低压室初始长度对火箭弹自力弹射出筒尾流场的影响

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

关键词:  自力弹射  燃气射流  起始冲击波  火箭弹  数值模拟

Key words:  Self-ejection  Jet flow  Initial shock wave  Rocket  Numerical simulation

摘要:

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。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，随着低压室初始长度增加，尾流场初始阶段震荡幅度增大且震荡时间延长；尾流场发展阶段内弹体位移增量及速度增量减小，尾流场稳定阶段内弹体位移增量及速度增量增加；自力弹射过程中低压室压强显著下降，为降低对发射装置结构强度的设计要求，低压室初始长度应在设计范围内选择较大值。

Abstract:

The change of the initial length of low pressure chamber will affect the value of pressure in low pressure chamber during the process of rocket self-ejection directly， and then the change can influence the characteristic of wake filed during rocket leaving the launcher by self-ejection. A solution model of wake field of rocket leaving the launcher by self-ejection based on two-dimension axisymmetric Navier-Stokes equation was set up， unsteady numerical simulation of the whole process of rocket launch by self-ejection was carried out by dynamic grid technology. The flow structure of the supersonic jet obtained by simulation with the model in this paper is consistent with the experiment schlieren graph. The rocket self-ejection test was carried out and the experimental data is in good agreement with the simulation data. On this basis， the effects of initial length of low pressure chamber on different stage of wake flow were analyzed. The results show that， with the increase of initial length of low pressure chamber， the amplitude and duration of flow vibration increase in the preliminary stage. The velocity increment and displacement increment decrease in growing phase and increase in steady phase. The pressure in low pressure chamber during the process of self-ejection decrease significantly. In order to reduce the requirement for the structural strength of launcher， the initial length of the low pressure chamber should select the larger value within the design range.