specification


4 FLUIDS AND LUBRICANTS SPECIFICATION4.1 General

The fluids and lubricants used in an engine are among the factors influencingserviceability, reliability and general operability of the propulsion plant.

Only fluids and lubricants approved by MTU may be used with MTU products. MTU issues alist of approved fluids and lubricants, for engine operation and engine preservation i.e.

lubricants (oils, greases and special-purpose lubricant substances) coolants (corrosion-inhibiting agents, anti-freeze agents) fuels preserving agents (corrosion-inhibiting oils for use in and on the engine)

The MTU approved fluids and lubricants as well as the requirements which they mustsatisfy are listed in the currently applicable MTU Fluids and Lubricants Specification.

MTU Fluids and Lubricants Specification (A001061/..) is available.

An operator wishing to use a fluid or lubricant that is not included in the Fluids andLubricants Specification must consult MTU.

4.2 MTU Approved Fuels

MGO/MDO according ISO 8217EN 590

DM DMA DMB DMC

Density at 15C kg/m 3 880-890 900 920

Lower calorific value kJ/kg

Figure 4.2.1: Fuel specification

( under preparation )



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5 Engine Performance Diagram


5 ENGINE PERFORMANCE DIAGRAMThe engine performance diagram serves as the basis for a number of calculations, but oneof its most important functions is to indicate the speed and power limits that must beobserved for propeller and waterjet design.

Figure 4.2.1: Structure of the performance diagram

I II : Status, sequential turbocharging

II UMBL : The engine operating values can be further optimized by employment of someblowing over facilities within the ATL-connection (ATL = tubocharger). Afterconnection of the second ATL, air charge is blown over to the exhaust linecontrolled by the engine electronics in order to increase the mass flow ratethrough the turbine. In combination with the improved situation of theworking line with reference to the compressor efficiency a higher loading-pressure and consequently an improvement of the engine operating values isobtained.

Engine speed[rpm]

Engine power [kW]

Min. engine

Speed (low idle)

Nominal speed = 100%

Speed band of

constant power

Limit of MCR

Nominal power = 100%

Propeller curve= power demand (P ~ n)

Power surplus(acceleration reserve)

I

II

IIUMBL

ATL switching border line


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Base for the layout of the performance diagram:

Application group (1A, 1B, 1DS) Reference conditions Definition of power rating and fuel consumption Time between overhauls/operating load profile

The engine performance diagram shows engine power plotted against engine speed. It alsoincludes the specific fuel consumption curves and operating-speed range limits, along withall other boundary conditions. Figure 4.2.2 shows a representative engine power diagram.


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Figure 4.2.2: Engine performance diagram


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Figure 4.2.5: Multihulls = catamarans, trimarans,

Figure 4.2.6: Semi-planing boat hull = high speed monohull with low displacement



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6 Propulsion, Interaction Engine

with Application


6 PROPULSION, INTERACTION ENGINE WITH APPLICATION6.1 Propulsor6.1.1 Abbreviations

The following abbreviations will be used in section 6. In the majority (marked with anasterisk) they are according to recommendations of the ITTC Symbols and TerminologyList, Draft Version1999 (International Towing Tank Conference).

Figure 6.1.1: Scheme of a propulsive unit (side view)

Symbol Name Definition or Explanation SI Unit

ITTC

B Fuel consumption m 3/h

D * Propeller diameter M

Hu Lower heating value or lowercaloric value

Lower heating value of fuel(preferred value 42800 kJ/kg)

kJ/kg

PB * Brake power Power at output flange of the diesel engine,power delivered by primer mover.

W

PD * Delivered power or propellerpower, propeller load

Power at propeller flange. W

PE * Effective power or resistancepower

Power for towing a ship. W

PS * Shaft power Power measured on the shaft. Poweravailable at the output flange of a gearbox. Ifno gearbox fitted: P S = P B

W

PS Generator apparent power W

Pp Generator active power W

RT * Total resistance Total resistance of a towed ship. N

T * Propeller thrust or waterjetthrust

N

Diesel EngineGearbox

PSPDPB

Propeller


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with Application


6.1.2 Propulsive Devices (Overview)The duty of a propulsive unit is to convert the power of the diesel engine into propulsivethrust. A propulsive device can be a:

Type General Characteristics

Fixed Pitch Propeller(FPP)

Ease of manufacture

Small hub size

Blade root dictates boss length

Design for single condition (design point)Absorbed power varies with propeller speed

No restriction on blade area or shape

Gearbox: reversing gear needed

Controllable PitchPropeller (CPP)

Constant or variable speed operation

Blade root is restricted by palm dimensions

Mechanical complexity

Restriction on blade area to maintain reversibility

Can accommodate multiple operating conditions

Increased manoeuvrability

Gearbox: if fully reversible no reversing gear needed

Waterjet Good directional control of thrust

Increased mechanical complexity

Avoids need for separate rudder


Diesel engine load independent of wind and sea stateHigh speed range (approx.>20 kn)

Gearbox: no reversing gear needed, but usually used toallow back flushing of water (reverse mode)


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with Application


Type General Characteristics

Rudderpropeller Good directional control of thrust

Increased mechanical complexity

Avoids need for rudder


Can employ ducted or non ducted FPP or CPP types

Low speed range (approx.


