Numerical investigation on the role of thermal radiation in hybrid rocket fuel pyrolysis

Thermal radiation is expected to play a non–negligible role on hybrid rocket fuel pyrolysis and overall motor internal ballistics. The way such a role is related to different operating conditions needs to be investigated through dedicated analyses involving computational fluid dynamics and radiative heat transfer simulations. In the present paper a computational fluid dynamics solver with gas–surface interaction capabilities is coupled to a radiative heat transfer code relying on the discrete transfer method. The importance of modeling thermal radiation in the prediction of hybrid rocket internal ballistics is first shown by rebuilding a literature experimental test campaign. A numerical parametric analysis is then carried out allowing a clear identification of the effects of mass flux, chamber pressure and port diameter on both radiative wall heat flux and its relative magnitude with respect to the total wall heating.