Analysis Of Motion Characteristics Of Projectile With Buffering Device During Water Entry

With the development of the navy,the projectile,which has the advantages of low risk,high hit rate and wide range of long-range attack,plays an important role in naval warfare.The weapon is subjected to the huge force at the moment and the local cavitation occurs when it enters water.The projectile body,the projectile trajectory and the hydrodynamic characteristics all have a great influence.In this paper,a new type of projectile with buffer device is taken as the research object.A series of numerical studies are carried out on its water entry process using ANSYS/LS-DYNA and ANSYS/Workbench bi-directional fluid-structure coupling.To study the motion characteristics of projectiles with different types of cavitation disks in40 ms of water entry.Taking the remaining velocity of projectile,maximum acceleration of projectile and change of buffer length as indicators,and choosing the projectile with the best attack capability during water entry.Thus,the structure of the cavitation disk is determined.Therefore,a truncated spherical cavitation disk is installed as a part of the buffer device.To study the motion characteristics of projectiles with different density buffer materials in40 ms of water entry.Taking the remaining velocity of projectile,maximum acceleration of projectile and change of buffer length as indicators,and choosing the projectile with the best buffering effect.Thus,the buffer material is determined.The polyurethane foam with 973 kg/m~3buffer is selected as a part of the buffer device.The buffering effect of buffer and the buffer device on projectile entering water are verified.The motion characteristics of a new torpedo at different entry angles are analyzed when it enters water at an initial velocity of 100 m/s.The relationship between torpedo residual velocity,maximum acceleration of torpedo,maximum change of buffer length,projectile trajectory and entry angle are investigated.Finally,the complete cavitation phenomenon of the projectile vertically is observed during water entry.The buffer device is installed on the projectile body to reduce the force and damage of the weapon,retain the maximum combat effect as far as possible.Observing the formation of cavitation is to provide reference for the length of the cavitation of the projectile water entry.It is of great significance to study the movement characteristics of the projectile.