高速射弹出水过程中水弹道问题研究

摘要

Based on the developed experimental device for high-speed projectile exiting from water,the development process of the supercavity,shedding and its interaction with free-surface during exiting from water of high-speed projectile were observed by a high speed camera.Based on the measured experimental data,the cavitation number σ and the drag coefficient Cd of the underwater body were calculated,and the polynomial fitting-formula of σ and Cd were given by referring to the formulas of Reichardt,Munzner and Logvinovich.A general correlation relationship between σ and Cd was obtained.If an angle of attack of the slender body presents during exiting from water,the collapse of asymmetric cavity can lead a deflection of trajectory.Increasing the aspect ratio and length of the body,the drag of the underwater body can be reduced.By using the FLUENT software and VOF method,the three-dimensional flow field of exiting-from-water process was numerically simulated.The computational results are in good agreement with the experimental results.An example for the deflection of underwater trajectory during exiting from water was given.The result shows that the collision and slippage between the underwater projectile and supercavity wall can lead to the deflection of underwater trajectory.%在研制高速射弹出水实验装置的基础上,利用实验和数值模拟的方法研究了细长圆柱型射弹(简称射弹)高速出水时包裹着射弹的超空泡的发展、脱落及其与自由面相互作用的全过程.根据测得的实验数据,计算出高速射弹出水过程中的空化数和阻力系数,参考Reichardt和Munzner以及Logvinovich公式,给出了阻力系数和空化数的多项式关系拟合公式,进一步形成了阻力系数归一化数值处理方法.结果表明:该高速射弹出水瞬间存在攻角时,非轴对称的空泡溃灭会使射弹的运动方向发生偏转;适当增大射弹的长径比或空化器长度,有利于高速射弹的水下运动减阻.基于FLUENT软件并采用VOF方法,对高速射弹出水过程进行了三维数值模拟,计算结果与实验结果吻合良好.该文还给出一个出水过程中水弹道偏转的示例,说明射弹在水下与超空泡壁面的碰撞滑移会引起水中弹道的偏移.