Numerical investigation on radiative heat loads in liquid rocket thrust chambers

In liquid rocket engines, wall heat transfer analyses are of primary importance for the thrust chamber design. Numerical investigations usually derive the convective heat flux from computational fluid dynamics simulations, whereas the radiative counterpart is often neglected. The goal of the present paper is a systematic numerical investigation on the role of radiative heat transfer on the overall thermal loads occurring in the thrust chamber of liquid rocket engines. To this purpose, a numerical code for thermal radiation computations is coupled to a computational fluid dynamics solver. The results of the numerical setup are discussed and compared to the available literature’s numerical data. Then, the radiative contribution to the overall heat flux in the thrust chamber of oxygen/ hydrogen and oxygen/methane liquid rocket engines is investigated through a wide parametric analysis. The results show that, in typical operating conditions, the radiative heat load is proportionally greater in methane-fueled engines than in hydrogen-fueled engines, and that the radiative contribution to the overall wall heat flux becomes increasingly relevant for large-scale low-chamber-pressure engines. A methodology for a quick preliminary evaluation of the radiative wall heat flux in liquid rocket thrust chambers is finally presented and verified against coupled simulations.