小推力液氧气甲烷火箭发动机的点火特性与燃烧性能

摘要

设计制造了一台推力为500 N的液氧气甲烷模型发动机,对其开展了一系列点火试验,火花塞的安装位置分头部与身部两种情况.结果表明,当使用头部火花塞点火时,发动机内的推进剂可以正常起火但火焰无法持续稳定,这主要是因为火花塞末端被置于喷雾浓度与气流速度均较低的区域,使得这个区域内产生的火焰无法为整个发动机提供足够的点火能量.然而,当使用身部火花塞时,发动机内的推进剂可以同时实现可靠点火与稳定燃烧,这主要是因为在身部,二种推进剂浓度与流速均足够.当氧燃混合比从2.61增加到3.49时,试验得到的燃烧室压力从0.474 MPa增加到0.925 MPa,同时燃烧效率从57.8%增加到95.1%,这主要是因为喷注器配置,导致在低工况下液氧无法得到充分破碎.%A 500 N model engine filled with LO2/GCH4was designed and manufactured. A series of ignition attempts were performed in it by both head spark plug and body spark plug. Results show that the engine can be ignited but the combustion cannot be sustained when head spark plug applied as the plug tip was set in the gaseous low-velocity zone with thin spray. This is mainly because flame from this zone cannot supply enough ignition energy for the whole chamber. However, reliable ignition and stable combustion can be achieved by body spark plug. As the O/F ratio increases from 2.61 to 3.49, chamber pressure increases from 0.474 to 0.925 MPa and combustion efficiency increases from 57.8% to 95.1%. This is determined by the injector configuration, which cannot produce the sufficiently breakup of the liquid oxygen on the low flow rate case.