Radiative Wall Heat Transfer Evaluation in Hybrid Rocket Thrust Chambers

A discrete transfer method algorithm is applied to a 1kN-thrust-class hybrid rocket engine burning paraffin–wax and gaseous oxygen to determine the radiative wall heat flux impinging on the fuel grain. Different approaches are employed, including gray gas, weighted sum of gray gases, and statistical narrow band. The radiative properties of the flowfield are presented and discussed, and the effect of different participating species, including H2O, CO2, CO, and C2H4, is assessed. A comparison of the different models is performed, showing how an inaccurate spectral model may lead to a significant error in the radiation emitted by the gaseous phase. An analysis on soot radiation is also carried out, investigating the effect of the soot volume fraction and of its profile, and comparing the results obtained with both gray and spectral models.