Numerical Simulation Of Water Entry Of The Supersonic Projectile

Trans-media attack weapon is a research hotspot in recent years,the main characteristic of it is that it can span interface in order to realize the effective movement in different medium environment,and it can be hidden,high efficient penetration,perform multiple tasks and integrates the water surface attack and underwater attack,which has very broad prospect.The water entry of supersonic projectile belongs to trans-media problem,but in the process of movement,the water entry instantly and underwater motion law has not been thoroughly studied,and involves the difficult problem of three-phase coupling of gas,liquid and solid of multi physical aspects about trans-medium,therefore,the water entry of the supersonic projectile physical mechanism research during impact process has important theoretical value and practical significance.At present,there are finite element method,SPH meshless method and ALE method for the calculation of water entry of supersonic projectile.However,there are few researches on the algorithm of solving the water entry of the supersonic projectile based on the Euler method in China.In this paper,it mainly develops a high precision format algorithm based on the Euler method,and studies the motion of the supersonic projectile in single medium and transmedium respectively,and analyzes a series of complex physical phenomena in the process of water entry of supersonic projectile,which also solves the difficult problem of three-phase coupling of gas,liquid and solid during the water entry of supersonic projectile and provides a new method for research trans-medium problems.The main contents are as follows:(1)Aiming at the defects of difficulty in tracking the material interface of the Euler method,the Level set method is introduced to track the physical interface,and then combined with high order accuracy WENO scheme for solving Euler equation,then the corresponding two-dimensional program was programmed,and the excellent performance of Level set method is verified by some examples.(2)Setting the correct reflective boundary with MGFM method and level set equation to deal with the interface of the fluid-solid coupling problem,then developing the corresponding program of the high-speed motion of projectile in the air,and it can be well simulated,which verifies the reliability of the program and sets a foundation for studying the water entry of the supersonic projectile.(3)M-Schmidt cavitation model is introduced,and then combined with rGFM ghostfluid method,Level set method and Euler equation,then developing the high-speed movement of projectile underwater program and simulating it successfully,which solves the difficulty of simulating cavitation phenomena during the water entry process.(4)Based on the treatment of the above convective solid interface and gas-liquid interface,a two-dimension program(LGWM2D)was developed to solve the problem of the water entry of the supersonic projectile by combining the M-Schmidt cavitation model.Using LGWM2 D program to simulate the water entry of the supersonic round projectile and flat head projectile,which clearly simulate a series of complicated physical phenomena,such as,the detached shock wave,the interaction between shock wave and the surface of the water,air cushion effect,the shock wave propagation in water,mouth cavity shape and surface surges.The study shows that the Euler method is applied to cross-media research,which can clearly capture the instantaneous interface and the development of the shocks,and lay the foundation for further study on the trans-medium problem.