Numerical modeling of supersonic combustion: validation and vitiation studies using FLUENT

Validation studies and a qualitative study of vitiation effects for supersonic combustion flows were performed using the commercial CFD (Computational Fluid Dynamics) software, FLUENT. A supersonic coaxial jet flame and a model supersonic combustor chosen for the validation studies, with the latter being used for studying the effects of vitiation. The validation study involved the use of a non-premixed equilibrium PDF (Probability Density Function), laminar finite-rate chemistry with 9 species and 20 reactions, and the realizable k-ε or RNG (re-normalization group) k-ε turbulence models. The results for this study compare well to the experimental data, with explanations given for any differences. For the vitiation study, radical species (H, O, and OH) were added to the inlet air stream of the model combustor in varying amounts. Fluent was shown to be sensitive enough to predict the effects of this alteration, showing a decrease in the ignition distance and combustion efficiency with the addition of these radical species.