Numerical simulation on transient working process of a solid propellant micro thruster

Solid propellant micro thruster is a key device to control the attitude and orbit control of micro spacecrafts. A 2-D unsteady simulation, based on the geometric model of the planar solid propellant micro thruster developed by LAAS-CNRS, was conducted using dynamic-mesh method and fluid-solid coupling heat transfer model to investigate the impact of the micro scale effects and the flow losses on thrust-time curve of thrusters. The results show that the micro scale effect has obvious impact on the flow field, whereas the effect on the thrust-time curve is almost negligible. Results show that, on the premise that the propellant burns with a steady burning rate, the tendency of heat loss is the main cause affecting the tendency of the flow losses. In addition, the solid propellant micro thruster with Macor Corning Ceramic wall has less heat loss, and the value reduces with time. Conversely, the heat loss for solid propellant micro thruster with silicon wall is larger and the value grows with time. Thus, whether the reduction of nozzle heat loss can compensate the growing of combustion chamber heat loss is the key to the maintaining of the thrust.