Experimental studies on combustion performance of beeswax-paraffin blended solid fuels in a hybrid rocket

Abstract

The study intends to investigate the physical, chemical and thermal characteristics of paraffin blended fuels to determine
their suitability as a solid fuel in a hybrid rocket. Wax fuels are a viable and efficient alternative to conventional rocket
fuels, having excellent structural strength and thermal and mechanical properties. By utilizing both axial and swirl injection
technique, the combustion performance of paraffin – beeswax blended fuels have been tested with a fabricated cylindrical
grain in a laboratory-scale rocket setting along with oxygen. The test outcomes revealed solid fuel compositions of more
beeswax content in paraffin wax on an oxygenated gaseous environment with a swirl-flow injection method has the highest
average regression rate of 1.649 mm/sec at 181 kg/m2s mass flux. Axially injected oxygen with pure paraffin wax has the
lowest value of 0.85 mm/sec at 96 kg/m2s. The regression rate comparisons revealed that oxygen injection by a swirl
injector increased the regression rates by 40% for mass fluxes greater than 80 kg/m2s. Compared to other studies, the
combustion efficiencies have been obtained in this study are good. Blended fuels can manage and increase combustion
efficiencies for axial and swirl flow conditions. Swirl injectors outperform axial injectors for oxygen injection and allow for
a higher proportion of Beeswax combined with paraffin. This study exclusively designed and manufactured an axial injector
and swirl injector, according to the required dimensions of a lab-scale hybrid rocket's combustion chamber, injector, and
exhaust nozzle, and their performances have been evaluated.