Experimental evaluation of HTPB/paraffin fuel blends for hybrid rocket applications

Hybrid rockets have many advantages over pure solid or liquid propellant rockets, but low fuel regression rates and correspondingly thrust hindered their application to operational systems. Paraffin-based fuels regress significantly faster than traditional polymeric formulations, such as HTPB, paraffin inclusion in HTPB represents a potential tool for performance augmentation hybrid rockets. A survey of the available literature indicated disparities regarding utility this approach which are resolved herein. Fuel specimen consisting plain HTPB; paraffin; loaded with molten macrocrystalline wax (10–75%) microcrystalline particles (10–60%) were manufactured evaluated thermal decomposition ballistic properties. samples heated (10 K/min) an argon atmosphere simultaneous TGA/DTA experiments. The enhanced low-temperature while had opposite effect. prepared grains burned gaseous oxygen on one two lab-scale range oxidizer mass fluxes (5–430 kg/m2-s) pressures (0.5–1.0 MPa). exhibited 300% increase rate HTPB. However, none mixed-fuel formulations notable, if any, enhancement at operating conditions. First principles modeling was completed combustion paraffin, systems comprised containing particles. is dominated by pyrolysis does not allow formation melt layer surface, that any due vaporization entrainment effects. This study first concurrently evaluate both demonstrated lack either strategy separate laboratories. results presented herein resolve indicate viable means tailoring behavior rocket