Direct Simulation Monte Carlo Analysis on Thrust Vectoring of a Supersonic Micro Nozzle using Bypass Mass Injection

Abstract: Converging diverging micro nozzle is fundamentally intended for flow acceleration through the generation of kinetic energy for the advanced micro-propulsion systems. Such supersonic micro nozzles have significant applications in the launching, propulsion and rapid directional control of the micro-satellites for a better maneuver. Micro scale analysis of such flow devices is extended to the rarefied flow regime. Present study has addressed thrust vectoring in a planar converging-diverging supersonic micro nozzle by the bypass mass injection technique. Direct Simulation Monte Carlo (DSMC) method has been used for numerical modelling. Primary focus is given on the thrust vectoring control of the micro nozzle with a throat height of 20 micro meter and an expansion ratio of 1.7. For the secondary injection, a rectangular channel of 5 different bypass widths (2 - 12 micro meter) is considered for two different outlet pressures (Pout = 10 kPa and 40 kPa) while keeping the inlet pressure (Pin) and temperature (Tin) fixed at 1 atm and 300 k respectively. The physical behavior of the micro nozzle is acknowledged through the analysis of Mach, pressure, temperature and density contours. Numerical results reveal that the secondary flow injection is adapted into the primary flow through the formation of a pressure bump in the diverging section. Moreover, the total mass flow rate, secondary flow percentage, thrust force, the thrust coefficient and specific impulse increase with the bypass channel width. A change in thrust direction is obtained which in turn produces a considerable vectoring effect in the supersonic micro nozzle. The vectoring angle for Pout of 40 kPa peaks at 6 micro meter bypass channel whereas a gradual increase of the vectoring angle with the bypass channel width is observed for Pout = 10 kPa.