Thermo-Fluid-Dynamics Analysis of Film Cooling in Overexpanded Rocket Nozzles

The key demand on future space transportation systems is the concurrent reduction of earth-to-orbit launch costs and the increase in launcher reliability and operational efficiency. A well known way of slightly improving performance of gas-generator open-cycle engines is the injection, in the nozzle divergent section, of the turbine exhaust gas, which is also used for wall film cooling. Although film cooling has been widely studied for the ondesign operation of conventional bell nozzles, its application to the case of advanced nozzles operating with separated flow presents different aspects, which are addressed here. In particular, the effect of film-cooling on separation and on side loads in dual bell nozzles is studied in the present paper with the help of numerical simulations