Modified laminar flamelet presumed probability density function for LES of premixed turbulent combustion

Abstract

The performance of the modified laminar flamelet probability density function (MLF-PDF) is studied as a presumed PDF for the PCM-FPI combustion model in LES. PCM-FPI is a low-cost flamelet model for turbulence–chemistry interactions in premixed and partially-premixed flames. The MLF-PDF couples the FPI tabulated detailed chemistry model with large eddy simulation. The performance of this PDF was examined before in an a priori analysis with DNS data [13] and in RANS simulations of laboratory-scale burners [14]. In this work, this PDF is first compared to the actual experimental PDF. Then it is demonstrated that the MLF-PDF recovers the filtered laminar flame speed which is an important factor when turbulence scales are larger than the flame thickness and are mostly resolved in the grid scale. Finally, this PDF is used in LES of a turbulent premixed bunsen flame. The mean radial distributions of temperature, a few major species and two radical species mass fractions are compared with experimental data. The results show that this new PDF is a viable option for the statistics of sub-grid scale progress variable fluctuations.