NUMERICAL INVESTIGATION OF STRUCTURAL AND STATISTICAL FEATURES OF PREMIXED FLAME UNDER INTENSE TURBULENCE

In this study results from large-eddy simulation (LES) employing the linear eddy mixing (LEM) model of a freely propagating methane/air turbulent premixed flame interacting with a decaying background turbulence field are analyzed to characterize the effects of Karlovitz number (Ka) ranging from 30 to 120 on the flame-turbulence interaction. The analysis is performed in terms of the resolved and the subgrid-scale (SGS) flame structure, by examining the instantaneous snapshots, spatially averaged profiles, propagation characteristics, and statistical features of the flame. The LES predicts the turbulence-chemistry interaction at high Ka, as in direct numerical simulation (DNS) and experimental studies. In particular, the effects of increased Ka, which results in enhanced mixing and homogenization within the flame region are captured in the simulations, thus providing confidence that LEM model has the potential to capture a wide range of operating conditions encompassing thin reaction zone to broken/distributed reaction zone regimes without requiring any model adjustment.