Chemical Reaction Effects on Wall Heat Flux in Liquid Rocket Thrust Chambers

Cooling of thrust chamber walls to allowable solid material temperature induces near wall recombination which may add a non-negligible contribution to the heat transfer from the hot gas to the wall. In this study, the role of near wall recombination is studied by suitable numerical analyses. Numerical results are 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 up to 30% with respect to the frozen value, whereas in the case of oxygen/hydrogen this value does not exceed 10%. Hence, reacting flow simulation is strongly recommended in case of methane fueled thrust chamber analysis, whereas in hydrogen fueled thrust chambers, especially at very high chamber pressure, the difference between reacting and frozen flow model is very small.