Displacement speed, flame surface density and burning rate in highly turbulent premixed flames characterized by low Lewis numbers

Direct numerical simulation data obtained from four pairs of turbulent, lean hydrogen–air, complex-chemistry flames are analysed to explore the influence molecular diffusion on flame surface density, displacement speed $S_d$ and density transport equation terms. Each pair involves (i) a where mixture-averaged diffusivities adopted Lewis number $Le$ is significantly less than unity (ii) an equidiffusive all set equal heat diffusivity mixture $Le=1$ , with other things being equal. Reported results show that higher turbulent burning rates simulated in former result mainly increase local fuel consumption rate, whereas area plays secondary role, especially more intense turbulence. The rate stems peak width zone significant. latter phenomenon importance richer both phenomena most pronounced vicinity leading edges, thus indicating crucial role played by edge premixed its propagation. Moreover, mean differs laminar even flames, varies substantially across brush may be negative at edges highly flames.