高速航行体齐射出水过程的空化与运动特性研究

Research on cavitation and motion characteristics of high-speed vehicles exiting water in underwater salvo

基于求解N-S方程的VOF方法,引入Schnerr-Sauer空化模型、SST k-ω湍流模型和6DOF刚体运动模型,通过重叠网格技术建立两发射弹齐射出水的数值计算模型,并进行了数值方法的有效性验证。研究了不同发射无量纲时差下射弹齐射出水过程的超空泡演化特性、射弹的弹道轨迹、偏转角变化和减阻性能,分析了超空泡流场的干扰机理。研究结果表明:同步发射出水时,射弹超空泡内侧扩张受到抑制,在出水阶段超空泡发生了非对称性溃灭;两射弹的弹道稳定性较差,其偏转角的最大值达到了3.1°;对于异步发射出水,首发射弹超空泡前沿轮廓基本对称,而次发射弹超空泡前沿轮廓内侧壁面发生膨胀,失去了对称性,随着发射时差的增大,次发射弹超空泡内侧前沿轮廓曲率变小。首发射弹在出水过程中能维持良好的弹道稳定性,次发射弹在压差作用下向内侧偏转,运动轨迹也向内侧偏移,运动过程中次发射弹的最大无量纲水平位移和最大偏转角随发射时差的增大而减小。相比异步发射出水,同步发射条件下射弹的无量纲竖直速度衰减略快。

By means of the VOF method for solving the N-S equation, the Schnerr-Sauer cavitation model,SST k-ω turbulence model and 6DOF rigid body motion model, the numerical calculation model of two projectiles exiting water in underwater salvo was established through the overlapping grid technology, and the effectiveness of the numerical method was verified. The supercavity evolution characteristics, the trajectory,deflection angle changes and the drag reduction performance in water exit of the salvo for different launch dimensionless time intervals were studied, and the interference mechanism of the supercavitating flow field was analyzed. The results show that when the two projectiles are launched synchronously in the water-exit process,the expansion of the wall surface of the supercavity inside is restrained, and the supercavity collapses asymmetrically in the water-exit stage. The trajectory stability of the two projectiles is poor, and the maximum deflection angle reaches 3.1°. For water-exit process in the asynchronous launch, the front part of supercavity profiles of the first projectile is basically symmetrical, while the wall of the front part of supercavity profiles inside of the second projectile expands and loses symmetry. With the increase of the launch time interval, the curvature of the front part of supercavity profiles inside of the second projectile decreases. The first projectile can maintain good trajectory stability in the water-exit process. The second projectile deflects inward under the action of the pressure difference, and the motion trajectory also shifts inward. The maximum dimensionless horizontal displacement and maximum deflection angle of the second projectile decrease with the increase of the launch time interval. Compared with the asynchronous launch, the dimensionless vertical velocity of the projectile decays slightly faster under the condition of synchronous launch.