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

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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 ?P
Flow meter
Pipe
D
L
Valve
Schematic of experimental Apparatus

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

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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
K is loss coefficient must be determined for each
situation
In this experiment you will find friction factor
for various pipes
For Short pipes with multiple fittings, the minor
losses are no longer minor!!
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Major loss
Differential Pressure Gauge- measure ?P
L
? µ e
V
Pipe
D

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

Using dimensional analysis we can show that
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Friction factor
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Friction Factor

• For Laminar flow ( Relt2300) inside a horizontal
  pipe, friction factor is independent of the
  surface roughness.

For Laminar flow

• For Turbulent flow ( Regt4000) it is not possible
  to derive analytical expressions.
• Empirical expressions relating friction factor,
  Reynolds number and relative roughness are
  available in literature

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Friction factor correlations

• f is not related explicitly Re and relative
  roughness in this equation.
• The following equation can be used instead

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Moodys chart for friction factor
f
Increases
Laminar f64/Re
Smooth
Transition
ReD
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Minor Losses
Valves
Bends
T joints
Expansions
Contractions

• 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

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Experiment 5 - New Experimental Set up
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Experiment 5 - Experimental Steps Details

• Overall Measurements
• Measure the Reservoir Height, H
• Measure the Distances L1, L2, etc.
• Measure the distances ?x1, ?x2, 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, ?P, 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 ?P, for
  six flow rates
• (3 H x 2 valve openings)

?x2