Simulations of paraffin-based hybrid rocket motors and comparison with experiments

A Reynolds-averaged Navier-Stokes solver is suitably set up to predict the flow field within paraffin-based hybrid rocket thrust chambers. The regression rate is modeled through a gas/surface interaction boundary condition based on wall mass and energy balances. In particular, the radiative heat flux contribution is included into the energy balance after being computed via discrete transfer method along the whole thrust chamber. The combustion process is modeled via finite-rate chemistry employing global reaction mechanisms. In particular, a thermal cracking reaction step for paraffin-wax is included into the mechanism. Moreover, the liquefied paraffin-wax is treated as a dense fluid because in the supercritical pressure regime. An experimental test campaign on a lab-scale gaseous oxygen/paraffin-wax hybrid rocket engine is fully simulated with the present computational fluid dynamics model. The main results obtained are presented for different test conditions. Comparisons with experimental data are carried out to identify possible future improvements.