小推力液体火箭发动机燃烧与传热数值仿真研究

针对边区液膜冷却型小推力液体火箭发动机,引入VOF模型模拟冷却液膜,使用数值仿真手段计算了发动机推力室突扩构型对燃烧效率与传热特性的影响.对比可见计算结果是可靠的,计算表明无量纲台阶高度H*从0.111增加到0.222,燃烧效率增加0.35个百分点、燃烧效率随无量纲台阶长度L*增加变化较小、另外传热特性受H*与L*的影响都不大.这表明在扩张型推力室中,燃烧效率下降的主要原因是壁面附近的气态MMH无法与氧化剂有效混合.

A numerical study of combustion and heat transfer in small thrust liquid rocket engine

By introducing VOF model to simulate the cooling liquid film in small thrust liquid rocket engine,numerical method was performed to calculate and evaluate the effects of the expansion size on combustion efficiency and heat transfer in the chamber.Comparison shows the calculation is reasonable.It has shown that as the dimensionless expansion height H* increases from 0.111 to 0.222,combustion efficiency and specific impulse increase by 0.35 % and 0.5s.However,the dimensionless expansion length L* plays a less significant role in the process.As it increases from 1.389 to 1.944,combustion efficiency and specific impulse decrease by 0.11 % and 0.3s respectively.It is evident that the heat transfer characteristics of thrust chamber keep stable in the variation of H* or L*.This shows in expansion thrust chamber,the main reason for combustion efficiency loss should be that gaseous MMH adjacent side wall cannot mix with gaseous oxidant efficiently.