Chemical reaction effects on heat loads of CH4/O2 and H2/O2 rockets

Cooling of liquid rocket thrust chamber walls to allowable solid material temperatures induces near-wall chemical reactions, which are known to have an important role on the heat transfer from the hot gas to the wall. In this study, the contribution of near-wall chemical reactions to heat flux is investigated and quantified by suitable numerical analyses. Numerical results are first compared to literature experimental data of wall heat flux in subscale calorimetric thrust chambers for both oxygen/methane and oxygen/hydrogen propellant combination. Then, a parametric analysis is carried out varying chamber pressure, wall temperature, and propellant combination. This study highlights that oxygen/methane combustion products are more subject to near-wall recombination phenomena. They provide an increase of wall heat flux between 20 and 30% with respect to the frozen flow model evaluation, whereas in the case of oxygen/hydrogen, the wall heat flux increase due to recombination reactions is between 7 and 14%.