| The mutual effects of turbulence and combustion are studied via analysis of computational data generated by direct numerical simulation (DNS) of a premixed methane-air flame in a shearless turbulence mixing layer. The chemical reaction is modeled with a 1-step, a 5-step and a 12-step reduced kinetics scheme. The 12-step mechanism is that of Sung et al. (1998) and is shown to accurately predict the characteristics of laminar premixed flames such as the flame thickness and the flame propagation speed. The flame behavior in various turbulent environments is investigated by changing the peak of the initial energy spectrum. Flame surface densities, flame strain and curvature statistics, the local structure of the flamelets, the local extinction and re-ignition, the turbulence generation and destruction by combustion and some other important phenomena in turbulent combustion are investigated. The importance of the chemical kinetics models in representing the flow/flame features and the accuracy of "simple" (1-step and 5-step) reduced schemes are also studied by comparing the results obtained using the more detailed kinetics mechanisms. |