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with Application


Type Typical Arrangements

Fixed Pitch Propeller(FPP)

Controllable PitchPropeller (CPP)

Waterjet

Rudderpropeller

Cycloidal Propeller


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with Application


Type Typical Arrangements

Twin-Propeller

Podded Propulsion


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with Application


Type Manoeuvring Characteristics

Fixed Pitch Propeller(FPP) Power demand: fixed relation between ship speed and

diesel engine power. Clear dependenceon hull resistance.

Ship speed: adjusting diesel engine speed.Astern: reversible gearbox.Control: not applicable.Gearbox: free standing, flange mounted,

V-drive arrangement.Rudder: needed.

Controllable PitchPropeller (CPP) Power demand: every possible pitch has its own fixed

relation to the effective power curve.Clear dependence on hull resistance.

Ship speed: adjusting diesel engine speed orpropeller pitch.

Astern: reversible gearbox or fully reversiblepropeller.

Control: hydraulic power pack arranged in shaftline or at the gearbox.Gearbox: free standing, flange mounted.Rudder: needed.

WaterjetPower demand: fixed relation between shaft speed and

diesel engine power. Small dependenceon hull resistance.

Ship speed: adjusting diesel engine speed.Astern: reversing bucket (optional).

Control: hydraulic power pack for steering andreversing bucket.

Gearbox: free standing, flange mounted.Rudder: if no steering equipment at waterjet.


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with Application


Type Manoeuvring Characteristics

RudderpropellerPower demand: fixed relation between ship speed and


Ship speed: adjusting diesel engine speed.Astern: turning the propeller pod.Control: hydraulic power pack for steering.Gearbox: standard.Rudder: no need.

Cycloidal PropellerPower demand: every possible blade pitch has its own

fixed relation to the effective powercurve. Clear dependence on hullresistance.

Ship speed: adjusting diesel engine speed or bladepitch.

Astern: control of thrust direction via bladepitch.

Control: hydraulic power pack.Gearbox: standard.Rudder: no need.

Twin-PropellerPower demand: fixed relation between ship speed and


Ship speed: adjusting diesel engine speed.Astern: turning the propeller pod.Control: hydraulic power pack for steering.Gearbox: standard.Rudder: no need.

Podded PropulsionPower demand: full electric propulsion, fixed relation

between ship speed and electric motor.Clear dependence on hull resistance.

Ship speed: adjusting motor speed (electrical).Astern: turning the pod or reversing the motor.Control: hydraulic power pack for steering.Gearbox: no need.Rudder: no need.


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6.1.3 Shaft Line and Gearbox LossesThe brake power (P B) of the diesel engine will be transferred via a shaft line to the propellerflange. All power consumers in the shaft line will be counted as mechanical losses ( m).The main loss will occur in the gearbox depending on how many gears and clutches areused and how many pumps are attached, where at the pumps will generate the main partof the losses.

B

Dm P

P= in (---) (E- 6.1.1)

PB = diesel engine brake Power

PD = delivered Powerm = mechanical efficiency

At the design point the following approximations can be used:

m = 0.98 non reversible gearboxm = 0.97 reversible gearbox

Information about the losses in the gearbox must be provided by the manufacturer.

The diesel engine has to deal with two different kinds of mechanical losses:

1. Static friction loss (no oil film yet)

2. Dynamic friction loss (built up oil film)

The dynamic friction losses in the shaft line bearings (


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6.2 Propeller6.2.1 Propeller Geometry

To understand the hydrodynamic action of a propeller it is essential to have a thoroughunderstanding of basic propeller geometry and the corresponding definitions. Figure 6.2.1shows what is meant by rake and skew of a propeller. The use of skew has been shown tobe effective in reducing vibratory forces, hull pressure induced vibration and retardingcavitation development. With rake the stress in the blade can be controlled and slightlythinner blade sections can be used, which can be advantageous from blade hydrodynamicconsiderations.

Figure 6.2.1: Scheme of propeller geometry (skew and rake)

Every propeller needs a hub to fix the blades and to place the control mechanism (CPP) forthe blades. This results in different hub sizes for a FPP and a CPP (propeller) and is acharacteristic difference between these two types. The hub size of a CPP is 10 to 15%larger (related to the diameter). See the figures in the overview section (6.1.2) also.

Another difference is the blade area ratio (A/A 0). Blade area ratio is simply the blade area,a defined form of the blade outline projection, divided by the propeller disc area (A 0). As acontrollable pitch propeller is usually fully reversible in the sense that its blades can passthrough zero pitch condition care has to be taken that the blades do not interfere witheach other. With equal number of blades a CPP can only realize a somewhat smaller arearatio than a FPP.

Skew

Rake

Diameter

Hub

Rotation


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The expression (P/D) is the commonly used pitch ratio. Alternatively the pitch angle canbe given. With

R2D = andRr

x = (dimensionless radius)

the characteristic pitch angle is defined at a propeller ratio of x=0.7. Unfortunately thereare several pitch definitions and the distinction between them is of considerableimportance to avoid analytical mistakes:

1. nose tail pitch

2. face pitch

The nosetail pitch line is today the most commonly used and referenced line. The facepitch line is basically a tangent to the section of the pressure side surface and used inolder model test series (e.g. the Wageningen B Series). Although the difference is not big itcan be the reason for using different values for the same propeller.

The following equation can be used to convert the pitch from P/D to or vice versa.

=

xD

Ptanarc 1


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To determine the propeller diameter (D) for a certain delivered power (P D) at a propellerspeed (n) and a ship speed (v) is a complex routine. For the Wageningen B-Series

propellers there are some calculation procedures available, which can be found in theliterature with all necessary assumptions that have to be made.

