53:071 Principles of HydraulicsLaboratory 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

g

VKhL2

2

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.

Procedures1. Bleed the pipe system and tubings.2. Establish stabilized maximum discharge in the

system.3. Measure the water temperature.4. Record the weir notch elevation.5. Measure the datum.6. Measure the piezometric heads for Tap 11, 12, 15,

and 16.7. Measure the head on weir.8. Reduce the discharge and repeat Step 6 and 7 for

four smaller discharges.9. Switch to another pipe and repeat Step 1 to 8.

Data Sheet 

Standard Pipe Streamlined Pipe

Trial # 1 2 3 4 5 1 2 3 4 5

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

                   

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)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

80000 90000 100000 110000 120000 130000 140000

Upstream Re

K

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.