Numerical Study Of Fluid-solid Coupling Characteristics Of A Projectile Body During Low-speed Water Entry

When the anti-submarine missile enters the water,the missile body hits the water surface and receives a great impact force.Therefore,it is very important to study the load characteristics of the projectile in the process of entering water.In this paper,the process of missile body entering water is simulated numerically,and the load distribution of missile body is taken into consideration,which can provide some guidance and reference for the structural design of anti-submarine missile.In this paper,based on ANSYS/LS-Dyna software,using the ALE method for projectile into the water at low speed process of fluid-solid coupling numerical simulation of the solid projectile is studied in different water velocity and different water entry Angle,Angle of attack,the projectile motion law and under the condition of load distribution,and analyzed the stress distribution of the flow field,the changing rule of the free surface flow,etc.In addition,the shell structure projectile body was studied,and the influence of wall thickness on the load distribution of shell structure projectile body was analyzed.The calculated results show that the maximum impact force of the projectile body is linearly related to the velocity of the projectile body,and the maximum impact force of the projectile body can be effectively reduced by reducing the angle of entry.However,with the decrease of the angle of entry,the axial force of the projectile body will increase,which may have a certain impact on the internal components.When slanting into water,the attitude of the projectile body will deflect to some extent under the action of bending moment.When there is an angle of attack,the force of the projectile body will change a little.Moreover,the size of the angle of attack has a great influence on the trajectory of the entry trajectory,which basically coincides with the direction of velocity.Increasing the wall thickness can effectively reduce the maximum stress of the structure and reduce the deformation of the missile body.However,as the mass increases,the maximum impact force will increase.Therefore,proper wall thickness should be selected to meet the requirement of structural strength and increase the missile’s payload.When the projectile body of the assembly structure enters the water,the center of the inner surface of the end face of its head and the connection between the projectile body and the ring are prone to stress concentration,which may cause the failure of the structure.Therefore,it can be judged whether the structure meets the requirement of overall strength.