Experimental investigation on the cavity evolution characteristics of the high-speed cylinder passing through the ice-hole

In this study, experimental research on the oblique water-entry process of the cylinder under the ice-free environment and the ice-hole condition based on the high-speed photography technology are conducted. The impact of the ice-hole constraint on the cavity evolution characteristics of the cylinder is investigated by dividing in three stages: the cavity expansion stage, the surface closure stage, and the deep closure stage. The oblique water-entry characteristics with different initial entry speeds under the ice-hole condition are carried out. Results show that during the cavity expansion stage, the free surface under the ice-hole condition does not form a bulge, and the splashing on the water-away side of the cylinder is suppressed by the ice-hole and is more dispersed. The ice-hole constraint leads to the obstruction of cavity expansion and the appearance of bending on the left side of the cavity near the free surface. During the surface closure stage, the ice-hole constraint causes the earlier occurrence of the cavity surface closure, and the reflected flow generated by the fluid inside the ice-hole hitting the ice plate causes the local impact collapse of the cavity. During the deep closure stage, the cavity wake under the ice-hole condition has a smaller vortex and consists of the local impact collapse, the shedding collapse, and the pull-off collapse. The ice-hole constraint accelerates the pinch-off and deep closure of the cavity. Ulteriorly, for the higher the initial water-entry velocity, the surface closure of the cavity appears earlier, the surface closure jet merges with the local impact collapse, and the collapse degree of the surface closure jet is more pronounced. The ice-hole constraint makes the cylinder velocity during the cavity expansion stage decay faster, and the higher the water-entry initial speed, the greater the velocity decay.