Computations of a Hydrogen-Fueled Scramjet Combustor on Locally Refined Meshes

Simulations of an experimental hydrogen-fueled scramjet combustor are conducted using a novel dynamic hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation (DHRL) modeling framework. The combustor has a Mach 2 core flow with a ramp fuel injector resulting in an equivalence ratio of 0.17. Three grid resolutions are obtained using local refinement by a factor of two in each direction in the fuel mixing and combustion region, and results from the three grids are used to understand the effect of grid refinement. Simulations reproduce temperature, pressure, velocity, and fuel concentrations in reasonable agreement with experimental measurements. Although heat release decreases on average, as the mesh is refined, peaks of heat release are intensified causing locally elevated temperatures. Spectral analysis of turbulence kinetic energy and heat release suggests stringent resolution requirements for reacting simulations capable of accurately resolving the effects of chemical reactions. Using the medium grid the DHRL model is compared to the improved delayed detached eddy simulation (IDDES) model and two Reynolds-averaged Navier-Stokes (RANS) models. Overall, the DHRL framework significantly outperforms other methods when compared to the experimental pressure rise. Additionally, spectral analysis suggests that the current framework is capable of accurately resolving turbulent structures at frequencies higher than IDDES. The study is the first documenting the use of DHRL for supersonic reacting flow and results suggest that it is a viable alternative to existing turbulence treatments for these types of flows.