Question

Two reservoirs are connected through a 930 m long. 0.3 m diameter pipe, which has a gate valve. The pipe entrance is sharp (loss coefficient = 0.5) and the valve is half-open (loss coefficient = 5.5). The head difference between the two reservoirs is 20 m. Assume the friction factor for the pipe as 0.03 and g=10 m/s${}^2$. The discharge in the pipe accounting for all minor and major losses is m${}^3$/s

• A. 0.1414

Answer 1

The correct option is A 0.1414

L = 930 m
D = 0.3 m
Apply energy equation between A and B

$20=\frac{0.5V^2}{2g}+\frac{\left(0.03\right)\left(930\right)V^2}{2g\left(0.3\right)}+\frac{5.5V^2}{2g}+\frac{V^2}{2g}$

$20=\frac{\left(0.03\right)\left(930\right)}{\left(0.3\right)}.\frac{V^2}{2g}+\frac{7.0V^2}{2g}$

$20=\frac{100V^2}{2g}$

V = 2 m/sec

$Q=\frac{\pi }{4}\left(0.3{)}^2\right(2)$

$Q=0.1414m^3/sec$