The size of a propeller cannot only be calculated theoretically, but must also be adapted tothe ship. The ship must provide the necessary space for the propeller including a sufficientclearance between propeller and hull (Figure 6.2.2). Due to hydrodynamic effects and/orcavitation the ship hull and the rudder can be mechanically excited, which can cause heavyvibrations at the stern or the rudder with the possibility of mechanical failures.

The values shown in Figure 6.2.2 are only a design proposal. For more detailed informationsee the recommendations of a classification society.

A few words to the effect of thrust breakdown. The power density of a propeller can onlybe increased to a certain limit, which depends on the propeller parameters and especiallyon the blade area ratio. Obviously the cavitation occurs first at the tip section of a bladeand extends downward with higher power consumption. It is a matter of definition whenthese effects are called thrust breakdown, e.g. if the cavitation exceeds below the 0.5radius.


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6.2.3 Direction of Propeller RotationThe direction of rotation can have consequences for manoeuvring and efficiencyconsiderations. Although the given explanations in literature are not really convincing thefollowing recommendations can be given:

Single shaft: (looking from aft at propeller)

FPP (fixed pitch propeller)

Direction of rotation: clockwise

CPP (controllable pitch propeller)

Direction of rotation: counter clockwise


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Twin shaft: (looking from aft at propeller)

FPP (fixed pitch propeller)

Port side: counter clockwise Starboard: clockwise

CPP (controllable pitch propeller)

Port side: clockwise Starboard: counter clockwise

For those who are still eager to hear a few words about the reasons for doing so, hereare some explanations from literature.

Propeller efficiency:It has been found that the rotation present in the wake field, due to the flow around theship, at the propeller disc can lead to a gain in propeller efficiency when the direction ofrotation of the propeller is opposite to the direction of rotation in the wake field.

Manoeuvring (single screw):

For a single screw ship the influence on manoeuvring is entirely determined by thepaddle wheel effect. When the ship is stationary and the propeller is started, thepropeller will move the afterbody of the ship in the direction of rotation. Thus with a


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6.2.4 Selection of Propeller Blade NumberBlade numbers generally range from two to seven. For merchant ships four, five or sixblades are favoured, although many tugs and fishing vessels frequently use three bladeddesigns. In naval applications where the generated noise become important bladenumbers of five and above predominate.

The number of blades shall be primarily determined by the need to avoid harmful resonantfrequencies of the ship structure and torsional machinery vibration frequencies. As bladenumber increases cavitation problems at the blade root can be enhanced, since the bladeclearance becomes less.

It is also found that propeller efficiency and optimum diameter increase as the number ofblades decreases and to some extent, the propeller speed (n) will dependent on the bladenumber.


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6.3 Propeller Curve6.3.1 Basics

When a ship is being towed and is not fitted with a propeller, the required force is calledresistance (R) and the necessary power to tow the ship at a certain speed (v) is:

vRP TE = in (kW) (E- 6.3.1)

PE = effective PowerRT = total resistancev = ship speed

Basis for the design of a propulsive device is the effective power (P E) curve for a ship,showing the relation between effective power and ship speed (v). The effective powercurve will be evaluated by a test facility or estimated with respect to a defined condition,i.e. usually the trial condition:

new ship, clean hull sea state 0-1 (calm water), wind Beaufort 2-3 load condition (defined, e.g. full load)

no current

The load of the propulsive device to match the effective power is called deliveredpower (P D) and the relation between the effective and delivered power is called thepropulsive efficiency ( D).

D

ED P

P= in (---) (E- 6.3.2)

D = propulsive efficiencyPE = effective PowerPD = delivered Power


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The propulsive efficiency is the product of:

Propulsive unit efficiency in open water ( 0)depending on type, size, speed, e.g.(at design point approx. 0 = 0.60 0.75).

Hull efficiency ( H)depending on wake fraction and thrust deduction fraction(at design point approx. 0.90 1.10).

Relative rotational efficiency ( R)depending on the propeller efficiency behind the shipand the propeller open water efficiency(at design point approx. 0.95 1.02).

RHOD = in (---) (E- 6.3.3)

The effective power varies not only with ship speed (v). Environmental conditions (wind,sea state), hull roughness (clean, fouling) and actual load condition of the ship have to betaken into consideration (Figure 6.3.1).

Figure 6.3.1: Influence of change in resistance on effective power curve (example)

Ship Speed (v)

E f f e c

t i v e

P o w e r

P E

effective pow er curve(in service)

ship speed diff erenceat const. Powe r (P E)

pow er diff erence atconst. Speed (v)

effective pow er curve(clean hull)


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Effective Power Curve

Propeller DesignThe result of the propeller design can be presented in a bunch of diagrams.

Figure 6.3.2: From effective to delivered power curve (example)

On the basis of a defined effective power curve a propeller will be designed. The relationbetween delivered power (P D) and ship speed (v) or propeller speed (n) can be shown insingle diagrams or a diagram using both ordinates. Figure 6.3.2. shows some examples.

The diagram with the propeller speed (n) as abscissa has the advantage that theperformance diagram of the diesel engine can be plotted in also.

Ship Speed (v)

E f f e c t

i v e

P o w e r

( P E

)

Ship Speed (v)

D e l i v e r e d

P o w e r

( P D

)

Propeller Speed (n)

D e l i v e r e

d P o w e r

( P D

)

As Required

A s

R e q u i r e

d

user defined


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Every change in the effective power curve will be seen in the propeller curve also. Theexample in Figure 6.3.3 shows that due to the cubic characteristic of the propeller curve

small changes can have great effects.

