超燃燃烧室中燃烧反应区域变化情况试验

Experiment on variation of combustion reaction region in a scramjet combustor

运用试验的方式在来流马赫数为2.5的条件下研究了气态燃料在直连式凹腔燃烧室内的燃烧过程,结合壁面压力测量以及OH-PLIF(OH-平面激光诱导荧光系统)方法分析了乙烯燃料在点火后1 ms内的燃烧反应区域发展过程和氢气燃料在稳焰时1 ms内的燃烧反应区域变化过程。结果表明凹腔后缘斜坡对于气态燃料的火焰传播起重要作用,初始燃烧区域在随来流到达后斜坡后会减速滞留,为附近的燃料提供适宜的点火环境。凹腔剪切层对气态燃料的稳焰燃烧起重要作用,剪切层内始终部分存在剧烈燃烧反应区域,这将为凹腔内部源源不断地提供点火能量,为维持凹腔内部燃料持续点火燃烧提供能源支撑。试验测得乙烯初始燃烧反应区域向凹腔上游的发展速度约为170 m/s。

The combustion process of gaseous fuel in a direct-connected cavity combustor was studied by experimental method under the condition of incoming Mach number 2.5;combined with wall pressure measurement and OH-PLIF(OH-planer laser-induced fluorescence)method,the development process of combustion reaction zone of ethylene fuel in 1 ms after ignition and the change process of combustion reaction zone of hydrogen fuel in 1 ms during flame stabilization were analyzed.The results showed that the slope of the trailing edge of the cavity played an important role in the flame propagation of gaseous fuel,and the initial combustion zone slowed down and stood still after arriving at the slope with the incoming flow,providing a suitable ignition environment for the nearby fuel.The cavity shear layer played an important role in the stable flame combustion of gaseous fuel,and there exists always a severe combustion reaction area in the shear layer,providing continuous ignition energy for the cavity and energy support for maintaining the continuous ignition and combustion of the fuel in the cavity.The development rate of the initial combustion reaction region of ethylene to the upstream cavity was about 170 m/s.