Simulation of the oblique entry motion of convolutional projectile into water

In order to study the influence of motion parameters and warhead shape on the oblique entry process of a projectile into water, adopting volume of fraction of gas-liquid two-phase flow and water vapor cavitation model. The three-dimensional kinematics and dynamics of the rigid body were coupled by nested grids, and the motion process of the projectile in the stage of speed 80~100 m/s tilting into water and opening cavitation process was simulated. According to the literature experiments, the prediction errors of the velocity and displacement of the underwater projectile are 0~6% and -8%~0, and the rotation angle error is - 6%~0. Through the simulation study of the water entry velocity and angle of entering water under multiple working conditions, it is found that with the increase of the water entry velocity, the axial impact load of the projectile increases. The maximum load is linearly related to the square of the speed, and the nonlinear attenuation rate of the velocity is large. The larger the angle of entry, the smaller the angular rate of rotation of the projectile body, the stronger the stability of movement. But the velocity decay rate is not affected by the angle of entry. The projectile body adopted a stepped head modification, compared with the conical nose projectile, the average velocity decay rate, rotation angular rate and maximum axial impact load of the body after the head stepped modification are reduced to 66.7%, 40% and 77.2% respectively. The motion stabilitity is improved significantly.