发动机起动燃气返腔仿真与影响分析

针对某液体火箭发动机在试车起动时出现的燃气发生器头部温度过高现象,建立了发动机起动时发生器及燃气系统内部流动的三维模型,通过Fluent流场计算对起动燃气路内流场进行了模拟和分析。从启动器起动0.65s定常流场计算结果与0～0.65s的瞬变流场计算结果中可以看出,火药启动器燃烧后的起动燃气沿倾斜的燃气入口进入燃气路,经内壁反射后冲入燃气发生器,燃气进入发生器头腔,造成了发生器头部温度过高。调节氧头腔氦吹除流量,进行起动的0.65s定常数值模拟。模拟结果表明,适当增大吹除流量是控制起动时发生器头部温度的一个行之有效的手段。再将燃气多通的燃气入口倾角改进为80°倾角和90°倾角,分别建立模型并进行了起动的0.65s定常数值模拟。模拟结果与原模型进行比较时发现,燃气入口倾角增大可以在一定程度上改变起动燃气路径,减少燃气返腔造成的头腔温度峰值过高的影响。

Backflow simulation and its influence analysis for gas generator of LRE

A 3D model of the generator and the gas flow inside the gas system while the engine is starting is established to eliminate the high-temperature phenomenon appearing at the head of LH2/LOX engine gas generator as the engine starts. The inner flow field in the starting gas line was simulated and analysed after flow field calculation with the Fluent software. The calculation results of the steady flow field as the starter works for 0.65 s and the unsteady flow field in the range of0-0.65 s show that the starting gas from the burned starter enters into the gas pipe by the declining gas intake, reflects on the inner wall, then goes into the gas generator and its head, and results in a over high temperature there. The numerical simulation of the steady flow field at 0.65 s was conducted. The result shows that the appropriate increase of the ablution flow and the gas intake angle （80° and 90° ） is an effective measure to reduce the influence of the high temperature on the engine.