微型推进系统技术方案研究

Study of micropropulsion system technical options

将微机电系统(MEMS)技术应用于微推进系统可以降低成本,减少风险,并可满足微型航天器对性能、体积和质量等的特殊要求。本文针对微电热推力器(FMMR)和微型双组元液体火箭发动机的技术方案进行研究,采用直接蒙特卡罗(DSMC)方法,对影响FMMR工作特性的因素进行了研究,并对其进行了性能评估;应用商用FLUANT软件,计算并分析了二维喷管流场的附面层情况;对无毒液体推进剂进行点火试验选择。研究结果表明,对于FMMR当采用H2O作为推进剂工质,比冲为68.247s,推力为0.225mN,效率为52.6%。通过采取其它措施可以进一步提高比冲、推力和效率。对于微型双组元液体火箭发动机,采用醇类作燃料时,起动平稳、响应时间短。通过系统集成和一体化设计,微推进系统在未来微型航天器上具有广阔的应用前景。

The cost and risk of micropropulsion can be greatly reduced by use of MEMS technology. The micropropulsion system based on MEMS can meet special requirements of spacecraft, such as performance, volume and weight. The technical option of free molecule micro resistojet (FMMR) thruster and micro bipropellant liquid rocket engine is studied in the paper. The characteristic of FMMR under various conditions is investigated by use of direct simulation Monte Carlo (DSMC) method, and its performance is also evaluated. Applying the FLUENT commercial software, the characteristic of flow in the layer of two dimension nozzle is calculated and analyzed. At the same time, the operation performance of various nontoxic propellants is researched. The results of study show that the specific impulse, thrust and efficiency is ISP =68.247s, F = 0.225mN and η = 52.6% respectively for FMMR using water (H2O) as propellant. For micro bipropellant liquid rocket engine, the chamber pressure is smooth and responsible time is rapidly during startup phase using hydrocarbon (methanol, ethanol or kerosene) as fuel. Through system integration, the micropropulsion has widely application prospect for in-orbit maneuvers on military and civil micro/nanospacecrafts in the future.