Application of the coherent flamelet model to counterflow turbulent premixed combustion and extinction

The Coherent Flamelet Model (CFM) is applied to symmetric counterflow turbu lent premixed flames of Kostiuk et al. (1993b). The flame source term is se t proportional to the sum of the mean and turbulent rate of strain while fl ame quenching is modeled by an additional multiplication factor to the flam e source term. The turbulent rate of strain is set proportional to the turb ulent intensity to match the correlation for the turbulent burning velocity by Abdel-Gayed et al. (1987). Mixing with ambient air is assumed to be pro portional to the mass fraction of the burned and unburned mixture in each c omputational cell. The predicted flame position and turbulent flow field co incide well with the experimental observations. The nestle exit velocity at extinction shows qualitative agreement for variation of the equivalence ra tio, nozzle separation distance and exit turbulence condition.