喷嘴结构对液氧煤油火箭发动机高频燃烧不稳定性的影响

Influence of Geometrical Structure of Coaxial Injector on High-frequency Combustion Instability for Staged Combustion LOX/kerosene Rocket Engine

为了筛选高压补燃循环液氧煤油火箭发动机的喷嘴,在喷注单元低压高频燃烧不稳定性模拟实验系统上开展实验,研究了喷嘴结构对燃烧稳定性边界的影响。实验使用气态空气与氧气的混合物作为氧化剂,加热的煤油蒸汽作为燃料;喷嘴为全尺寸气液同轴直流离心式喷嘴,模拟燃烧室与真实燃烧室的固有声学频率相等。根据测量模拟燃烧室内的脉动压力区分大幅振荡、小幅振荡和稳定工作。研究结果表明,喷嘴长度、缩进室长度和入口节流嘴直径对高频燃烧不稳定性裕量有很大影响,并存在相对最佳值。

Combustion stability boundary was investigated experimentally by using a subscale chamber for screening the coaxial injectors of a high-pressure staged combustion LOX/kerosene rocket engine. The geometrical dimension and operating condition of injector were determined with the single-injector firing modeling experimental system. The gaseous propellant components were used to provide actual volumentric flow rates under low pressure, which is practically equal to atmospheric pressure. Inherent acoustic frequency of subscale combustion chamber is consistent with the actual combustion chamber. Results show that two major instability regions are identified by the parameters of combustion-chamber pressure and mixture ratio. The geometrical structures including total length, retractive length of injector and entry diameter have crucial effect on the combustion instability boundary, and have a relative optimal range.