Figure 6.3.3: Effect of change in resistance on delivered power curve (example)

Although the curves in Figure 6.3.1 and Figure 6.3.3 are similar in shape they are different.

The effective and the delivered power will be related by the propulsive efficiency ( D). Thismeans that the propeller curve is only valid for the designed propeller. Changing thegeometry of the propeller (e.g. diameter, area ratio, pitch or the number of blades) leads toa new power-speed relation, i.e. a new propeller curve. If the effective power curvechanges, e.g. from clean hull and fair weather to fouled hull and heavy weather thepropeller curve will also change.

That leads to the conclusion: A change in the propeller curve can be initiated by the ship(effective power) or by a modification of the propeller.

Propeller Speed (n)

D e l i v e r e d

P o w e r

P D

propeller curve(in service)

propeller curve(clean hull)

pow er diff erence at const.Propeller Speed (n)

propeller speed differenceat const. Powe r (P D )


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FPP: The propeller curve has a fixed relation to the effective power curve and will beinfluenced by the ship (effective power) only.

CPP: Every possible pitch has its own fixed relation to the effective power curve. Thisleads to a bunch of propeller curves (Figure 6.3.4). The propeller curve will beinfluenced by the ship (effective power) and the propeller pitch.

Figure 6.3.4: Effect of different propeller pitches on delivered power (example)

This different behaviour will have distinct consequences on the design of the chosenpropeller type.

Propeller Speed (n)

D e l

i v e r e d

P o w e r

P D

CPP (Controllable Pitch Propeller)

propeller curves = lines of constant pitch

constant ship speed

pitch increases

design pitch


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6.3.2 Theoretical Propeller CurveDiameter (D), delivered power (P D) and shaft speed (n) of the propeller can be calculatedby the propeller manufacturer when the effective power curve is given and the designspeed (v) and the installed brake power (P B) have been chosen. Power and propellerspeed (n) have to match the installed power of the diesel engine.

If only the design point of the propeller or the diesel engine is known, a simpleapproximation can be done by a theoretical propeller curve.

3prop

design3

P

designDD n

n

PP

=

PD = delivered powernprop = propeller speedfixed propeller geometry

3

design3

designBB nn

PP

=

PB = diesel engine brake powern = diesel engine speedfixed propeller geometry

Diesel engine and propeller have a fixed relation via the propeller shaft and therefore theequation can be used for P B and P D as well.

There will be differences to the real curve, depending on the hull form (see chapter 5 also)

as the decisive factor, and taking into account that the propeller geometry is fixed. Thatmeans the approximation of a controllable pitch propeller is only valid for the design pitch.

There is another restriction for the lower speed range. Below a certain speed (v) the windforces can become dominant and the delivered power does not decrease any more.


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Something to remember: Cubical propeller curve, why n 3 ?

V = volume flowA =propeller disc areac = flow speedD = propeller diameter (constant for a given design)

Bernoulli equation (c 1=0)p = pressure

P = power

theoretical propeller curvepower is proportional to n 3 (propeller speed)

power is proportional to v 3 (ship speed)23

53

2

3

2

Dc~P

or Dn~P

:resultThe

VpP

2cp

Dn~V

:toleadsThis

Dnc4Dc AcV

=

=

===


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6.3.3 Estimating the Required Diesel Engine PowerIn some cases the required total diesel engine brake power (P B) for a ship has to beestimated in a very early stage of a project and only estimations of the effective power (P E)or the total Resistance (R T) are available.

With Equation (E- 6.1.1), (E- 6.3.1) and (E- 6.3.2) a rough estimation for the required totaldiesel engine brake power (P B) at ship speed (v) can be done.

mD

TB

5144.0vRP

= in (kW) (E- 6.3.4)

or

mD

EB

PP

= in (kW) (E- 6.3.5)

PB = total diesel engine brake power in kWPE = effective Power in kWRT = total resistance at ship speed (v) in kNv = ship speed in knot(0.5144 used to convert knot to m/s)D = propulsive efficiencym = mechanical efficiency

At the design point the following approximation can be used for the efficiencies:

m = 0.97D = 0.60

The result is the total diesel engine break power (P B) for the ship. This value must bedistributed onto the desired number of diesel engines.


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6.4 Propeller and Performance Diagram6.4.1 Driving Mode

Power (P D) and propeller speed (n) have to match the installed power for thepropulsion (P B). Only the sea trials show whether estimations are correct or not.

At this stage of evaluation a diesel engine has been selected and a design point inside theperformance diagram of the diesel engine has to be chosen. In addition to thehydrodynamic aspects (see Figure 6.3.2, Propeller Curve), manufacturing tolerances haveto be taken into account.

Manufacturing tolerance in pitch, surface and profile influence the power absorption ofthe propeller.

Hull resistance can vary due to inevitable differences in load and shape.

Figure 6.4.1: Change in delivered power due to weather, draught and fouling

Hydrodynamical and geometrical aspects (Figure 6.4.1) can shift the propeller curve ( A) tothe left side of the performance diagram ( C). Certain models of diesel engines are moresensitive to this shifting than others. As a consequence, the ship may not be able tooperate at full speed when the hull has fouled, the weather deteriorates or the draught hasincreased.

