液氧煤油补燃发动机喷注器高频燃烧不稳定性的试验研究

针对液氧煤油高压补燃循环发动机高频燃烧不稳定性这一突出问题，建立了喷注单元的低压高频燃烧不稳定性模拟试验系统，使用气气推进剂。利用相似准则设计了缩比燃烧室，研究了全尺寸气液同轴式喷注器的结构尺寸和工作参数对燃烧稳定性的影响。结果表明，激发高频燃烧不稳定性时火焰变短，燃烧室压力出现大幅振荡并伴随啸叫；喷注器缩进室长度对燃烧稳定性裕量有很大影响并存在相对最佳值。试验结果可以指导发动机燃烧室的燃烧稳定性设计和评估，在发动机研制初期筛选燃烧稳定性相对最好的喷注器结构。

Experimental Study on High Frequency Combustion Instability with Coaxial Injector of Staged Combustion LOX/kerosene Rocket Engine

A single-injector firing model is established for the high-frequency combustion instability of staged combustion LOX/kerosene rocket engine with high pressure and high temperature in the combustion chamber.The gaseous propellant components are used to provide actual volumentric flow rates at low pressure level practically equal to atmospheric pressure.A scaling-down combustion chamber model is designed and built based on the similarity theory,and single bipropellant coaxial injector specimens are installed on the combustion-chamber head.The effects of structural parameters and operating conditions on high-frequency combustion stability are obtained from pressure-oscillation decrements.The results show that the flames become short,and the high pressure oscillations and squealing appear when the high-frequency combustion instability is excited.The retractive length of the injector would have crucial effect on the combustion instability boundaries and the margins,and have a optimal range.The results of simulation test could served in the engine design.