凝胶一甲基肼/四氧化二氮雾化特性试验研究

Experimental Study on Spray Characteristic of Gelled Methylhydrazine/Nitrogen Tetroxide

关键词:  推进剂  凝胶  喷嘴  雾化  燃烧

Key words:  Propellant  Gel  Injector  Spray  Combustion

摘要:

为了研究凝胶一甲基肼/四氧化二氮（MMH/NTO）的雾化特性，在单喷嘴矩形燃烧室内进行凝胶MMH/NTO喷雾燃烧过程的可视化试验研究。试验采用两股燃料撞击一股氧化剂（F-O-F）及两股氧化剂撞击一股燃料（O-F-O）的三股互击式喷嘴，试验时先关闭中间路推进剂，采用高速摄影观测了两侧推进剂90°自击雾化图像，随后观测了燃烧条件下凝胶MMH/NTO三股互击时液相推进剂的雾场阴影图像，通过图像处理，分析了喷嘴类型及射流速度对雾化锥角及破碎长度的影响。结果表明，凝胶NTO自击雾化时雾场以细小液滴为主，而凝胶MMH黏度较高，雾化较困难，自击雾化时雾场主要是液膜和液丝，故可推断燃烧条件下凝胶MMH/NTO液相推进剂雾场阴影图像里观察到液膜和液丝主要是凝胶MMH推进剂；与90°两股撞击喷嘴相比，F-O-F形式三股互击式喷嘴的能量利用率较低，采用F-O-F形式三股互击式喷嘴时凝胶MMH/NTO的雾化锥角小于凝胶MMH推进剂90°自击雾化；相对F-O-F形式三股互击式喷嘴，凝胶MMH/NTO采用O-F-O形式三股互击式喷嘴时的雾化锥角更大，破碎长度更短，故采用O-F-O形式三股互击式喷嘴时凝胶MMH/NTO的雾化性能更优。

Abstract:

Aiming at elucidating the detailed spray characteristic of gelled methylhydrazine/nitrogen tetroxide(MMH/NTO), visual experiment was conducted to investigate the phenomena involved in the spray and combustion process of gelled MMH/NTO in a visualized square combustion chamber with a single injector. Triplet impinging injector，fuel-oxidizer-fuel(F-O-F) and oxidizer-fuel-oxidizer(O-F-O) were used in the experiment. Through closing the middle channel temporarily, the spray images of gelled MMH and NTO using 90° like-impinging injector were obtained by high-speed camera firstly, then spray images of gelled MMH/NTO using triplet impinging injector in hot-fire were obtained with the help of high-speed camera. Spray cone angle, breakup length were obtained by image processing technology, then the effect of nozzle type, jet velocity were discussed. The results show that small droplets were seen in the spray images of gelled NTO mainly, however, the atomization of gelled MMH is poor due to high viscosity, only liquid sheets and filaments throughout the entire field of view were seen in the spray images of gelled MMH, hence liquid sheets and filaments seen in the spray images of gelled MMH/NTO in hot-fire test are mainly gelled MMH. Comparing with the spray cone angle of gelled MMH using 90°like-impinging injector, the spray cone angle of gelled MMH/NTO using triplet impinging injector of F-O-F type is smaller, so the energy utilization efficiency of F-O-F type triplet impinging injector is lower. The spray cone angle of gelled MMH/NTO using O-F-O type triplet impinging injector is bigger than that using F-O-F type triplet impinging injector, and the breakup length of gelled MMH/NTO using O-F-O type triplet impinging injector is shorter, so the atomization of gelled MMH/NTO using O-F-O type triplet impinging inject is better.