RÉSUMÉ

Methanol diffusion flames are computed with a 2-D Large-Eddy Simulation that uses a partial equilibrium/two-scalar exponential PDF model applied at the subgrid (SGS) level. Turbulent kinetic and scalar energy equations provide the SGS closure. The PDF scalar covariances are obtained from similarity between resolved and modeled fluctuations.
Turbulence/chemistry interactions are addressed by coupling the partial equilibrium to the extinction/reignition regime that is modeled by a two-scalar reactedness-mixture fraction exponential PDF. A Lagrangian equation and a local extinction criterion represent the turbulent evolution of the reactedness progress variable. Modeling assumptions that correlated the bimodal/monomodal behavior and the interactions of the disparate time-scales of the flame structure complemented the model. Comparisons with data indicate that the methodology describes significant trends over a range of turbulent and chemical time-scale conditions close to extinction thus broadening the scope of application of the procedure.