Water Hammer (Joukowsky Equation) Surge Calculator
Calculate peak acoustic pressure surge (ΔP), total transient head (Hmax), and critical valve closure time (tc = 2L/a) per classical Joukowsky theory.
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Frequently Asked Questions
What is the Joukowsky equation for water hammer?
Discovered independently by Nikolai Zhukovsky (1898) and Johannes von Kries (1883), ΔP = ρ·a·Δv predicts the maximum instantaneous pressure rise when fluid momentum is abruptly converted to acoustic compression energy.
Why is the pipe reflection period 2L/a the boundary between fast and slow closure?
2L/a is the exact time required for the initial compression wave to travel to the reservoir and return as a reflected rarefaction (relief) wave. If the valve is closed before 2L/a, no relief wave arrives to attenuate the peak pressure.
What damage does unmitigated water hammer cause?
Unmitigated water hammer causes catastrophic pipe rupture, flange gasket blowout, check valve slam, pump casing fracture, and support anchor failure due to massive unbalanced axial thrust loads.