Kinetic energy evaluation for the steam explosion in a shallow pool with a spreading melt layer at the bottom

Steam explosion experiments with a melt layer spreading at the bottom of a shallow water pool, namely the PULiMS-E6 and SES-S1 by KTH, Sweden, were simulated by the steam explosion simulation code, JASMINE. The observed impulses in the experiments were successfully reproduced by simulations with assumed premixing conditions. With those simulation results, the adequacy of the kinetic energy evaluation method used for the experiments were examined by comparison of the kinetic energy directly obtained in the simulation, E k , and the one evaluated based on the impulse and the water mass limited to the center area above the premixing zone, E kic . It showed that the impulse based kinetic energy evaluation gives about five times overestimation. The impact of the water pool geometry on the validity of the impulse based kinetic energy evaluation method was further examined by a parametric study with variations of the pool geometry in the simulations of PULiMS-E6 and SES-S1 as well as high pressure bubble expansion simulations. The results for the relation of E kic / E k and the geometric factors were consistent between the cases for the experiments and the bubble expansion. The results showed that: (1) for the shallow water pool regime, E kic / E k shows a trend of convergence to 4–5, (2) for deep water pool regime, the impulse based kinetic energy evaluation with the whole water mass, E ki , rather than E kic , gives a good estimation. A set of empirical formulas was obtained for E kic / E k .