Hydraulics Lab Manual
Transcript of Hydraulics Lab Manual
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CE
Hydraulics
Laboratory Manual
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CE Hydraulics
Experimental Lab No.1
FLOWS IN PIPE NETWORKS
Purpose: To study and compare head losses in various pipe systems.
Apparatus: Fluid Circuit System
Procedure:1. Remove air from manometers
2. Arrange the circuit to run test on pipes 1, 2, and 3 in series (do not use the smallest pipe).Take comparative measurements for each of the three, 66 inch lengths of pipe at 3 flow
rates.
3. Repeat (2) rearranging the pipes into a parallel configuration.
Report:
1. Present data in both tabular and graph forms, that is plot headloss versus discharge for
each pipe system.
2. What conclusions can you draw about head losses in the various pipes of each system?
3. What is the effect of putting the pipes in parallel as compared to series?
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CE Hydraulics
Experimental laboratory #2
CENTRIFUGAL PUMP
Purpose: Develop the characteristic curve for a centrifugal pump.
Theory: A centrifugal pump imparts energy to a fluid by developing a centrifugal force
through the action of vanes on the fluid. The discharge from a centrifugal pump, run at constant
speed (rpm), depends on the head looses of the system against which it is pumping. A plot of thehead difference (in head) across the pump vs. the discharge at that head difference is the pump
characteristic curve.
Apparatus: To perform this experiment, the following materials are required: a centrifugalpump, a water tank, a pressure gage, a tachometer, a stopwatch, a graduated cylinder, and a scale
or ruler.
Procedure:
1. With the storage tank filled to a level above the pump inlet, open all valves fully andbring the pump to full speed (approx. 1750 rpm). The speed is read on the tachometer (in
rpm x 10).
2. Measure the flow using a stopwatch and graduated cylinder or bucket as required.
3. Observe the pressure difference across the pump and the elevations of the pump inlet and
outlet.
4. Repeat steps 2 and 3 at least four more times (once with the valve completely closed),
closing the gate valve slightly each time causing a pressure difference to increase. Allowthe system to reach a new equilibrium before each measurement.
5. Repeat steps 2 through 5 for pump speeds of 1500 and 1200 rpm.
Report:
1. Plot the pump characteristic curve for each pump speed and discuss the relationshipbetween head and discharge.
2. Compute the water horsepower at each flow rate and head difference.
3. Discuss the accuracy of the method used to determine the flow rate and head difference
across the pump. Estimate the magnitude of any suspected error.
4. Discuss how you would develop an experiment to evaluate the efficiency of the pump.
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CE HydraulicsExperimental laboratory #3
HYDRAULIC JUMP
Objective: To observe and understand the characteristics of the hydraulic jump and the sluicegate used in the flume to create conditions allowing the jump to occur.
Apparatus: Flume and sluice gate.
Theory: The hydraulic jump occurs when flow transitions from supercritical to subcritical
flow in an open channel. It is a case of rapidly varied, steady flow. In a horizontal, rectangular
channel, the sequent (downstream) depth is related to the initial (upstream) depth by the equation:
where y2 is the initial depth, y3 is the sequent depth, b is the width of flume and Q is the flow rate.
In the laboratory flume, the initial depth is produced using a sluice gate which controls the flow
under the gate (the initial depth in the hydraulic jump) based on the depth of flow upstream ofthe gate, y1, as shown below. The sluice gate is analyzed using the energy equation.
Procedure: For each of three flow rates (160, 220 and 275 gpm) and associated sluice gateopenings (1", 1" and 2") observe y1, y2 and y3.
Analysis and Report:
a. For the measured depths, y1, y2 and y3, determine if the flow is subcritical or
supercritical.
b. For each of the measured values of y2, calculate the theoretical value of y3 and
compare to the observed value.
c. For each flow rate, plot the specific energy curve and identify the depths of
interest. (y1, y2, y3, yc)
d. Compute and plot the energy losses in the jump for each sluice gate opening and
plot as a function of flow rate.
e. For each sluice gate opening, compute the losses occurring in flow under thesluice gate and plot as a function of flow rate.
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CE HydraulicsComputational Lab No. 1
SOLUTION OF NONLINEAR EQUATIONS IN THE ANALYSIS OF PRESSURIZED
PIPEFLOW
Objective: Determining either the flow-rate or pipe diameter for a pressurized pipe systemrequires the solution of a nonlinear equation. Depending on the resistance equation and
whether there are significant minor losses, the resulting nonlinear equation may have to
be solved repeatedly as part of the solution process. The objective of this lab is to use anonlinear equation solver of your choice to solve a pressurized pipe flow problem, to
compare the process and results of using two different resistance equations and to
evaluate the effects of some modifications in the piping system.
Approach: Develop a general equation for determining the flow rate in the pressurized
piping system shown in Figure 1 given data on the system configuration (pipe material,
diameter, length, layout, minor loss coefficients, pressure requirements, etc.) for twocases: where the head loss is computed by the Darcy-Weisbach and the Hazen- Williams
equations. Given the resulting nonlinear equation, select an approach for solution (e.g.
