Development of Flame Holding System in Scamjet by Flame Jet

为了发展超燃冲压发动机的火焰保持系统，通过测量火焰射流中的自由基，研究了火焰射流的点火机理，得到了以下结论：(1)从火焰喷射的CH发射和OH荧光测量中发现，活性物质从喷口发出的时间可能受传统汽车点火电路产生的火花放电时间的支配，其数量级为几毫秒。(2)射流在两个平面的OH荧光图像中均观察到大尺度涡旋结构；这个平面包含了喷流轴和垂直于喷流轴的平面。(3)火焰射流发生器腔内使用的混合物越丰富，射流的OH荧光面积越大，荧光强度越高。(4)射流OH荧光的面积和强度受空腔体积和孔直径的影响。

In order to develop the flame holding system in Scramjet, the ignition mechanism of Flame Jet was investigated by measuring radicals in the jet, and the following conclusions were obtained.(1) It was revealed from both CH emission and OH fluorescence measurements in Flame Jet that the period of active species issuing from the orifice presumably be governed by the duration of spark discharge produced by a conventional automobile ignition circuit, that is of an order of a few milliseconds.(2) The large scale vortex structure was observed in the images of OH fluorescence of the jet in both planes ; the plane contained the jet axis and that perpendicular to the jet axis.(3) The area and the intensity of the OH fluorescence of the jet were larger and higher with the use of richer mixtures in the cavity of Flame Jet generator.(4) The area and the intensity of the OH fluorescence of the jet were affected by the cavity volume and the orifice diameter.