Chapter 8 – Pipe Flow
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Transcript of Chapter 8 – Pipe Flow
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Chapter 8 – Pipe FlowCE30460 - Fluid MechanicsDiogo Bolster
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Laminar or Turbulent Flow
Turbulent Flow http://www.youtube.com/watch?v=NplrDarMDF8
Laminar Flow http://www.youtube.com/watch?v=KqqtOb30jWs&NR=1
Re<1000
Re>4000
Re=UDr/m
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Fully Developed Flow
Entrance length:
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Fully Developed Laminar Flow
We’ve done this one already in chapter 6
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What about Turbulent Flow
Typically: n is between 6 and 10
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Dimensional AnalysisPressure Drop depends on
Mean velocity VDiameter DPipe length lWall Roughness eViscosity mDensity r
By dimensional Analysis
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Pressure drop must increase linearly with length of tube
Recall from chapter 5
Therefore we can say that (part of) the loss in a pipe is
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Δp1
2 ρV2
=lDf Re,
εD
⎛ ⎝ ⎜
⎞ ⎠ ⎟
Friction factor – look up in table
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hL ,major =lDV 2
2gf Re,
εD
⎛ ⎝ ⎜
⎞ ⎠ ⎟
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Moody Diagram (Friction Factor)
For non-laminar flow approximately true that
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1f
= −1.8logεD
3.7
⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
1.11
+6.9Re
⎡
⎣
⎢ ⎢
⎤
⎦
⎥ ⎥
For laminar
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f =64Re
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Roughness (Typical)
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Minor Losses
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hL ,min =KLV 2
2g
KL depends on the flow (expansion, contraction, bend, etc)
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Minor Losses
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Minor Losses
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Sample Problem
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Sample Problem
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Sample Problem
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Pipe Flow Measurement
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Q =CQideal =CA0
2 p1 − p2( )ρ 1 − β4( )
C is a constant that depends on geometry
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Sample Problem
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More Problems
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Single Pipe – Determine Pressure Drop
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Single Pipe – Determine Flowrate
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Single Pipe – Determine Diameter
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Multiple Pipe Systems