53:071 Principles of Hydraulics
Laboratory Experiment #2
Local Losses in Pipe Flows
Li-Chuan Chen, Marian Muste, and
Larry Weber
Objective
To determine the head loss coefficient
for a designated pipe fitting and its
Reynolds’ number dependence.
Principle
V2
hL  K
2g
Apparatus — Standard Pipe
Geometrical characteristics for the pipeline system
can be found in the appendices in the handout.
Apparatus — Streamlined Pipe
Geometrical characteristics for the pipeline system
can be found in the appendices in the handout.
What are we going to do?
We are going to measure the upstream
and downstream piezometric heads of a
90° bend for both standard and
streamlined pipes.
Procedures
1. Bleed the pipe system and tubings.
2. Establish stabilized maximum discharge in the
3.
4.
5.
6.
7.
8.
9.
system.
Measure the water temperature.
Record the weir notch elevation.
Measure the datum.
Measure the piezometric heads for Tap 11, 12,
15, and 16.
Measure the head on weir.
Reduce the discharge and repeat Step 6 and 7 for
four smaller discharges.
Switch to another pipe and repeat Step 1 to 8.
Data Sheet
Standard Pipe
Trial #
Water Temp.
(F)
Weir Notch
Elev. (ft)
Water Surface
Elev. (ft)
Datum (ft Hg)
Piez.
head
(ft
Hg)
Tap
11
Tap
12
Tap
15
Tap
16
1
2
3
4
Streamlined Pipe
5
1
2
3
4
5
Analysis
Compute velocity, piezometric, and energy
heads at each pressure tap.
Compute the loss coefficient (K) and
Reynolds’ number (Re) for each trial.
Plot K vs. Re for both standard and
streamlined pipes.
Compare the experiment results with
empirical values and trends found in
hydraulics and fluids textbooks.
Sample Result
Standard Pipe
(Average = 0.509)
1.0
0.9
0.8
0.7
0.6
K 0.5
0.4
0.3
0.2
0.1
0.0
80000
90000
100000
110000
Upstream Re
120000
130000
140000
Further Consideration
Discuss the dependence of K to Re. Does it
agree with the published values and trends?
If the device and approach pipe are taken to
be a 1:50 scale model of a prototype
situation, calculate the prototype horsepower
that would be required to overcome the
losses in the prototype device.