Design and optimization of a mass-efficient pancake hybrid rocket motor with vortex flow for in-space applications

Abstract

Hybrid rocket motors are increasingly considered a promising option for in-space propulsion due to their safety, cost efficiency, simplicity, and restart capability. This study presents a compact pancake hybrid rocket motor with a reduced length to diameter ratio (L/D) for improved structural and volumetric efficiency. The geometry induces rotational oxidizer flow over the fuel surface, enhancing heat transfer and accelerating regression. An HDPE and nitrous oxide system achieving 330 seconds is considered for the analysis. Simulations in ANSYS Fluent under vacuum conditions are evaluated for different combustion chamber height and injector numbers to see the characteristics of the oxidizer flow, heat flux, and wall shear that are the key factors influencing regression. The pancake configuration is expected to match thrust while reducing mass and volume, offering a promising architecture for future in-space applications