Numerical Study On Water Entry Of Missile Aft Dome Based On Overlapping Grid Technique

Ballistic missiles are usually in cold launch with aft dome in order to protect their engines.The trajectory and impact loading in the process of water fall of aft dome are really important for the safety of ships carrying out the launching task.Therefor,it is of great theoretical significance and applicable value to study on this process.In the present paper,the numerical study are applied to discuss the motion characteristics and hydrodynamic characters during water falling.This will provide reference basis for predicting the trajectory.The main contents and some achievement are as follow:Considering the polyphase and turbulence in the process of water entry,the VOF multi-phase model and standard k-? method are introduced,and surface tension are also brought.A Coupled solution for multiphase flow field and motion which could describe the process of water entry more accurately is established based on overlapping grid technique.And effectiveness of numerical methods are tested using the experimental data to verify the effectiveness.The water entry problem under different initial motion parameters is researched by simulation based upon the numerical methods established in this thesis.Particular attention is focus on the flow performance,motion characteristics and hydrodynamic characters in the process of water entry of aft dome with different initial motional parameters.The influence of the velocity of water entry and the attack angle on the evolution process of cavitation,the time-varying process of hydrodynamic coefficients and the motion trail are obtained.By the numerical simulation of the aft dome water entry under different initial motion parameters,the developing of density and environmental parameters is studied.The flow field characteristics,kinematic characteristics and hydrodynamic characteristics are analyzed.The effects of density and environmental parameters on the evolution of cavity,the time-varying process of hydrodynamic coefficients and the motion trajectory are aslo analyzed.