Numerical analysis of paraffin-wax/oxygen hybrid rocket engines

A predictive numerical approach, based on Reynolds-averaged Navier–Stokes simulations including the effects of turbulence, chemistry, fluid/surface interaction, and radiation, has been developed for paraffin-wax/oxygen hybrid rocket engines. A recently fired single-port paraffin-based hybrid rocket engine, with chamber pressures up to 19.1 bar, is taken as reference for the discussion of the results of the numerical simulations, which outline important features of the internal ballistics otherwise not observed in the experiments. For the engine under consideration, radiation accounts for 33–62% of the total wall heat flux on the grain, depending on the radial dimension and chamber pressure. The rebuilding of the experimental time-averaged regression rate and chamber pressure is carried out with fair success, enabling their prediction with a maximum error of 15 and 10%, respectively. The numerical model can aid the design and the optimization of future paraffin-based hybrid rocket engines.