Turbulent burning velocity in premixed combustion

The present work presents local parameters and processes in premixed combustion of lean hydrogen and methane flames using the methodology of three-dimensional Direct Numerical Simulations (DNS). The set of vortexes used has the same length scale for all flames studied, but the global consumption speed of the hydrogen flame increases much quicker with the increase of the flame front area than the speed of the methane flames. It is shown further that the Lewis number of the fuel together with the flame front curvature plays the decisive role for the appearance of local flame extinction. These conclusions are drawn from a series of simulations where only the diffusion coefficient of the fuel has been varied considerably thus achieving full control on the local extinction.