60

70

80

90

100

110

120

80 85 90 95 100 105 110

Propeller rpm in ( % ) Rated Speed

B r a

k e P o w e r

P B

i n ( % ) R a t e d

P o w e r

propeller curve

MCR curve 11

2

3

A

B

C

MCR curve 2

5

100% = rated pow er100% = rated speed


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In Figure 6.4.1 two diesel engines (MCR curves 1 and 2) from various manufacturers withdifferent performance limits are shown. A change in the propeller curve from ( A) to ( C)

leads to the following behaviour:A The diesel engine can run with full speed (n). No limitation arises (point 1). But the

propeller does not absorb the maximum available power.

B The diesel engine can run with full speed (n) and reach its full power. No limitationarises (point 2).

C Due to the load limits (MTU: fuel stop power) both diesel engines are not able toprovide the required power for full speed (n) at point (3). In this case the dieselengines reduce their speed (n) in order to find a new operation point within theperformance limits. For the diesel engine with MCR curve 1 this is point (4) and forthe other diesel engine point (5). The differences between the two operatingpoints (4) and (5) are the magnitude of reduction in ship speed (v) which can beconsiderably high.

A similar behaviour is experienced in a two-shaft arrangement which has been switchedover in a single shaft mode. Figure 6.4.2 shows the arrangement with diesel engines of thesame type one per shaft. The output power has been added over the speed range (MCRcurve 1) and the propeller curve running through point 1. Each diesel engine takes half theload of the required brake power (P B).

Figure 6.4.2: Diesel engine failure in a two shaft arrangement

MCR curve 2 shows the available brake power (P B) of one diesel engine. If one dieselengine is shut down, the effective power of the ship relates to one propeller instead of twowith the consequence of a new propeller curve (single shaft propeller curve).

0

20

40

60

80

100

120

20 30 40 50 60 70 80 90 100 110


B r a

k e

P o w e r

P B

i n ( % ) T o

t a l R a

t e d P o w e r MCR curve 1

(2 diesel engines, one per shaf t)

MCR curve 2(single shaft)1 diesel engine

1

2

single shaftpropeller curve

tw o shaftpropeller curve

fixed pitchpropeller

100% = rated pow er

fixed pi tch propeller

100% = rated power100% = rated speed


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The running diesel engine has to find a new operating point on the single shaft propellercurve within its performance limits. In this example, point (2) is the new operating point for

the diesel engine. The point marks also the maximum available brake power (P B) (andspeed (n)) in the single shaft mode for this ship.

In case that the diesel engine finds no operating point it will stall. This will also point outthat with the chosen diesel engines the ship cannot be run in single shaft mode. In thiscase a CPP has to be selected.

These are some reasons why the design point of the diesel engine should be carefullyspecified with respect to the load limits and the kind of propeller (FPP, CPP) that is to beused.


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The design allows the propeller to run at 100% rated power (P B) as long as the propellercurve does not pass point 4 (lugging point). The maximum ship speed (v) will decrease

slowly with the left shifting of the propeller curve towards point 3.

Standard procedure (usable for all type of diesel engines):

Point 1: Preferred/recommended design point for the propeller.

In the design point the propeller runs at 100% rated speed (n) and small amount (designmargin) below 100% rated power. In this case at trial condition the diesel engine iseffectively working at a derated condition (point 1, trial effective power curve = propellercurve A). In poorer weather or with growing lifetime the propeller curve will move to theleft and the maximum power will be used (point 2, propeller curve B).

The design allows the propeller to run at 100% rpm (rated speed) as long as the propellercurve does not pass point 2. The ship speed (v) will increase with the shifting of thepropeller curve and reaches its maximum at point 2.

Using this procedure the designer has to consider that it may be not possible todemonstrate the full speed (v) capability of the ship at trial conditions, because thespeed (n) of the diesel engine is limited to 100% rated speed.

The difference between 100% rated power and design power is called "sea margin"(= design margin). If there are no specific demands, a design margin of approx. 6 to 10%shall be used. The rated power will be met by propeller curve A at 102 to 103.5% ratedspeed but this is only theoretical.

Summary:

Both procedures or a mixture can be used for choosing the design point of a fixed pitchpropeller and a flat rated diesel engine. If the application demands no specific propellerdesign point, the MTU recommendation shall be used (point 2 = primary design point forthe propeller).

No matter what design point is chosen the propeller curve runs on a fixed curve through

the performance range of the diesel engine. So, a few additional aspects shall not beforgotten:

If the delivered power curve through the design point does not pass through the regionof minimum fuel consumption, no change will be possible afterwards.

If the power curve comes too close to the diesel engine surge limits, the curve cannotbe moved away from this region with the result of a blocked operation range.


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6.4.3 Controllable Pitch Propeller (CPP)The controllable pitch propeller can be seen as an extension to the fixed pitch propeller.Each pitch results in a new propeller curve. A typical example is shown in Figure 6.4.4where the controllable pitch propeller characteristic is superimposed on a diesel enginecharacteristic.

Figure 6.4.4: CPP characteristic in a typical diesel engine performance diagram

Every change in the pitch of the propeller changes the relation between propeller speed (n)and brake power (P B) for the ship.

Due to possible later adjustment of the propeller pitch there are no restrictions for thedesign point within the diesel engines performance diagram. The point at 100% brakepower (P B) and speed (n) should be chosen (Figure 6.4.5).

The available pitch range is not fixed. It is a part of the customers specification for thepropeller. On the manufacturers side it is limited by the size of the hub and the maximumblade forces. Generally the available pitch range will be related to the design pitch and begiven in degrees. The range above the design pitch is very small because there is nogeneral need, except in special applications.

