Large-Eddy/Reynolds-Averaged Navier-Stokes Simulations of Reactive Flow in Dual-Mode Scramjet Combustor

Numerical simulations of the turbulent reactive flow within a model scramjet combustor configuration, experimentally mapped at the University of Virginia's Scramjet Combustion Facility at an equivalence ratio of 0.17, are described in this paper. A hybrid large-eddy simulation/Reynolds-averaged Navier-Stokes method is used, with special attention focused on capturing facility-specific effects, such as asymmetric inflow temperature distributions, on flow development within the combustor. Predictions obtained using two nine-species hydrogen oxidation models are compared with experimental data obtained using coherent anti-Stokes Raman spectroscopy, hydroxyl radical planar laser-induced fluorescence, stereoscopic particle image velocimetry, and focusing schlieren techniques. The large-eddy simulation/Reynolds-averaged Navier-Stokes models accurately capture the mean structure of the fully developed flame but tend to overpredict fluctuation levels toward the outer edge of the reactive plume. Model predictions worsen in the flame-anchoring region just downstream of the fuel injector. Here, turbulence/chemistry interactions are more pronounced, and the flame is more influenced by the inflow conditions. Comparisons with hydroxyl radical planar laser-induced fluorescence imagery indicate that the large-eddy simulation/Reynolds-averaged Navier-Stokes model can capture the effects of larger turbulent scales in deforming the flame structure but does not capture the effects of small turbulent structures in broadening the OH profiles.