某固体火箭发动机点火启动过程三维流场一体化仿真

Integrated simulation on 3D flow field during ignition start-up of SRM

以某固体发动机的燃烧室和喷管为一体化研究对象,采用三维流场控制方程,应用有限体积法计算了发动机点火启动过程中燃烧室和喷管内燃气的流场特性。发动机药柱上的着火点最初出现在药柱星角尖上,然后向四周扩展;在药柱点火初期,燃气压力波先于火焰峰到达喷管;随着燃烧室内燃气压力升高,压力沿轴向分布逐渐平缓;当喷管进口压力与出口背压比达到某一值时,喷管扩张段内出现一道激波,随着压力比的升高,激波最终移出喷管,燃气流速在喷管出口处达到最大值。

Taking the chamber and nozzle of a SRM as investigation subject, the flow field characteristics of fuel gas in the chamber and nozzle during ignition start-up of motor were calculated by means of 3D flow field governing equations and finite volume method. The ignition point of motor grain firstly occurred at the star tip of the grain and spreaded towards all directions. At the beginning of grain ignition, the gas pressure wave prior to the flame arrived at the nozzle inlet. With the increase of gas pressure in the chamber,gas pressure along axial direction became gradually gentle. When the ratio of inlet pressure to exit back pressure of the nozzle reached a certain value, there existed a shock wave in the divergent nozzle; with the increase of pressure ratio, the shock wave can move outside the nozzle, and the velocity of gas can reach the maximum at the nozzle exit.