Simulation Model for Catalytic Monopropellant Hydrazine Thrusters

Abstract

Abstract Hydrazine thrusters are often used as actuators for spacecraft attitude and orbit control systems, for example for the missions of METEOSAT, OTS, INTELSAT and GIOTTO. The reason is that hydrazine requires less hardware than other propellants, and thrusters with thrust levels down to 0.5 N with reproducible minimum impulse bit down to 0.005 N are available. In order to design the spacecraft attitude and orbit system it is necessary to provide the control engineers with a simulation model of the thruster which allows to have informations at all possible system conditions, and especially during pulsed mode firings. As an analytical model, based on a complete description of the chemical and physical phenomena occurring during thruster firing is not easy to obtain, in this paper we will present a simulation model based on the test firings of the thruster. Simulation results will be provided for a 20 N catalytic hydrazine thruster.