Abstract
In multi-cycle operation of Microwave Rocket, the influence of the density non-uniformity formed in a thruster on the resulting propulsive impulse remains unclear. In order to analyze the thrust performance in a thruster containing a hot residual gas, a new millimeter-wave discharge propagation model was developed. By coupling it with a reed-valve's fluid-structure interaction model, a full-scale analysis up to the second cycle operation was performed changing the thruster radius from 16 mm to 40 mm with the fixed millimeter-wave beam radius of 20.4 mm. As a result, the partial filling rate monotonically decreased with the thruster radius, while the hot residual gas at the center of the thruster was most prominent in the case with the radius of 24 mm. With a smaller radius, the inflow gas from the reed valve directly reached the center, and with a larger radius the inlet gas was transfered by vortices formed inside the thruster. During the second cycle, the decrease in the propulsive impulse was most noticeable for the case with the radius of 24 mm, illustrating that the thrust performance was strongly associated with the residual gas density at the center of the thruster, rather than the partial filling rate.
