'Water hammer' in a pipeline occurs due to:
Choose the correct answer
Gradual pressure increase from pump
Sudden change in flow velocity (valve closure) causing pressure wave propagation — pressure rise = ρcΔV
Only occurs in open channels
Air entrainment in pump
Correct Answer
B. Sudden change in flow velocity (valve closure) causing pressure wave propagation — pressure rise = ρcΔV
Why is this the answer?
Water hammer: pressure surge when flow is suddenly stopped (valve closed). Pressure rise = ρ × c × ΔV where c = wave celerity = √(K/ρ) for rigid pipe (K = bulk modulus). For elastic pipe: c = √(K/(ρ(1+KD/tE))). Prevents by: slow valve closure (time > 2L/c), surge tanks, pressure relief valves, air vessels.
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