Download Lab 5 - Wright State University

Wright State University
Department of Mechanical and Materials Engineering
Fall 2004
ME 317: FLUID DYNAMICS LABORATORY
Experiment 5: Fluid Circuits Demonstrator
Objective: The objective of this experiment is to study the effects of friction on the
pressure drop when water flows through pipes made of different materials.
References: Fox, McDonald and Pritchard, Introduction to Fluid Mechanics, 6th edn.,
Section 8-7: Calculation of Head Loss.
Preparation: Read the reference material and these instructions, then perform the
experiment with your assigned group.
Equipment Needed: Flow circuit in Room 122, manometer bank.
Experimental Procedure: The flow circuit consists of a recirculation tank, a centrifugal
pump, a ball valve, a sharp-edged orifice flow meter, three lengths of ½ inch (nominal)
pipe, and a bank of manometers. The centrifugal pump forces the water from the
recirculation tank through the valve and past the orifice plate flow meter, which was
calibrated in Lab 4. Downstream from the flow meter is a length of ½ inch copper pipe, a
length of ½ inch stainless steel pipe, and a length of ½ inch PVC pipe, which all have
pressure taps to determine the pressure drops. The pressure drop within each length of
pipe is read by the bank of manometers in inches of water. The mass flow rate of water
through the system is set using the ball valve. The length between the pressure taps for
the three pipes are all L = 24 inches. The inside diameter of the ½ inch copper pipe is Dc
= 0.545 inches, the inside diameter of the ½ inch stainless steel pipe is Dss = 0.674 inches,
and the inside diameter of the ½ inch PVC pipe is DPVC = 0.546 inches.
1. Measurements
a. Close the ball valve.
b. Turn the centrifugal pump on by plugging the extension cord into the wall.
c. Slowly move the ball valve until the pressure difference between the highpressure side and the low-pressure side of the manometer for the flow meter is
close to the first value shown on the worksheet provided.
d. Record the upstream and downstream pressures for the flow meter and the
three lengths of pipe.
e. Adjust the valve such that the pressure difference for the flow meter is close to
the next setting on the worksheet provided.
f. Repeat steps (d) and (e) for each setting.
g. Turn the pump off.
Wright State University
Department of Mechanical and Materials Engineering
Fall 2004
ME 317: FLUID DYNAMICS LABORATORY
Experiment 5: Fluid Circuits Demonstrator
2. Data Reduction
a. The laboratory teaching assistant will obtain a copy of the experimental data
taken by each lab section, which will be forwarded in electronic form to me.
Download the data from all of the lab sections for data reduction at my
website: http://www.cs.wright.edu/people/faculty/sthomas/me317.html
b. Create an Excel spreadsheet to calculate following: the predicted mass flow
rate based on the average discharge coefficient of the orifice flow meter, the
Reynolds number for each length of pipe, and the Darcy friction factor for
each length of pipe (f). Remember that the Reynolds number for each length of
pipe must be calculated separately due to the fact that the inside diameters of
the three pipes are all different.
c. Create a graph by plotting the Darcy friction factor for the three pipe sections
on the y-axis versus the Reynolds number on the x-axis. Also show the plot of
the Blasius correlation for turbulent flow in smooth pipes:
0.316 

f 

Re 0.25 

Report: Prepare a brief report in the usual format. The above-mentioned Excel
spreadsheet and the graphs are to be included. The Darcy friction factor is given by
P
LV2
hl 
 f
ρ
D 2
Answer the following questions:
1. Is the friction factor predicted well by the analysis? Why or why not?
2. Discuss some issues in which this lab could be redesigned in order to achieve better
results.
Wright State University
Department of Mechanical and Materials Engineering
Fall 2004
ME 317: FLUID DYNAMICS LABORATORY
Experiment 5: Fluid Circuits Demonstrator Data Sheet
Pressure (inches of H2O)
Stainless
Steel
PVC
Approximate
Manometer Down
Delta P
2.5
5.0
7.5
10.0
12.5
15.0
17.5
20.0
22.5
25.0
Up
Down
Up
Copper
Down
Up
Flow Meter
Down
Up