Numerical simulation of fragmentation processes in vapor explosions using Moving Particle Semi-implicit method

Numerical analysis of liquid metal fragmentation in vapor explosions is presented. The method used is Moving Particle Semi-implicit (MPS) method, where fluids are represented by particles and physical processes are simulated by particle interactions without grids. in this study a calculation model for evaporation is developed. New vapor particles are generated on the interface during the calculation according to the heat transfer to the interface. In order to examine two thermal fragmentation models, impingement of water jets on a liquid metal pool is calculated by assuming the collapse of the vapor film around a liquid metal drop. Water, steam and liquid metal are simultaneously calculated with evaporation. A filament is observed between two water jets as assumed by Ciccarelli and Frost. Penetration of the jet under the liquid metal surface does not appear. The behavior mainly depends on the density ratio of the jet fluid to the pool;fluid. The penetration appears when the jet fluid density is larger. The density ratios of water to tin and water to UO2 are in the range of the filament generation.