MODELING OF SUPERSONIC TURBULENT COMBUSTION USING ASSUMED PROBABILITYDENSITY-FUNCTIONS

Recent calculations of turbulent supersonic reacting shear flows using an assumed multivariate beta probability density function (PDF) resul ted in reduced production rates and a delay in the onset of combustion . This result is not consistent with available measurements. Earlier w ork was based on a one-equation turbulence model that required a speci fication of the Length scale, PDFs that did not yield Favre-averaged q uantities, and the gradient diffusion assumption. The present work inc orporates a two-equation turbulence model based on a kappa-omega formu lation, a PDF that yields Favre averages, and relaxes the gradient dif fusion assumption. Results suggest that the form of the assumed multiv ariate PDF and the gradient diffusion assumption are the main causes o f the discrepancy.