Solver in Excel, MATLAB program). Test the approach on an appropriate exampleproblem in the text. Once you are sure your process provides the correct solution, apply it
to the system presented in Figure 1.
Report: Describe the development of the equation for Q and define all of the variables
(but present only the original equation(s) and the resulting equation that you develop).
Provide a detailed description (e.g. a flow diagram) of the procedure used to solve theproblem. Reference the values you used to describe the piping system including selection
of minor loss coefficients, resistance coefficients, etc. In the report you should present the
flow rate as a function of valve opening in graphical form for both resistance equations
and for all three pipe configurations (3 graphs, properly labelled). In the discussioncomment on the effect of the resistance equation and the effect of changing the pipe
diameter and material on the flow rate computed for the system.
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Solve this problem:The piping system in a typical dwelling in an older home is shown below. The exit diameter of
the faucet is -inch. All of the piping is galvanized iron and the fittings are threaded. Pressure inthe main is 40 psi (gage).
1. Determine the flow rate, using both the Darcy-Weisbach and the Hazen-Williamsequation, when the faucet valve is fully open, open, open and open.
2. Using only the Hazen-Williams equation, determine the effect on the flowrate of
replacing the section of pipe with a 1 pipe.
3. Using the Hazen-Williams equation, determine the impact on the flowrate of replacing
the4. galvanized pipe in the original problem with copper tubing of the same diameter.
Data for the globe valve (from White, 5th edition, 2003)
Fractional opening K/K open1.00 1.03
0.70 1.38
0.50 1.75
0.30 3.75
1.00 1.03
0.70 1.38
0.50 1.75
0.30 3.75
Figure 1: Portion of a household plumbing system for which you want to compute the flowrate.
(Note: drawing not to scale
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CE Hydraulics
Computational Lab No. 2
PIPE NETWORK FLOW ANALYSIS
Objective: Apply a pipe network analysis program to determine the flow and pressure in
a pipe network given inflows, demands (outflows), the lengths and diameters
of pipes and the characteristics of a pump.
Apparatus: Haestad methods WaterCad program.
Theory: Hardy Cross Pipe Network Analysis as presented in lecture.
Report:
1. For the network shown, set up the problem in WaterCad.
2. Solve for the distribution of flow and pressure in the system assuming all
pipes are new cast iron.
3. Repeat the solution assuming that the pipes are now old cast iron.
4. Describe the effects of aging on the performance of the pipe network - flowdistribution and pressure.
5. A minimum pressure of 40psi is required in the system. If this criterion isnot met,describehow can the system be redesigned to achieve it?
Data for the pipe network are as follows. Schematic is on the following page.
All pipes are 6 cast iron.
Reservoirs Pump Characteristics
Flow (cfs) Head (ft)
R-1 180 ft. 1.0 40R-2 200 ft 1.5 35
2.0 26
Pipes JunctionsLength Demand (cfs)
P-1 500 J-1 0
P-2 800 J-2 0
P-3 1000 J-3 1P-4 800 J-4 2
P-5 1200 J-5 2
P-6 1000P-7 500
P-8 500
P-9 500`
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CE Hydraulics
Computational lab No. 3GRADUALLY VARIED FLOW CALCULATIONS
Objective: Develop a computer-based solution (e.g. spreadsheet) to calculate the water surface
profile for a gradually varied flow situation.
Theory: Gradually varied flow in open channels results when disturbances cause the depth of
flow to deviate from the normal depth. Depending on whether the flow is sub orsupercritical, the effects of these disturbances are propagated upstream or
downstream, affecting the depth of flow. Calculations of flow depth in graduallyvaried flow are based on the energy equation. Manning's equation is used to
compute losses due to frictional resistance. One method for the computation of thedepth of flow at various points along the channel (called the flow profile) is thedirect step method, applicable to prismatic channels. Using this approach, the
distance between specified depths are calculated.
Procedure: Use the direct step method to compute the flow profile in the rectangular, concrete
lined channel shown below. The channel has a bed slope of 0.0002 and the width is25 ft.
where the weir coefficient, C, is 3.95. Compute the profile to the point where the depth of
flow is within 5% of the normal depth.
As part of the computational scheme, compute the normal and critical depth for the channel
to verify whether the flow is sub or super critical. Plot the resulting flow profile.
Analyses and Report:
Perform the computation for a flow rate of 310 cfs, an appropriate roughness
coefficient and the specified slope. Repeat these calculations, increasing and thendecreasing the flow rate, the slope and the roughness by 10% (one at a time). (This
procedure is called a sensitivity analysis). Provide a graphical display of the results.Discuss the sensitivity of the distance required to approach the normal depth on
variations in the flow rate, the channel slope and the roughness coefficient. Discusssome reasons why this sort of analysis (sensitivity analysis) may be of interest.