Cfd analysis of paraffin-based hybrid rockets with coupled nozzle erosion characterization

A multiphysics internal ballistics prediction approach is presented for oxygen/paraffin– wax hybrid rocket engines. The approach is able to model flow field evolution with homogeneous combustion in the gas phase coupled with thermal radiation exchange and gas-surface interaction modeling for the liquefying fuel in the combustion chamber and for the ablating pre-and post-chamber and converging–diverging nozzle. The gas-solid phase coupling for both the liquefying fuel and the ablating thermal protection material is handled through a fully customized gas-surface interaction wall boundary condition that is tightly integrated within the CFD solver. Thermal radiation is modeled separately by a radiative heat transfer code in order to compute the radiative wall heat flux needed by the gas-surface interaction balance equations. Results highlight the complex interaction between the radially non–uniform flow field originating from the regression and combustion of the paraffin–wax cylindrical grain and the nozzle ablation process.