喷管分离流动及其侧向载荷

Flow separation and side-load in nozzle

利用商业软件CFX对某液体火箭大面积比喷管地面条件下的分离流动进行了三维数值模拟.计算获得了喷管入口总压从8MPa减小到1MPa时的流场参数分布和侧向力载荷情况.结果表明,随着入口总压的降低,喷管内流场会依次经历自由激波分离和受限激波分离两种分离激波模态.受限激波分离模态下喷管壁面压强具有较大波动,再附着点压强甚至高于环境压强.流动分离情况下,喷管将受到一定侧向载荷作用,载荷方向随机分布.入口总压为4MPa时计算得到的侧向载荷最大,实际侧向载荷峰值可能出现在自由激波分离与受限激波分离转换瞬间.

A three-dimensional numerical simulation about the separation flow in the high-altitude nozzle of a liquid rocket engine on ground was conducted.It obtaines the flow field parameters and the side-loads under work conditions from 8MPa inlet total pressure to 1MPa inlet total pressure.The results indicate that,with the reduction of inlet total pressure,the nozzle flow field will sequentially experience free shock separation mode and restricted shock separation mode.In restricted shock separation mode,the wall pressure has great fluctuation,and is even beyond the ambient pressure in reattachment point.In separated flow fields,side-loads will occur,the directions of side-loads are random.The calculation obtaines the biggest side-load under 4MPa inlet total pressure.It can be predicted that the side-load peak will appear with the exchange between free shock separation mode and restricted shock separation mode.