为研究撞击式喷嘴凝胶自燃推进剂着火及火焰特性，在单喷嘴矩形燃烧室内进行了凝胶一甲基肼/四氧化二氮（MMH/NTO）喷雾燃烧过程试验研究。试验采用75°、90°、105°撞击角两股互击式喷注单元和90°撞击角两股燃料撞击一股氧化剂（F-O-F）、两股氧化剂撞击一股燃料（O-F-O）三股互击式喷嘴，首先采用高速摄影与纹影技术结合拍摄了燃烧过程纹影图像，随后采用高速摄影直接拍摄了燃烧过程火焰自然辐射发光图像。通过图像处理，提取了火焰着火距离、火焰轴向传播速度、火焰夹角以及反应长度，并分析了喷嘴类型、燃料射流速度的影响。试验结果表明，凝胶MMH/NTO燃烧主要发生在液膜破碎成液丝之后，射流速度越快，燃气扩散速度越快；凝胶MMH/NTO推进剂采用105°撞击角两股互击式喷嘴时着火距离最短；凝胶MMH/NTO着火时火焰轴向传播速度随燃料射流速度增加而增加，撞击角为90°时火焰沿喷注面下游传播速度较快；凝胶MMH/NTO稳态燃烧时火焰夹角随燃料射流速度增加而增加，反应距离随燃料射流速度增加而减小，其中90°两股互击式喷嘴火焰夹角最大，105°两股互击式喷嘴反应距离最短。
Aiming at elucidating the detailed ignition and flame characteristics of gelled hypergolic bipropellants utilizing impinging injector, experiment was conducted to investigate the phenomena involved in the combustion processes of gelled methylhydrazine/nitrogen tetroxide(MMH/NTO) in a square combustion chamber with a single impinging injector. Unlike-impinging injector, including 75°,90°and 105°impinging angle, and 90°impinging angle triplet impinging injector, including fuel-oxidizer-fuel(F-O-F) and oxidizer-fuel-oxidizer(O-F-O), were used in the exper-iment. Schlieren technology and a high-speed camera were combined to investigate the spray and combustion processes firstly, then natural flame images were obtained by a high-speed camera directly. Ignition distance, flame speed, flame angle and induction distance were obtained by image processing technology, and then the effect of injector type and jet velocity of fuel were discussed in the study. The results show that the combustion of gelled MMH/NTO was occurred after liquid sheets breakup into ligaments, and gas diffusion rate increase with the increasing of fuel jet velocity. The ignition distance of gelled MMH/NTO is shortest when using 105°unlike-impinging injector. The axial flame speed increase with the increasing of fuel jet velocity, and it is fastest when impinging angle is 90°。During the process of steady combustion, flame angle increase when jet velocity of fuel is increase, but the induction distance decrease conversely, generally, flame angle is maximum when using 90°unlike-impinging injector, and induction distance is shortest if using 105° unlike-impinging injector.
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