Numerical estimation of nozzle throat heat flux in oxygen-methane rocket engines

The prediction of wall heat flux at the nozzle throat is of paramount importance in liquid rocket engine (LRE) design for both sizing and safety purposes. Computational fluid dynamics (CFD) simulations can aid in the prediction, provided that they can be effectively used during the design phase and that suitable modeling is employed. In this framework, this study aims at evaluating the suitability of a Reynolds-averaged Navier–Stokes-based CFD approach to predict in affordable times the nozzle wall heat flux of LREs employing the oxygen–methane propellant combination, which is nowadays attracting the attention of many developers. The interest to study the throat heat flux estimation for oxygen–methane engines comes from the known greater role played by the near-wall recombination reactions, as compared to the oxygen–hydrogen propellant pair. Nevertheless, only few indirect experimental measurements are available in the open literature for the validation of numerical tools. Recently published experimental data are used here as benchmark for the comparison of numerical simulations obtained with different assumptions. Results confirm that, for a well-designed engine, the details of injection and combustion processes have only a secondary effect on the prediction of throat heat flux.