Tests and simulations on 200N paraffin-oxygen hybrid rocket engines with different fuel grain lengths

Abstract

Abstract. An experimental campaign, in the framework of the HYPROB-NEW hybrid rocket studies, was carried out on a 200N-thrust class hybrid rocket engine, using gaseous oxygen as the oxidizer and paraffin wax-based fuel, to investigate the effect of fuel grain length on motor performance and internal ballistics. Numerical analysis have been also performed to support the experimental findings. It was observed that, for given oxidizer flow rate, fuel grain length directly affects the characteristic velocity, because of its influence on residence time and mixing efficiency, so that the shortest grain configuration displayed the lowest performance. Moreover, CFD simulations provided an estimation of the regression rate profile along the grain length, providing a possible interpretation for the measured space-time-averaged fuel regression rate. Finally, a method for the rebuilding of the convective heat-transfer coefficient in the nozzle was used, based on a combination of numerical simulations and experimental acquisitions.