Experiment 5 Pipe Flow-Major and Minor losses ( review)

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# Experiment 5 Pipe Flow-Major and Minor losses ( review) - PowerPoint PPT Presentation

H. Reservoir. Experiment 5 Pipe Flow-Major and Minor losses ( review). The goal is to study pressure losses due to viscous ( frictional) effects in fluid flows through pipes. Differential Pressure Gauge- measure Δ P. Flow meter. Pipe. D. L. Valve. Schematic of experimental Apparatus.

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## Experiment 5 Pipe Flow-Major and Minor losses ( review)

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Presentation Transcript

H

Reservoir

Experiment 5Pipe Flow-Major and Minor losses ( review)
• The goal is to study pressure losses due to viscous ( frictional) effects in fluid flows through pipes

Differential Pressure Gauge- measure ΔP

Flow meter

Pipe

D

L

Valve

Schematic of experimental Apparatus

• Pipes with different Diameter, Length, and surface characteristics will be used for the experiments
Major and Minor losses

Total Head Loss( hLT) = Major Loss(hL)+Minor Loss (hLM)

Due to sudden expansion, contraction, fittings etc

Due to wall friction

In this experiment you will find friction factor for various pipes

K is loss coefficient must be determined for each situation

For Short pipes with multiple fittings, the minor losses are no longer “minor”!!

Major loss

Differential Pressure Gauge- measure ΔP

• Physical problem is to relate pressure drop to fluid parameters and pipe geometry

L

ρμε

V

Pipe

D

Using dimensional analysis we can show that

Friction Factor
• For Laminar flow ( Re<2300) inside a horizontal pipe, friction factor is independent of the surface roughness.

For Laminar flow

• For Turbulent flow ( Re>4000) it is not possible to derive analytical expressions.
• Empirical expressions relating friction factor, Reynolds number and relative roughness are available in literature
Friction factor correlations

f is not related explicitly Re and relative roughness in this equation.

The following equation can be used instead

Moody’s chart for friction factor

f

Increases

Laminar

f=64/Re

Smooth

Transition

ReD

Minor Losses
• Flow separation and associated viscous effects will tend to decrease the flow energy and hence the losses
• The phenomenon is fairly complicated. Loss coefficient ‘K’ will take care of this complicities

Valves

Bends

T joints

Expansions

Contractions

Reservoir

H

L1

L2

L3

L4

Δx3

Δx1

Δx2

Experiment 5 - Experimental Steps & Details
• Overall Measurements
• Measure the Reservoir Height, H
• Measure the Distances L1, L2, etc.
• Measure the distances Δx1, Δx2, etc. Measure the pipe diameters
• For EACH PIPE Follow Steps below
• Set the reservoir height, H, to the maximum level, approx. close to the ‘spill-over’ partition height. Record the level.
• Adjust the flow rate to a relatively high value, wait for steady flow to be established.
• Measure the flow rate.
• Measure the pressure drop, ΔP, for this flow rate.
• Reduce the flow rate, by using the valves, repeat steps 1 & 2.
• Reduce the reservoir height and repeat steps 1-3.
• Repeat all steps until 3 reservoir heights have been measured
• Hence for each pipe, you will measure ΔP, for six flow rates
• (3 H x 2 valve openings)

Δx2