Measurements have been conducted at the University of Virginia Supersonic CombustionFacility in configuration C of the dual-mode scramjet. This is a continuation of previously published works on configuration A. The scramjet is hydrogen fueled and operated at two equivalence ratios, one representative of the "scram" mode and the other of the "ram" mode. Dual-pump CARS was used to acquire the mole fractions of the major species as well as the rotational and vibrational temperatures of N 2 . Developments in methods and uncertainties in fitting CARS spectra for vibrational temperature are discussed. Mean quantities and the standard deviation of the turbulent fluctuations at multiple planes in the flow path are presented. In the "scram" case the combustion of fuel is completed before the end of the measurement domain, while for the ram case the measurement domain extends into the region where the flow is accelerating and combustion is almost completed. Higher vibrational than rotational temperature is observed in those parts of the hot combustion plume where there is substantial H 2 (and hence chemical reaction) present.
Numerical simulations of reacting and non-reacting flows within a scramjet combustor configuration experimentally mapped at the University of Virginia's Scramjet Combustion Facility (operating with Configuration "A") are described in this paper. Reynolds-Averaged Navier-Stokes (RANS) and hybrid Large Eddy Simulation / Reynolds-Averaged Navier-Stokes (LES / RANS) methods are utilized, with the intent of comparing essentially 'blind' predictions with results from non-intrusive flow-field measurement methods including coherent anti-Stokes Raman spectroscopy (CARS), hydroxyl radical planar laser-induced fluorescence (OH-PLIF), stereoscopic particle image velocimetry (SPIV), wavelength modulation spectroscopy (WMS), and focusing Schlieren. NC State's REACTMB solver was used both for RANS and LES / RANS, along with a 9-species, 19reaction H 2-air kinetics mechanism by Jachimowski. Inviscid fluxes were evaluated using Edwards' LDFSS flux-splitting scheme, and the Menter BSL turbulence model was utilized in both full-domain RANS simulations and as the unsteady RANS portion of the LES / RANS closure. Simulations were executed and compared with experiment at two equivalence ratios, Ф = 0.17 and Ф = 0.34. Results show that the Ф = 0.17 flame is hotter near the injector while the Ф = 0.34 flame is displaced further downstream in the combustor, though it is still anchored to the injector. Reactant mixing was predicted to be much better at the lower equivalence ratio. The LES / RANS model appears to predict lower overall heat release compared to RANS (at least for Ф = 0.17), and its capability to capture the direct effects of larger turbulent eddies leads to much better predictions of reactant mixing and combustion in the flame stabilization region downstream of the fuel injector. Numerical results from the LES/RANS model also show very good agreement with OH-PLIF and SPIV measurements. An un-damped long-wave oscillation of the pre-combustion shock train, which caused convergence problems in some RANS simulations, was also captured in LES / RANS simulations, which were able to accommodate its effects accurately.
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