低压室初始长度对火箭弹自力弹射出筒尾流场的影响

低压室初始长度的改变直接影响火箭弹自力弹射过程中低压室压强的建立，进而对弹射出筒过程中的尾流场产生影响。本文基于二维轴对称N-S方程建立了火箭弹自力弹射出筒尾流场的数值计算模型，采用动网格技术对弹射出筒的全过程进行了非定常数值计算。采用文中计算模型对超声速冲击射流试验进行了模拟，得到的流场结构与试验纹影图匹配良好；开展了自力弹射的实弹发射试验，仿真数据与试验数据的一致性较好，在此基础上分析了低压室初始长度对尾流场不同阶段的影响。结果表明，随低压室初始长度的增加，发射筒底部的第一个压强峰值增大；尾流场初始阶段震荡幅度增加且震荡时间延长；尾流场发展阶段内弹体的位移增量及速度增量减小，低压室压强峰值及峰值过后的压强下降速度减小；尾流场稳定阶段内弹体的位移增量及速度增量增加。

Effects of Initial Length of Low Pressure Chamber on Wake Field of Rocket Leaving Launcher by Self-Ejection

The change of the initial length of low pressure chamber will affect the value of pressure in the low pressure chamber,and then the change can influence the characteristic of the rocket wake filed during the self-ejection process.In order to study the influence of initial length,a solution model of the wake field based on two-dimension axisymmetric Navier-Stokes equation was set up.The whole process of self-ejection is simulated by using the dynamic grid technology.The simulation result of the supersonic jet structure by using the model in this paper is consistent with the experiment schlieren graph.The rocket self-ejection test is carried out and the experimental data is in good agreement with the simulation data.On this basis,the effects of initial length on different stage of wake flow are analyzed.With the increase of initial length,the first pressure peak at the projector bottom increase.At the preliminary stage of wake field,the amplitude and duration of gas flow vibration increase.The ?v and ?l in growing stage decrease,the peak of pressure in low pressure chamber decrease and the rate of pressure decline after peak slowed down.The ?v and ?l increase in steady stage.