Experimental investigation on cavity evolution characteristics of structure passing through crushed ice area

Abstract

To investigate the influence of the crushed ice cover density on the structure's water-entry cavity evolution, experiments were conducted with three different crushed ice cover densities based on water-entry experimental platform. By comparing the water-entry process of an inclined structure in different conditions, the influence of ice cover density on cavity evolution during the water-entry process is analyzed. The results show that the crushed ice will hinder the outward expansion of the liquid surface fluid, resulting in the reduction of the diameter of the cavity; the crushed ice will also hinder the inward contraction of the free surface fluid, prolonging the time of the expansion of the cavity, then the total volume of air within the cavity will augment, resulting in a reduction of the pressure differential between the interior and exterior of the cavity, which will ultimately lead to a delay in the time of the cavity's closure. As the density of the crushed ice cover increases, its inward contraction of the free surface fluid obstruction is gradually enhanced, further prolonging the closure time of the cavity, the length and maximum diameter of the cavity is also increased accordingly. In lower crushed ice cover densities, jets point to the interior of the cavity during its collapse. In addition, under the condition of higher crushed ice cover densities, the wall of the cavity is wrinkled by the irregular impact of the fluid. Cavity closure occurs below the free surface, and the large influx of air slows down the collapse of the cavity, with the increase in the depth of the structure into the water, the cavity occurs a deep necking phenomenon under the effect of ambient pressure.