Empirical and Computational Performance Prediction for Monopropellant Hydrazine Thruster Employed for Satellite

Abstract

A ground hot-fire test and numerical simulations were conducted to analyze the high-temperature gas flow in a monopropellant hydrazine thruster used for the reaction control of small satellites. A 5 N grade thruster was used for these tests and simulations. The ground hot-fire test results show the basic characteristics of a hydrazine thruster and were used as verification criteria for the numerical analysis. It was found that the fraction of ammonia dissociation is an essential variable for determining the thruster performance based on a one-dimensional isentropic analysis. A relatively simple relation between the catalyst bed temperature and the fraction of ammonia dissociation adopted in the simulation showed that it reduces the analysis error from an arbitrary assumption of the fraction of ammonia dissociation without solving the complicated hydrazine catalytic reaction. The thruster performance was effectively predicted by numerical analysis, which includes the effect of fraction of ammonia dissociation. The significant features of the analysis program are that solving the complicated hydrazine decomposition process can be avoided and that two-dimensional flowfield information in the thruster can be provided covering a wide range of propellant inlet pressures from 3.45 to 24.14 bar.