Research of mechanisms of interaction of melt and coolant by means of small-sized experiments with solid and liquid metal samples

Abstract

Abstract Several basic fragmentation hypotheses described in the literature for the case of fine-scale spontaneous vapor explosion, when single hot drops are falling in the coolant, are analyzed. It is shown that all of them, depending on the experimental conditions, describe the real physical phenomena. It is highlighted, that the process of fragmentation during the spontaneous vapor explosion is directly connected to the regime of the film boiling collapse of the underheated liquid, which is still underexplored. The experiments on the liquid drops fragmentation are complemented by those with surface boiling at the solid metal samples of semi-spherical form. The connection between the vapor explosion of water and the increase of the surface wettability is confirmed. The video material, indicating the possibility of formation of liquid jets that strike the hot surface during the collapse of the vapor shell, is obtained. The time interval (duration of the contact) between the first contact of the coolant with the hot surface and the explosion boiling of the liquid is experimentally determined. The dependence of the contact duration on the temperature of the overheated wall is determined and its comparison with the theoretical estimations is provided.