Question

A flow control valve at the end of a 1 km long pipe is closed gradually in 10 seconds. If the rise of pressure head due to water hammer is 20 meters of water. What the velocity of water before the valve closure?
$(g=10m/s^2)$

• A. $4m/s$
• B. $8m/s$
• C. $6m/s$
• D. $2m/s$

Answer 1

The correct option is D $2m/s$

$\Delta h=$ water hammer head

$head=\frac{\Delta h_{WH}}{\rho g}=\frac{\frac{\rho .V.L.}{t}}{\rho g}$

$\Rightarrow \Delta h_{WH}=\frac{V.L}{gt}$

$\Rightarrow 20=\frac{V\times (1\times {10}^3)}{10\times 10}$

$\therefore V=2m/s$