Non-equilibrium modeling and multi-parameter operating-regime mapping of cavitating water hammer in liquid-hydrogen propellant feed lines

A homogeneous non-equilibrium model is developed for cavitating water hammer in liquid hydrogen propellant feed lines, incorporating pipe-wall elasticity, energy transport, unsteady friction, and finite-rate phase change. Validation against liquid-nitrogen experiments gives mean absolute relative errors of 3.88% for six major pressure peaks and 4.61% for the intervals between the first two peaks. The validated model is then applied to 300 operating conditions generated by optimal Latin hypercube sampling. Kriging models accurately predict the maximum pressure Pmax and maximum vapor volume Vv,max, while Sobol analysis shows that initial flow velocity dominates Pmax and that valve-closure time and initial velocity jointly control Vv,max. Among the cavitating cases, 44.9% reach Pmax at the second pressure peak or later. Increasing inlet temperature from 16 to 21 K enlarges the significant-cavitation region from 36.5% to 45.6%, while stronger cavitation does not necessarily result in a higher Pmax.