Direct Numerical Simulations of high Karlovitz number premixed flames for the analysis and modeling of the displacement speed.

An a priori model for premixed turbulent flame combustion in the thin reaction zone (TRZ) regime is presented. This deduced from analysis of data series direct numerical simulations (DNS) stoichiometric (ϕ=1.0) iso-octane flames, with Karlovitz number ranging 2.9 to 46.2. For each case two flames are considered: one unity Lewis numbers isolate effect turbulence on flame, and non-unity study influence differential diffusion. First shown remain leading focus this specific iso-surface how it affected by turbulence. Second, displacement speed Sd shows differentiate dependency tangential strain rate curvature. modeled through an expression formally similar ones used laminar theories, but using effective Markstein lengths place ones. These depend decrease when increases, agreement previous studies showing reduction Karlovitz. From these DNS, extension coherent (CFM) TRZ proposed, fine-grained surface density (FSD) located zone. Models speed, rate, stretch due curvature proposed. The evaluation closures significant improvement compared flamelet formulations.