Approximating idealized hybrid rocket fuel port geometries using steps

International audience; In this work, a novel approach to increase the performance of a Hybrid Rocket Engine (HRE) by approximating any idealized fuel port geometry by steps inside the fuel grain is proposed. This work serves as a first investigation into the effect of single steps inside the fuel grains of a typical HRE. In numerical simulations, it is shown that forward- and backward-facing steps have the potential to increase the average regression rate as they promote the turbulence and heat transfer inside the turbulent boundary layer. Both types of steps are more effective at lower oxidizer mass fluxes. Finally, as a first estimation, a set of best practices for the distribution of steps along a profile could be derived.