Robust Wall-Modeled LES With Flux Reconstruction Scheme Toward Accurate Heat Flux Prediction in Rocket Engine Combustors

In this study, wall-modeled large eddy simulation (WMLES) with an equilibrium wall model for reacting flows is performed under cold wall conditions, and its predictive performance is evaluated. The governing equations are discretized with the flux reconstruction (FR) scheme, which is suited for large-scale numerical simulations. When the FR scheme is combined with the wall model, numerical instability tends to occur in the coarse grid near the wall. Moreover, this instability becomes significantly more severe under cold wall conditions than under adiabatic wall conditions. To ensure the numerical stability, artificial viscosity is added only in the region close to the wall. To evaluate the predictive performance of the equilibrium wall model for reacting flows, we first conduct the WMLES for a turbulent channel flow with burnt stoichiometric hydrogen/oxygen gas. Both the turbulent statistics and wall heat flux obtained by the WMLES agree well with the wall-resolved LES, which is also conducted in this study. Subsequently, as a more practical application, WMLES is performed for the single-element injector combustion chamber experiment conducted at the Technical University of Munich. In this experiment, gaseous hydrogen and gaseous oxygen are introduced through the injectors. The wall heat flux predicted by the WMLES is in close agreement with the experimental result. However, the wall pressure is underpredicted. Further investigation is needed to identify the cause of this underprediction.