空心弹高速斜入水弹道稳定性研究

STUDY ON THE BALLISTIC STABILITY OF HOLOW PROJECTIAL DURING HIGH-SPEED OBLIQUE WATER ENTRY

空心弹是一种具有通孔结构的新型射弹,与相同口径的实心射弹相比,阻力更小,在同等装药量的条件下具有初速高的优点,其入水时呈现复杂的入水流体动力学和弹道特性.文章基于雷诺时均Navier-Stokes方程、VOF(volume of fluid)多相流模型、SST(shear stress transfer)k-ω湍流模型、Schnerr-Sauer空化模型、六自由度模型和重叠网格技术对空心弹高速入水进行了数值模拟,研究了入水速度和角度对空心弹入水空泡、空化、载荷和弹道稳定性的影响.将数值计算结果与实验结果进行对照,空泡形态和质心轨迹曲线与实验结果吻合较好,验证了数值模拟方法的可行性.结果表明:空心弹入水速度对空泡的大小和空泡内空化的程度影响较大,随着入水速度越高,空泡也越大,空化越明显,弹体的速度衰减越快,弹道越不稳定,弹体失稳越早;随着入水速度越低,空心弹的阻力和升力系数越小,弹体运动越稳定.入水角度对空泡的大小及弹体的偏转程度有较大影响,入水角度越大,弹体偏转时刻的空泡越大,空泡内的空化越明显,弹体头部的高压区域越小,阻力、升力和力矩系数越小,相同时间内弹体的偏转角越小,弹体姿态越稳定.入水角度越小,弹体的偏转角增加的越快,弹体运动越不稳定.

The hollow projectile is a new type of projectile that features a through-hole structure.It offers advantages such as reduced drag compared to the solid projectiles of the same outer diameter,while still achieving high initial velocity when using the same charge.It exhibits complex hydrodynamic and trajectory characteristics when entering water.A numerical simulation study of the high-speed water entry of the hollow projectiles was carried out based on the Reynolds average Navier-Stokes(RANS)equation,the volume of fluid(VOF)multi-phase flow model,the shear stress transfer(SST)k-ωturbulence model,the Schnerr and Sauer cavity model,the six degrees of freedom(6-DOF)motion simulation method,and the overlapping grid technology.The effects of water entry velocity and angle on the water-entry cavity,cavitation,load and ballistic stability were investigated.Comparing the numerical calculation results with the experimental results,the cavity morphology and the center-of-mass trajectory curves were in good agreement with the experimental results,which verified the feasibility of the numerical simulation method.The results show that the water entry velocities have a greater influence on the size of the cavity and the degree of cavitation in the cavity.The higher the water entry velocity,the larger the cavity,the more obvious the cavitation,the faster the velocity decay of the projectile,the more unstable the trajectory,and the earlier the projectile destabilization.The lower the water entry velocity,the smaller the drag and lift coefficients of the hollow projectile are,and the more stable the motion of the projectile is.The water entry angle has a significant impact on the size of the cavity and the degree of deviation of the projectile.The larger the water entry angle is,the larger the cavity at the moment of the projectile deflection is,the more obvious the cavitation inside the cavity is,the smaller the high-pressure region of the head of the projectile is,the smaller the drag,lift,and moment coefficients are,the smaller the deflection angle of the projectile is at the same time,and the more stable the attitude of the projectile is.The smaller the angle of water entry,the faster the deflection angle of the projectile increases,and the more unstable the motion of the projectile will be.