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Pipeflow Type 2 Application (continued)

Example

z₁ = V₂²/2g + [f(L/D) + K )] V₂²/2g = [ 1 + [f(L/D) + K )] V₂²/2g (ft) (1)

H = [ 1 + [f(L/D) + K )] V₂²/2g = [ 1 + 600f + 0.5 ] V₂²/ 64.4

80 = [ 600f + 1.5 ] V₂²/ 64.4 or V₂² = 5152 / (600f + 1.5) (1A)

For galvanized iron pipe e = 0.0005 ft and e/D = 0.003

From the Moody Diagram for turbulent flow and 1.22x10^-5 , f = 0.026

Then from (1A) V₂ = 17.35 fps Use this value to calculate the new Reynolds Number.

The new Reynolds Number using the velocity and the relative roughness is:

Reynolds Number = VD/ν where D = 1/6 ft and ν = kinematic viscosity for

water at 60^oF = 1.22x10^-5 ft²/sec.

Re = (17.35)(1/6)/ 1.22x10^-5 = 2.37x10⁵

So from the Moody Chart f ~ 0.027 Small change. So stop iteration.

The discharge Q = (Area of Pipe) (Discharge velocity) = (π)(1/6)² /4][17.35] = 0.38 cfs (result)