0

20

40

60

80

100

20 40 60 80 100


B r a

k e P o w e r

P B

i n ( % ) R a t e d

P o w e r

controllable pitch propeller

100% = rated power100% = rated speed


constant ship speed

MCR curve

pitch increases

design pitch


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Figure 6.4.5: Controllable pitch propeller design point

The performance of a CPP at design pitch can be calculated like a FPP. When off designperformance is needed use should not be made of fixed pitch characteristics beyond 5

from design pitch because the effect of section distortion affects the calculationconsiderably.

The controllable pitch gives a lot of options:

If the delivered power curve through the design point (design pitch) does not passthrough the minimum fuel consumption region, it is possible to adjust the pitch atpartial load conditions.

If the power curve comes too close to the diesel engine MCR limit, the operating curvecan be moved away from this region.

If the ship during trials is not able to achieve the design brake power (P B) the designpitch can be corrected or when the ship resistance increases with service life, thedesign brake power (P B) and speed (n) will stay available.

A CPP can be chosen with a fully reversible position and the ship can move asternwithout the need of a reversing gearbox. The stopping distance will be significantlylower than with a FPP. Generally the manoeuvring characteristics are better.

A CPP can be chosen with a feathering position (minimum resistance), if a single shaftmode is part of the operational profile.

60

70

80

90

100

110

80 85 90 95 100 105 110


B r a

k e P o w e r

P B

i n ( %

) R a

t e d P o w e r

propeller curve(design pitch)

MCR curve

controllable pitch propeller


design point


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But you have to pay for the advantages:

The controllable pitch propeller is more expensive than a FPP.

If the propeller will be set out of the design pitch the efficiency decreases.

Additional space inside the ship has to be provided for the propeller control unit.

Due to its internal mechanism the propeller has a bigger hub than a FPP (approx. 50%),this can lead to a somewhat higher diameter.

If the propeller is fully reversible, care has to be taken that the blades will not interferewith each other when passing zero pitch. The upper blade area ratio will be limited.

There is an additional aspect that should be mentioned. If the diesel engine has a very

slender performance diagram, the design propeller curve will not lie inside the diagram forthe lower power range. This type of diesel engine can be used only with a propellercontrolled by a pitch RPM relationship, frequently called combinator diagram . Only inthe last third of the power range the propeller can run at design pitch.

Another reason is the access to the region of minimum fuel consumption. In doing so thepropeller can come very close to the diesel engine surge limits. A programmedcombinator diagram could give the best overall performance as well.

With an MTU diesel engine the propeller can run in combinator mode, however, this isnot necessary due to the wide performance range of the diesel engine.

Another application is a constant speed generator attached to the gearbox. The dieselengine runs at constant speed (n) feeding the generator and the ship speed (v) will becontrolled by the propeller pitch. This is a standard design for merchant ships runningmost of their service time at high power rates.


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In the next example (Figure 6.4.7) the pitch of a CPP will be controlled by combinator. Aconstant speed generator is attached to the gearbox and shall run above 50% diesel

engine load. In the lower power range the propeller shall run on design pitch. The thick linein the performance diagram shows the power-speed-pitch relation of the propeller.

In the lower power range until point 3 the CPP runs at design pitch. Between point 3 andpoint 2 the diesel engine speed will be raised with decreasing propeller pitch. The shipspeed will not change significantly. At point 2 the operating speed (n) for the attachedgenerator has been reached. Between point 2 and point 1 the diesel engine runs atconstant speed (n) feeding the propeller and the generator. The ship speed (v) will becontrolled by the propeller pitch.

Figure 6.4.7: Example: Constant speed generator in operation with CPP

0

20

40

60

80

100

40 60 80 100 120


B r a

k e P o w e r

P B

i n ( % ) R a t e d

P o w e r

CPP



constant ship speed

MCR curv e

pitch increases

design pitch

Generator operating range

1

2

3


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6.5 Waterjet and Performance Diagram6.5.1 Geometry and Design Point

The main application for a waterjet is in the higher speed range, lets say above 20 kn. Thepropulsive efficiency of a waterjet decreases considerably with speed (v) reduction. Below20 to 24 kn a propeller should be preferred.

A waterjet is like a propeller a hydrodynamical propulsive device but is arranged inside theship and behaves more like a pump than as a propeller.

1. Inlet duct 7. Thrust bearing2. Impeller 8. Steering deflector3. Stator bowl 9. Hydraulic steering cylinder4. Nozzle 10. Hydraulic bucket cylinder5. Shaft 11. Inspection opening6. Sealing box

Figure 6.5.1: Waterjet

Nozzle Pump Inlet

Impeller Stator

Height abovewater line

V = Ship speed

Cross section Effective inletvelocity

Inlet duct

Ship hull

Shaft

34

11 65910

8

1

2

7


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This relation can lead to the fact that at 100% shaft speed (n) the waterjet cannot absorbthe diesel engines brake power (P B). Therefore a design point at brake power and

approx. 1 - 2% below 100% diesel engine shaft speed (n) (design margin) shall be chosen(Figure 6.5.2, design point 1). If the propeller curve shifts to the left the ship speed (v) willdecrease but no change will be seen in Figure 6.5.2 because the waterjet is still runningwith its demanded speed (n) and brake power (P B). That is the reason why this diagram hasa limited use for choosing a waterjet design point. It will only give an impression about therelation between the propeller curve, the lines of constant fuel consumption, the designmargin and the margin to the diesel engine MCR limit curve. This relations will remainindependent of the ship load as before.

