4. Laminar flow, frictional head loss
[Energieverlies tgv wrijving]
Total Head
32 โ ๐ โ ๐ฟ โ ๐ Pressure Head
โ๐ =
๐ โ ๐ โ ๐ท2
โ๐ = frictional head loss โH [m]
๐= Absolute viscosity [kg/ms]
๐ฟ= Length between the Head Loss [m]
๐= mean velocity [m/s]
D= Hydraulic Diameter [m]
๐= Density of liquid [kg/m3]
2 ๐= earths gravity [m/s2]
6. Head loss /Energy loss [m]
โข Turbulent flow u 2
โข Friction loss (wrijvingsverlies) ฮฮ ๏ฝ ๏ธ ๏ [m]
2g
โข Local loss (lokaal verlies)
โข ฮH = Head loss or Energy loss [m]
โข u2/2g = Velocity head [m]
โข ฮพ (ksie) = Loss coรซfficiรซnt [1]
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7. 2 2
Darcy-Weisbach L u u
ฮฮ f ๏ฝ ๏ฌ ๏ ๏ ๏ฝ๏ธ ๏
4 R 2g 2g
Total Head
L
๏ธf ๏ฝ ๏ฌ๏
Pressure Head
4R
โข ฮH = Head loss by friction [m]
โข u2/2g = Velocity head [m]
โข L = Length [m]
โข ฮป = (lamda) = Friction coรซfficiรซnt[1]
โข ฮพ (ksie) = Loss coรซfficiรซnt [1]
3 โข R = hydraulic radius [m]
8. Remarks friction loss Darcy-Weisbach
โข ฮป (boundary roughness) depends on material and
construction. ฮป often between 0,01 and 0,10
โข ฮป is not a constant, depends on โboundary layerโ.
โSmoothโ or โRoughโ, Most of the time โSmoothโ
How to calculate ฮป !!!
โข During exams Fluid Dynamics, the ฮป will be given
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