燃烧条件下自燃推进剂的雾场及火焰实验研究

Experimental study on the spray and flame of hypergolic bipropellants in hot-fire test

为研究双组元自燃推进剂喷雾燃烧的特点,在单互击式喷嘴矩形燃烧室内开展了一甲基肼/四氧化二氮(MMH/NTO)推进剂喷雾燃烧过程可视化实验,采用高速相机直接拍摄并获得了MMH/NTO的火焰自然发光图像,采用高速相机及光源后置消光法拍摄并获得了燃烧条件下MMH/NTO撞击后的雾场图像。通过实验得到了以下结论:燃烧条件下,MMH/NTO液相主要集中在喷注面附近的喷射雾化区,其面积随燃料射流速度增大而增大;MMH/NTO着火点距离喷注面距离及着火过程的火焰传播速度随推进剂喷射速度增加而增大;按自然发光亮度划分,MMH/NTO火焰分为外层火焰、内层火焰及焰心,焰心亮度最高,其面积随燃料喷射速度增加先减小后增大;MMH/NTO反应长度及火焰张角随燃料喷射速度增加而增大,与喷射雾化区随燃料喷射速度的变化趋势一致。

In order to study the detailed spray and combustion characteristic of hypergolic bipropellants utilizing unlike-impinging injector,experimental study was conducted to investigate the phenomena involved in the spray and combustion processes of neat methylhydrazine/nitrogen tetroxide(MMH/NTO) in a visualized combustion chamber.High-speed camera was used to record the natural flame luminosity firstly,then high-speed camera and back illumination light extinction was combined to record the spray images in hot-fire test.The results show that liquid propellants visible are mainly distributed in injection/atomization zone which is near the injector,and the area of injection/atomization zone increase with the increasing of fuel jet velocity.The distance from ignition position to injector face and flame propagation velocity also increase with the increasing of fuel jet velocity.Judging from the flame luminosity,the flame of MMH/NTO could be divided into outer flame,inner flame and flame core with highest brishtness.The area of flame core decrease firstly and then increase with the increasing of fuel jet velocity.The induction length and angle of flame increase with the increasing of fuel jet velocity as well as the injection/atomization zone.