Abstract: This paper will present an algebraic model closure of the turbulent fluxes as the sum of two contributions acting in opposite directions, one induced by turbulent motions and the other by thermal expansion. The turbulent transport is analyzed that for a sufficiently high turbulence level, the flame is unable to impose its own dynamics to the flow field, and the turbulent transport is of the gradient transport type for the reacting scalar c and when the turbulence level remains low, the thermal expansion due to heat release dominates the process of turbulent scalar transport and the turbulent transport is of a counter gradient turbulent transport. The combustion will occur in a variable equivalence ratio and as partially premixed combustion is highlighted as one of the most relevant and important modeling challenges in the field of turbulent premixed combustion, we will use the LW-P model of combustion for this situation. The resulting model is combined with the second order model of turbulence Rij, ? has evidenced the pressure drop across the flame due to counter gradient diffusion turbulent fluxes which has well predicted the jump of the axial velocity across the flame brush. A numerical simulation which corresponds to the experimental conditions of the experiment of Escudié and Haddar is presented in order to validate the model. The comparison of the results with the measurements were showing remarkable consistency and indicates that the model is a valid approach for predicting partially turbulent premixed flames stabilized in a stagnation flow.

Key words: Partially premixed combustion, Stagnating flow, Libby-Williams-Poitiers model, Numerical combustion simulation, Counter gradient diffusion turbulent fluxes