INTRODUCTION OF DILUTION IN THE BML MODEL - APPLICATION TO A STAGNATING TURBULENT FLAME

An extension of the BML model to the case of combustion of lean mixtur es with variable equivalence ratio is presented in this paper. The dil ution of both burnt products and fresh reactants by the surrounding ai r is taken into account by introducing the mixture fraction f in addit ion to the progress variable c. Statistical analysis of the reactive f low is achieved by using a joint pdf of c and f allowing calculation o f mean quantities. Extinction of individual flamelets due to local dil ution of fresh reactants is also considered. The influence of dilution , i.e., variable equivalence ratio, on the local mean heat release par ameter as well as on the mean chemical production rate is described. A pplication of this modified model to the case of a stagnating turbulen t flame stabilized close to a solid wall shows that the mean flame bru sh is predicted to be detached from the burner, in agreement with avai lable experimental observations. Qualitative and quantitative modifica tions of the mean structure of the flame due to dilution are also inve stigated.