关键词: 凝胶推进剂;自燃;互击式喷嘴;雾化;燃烧

Abstract: 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.

Key words: Gelled bipropellants;Hypergolic;Unlike-impinging injector;Spray;Combustion