水下高速射弹空泡形态与阻力特性研究

Cavity Shape and Drag Characteristics of Underwater High-speed Projectile

试验研究射弹在水下带空泡高速运动存在诸多限制,为了获得水下高速射弹的空泡形态和阻力系数的变化规律,分别采用CFD仿真软件和应用基于空泡截面独立扩张原理建立的公式来研究水下高速射弹的空泡形态及阻力特性。研究结果表明,仿真计算结果与公式计算结果吻合良好;随着空化数的减小,空泡的相对长度、相对直径和长细比都在增大;在小空化数下,空泡前部形态基本不变,阻力系数主要为压差阻力系数,其值基本不变。提出了水下高速射弹外形设计步骤:公式计算初步建立模型—仿真计算修改模型—试验确立模型,旨在为射弹的外形设计提供参考。

Experimental study of projectile has many restrictions under underwater high-speed motion with cavity. To obtain the variation rules of cavity shape and drag characteristics of an underwater high-speed projectile, we investigated cavity shape and drag characteristics of the projectile by using computational fluid dynamics （CFD） and a formula based on the independent expansion principle of cavity sections. Conclusions are drawn that the numerical simulation agrees well with the computation of the formula; the relative length, relative diameter and slenderness ratio of cavity increase with the reduction of cavitation number; for small cavitation number, the shape of cavity front changes little, and the stable pressure difference coefficient becomes the main part of drag coefficient. We suggest the steps of shape design of the underwater high-speed projectile as follows： 1） tentative modeling by formula computing; 2） modifying model by numerical simulation; 3） establishing model bv experimental method.