关键词: 入水稳定性, 射弹头型, 入水冲击, 入水空泡, 高速入水, 计算流体力学

Abstract:

Cavitation evolution characteristics and water entry stability of projectiles with different nose shapes during high-speed oblique water entry impact and underwater navigation phases with cavitation are studied to provide a theoretical basis for high-speed projectiles， air-dropped torpedoes and other trans-medium weapons to attack targets with high accuracy. Combined with high-speed full flow field visualization experiments technology and numerical simulation analysis， influence of projectile nose shapes on water entry cavitation shapes， cavitation size， movement speed， pitch angle and water entry stability is emphatically discussed by comparing the high-speed oblique water entry process of projectiles with three different nose shapes. Comparison involves cylindrical flat nose， hemispherical nose and 90° cone nose.Results show that although the process of water entry and underwater navigation with cavitation of the three projectiles are the same， the nose shape has a significant influence on water entry cavitation characteristics and water entry stability of projectiles during high-speed oblique water entry. In the water entry phase， the water entry cavitation diameter of the cylinder flat nosed projectile is the largest， followed by the 90° cone nosed projectile， and the smallest being the hemispherical nosed projectile. The water entry impact load decreases in the order of cylindrical flat nosed projectile， hemispherical nosed projectile and 90° cone nosed projectile. During the underwater navigation phase with cavitation， the maximum length-to-diameter ratio of the water entry cavitation of the cylindrical flat nosed projectile reaches 7.187， which is large in diameter and short in length； on the contrary， the maximum length-to-diameter ratio of the water entry cavitation of the hemispherical nosed projectile is as high as 10.864， and the cavitation shows a slender shape. However， the cavitation shape of the 90° cone nosed projectile is extremely unstable due to the destruction of the cavitation wall. In the whole water entry process， the hemispherical nosed projectile has the best water entry stability， followed by the cylindrical flat nosed projectile， and the 90° cone nosed projectile has the worst water entry stability.

Key words: water entry stability, projectile nose shape, water entry impact, water entry cavitation, high-speed water entry, computational fluid dynamics