Study On Fluid-solid Coupling Load Characteristics Of Water Entry Of Projectile

Since the birth of the problem of water entry,the research on the impact of water entry has not stopped.As the main cause of the damage of the vehicle when it enters the water,the impact load may even make the vehicle completely lose its original function.Therefore,it is important practical significance to study of the impact load for the aspects of the vehicle structural design and the reduction of the damage risk.This paper is mainly aimed at the current research on the impact of the structure into the water,which seldom consider the elastoplastic problem of the structure.ANSYS fluid-structure coupling is using to calculate the impact load of the revolving structure and the stress,strain and deformation of the structure under the action of the load.The main research contents are as follows:Firstly,the existing commercial software FLUENT is used to simulate and calculate the impact force of two-dimensional wedges with different velocities,half width and bottom lift angles,and the relationship between the impact force and time,speed,half width and bottom lift Angle was obtained,And it is compared with the change rule of the impact force deduced from the theoretical model.It is found that the simulation results are similar to the formula derived from the theoretical model,which verifies the reliability of the simulation results.Then,FLUENT is used to simulate the water inlet process of truncated cone type rotors with three different head types at 30°-90° water inlet Angle.The law of impact force changing with time and the pressure distribution in flow field are obtained.The analysis results show that for the same model,the maximum pressure will be exerted on the head surface of the structure when water enters vertically,and the pressure on the head surface of the structure will decrease with the decrease of the water entry Angle.For different models,under the same Angle of entry,the larger the diameter of the head section,the greater the pressure on the rotating body.Finally,based on the previous analysis of the peak load pressure under different inlet pressure angles,the inlet process of rotary body structures with different materials and heads was coupled with multiple working conditions for the inlet Angle(vertical water-entry)when the maximum inlet pressure appeared.The stress,strain and deformation of each working condition are obtained.The results show that the peak values of strain and deformation of the three rotary structures are steel,titanium alloy and aluminum alloy from small to large.Under the condition of the same material,the peak values of strain and deformation increased with the increase of the cross section diameter of the model head.