With this behaviour in mind design point 2 (Figure 6.5.2) can be chosen also. The leftmostdesign shaft speed (n) should be 1.5% above the speed (n) of the lugging point. Theadvantage is a less fuel consumption but the margin to the MCR curve (accelerationreserve) decreases.

Because this behaviour is very fundamental a further example shall be given.

Figure 6.5.3: Platform with pump

Imagine a platform on wheels with a water tank and a pump on its loading area (Figure6.5.3 ). The water will be ejected horizontally in the air opposite to the direction of motion.The platform will start to move on the ground and no matter how fast the platform willmove, the pump will always eject the same amount of water using the same power. This istrue also if an obstacle stops the platform. The pump will not be affected by the behaviourof the platform. In other words the generated thrust depends only on the amount of

ejected water. Although this is simplified, it shows the fundamental difference between apropeller and a waterjet. Let us take a step ahead. Even if there are two separated pumpson the loading area, they will not interfere which each other, independent whether they areor not of equal size or running at different power pumping different amounts of water.


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For this reasons another diagram has to be used which shows more consideration to thebehaviour of a waterjet (Figure 6.5.4).

Figure 6.5.4: Waterjet performance diagram

The figure shows the design propeller curve together with the waterjet performancediagram and instead of effective power the thrust is used. Because the ship speed (v) andthe engine speed (n) of the diesel are not related to each other the performance diagramof the diesel engine can not be represented in the figure.

A few words to the shown cavitation inception line: These lines are specific to the chosenwaterjet and should not be compared between different manufacturers. For instance,KaMeWa divides its diagrams by two lines into three zones, showing different stages ofcavitation. Generally these lines shall no be taken as absolute limits but as designguidelines.

If the propeller curve shifts to the left the ship speed (v) will decrease and the distance tothe cavitation inception limit will be reduced. The reason for this behaviour is that thestagnation pressure in the inlet duct goes down and the waterjet starts to suck the waterthrough the duct.

The thrust of a waterjet is the product of water mass flow and the speed of the ejectedwater. That means that a certain thrust can be generated by a smaller or a bigger waterjet.In the smaller one the speed of water is higher i.e. the distance between the design pointand the cavitation inception line is smaller also.

If there is limited space for installation or the operation time of the waterjet is short thedesigner will probably choose a small waterjet with a lesser distance to the cavitation area.

0

20

40

60

80

100

120

140

0 20 40 60 80 100

Ship Speed in ( % ) Rated Speed

T h r u s t

i n ( %

) R a

t e d T h r u s

t

Waterjet

constant brake pow er

propeller curve

cavitation inception limit

fuel stop pow er

design point


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The risk of getting air into the inlet duct of the waterjet depends on the specificarrangement in the ship and on the sea state. In this case the control system has toprotect the diesel engine from any overspeed and due to the low inertial mass of the shaftline it is more demanding than for a propeller. The matching MTU control system has beenadapted for this task.


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6.5.2 Estimation of Size and Shaft SpeedThe design shaft speed (n) of the waterjet depends on type, size and application and willbe provided by the manufacturer. If the installed brake power (P B) and the ship designspeed (n) are known Figure 6.5.5 and Figure 6.5.6 can be used for a quick look.

Figure 6.5.5: Estimating the size of a waterjet (inlet duct diameter)

Figure 6.5.6: Estimating the design impeller speed of a waterjet

10

20

30

40

50

0 5000 10000 15000 20000

Brake Power in (kW)

S h i p S p e e

d i n ( k n

)

0.5 1.0 1.2 1.4 m (size inlet duct)

2.0

2.4

0

200

400

600

800

1000

0,5 1,0 1,5 2,0 2,5

Inlet Duct in (m)

W a t e r

J e t S p e e d

i n ( m i n - 1 )

500 kW

Brake Pow er 500 kW 1000 kW 2000 kW 5000 kW 10000 kW 20000 kW

20000 kW


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6.6 Fuel Consumption6.6.1 General Assumptions

The calculation of the fuel consumption for the diesel engines depends on a lot ofassumptions. If the fuel calculation for a designed ship will be done by different people youwill get different results, if you do not have a good specification. Nevertheless the size ofthe fuel storage tanks is an important impact on the ship design.

The following values are required for calculation of the fuel consumption:(ref to chapter 6.6.6 for more detailed information)

1 Status and displacement of the ship (e.g. new ship, clean hull, full load)

2 Weather condition and sea state (e.g. wind Beaufort 2, sea state 2-3).

3 Ambient condition

4 Speed-power (ship speed (v) - brake power (P B)) diagram for assumed displacement,weather condition and sea state.

5 Propulsion plant and design condition (e.g. total installed brake power (P B) forpropulsion, ship speed (v), propeller shaft speed (n), number of diesel engines pershaft).

6 Performance diagram of the diesel engine including the lines of specific fuel

consumption for the required lower heating value (H u), otherwise the values have tobe corrected.

7 Lower heating value of fuel (e.g. H u = 42800 kJ/kg for diesel oil).

8 Fuel density (e.g. fuel=830 kg/m 3).9 Gear ratio if a gearbox is used (for the relation between propeller shaft speed and

diesel engine speed).

10 Fuel consumption of the diesel generator set runningwith a defined percentage of the installed mechanical power (e.g. all sets at 33%).

