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%.