单组元脉冲推力器挤压和排气过程分析

高室压脉冲推力器使用可移动的喷注器,能够得到比供给压强高得多的燃烧室压强。为了分析其工作特性,建立了单组元脉冲推力器挤压和排气过程的数学模型,以硝酸羟铵(HAN)基单组元推进剂为例,采用四阶龙格-库塔法进行了求解。结果表明,燃烧室最大压强和平均压强都大于推进剂入口压强,而燃烧室内近似等容的燃烧过程是压强升高的原因。与所用推进剂、平均推力和面积比都相同的常规推力器相比较表明,脉冲推力器的真空比冲提高5 s,而喷管喉部面积减小89%,若两者喷管出口面积相同,则脉冲推力器的比冲将提高31.5%。

Study on extrusion and exhaust process of monopropellant pulse thruster

By using a moving injector,the combustion chamber pressure of pulse thruster may be much higher than feed system supply pressure.In order to analyze the characteristics of pulse thruster,a mathematical model for extrusion and exhaust process of monopropellant engine was developed.Using Hydroxyl Ammonium Nitrate(HAN)-based monopropellant as an example,the equation sets were calculated with fourth-degree Runge-Kutta method.According to calculating results,the maximal pressure as well as average pressure of combustion chamber are higher than supply pressure,on account of the approximate constant-volume combustion.The performance difference between pulse thruster and conventional constant-pressure thruster was compared.Results show that,under the same mean thrust and area ratio,the specific impulse of pulse thruster has increased 5 s,whereas,the throat area reduces 89%.If the exit area of nozzle is equal,the specific impulse of pulse thruster would increase 31.5%.