Graphite nozzle erosion trends in paraffin/oxygen hybrid rockets

Nozzle erosion predictions are fundamental to increase the technology readiness level of hybrid rocket engines. In this work, Reynolds-averaged Navier–Stokes simulations of the internal ballistics of paraffin/oxygen engines coupled with graphite nozzle ablation are performed under various operating conditions. Additional simulations considering uniform inlet conditions at the postchamber entrance underline the complex interaction between nozzle erosion and the radially nonuniform flowfield originating from incomplete mixing and combustion. Moreover, the favored combustion efficiency resulting from an increase of the postchamber length is evaluated in terms of nozzle erosion in a wide range of oxidizer-to-fuel ratios. Because of the interaction between wall and gas-phase reactions, erosion mass fluxes are observed to monotonically grow with decreasing equivalence ratios.