Regression Rate Characterization of HTPB‐Paraffin Based Solid Fuels for Hybrid Rocket
Sri Nithya Mahottamananda, Nagarajan P. Kadiresh, Yash Pal
Abstract
Abstract Hybrid rockets are entitled with unique features such as simplicity, thrust modulation, safety, and low cost compared to that of conventional liquid and solid rockets. Despite their distinct advantages, the polymeric solid fuels exhibit a low regression rate, which limits their potential applications for the various space missions. In this study, pure hydroxyl‐terminated polybutadiene (HTPB), paraffin wax, and blended HTPB‐paraffin solid fuels, namely 80P, 60P, 40P, 25P were characterized for ballistic performance. The viscosity, local regression rate, average regression rate and combustion chamber pressure of solid fuels were evaluated on a lab‐scale ballistic motor. It was found that the viscosity of blended fuels decreased with increasing the paraffin wt. % in the formulation. The local regression rates of blended fuels increased in the range of 0.53 mm/s to 1.58 mm/s at oxidizer mass flux range of 85 kg/m 2 s to 150 kg/m 2 s. The results indicate that increasing the wt.% of paraffin in the blend will enhance the average regression rate performance, besides suppressing the low‐pressure oscillations during steady‐state operation.