Study gas flow heating in micro-nozzle through walls instead of preheating

Abstract

Previously, Preheating has been established in micro-nozzles to increase the specific impulse of thrusters and increase thrust level. However, heating may cause higher viscous losses in micro-nozzles working at low Reynolds numbers. In this work, heating is combined with gas expansion by using heated walls for convergent-divergent micro-nozzle. The flow in 2D micro-nozzle with heat generation inside the side-walls has been numerically simulated and analyzed. A wide range of low Reynolds numbers flow is tested to investigate the effect of flow parameters. A range of diverse amounts of heat fluxes is also examined to study the effect of heat flux intensity and distribution. Heat evolving in a micro-nozzle wall shows improvement of thrust level and specific impulse due to an increase in both gas density and pressure generally. However, there is a loss in exit velocity and increase in the thickness of the subsonic boundary layer. It is observed that heat transfer can improve the performance of the nozzle as that happens in preheating, due to lower gas temperature at expansion region. The effect of heating looks more significant at lower Reynolds numbers flow investigated.