冲压发动机燃烧室内低频燃烧不稳定试验

Experimental research on low-frequency instability in ramjet combustor

在高空亚燃冲压发动机研究中,燃烧不稳定是一个突出问题。为解决30km,Ma=4亚燃冲压发动机直连式试验中所出现的低频燃烧不稳定问题,分析了燃烧室的声学特性,得出了燃烧不稳定的主要特征是燃烧放热与一阶纵向声振模态相耦合。采取在燃烧室内增加后向台阶形成凹腔的方法,成功得到了较为稳定的燃烧。

Combustion instability is one of the most crucial problems for developing high-altitude ramjet.To solve combustion instability problem occurred in a direct-connected experiments of a 30km,Ma=4 ramjet,acoustic characteristics are analyzed.Results show that the main character of combustion instability is due to the coupling of heat release and longitudinal acoustic oscillation.Then relative stable combustion is achieved in cavity-type combustor by adding backward step.