11 Usable volume of the fuel storage tank (e.g. 95%).

12 Operating profile (e.g. cruising speed (v) or speed profile).

It is obvious that an incomplete specification of these values can lead to calculationdifferences.


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The standard questions that arise in connection with fuel consumption are:

1. Fuel consumption at design condition.

2. The ship should run XXX sm on YY kn e.g. 1000sm on 12kn. The required fuelvolume can be a design value for the necessary fuel storage volume.

3. How long can the ship stay at sea for a given operating profile or the ship shall stayZZ days at sea with a given mission profile. The required fuel volume can be a designvalue for the necessary fuel storage volume.


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6.6.2 Operating ProfileThe time between leaving and entering a port can be divided into several portions of timeat constant speed ranges. Such list of time periods and speed ranges is called operatingprofile.

Each ship has a characteristic operating profile which is determined by the owner to meetthe commercial needs of the particular service. The result is a wide difference between theoperating profiles of various ship types, e.g. a freighter, a fast ferry and a OPV, and one ofthe reasons why the design basis for a particular vessel must be chosen with care.Nevertheless an operating profile can change throughout the life of a ship, depending on avariety of circumstances.

The operating profiles shown in Figure 6.6.1 and Figure 6.6.2 are very raw and shall onlygive an impression how such profiles can look like. Both operating profiles are equal. Theyare shown in different style for those who are not familiar with one of the presentations.


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Example: Freighter: Leaving the port and thenrunning continuously at design speed.

Example: Ferry: Nearly the same as a freighter butwhen operating between islands thereare often speed restrictions.

Example: OPV: The shown tasks are at loiteringspeed (maybe embargo control), cruisingspeed (cruising in formation) and fastmanoeuvring.

Figure 6.6.1: Examples of operating profiles (freighter, fast ferry, OPV)

0

20

40

60

80

100

Time in (%) Operating Time

S p

e e

d i n ( % ) R a

t e d S p e e

d

Fast Ferry

0 20 40 60 80 100

0

20

40

60

80

100


S p e e

d i n ( % ) R a

t e d S p e e

d

Offshore Patrol Vessel

0 20 40 60 80 100

0

20

40

60

80

100


S p e e

d i n ( % ) R a

t e d S p e e

d

Freighter

0 20 40 60 80 100


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Example: Freighter: Leaving the port and thenrunning continuously at design speed.

Example: Ferry: Nearly the same as a freighter butwhen operating between islands thereare often speed restrictions.

Example: OPV: The shown tasks are at loiteringspeed (maybe embargo control), cruisingspeed (cruising in formation) and fastmanoeuvring.

Figure 6.6.2: Examples of operating profiles (freighter, fast ferry, OPV)

0

20

40

60

0 - 25 25 - 50 50 - 70 70 - 85 85 - 100

Speed Range in (%) Rated Speed

T i m e

i n ( % ) O p e r a

t i n g

T i m e

Fast Ferry

0

20

40

60

0 - 25 25 - 40 40 - 70 70 - 85 85 - 95 >95

Speed Range in (%) Rated Speed

T i m e

i n ( % ) O p e r a t

i n g

T i m e

Offshore Patrol Vessel

0

20

40

60

80

100

10 5 10 75


S p e e

d i n ( % ) R a

t e d S p e e

d

Freighter


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The owner should specify the operating profile, the operating hours per year and thenumber of missions per year. A mission is the time period needed to run one operating

profile.In the design phase this specification can be used to calculate the fuel consumption fordifferent propulsion alternatives, the TBO and as a first guess for the life cycle cost.

Example of a user defined operating profile for a ship in tabulated form:

Operating Profile (Ship)

Ship Speed (kn) Time Period (%)

0 9 159 - 15 35

15 - 21 40

21 max. 10

Generally, speed ranges will be shown in a operating profile, but for the calculation of thefuel consumption precise speed values have to be given, otherwise the results are notcomparable. From that follows the brake power of the diesel engine e.g. at the upperbound of the given speed ranges.

Example: Owner defined operating profile for a diesel engine:

Operating Profile (Diesel Engine)

Brake Power(%)

Time Period(%)

3 15

18 35

74 40

100 10

On the basis of such a operating profile the available TBO for the chosen diesel enginerating can be calculated.

0

20

40

60

80

100


B r a

k e P o w e r

i n ( % )

0 20 40 60 80 100


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Alternatively, if the owner has not the experience to prepare a operating profile, the fuelconsumption can be calculated on the basis of the standard load profile of the chosen

diesel engine rating (e.g. 1A ,1B or 1DS).

More information about load profile and TBO see chapter 2 and 3.

Example: 1DS diesel engine rating (TBO 9000h)

Operating Profile (Diesel Engine)

Brake Power

(%)

Time Period

(%)10 20

70 70

100 100

20

40

60

80

100


B r a

k e P o w e r

i n ( % )

0 20 40 60 80 100


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6.6.3 Fuel Consumption at Design ConditionWith the provided information (see section 6.6.1) the fuel consumption at a given brakepower (P B) and diesel engine speed (n) can be calculated. If no tolerances are given in thefuel consumption diagram, a margin of 5% has to be added to the calculated value.

fuel

eB bPB= in (m 3/h) (E- 6.6.1)

be = specific fuel consumption (kg/kWh)B = fuel consumption (m 3/h)PB = diesel engine brake power (kW) fuel = fuel density (kg/m3)

Additional consumers, e.g. gensets have to be added to calculat

Technical Project Guide Marine Application Part1 - General

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