空化器形状对超空泡射弹尾拍运动影响的数值研究

NUMERICAL SIMULATION ON THE INFLUENCE OF CAVITATOR SHAPES ON THE TAIL-SLAP OF SUPERCAVITATING PROJECTILES

为研究空化器形状对超空泡射弹尾拍航行时运动特性的影响,基于有限体积法和Mixture多相流模型,结合动网格技术构建了三维自由尾拍运动仿真模型,在两种长径比下比较了平头弹、凹口弹、锥头弹的尾拍运动特性,并分析了其水动力影响因素。结果表明:较小长径比下,平头弹可以保持运动稳定,凹口弹和锥头弹易失稳,主要是由于空化器产生的空泡尺寸差异导致其临界失稳攻角依次降低。较大长径比下,临界失稳攻角消失,三种头型射弹均能保持尾拍稳定,锥头弹在速度较高时以“单侧尾拍”保持稳定,速度降低后以“双侧尾拍”保持稳定,而平头弹和凹口弹始终以“双侧尾拍”保持稳定;锥头弹由于“单侧尾拍”会产生与初始扰动方向相反的垂直位移,而平头弹和凹口弹由于弹头升力产生与初始扰动方向相同的垂直位移。

To investigate the influence of cavitator shapes on the motion characteristics of a supercavitating projectile during its tail-slap process,a three-dimensional free tail-slap motion simulation model was established based on the finite volume method and Mixture multiphase flow model,combined with the dynamic mesh technology.Under the conditions of different aspect ratios,the motion characteristics of projectiles with a flat head,a notched head and a conical head were compared during the tail-slap processes and the hydrodynamic factors were analyzed.When the aspect ratios are small,the motion of the projectile with a flat head kept stable,while the projectiles with a notched head and a conical head were prone to instability.The main reason was that the critical instability angle of attack decreased successively due to the differences of cavity size generated by the cavitators.When the aspect ratios are large,all three types of projectiles kept the tail-slap stable with the disappearance of the critical instability angle of attack.The projectile with a conical head kept stable in the“unilateral tail-slap”mode at high speeds,and in the“bilateral tail-slap”mode at a lower speed.The projectiles with a flat head and notched head were always stable in the“bilateral tail-slap”mode.For the projectiles with a flat head and notched head,vertical displacement in the same direction as the initial disturbance was produced due to the lifting force of warhead,while the direction was opposite for the projectile with a conical head due to the“unilateral tail-slap”mode.