Study On Cavity Evolution And Motion Characteristics Of Water-entry Of The Structure Under The Disturbance Of Floating Ice

With the increasing strategic position of the Arctic region,it is extremely urgent to vigorously develop advanced marine weapons and equipment that can be applied to combat in Arctic floating ice sea area.However,the free surface in polar regions is often covered with floating ice.During the process of water-entry,the collision between structure and floating ice,the cavity is blocked by the floating ice to expand,and the moving floating ice pulls the cavity to make it fall off,which will inevitably make the process of water-entry of the structure under the floating ice environment more complex.Therefore,it has important engineering application value to carry out study on the problem of structure water-entry under floating ice environment.This paper mainly focuses on the study on the cavity evolution and motion characteristics of water-entry of the structure under the floating ice environment.The study on the fluid-structure coupling numerical simulation method of the structure water-entry under the floating ice environment,the cavity evolution and motion characteristics of oblique water-entry of the structure under the ice-free environment,and the cavity evolution and motion characteristics of water-entry of the structure under the floating ice environment are discussed in depth.The main research contents are as follows:(1)Experimental and numerical research for structure water-entry under ice-free environment.A water-entry experiment system for structure under ice-free environment has been established,and a numerical method for structure water-entry under ice-free environment has been established.Water-entry experiments and numerical simulations of the structure under the same operating condition have been carried out,verifying the effectiveness of the numerical model for structure water-entry under ice-free environment.(2)Study on the cavity evolution and motion characteristics of oblique water-entry of the structure under the ice-free environment.Using a combination of experimental and numerical simulation methods,detailed research was conducted on the evolution and motion characteristics of the oblique water-entry of structures under different initial angles,velocities,and angles of attack.The results show that a decrease of the angle of water-entry weakens the stability of the structure’s water-entry motion,and the increase of the initial velocity of waterentry mainly affects the shape and size of the cavity,while the angle of attack has a direct effect on the motion of the structure water-entry.(3)Experimental and numerical study for structure water-entry under floating ice environment.A water-entry experiment system for structure disturbed by floating ice was established.Based on the numerical method for structure water-entry under ice-free environment,a solid calculation model was coupled to establish a numerical calculation method for structure water-entry disturbed by floating ice.The effectiveness of the established fluidsolid coupling numerical method was verified by comparing simulation and experimental results under the same conditions.(4)Study on the cavity evolution and motion characteristics of water-entry of the structure under floating ice environment.Based on STAR-CCM+ and ABAQUS software,the simulation calculation of the structure’s water-entry process under different conditions of floating ice quantity,water entry position and whether there is floating ice was carried out.The cavity evolution and motion characteristics of water entry of the structure were studied by using the calculation results of the cavity evolution cloud diagram,the head pressure distribution,the vorticity diagram,the structure motion curve and so on.The results show that the existence of a single ice floe will destroy the symmetry of the evolution of the structure’s cavity in the waterentry process.When the ice floe collides with the structure,the stability of the structure will be greatly reduced.The impact of the ice floe on the structure’s cavity evolution is also different in the case of multiple ice floes with different positions in the water-entry process.