摘要
基于均质平衡多相流理论,建立了水下高速射弹超空泡形成过程的数理模型,对12.7 mm口径射弹进行了水下射击试验,验证了模型的合理性。对不同速度的76 mm射弹进行了数值模拟。结果表明:在弹丸表面,沿轴线各点依次产生空化现象,但在弹丸头部区域内各点水蒸气含量呈线性增加;在弹丸圆柱部区域,各点水蒸气含量先快速上升至0.3~0.4,随后维持平台期,再快速上升。射弹速度越快,平台期越短,超空泡形成得越快,超空泡形成时间满足指数型变化规律。在弹丸头部,空泡发展速率由快速的线性衰减阶段过渡到近似呈缓慢线性衰减的阶段。射弹速度越快,空泡发展速率越高,第一阶段中衰减得越快,衰减幅度也越大,而第二阶段中的衰减速度几乎不变。在弹丸圆柱部,空泡发展速率的变化分为快速衰减阶段与缓慢衰减阶段。射弹速度越快,空泡发展速率越高,第二阶段中衰减得也越快。弹丸表面摩擦阻力系数变化特性与弹丸圆柱部空化特性相对应。弹丸速度越快,阻力系数衰减越快,达到稳定时的值也越小;当速度高于1100 m/s后,阻力系数达到稳定的时间几乎不变,达到稳定时的数值变化也不大。
Based on the homogenous equilibrium multiphase-flow theory,the mathematical model of the supercavitation formation process of underwater high-speed projectile was established.The underwater shooting experiment of the 12.7 mm caliber projectile was carried out to verify the rationality of the model.Numerical simulations were carried out for 76 mm projectiles of different velocities.The results show that,on the surface of the projectile,cavitation occurs in sequence along the axis.In the region of the projectile head,the water vapor content increases linearly at each point.In the cylindrical region of the projectile,the water vapor content at each point rises rapidly to 0.3~0.4 and then maintains the plateau period,and then rises rapidly.The faster the projectile is,the shorter the plateau period is,the more quickly the supercavitation forms,and the supercavitation formation time satisfies exponential change law.In the projectile head region,the change process of the cavitation growth rate can be divided into two stages,from a fast linear decay phase to a phase that approximately slowly linearly attenuates.The faster the projectile is,the higher the rate of cavitation development,and the faster the attenuation in the first stages,the greater the attenuation,and the decay rate in the second phase is almost constant.In the cylindrical part of the projectile,the change process of the cavitation growth rate can be divided into two stages,a fast decay stage and a slow decay stage.The faster the projectile is,the higher the rate of cavitation development,and the faster the attenuation in the second phase.The variation characteristics of the viscous drag coefficient of the projectile surface corresponds to the cavitation characteristics of the projectile cylinder.The faster the projectile is,the more quickly the drag coefficient attenuates,and the smaller the value when it reaches stability.When the velocity is higher than 1100 m/s,the time when the drag coefficient is stable is almost constant,and the value change is little when it reaches stability.
作者
胡雨博
余永刚
HU Yubo;YU Yonggang(School of Energy and Power Engineering,Nanjing University of Science and Technology,Nanjing 210094,China)
出处
《弹道学报》
EI
CSCD
北大核心
2020年第1期1-8,共8页
Journal of Ballistics
基金
国家自然科学基金项目(11372139)。
关键词
高速射弹
流体力学
自然超空泡
数值模拟
high-speed projectile
fluid mechanics
natural supercavitation
numerical simulation
