Structure of Premixed Turbulent Flames in Flamelet and Thin-Reaction-Zone Regimes

The structure of turbulent premixed flame has many facets in practical combustors due to widely varying turbulence-chemistry interactions that can occur. Premixed com-bustion in the flamelet, the corrugated flamelet and the distributed reaction (recently called the thin-reaction zones) regimes can coexist within the same device. Models used within large-eddy simulation (LES) methodology to simulate practical systems must therefore, be able to predict these space- and time-varying flame structure and prop-agation characteristics without requiring ad-hoc changes. Here, the linear-eddy model (LEM) developed earlier for the flamelet regime has been extended and used to simu-late premixed flames over the entire parameter space. A 15-step, 19-species methane-air mechanism has been used in the In-situ Adaptive Tabulation (ISAT) procedure to investi-gate premixed flame structure from the flamelet,the thin-reaction- zones and well-stirred reactor regimes without any ad-hoc modifications. Qualitative and quantitative compari-son with experimental observations show that the LEM is capable of capturing the flame structure in flamelet,thin-reaction-zones and well-stirred reactor regimes. This confirms its viability as a practical model for use within LES. u’ SL