A new approach based on flamelet concept using tabulated chemistry for premixed turbulent combustion

†A new approach to couple a tabulated chemistry combustion model (the Flame Prolongation of ILDM model of Gicquel & al.) with an industrial type CFD code is introduced. This specific coupling method is required by the architecture of such CFD solvers that must handle with industrial reacting flows simulations often involving complex geometries and multiphysical phenomena. The proposed method can be devided into two main steps. First, the set of transported species is determined. Then a corrective term is added to the chemical reaction rates interpolated in the FPI database to balance the perturbations created accross the flame. This method is at first successfully validated on a simple but challenging academic test case: a monodimensional laminar methane/air premixed flame. After having tested the model in a laminar context, we discuss the issues introduced by turbulence/chemistry interactions. We propose here to use a presumed PDF model along with the FPI database. This model lies within the framework of flamelet models for premixed combustion as the turbulent flame structure is assumed being locally similar to a monodimensional laminar premixed flame. The presumed PDF approach was chosen because it provides an excellent compromise between accuracy and CPU computation time and enables the construction of a new ”turbulent” FPI database containing mean chemical variables. In this context, the modelisation of the progress variable variance, required for the interpolations in the turbulent table, remains a particularly challenging issue. The evaluation of the scalar dissipation rate is especially crucial and we chose to use a model based on the BML assumption to account for the reciprocal influence of chemistry on turbulence as well as flame brush resolution. Finally, results obtained for a turbulent lean premixed flame stabilized behind a conical blu body are discussed. Comparisons are made between an algebraic model for the variance and a transport equation approach. The overall results are in good agreements with measurments which is very promising for more practical applications.