308-29-31

# 308-29-31 - NCSU MAE308 29. Water flows at a rate of 1.0...

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NCSU MAE308 29. Water flows at a rate of 1.0 m 3 /s through a rough concrete pipe having surface roughness ε=3 mm that connects two ponds. Determine the pipe diameter if the elevation difference between the two ponds is 10 m and the pipe length is 1000 m. Neglect minor losses. Also compute the Reynolds number. Is the pipe flow laminar or turbulent? ε=3mm, Q=1m 3 /s D 1135684 D ) 00112 . 0 ( π ) 1 )( 999 ( 4 D πμ Q ρ 4 D 4 π μ DQ ρ A μ DQ ρ μ vD ρ Re 2 D = = = = = = (1) BE: f 2 1 f f s 2 2 2 2 1 2 1 1 gh ) z z ( g w w w gz v 2 1 ρ p gz v 2 1 ρ p = - = + + + + = + + ) z z ( Lv gD 2 f ) z z ( g 2 v D fL 2 1 2 2 1 2 - = - = ) 10 ( ) 1 )( 1000 ( 8 D ) 807 . 9 ( π ) z z ( LQ 8 gD π ) z z ( Q D 16 π L gD 2 ) z z ( Q A L gD 2 f 2 5 2 2 1 2 5 2 2 1 2 4 2 2 1 2 2 = - = - = - = f=0.121D 5 or D=1.526f 1/5 (2) surface roughness D 003 . 0 D ε = (3) 4 “equations”, i.e. Eqs. (1), (2), (3) and Moody, for 4 unknowns, Re D , D, f and ε /D. Iterate with first guess f=0.02

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## This note was uploaded on 08/01/2008 for the course MAE 308 taught by Professor Danby during the Fall '08 term at N.C. State.

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308-29-31 - NCSU MAE308 29. Water flows at a rate of 1.0...

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