Numerical study on the water-entry characteristics of asynchronous parallel projectiles at an oblique impact angle

This study investigates the water-entry problems of asynchronous parallel projectiles with oblique entry speeds of 200 m/s for different water-entry intervals and two different water-entry sequences numerically. The experiment of the water-entry of the projectile with an oblique impact angle is conducted to verify the numerical method. The influences of the oblique asynchronous parallel water-entry on the evolutions of the cavitating flow and the movement characteristics under different working conditions are studied in detail. It can be found that for the minimum interval, the first launch projectile is not able to generate a complete cavity to encapsulate its body due to the intense compression of the cavity of the following launch projectile, and its movement is seriously affected and ultimately destabilized. Simultaneously, compared with the first launch projectile entering the water from the side close to the initial free surface, the cavity of the first launch projectile entering the water from the side away from the initial free surface is squeezed more, wetted earlier and destabilized faster. With the increase of the interval, the influence of the following launch projectile on the cavity evolution and movement stability of the first launch projectile weakens. Besides, for the following launch projectile, due to the continuous impact of the cavitating flow of the first launch projectile, the profile of the cavity of the following launch projectile presents asymmetry. For the minimum interval, the projectile deflects faster and towards the inner side of the projectile, while for the larger intervals, the projectile deflects to the outer side of the projectile and becomes unstable.