凝胶自燃推进剂撞击雾化燃烧特性试验研究

为研究凝胶自燃推进剂撞击雾化的燃烧特性,在单互击式喷嘴矩形燃烧室内进行了一甲基肼和四氧化二氮(MMH/NTO)及凝胶MMH/NTO喷雾燃烧过程的对比试验。试验拍摄了燃烧条件下液态推进剂的雾化图像及OH基自发辐射图像,其中雾化图像采用高速相机及阴影方法拍摄,OH基自发辐射图像采用带OH基滤光装置的高速相机拍摄。结果表明:MMH/NTO撞击后能快速气化,只能观察到喷注面附近喷雾扇及少量细小液滴,而凝胶MMH/NTO撞击后形成的液膜及贯穿视场的液丝清晰可见,推进剂未完全气化燃烧,造成燃烧性能下降;凝胶MMH/NTO推进剂氧化剂燃料蒸发速率不匹配,彩色阴影图像可观察到大量待反应红棕色NO2气体;根据OH基自发辐射光亮度及分布,MMH/NTO在撞击角为75°,燃料射流速度为23m/s时即可充分燃烧,但凝胶MMH/NTO充分雾化燃烧需求撞击角及射流速度更大,着火及充分燃烧需求燃烧室更长。

Experimental Study on Combustion Characteristic of GelledHypergolic Bipropellants Utilizing Impinging Injector

Aiming at elucidating the detailed combustion characteristic of gelled hypergolic bipropellants utilizing unlike-impinging injector, comparative experiment was conducted to investigate the phenomena involved in the spray and combustion processes of neat and gelled methylhydrazine/nitrogen tetroxide (MMH/NTO) in a square combustion chamber with a single unlike-impinging injector. Shadow technology and a high-speed camera were combined to investigate the spray information of liquid propellants in hot-fire test, another camera with a OH*-pass filter was used to record the OH-radical emission at the same time. The results show that the spray of MMH/NTO could evaporate rapidly , only fan-shaped spray near the injector and less droplets could be observed in shadow images. However, liquid sheet and Ligaments throughout the entire field of view could be seen clearly in shadow images of gelled MMH/NTO, then some propellants do not evaporate in the field of view, and the combustion efficiency might decrease possibly. Because the evaporation rate of gelled MMH/NTO is mismatching, much reddish-brown NO₂ unreacted could be seen in shadow images. Judging from the OH-radical emission luminosity and distribution, neat MMH/NTO could keep efficient burning when impinging angle is 75°and fuel jet velocity is 23m/s, but gelled MMH/NTO need bigger impinging and jet velocity, moreover, longer combustion chamber is needed to ignition and better combustion at the same time.