基于纳米铝热剂的MEMS固体微推力器点火实验研究

关键词:固体微推力器；纳米铝热剂；真空；动态测试；羽流

关键词:  固体微推力器  纳米铝热剂  真空  动态测试  羽流

Key words:  Solid micro-thruster  Nanothermite propellant  Vacuum  Dynamic test  Plume

摘要:

MEMS固体微推力器可以形成单元数量巨大的微推力器阵列，适合低成本微、纳卫星系统，是极具潜力的新型卫星推力器。为研究基于纳米铝热剂的MEMS推力器工作特性，开展了大气和真空点火实验。大气下的燃烧羽流与空气进一步燃烧，导致羽流的发光持续时间约数ms，远大于真空试验，过估了在真空条件下的推力器作用时间。真空试验获得了动态推力特征和有效工作时间(约250μs)，估算推力器的冲量约55μN·s～80μN·s。羽流影响范围的直径约为30mm、流向约70mm，羽流颗粒的运动速度约132m/s。测试结果显示，底部点火先将推进剂挤出喷孔，而后在外部燃烧和爆炸。羽流形貌有两种特征:一种是剧烈爆炸，产生蘑菇云状气体产物；而另一种未产生气状产物。前者的冲量和有效工作时间大于后者。

Abstract:

Combined with micro electro mechanical systems (MEMS)，solid propellant micro-thruster can form array with gigantic unit number. This new thruster has great potential for micro/nano-satellite. For studying the operation performance of the thruster with nanothermite propellant，experiments were done at both atmospheric and vacuum conditions. Due to the continuous reaction between plume and the surround air，duration of plume emission is far longer than vacuum. Therefore，atmospheric test overestimates the effective time of thruster. For vacuum cases，the dynamic thrust characteristic and the effective time (about 250μs) were obtained，inferring the impulse about 55μN·s～80μN·s. Particle velocity of the plume is about 132m/s and the diameter of the influence range is about 30mm while streamwise length is about 70mm. These diagnoses indicate that the propellant was pushed out of the combustor by the base ignition before its explosion and combustion. Two plume characteristics were found in vacuum case，first had violent explosions and gas product like mushroom while the second without gas product. The impulse and effective time of the former characteristic are greater than the latter.