On the question of the fine fragmentation of liquid-metal droplets during steam explosions

The presented results are based on experimental and computational studies aimed at justifying the application of the cavitation-acoustic hypothesis in describing the process of “fine” fragmentation of hot droplets falling into cold water. Such a process plays a crucial role in small-scale steam explosions. Brief descriptions of other possible mechanisms for the fragmentation of liquid-metal droplets under different conditions are provided, with the main focus given to the fragmentation process induced by shock waves generated by pulsed laser irradiation and mechanical impact. Experimental data on pressure impulses resulting from the collapse of vapor bubbles formed upon contact between the coolant (cold water) and the overheated surface are presented. It is demonstrated that the obtained data, along with photographic evidence of the molten fragments, are consistent with the assumption of the development of the fine fragmentation process according to the cavitation-acoustic scenario. Approximate calculations conducted within the acoustic approximation support this hypothesis.