ASSUMED JOINT PROBABILITY DENSITY-FUNCTION APPROACH FOR SUPERSONIC TURBULENT COMBUSTION

In a recent experiment, Cheng et al. used uv spontaneous vibrational Raman scattering and laser-induced predissociative fluorescence techniques for simultaneous measurements of temperature and concentrations of O2, H-2, H2O, OH, and N2 (and the rms of their fluctuations) in supersonic turbulate reacting shear layers. Because present computational techniques are not suited for the prediction of all of the above measurements, a new approach has been developed and is being used to predict all relevant flow properties and the rms of their fluctuations (where appropriate). The approach explores the use of a multivariate Beta PDF for concentrations. In particular, a version developed by Girimaji to model scalar mixing in turbulent flows is employed. Predictions using this model were, in general, satisfactory in regions preceding ignition, but not in regions downstream of ignition. Part of the discrepancy is a result of our current inability to relate Favre and time averages.