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loss-1

loss-1 - Another parameter that influences the friction is...

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Frictional losses in piping system loss head frictional 2 2 equation, s Bernoulli' Extended 2 1 2 2 2 2 1 2 1 1 = = = - + + = - - + + + L L E A h p p p z g V p h h h z g V p g g g g P 1 P 2 Consider a laminar, fully developed circular pipe flow p P+dp τ w [ ( )]( ) ( ) , , p p dp R R dx dp R dx p p p h g L D f L D V g w w L w - + = - = = - = = F H I K = F H I K F H G I K J p t p t g g t r 2 1 2 2 2 2 4 2 Pressure force balances frictional force integrate from 1 to 2 where f is defined as frictional factor characterizing pressure loss due to pipe wall shear stress t r w f V = F H I K F H G I K J 4 2 2 Darcy’s Equation: R: radius, D: diameter L: pipe length τ w : wall shear stress

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When the pipe flow is laminar, it can be shown (not here) that by recognizing that as Reynolds number Therefore, frictional factor is a function of the Reynolds number Similarly, for a turbulent flow, f = function of Reynolds number also
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Unformatted text preview: . Another parameter that influences the friction is the surface roughness as relativeto the pipe diameter D Such that D Pipe frictional factor is a function of pipe Reynolds number and the relative roughness of pipe. This relation is sketched in the Moody diagram as shown in the following page. The diagram shows f as a function of the Reynolds number (Re), with a series of parametric curves related to the relative roughness D f VD VD f f F f F = = = = = F H I K F H I K 64 64 m r r m e e e , Re , Re , (Re) . Re, : ....
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loss-1 - Another parameter that influences the friction is...

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