Design and Simulation of Single Capillary Injector and Circular Injector Plate for a Monopropellant Thruster

Hydrazine monopropellant thrusters are widely used in space missions. The most common use of these thrusters is in reactive control systems. In this research, design and simulation of a single capillary injector and three-hole circular injector plate of a 10N Hydrazine monopropellant thruster were performed. The injector and injector plate were designed based on the mass flow rate. Ansys Fluent software was used to simulate them. Volume of fluid (VOF) method was used to simulate such a flow and turbulence was simulated by k-e model. The characteristics of the injector and injector plate including mass flow rate and average velocity in the injector nozzle were calculated by changing the inlet pressure. The results showed that the injector and the injector plate have the ability to supply the desired mass flow rate of the monopropellant thruster at a known design pressure. Therefore, the final dimensions were selected for the design and construction of the injector. In fact the capillary injector اhas replaced the swirl injector with hollow cone spray used in the previous version of this thruster. The dimension of the chamber was significantly reduced by using the capillary injector, which reduces both the volume of the expensive iridium catalyst and weight of the thruster.