液体火箭发动机非稳态燃烧过程对其稳定性的影响

Effects of unsteady combustion process on combustion instability of liquid rocket engine

基于模型分析了由非稳态燃烧过程引起的不稳定热释放这一激励源项对稳定性的影响,探讨了相应的激励机理。采用小扰动分析方法,将一维层流预混火焰燃烧模型方程分解为稳态和非稳态两类控制方程,建立了线性增长率中燃烧释热项的计算方法,获得了温度及释热量的空间分布,探讨了初始温度及比热比变化对其影响规律。结果表明:采用高能推进剂的燃烧系统具有相对较低的稳定性,而对于同一种推进剂,比热比的增加会导致稳定性对频率的敏感程度增加,且具有明显的频率选择性。

Based on theoretical model,the effect of unstable combustion heat release induced by unsteady combustion process,the most important source term of exciting on combustion stability and its triggering mechanism were analyzed and discussed.Then one dimensional premixed laminar flame model was separated into stable and unstable forms by the small perturbation analysis way,and the calculating method for heat release term in linear growth rate was built.With the distributions of temperature and heat release in space,the effects of varying initial temperature and specific heat ratio on this term were investigated.It is indicated that the combustion system using energetic propellants with low initial temperature always behaves more stably.For the same kind of propellant,increasing the specific ratio will make stability more sensitive to frequency,which will be more clearly for some frequency range.