深度节流补燃循环发动机系统稳定性研究

补燃循环发动机深度节流过程中,系统参数大范围变化,低工况时喷注器压降和供应系统节流元件压降较低,容易出现推进剂供应系统与热力组件耦合的不稳定问题。针对10∶1深度节流富氧补燃循环发动机,通过Nyquist稳定性分析方法,对发动机全工况范围内泵后供应系统和燃气系统耦合稳定性进行仿真研究。结果表明:富氧补燃循环发动机燃料供应路与燃气路形成的闭环系统在低工况时,稳定裕度较低,改善燃气发生器喷雾燃烧效果以缩短时滞、增加燃气停留时间、在靠近燃气发生器位置增加供应系统压降能提高系统稳定裕度。

Study on system stability of deep-throttling staged combustion cycled engine

During the deep-throttling process of staged combustion cycled engine,the system parameters vary in a large range.Under the low operating condition,the injection pressure drop and the pressure drop of feed system throttling element are relatively low,so the coupling instability between the propellant feed system and the thermal component is easy to occur.For the 10∶1 deep-throttling oxygen-enriched staged combustion cycled engine,the coupling stability of the after-pump feed system and the gas system within the full operating range was studied by Nyquist stability analysis method.The results show that the stability margin of the closed-loop system composed of the fuel feed circuit and the gas circuit is low under low operating conditions of the oxygen-enriched staged combustion cycled engine.The system stability margin is able to be enhanced by improving the evaporation and combustion effect of the gas generator to shorten the time lag,increasing the gas residence time,and increasing the pressure drop near the gas generator.