Cavity evolution of the high-speed cylinder entering the water under different ice-hole diameter constraints

Abstract

In this study, experimental research on the oblique water-entry process of the high-speed cylinder under the ice-free condition and three different ice-hole diameter conditions based on the high-speed photography technology is carried out. The experimental repeatability is verified. The influence of the ice-hole constraint on the evolution process of the cavity of the cylinder is investigated by dividing in three stages: the cavity expansion stage, the surface closure stage, and the deep closure stage. Besides, the evolution characteristics of the cavity under four different experimental conditions are studied. Results show that during the cavity expansion stage, the cavity expansion is constrained by the ice-hole. The left side of the cavity near the free surface is curved. With the increase of the ice-hole diameter, the curvature of the left side profile of the cavity gradually decreases. The liquid around the water-entry point impacts the inner wall of the ice-hole to generate a reflective flow. During the surface closure stage, the impact of the reflective flow inhibits the contraction of the right side of the cavity wall, which further induces that the surface closure of the cavity is delayed. Besides, under the influence of smaller ice-hole, the right tail of the cavity wall is impacted by the reflective flow and a local impact collapse occurs. As the diameter of the ice-hole increases, the right tail of the cavity wall is folded but does not collapse significantly, and independent surface closure jet and reflective flow can be observed. During the deep closure stage, under the ice-hole constraint, in addition to the puff-off collapse, it can be found that the shedding collapse is accompanied by the local impact collapse. The occurrence of cavity deep closure of the cylinder is accelerated.