平衡风速下十字形伞弹系统姿态摆动分析

Study on Attitude Swing of Cross Parachute-bomb System in Balanced Wind Speed

以一定高度和速度飞行的母弹从其伞弹舱中抛撒伞弹系统群,各个伞弹系统的姿态摆动情况将影响其落点及落角,进而影响其作战效能。采用立式风洞试验和非定常数值仿真(CFD),分析平衡风速下十字形伞弹系统的姿态摆动情况。通过立式风洞试验,可确定柔性伞的外形、伞弹系统的阻力系数和摆动频率,并创新"拉拽式"试验模型的约束方法;采用基于三维N-S方程的CFX软件,进行伞弹系统非定常数值仿真,分析其摆动机理。结果表明:数值仿真得到的阻力系数、法向力系数、侧向力系数及其摆动频率,均与风洞试验结果相吻合,即数值仿真结果能够反映风洞试验中伞弹系统的摆动情况;伞弹系统的流场极不稳定,伞衣内部有一对方向相反、强度交替变化的旋涡,伞衣外部存在不稳定分离流动,二者相互关联,使得气动参数呈周期性波动,导致伞弹系统的姿态摆动。

The projectile which works in a certain speed and altitude throws parachute-bomb system, and swing of parachute-bomb systems influence interception and impact angle and attack effect. Attitude swing of cross parachute-bomb system in balanced wind speed is studied by test of vertical wind tunnel and unsteady numerical simulation. The constraint method of ＇pulling＇ is presented in the test, and the shape and drag coefficient and swing frequency of parachute is obtained by way of the test. On this basis, the reason of parachute swing is fur- ther studied by three-dimensional unsteady numerical simulation. The results indicate that the computational drag coefficient and frequency of normal force coefficient（lateral force coefficient） is close to that of the experiment, and the flow around the parachute is unsteady. There are two vortices（a pair of vortex）, whose directions are contrary and intensities vary alternately in the parachute. Moreover, there is the unsteady detached flow upon the parachute. The vortices relate with the unsteady detached flow. Aerodynamic coefficients change periodi- cally. Thus, the attitude of the parachute-bomb system become unstable. The method of wind tunnel test and numerical simulation would be referenced in the design of similar parachute-bomb system. And the conclusion can provide a theoretical basis to optimize the parachute-bomb system.