高速射弹小角度入水弹道特性研究

Trajectory and Cavitation Characteristics of High-Speed Projectiles at Small Angle of Water Entry

研究高速射弹小角度入水过程中的空化现象和弹体运动规律.计算采用VOF多相流模型捕捉空泡界面,采用Schnerr and Sauer空化模型模拟空化现象,弹体运动通过6自由度方程与重叠网格技术进行求解.计算分析了弹体小角度入水过程中的弹道特性、空泡的演化规律及射弹的流体动力特性,初步探索了高速射弹的小角度入水时产生的弹跳现象.研究表明:此高速运动的旋转射弹在小角度入水时,弹体轨迹和姿态容易发生很大的变化,空泡形态不对称,弹体大面积沾湿导致弹体受到很大的流体动力和力矩,弹体运动失稳产生弹跳翻转现象.分析表明,弹体小角度入水容易沾湿,沾湿对流体动力及其运动姿态有着极大的影响,弹体的不对称沾湿是超空泡射弹失稳的重要原因.

The cavitation phenomena and ballistic characteristics of high-speed rotating projectiles entering the water with a small angle were numerically studied.The VOF multiphase model was introduced to capture the vacuole interface and the free liquid surface.The Schnerr-Sauer cavitation model was used to simulate the generation and evolution of cavitation process.The motion of the missile was calculated by the overset mesh technique and the six-degree-of-freedom algorithm.Then the trajectory characteristics,cavitation evolution and hydrodynamic properties of projectile were studied in the process of small angle water entry.The bouncing and fluttering phenomenon of the high-speed spinning projectile with small water entry angle was preliminarily explored.The results showed that when the initial launching angle was too small,the posture of the projectile tended to change greatly,the asymmetric shape of the vacuole and the large wet area of the projectile caused the moving body to receive large fluid dynamics and moments;the motion of the projectile was unstable and resulted in the bouncing and fluttering phenomena.The analysis shows that the projectile is easy to get wet with too small water entry angle.The wetting of the projectile has a great influence on the hydrodynamics and the motion state of the projectile.The asymmetric wetting of the projectile is an essential factor for the instability of super-cavitation projectiles.