Local Flame Structure of a H2-Air Turbulent Premixed Flame.

Abstract

Direct numerical simulation of a H2-Air turbulent premixed flame propagating in two-dimensional homogeneous isotropic turbulence was conducted to clarify local flame structure of turbulent premixed flames. Detailed kinetic mechanism including 21 elementary reactions and 8 reactive species was used to simulate H2-Air combustion in turbulence. Local heat releases are well correlated with curvatures of the flame elements. Flames convex toward the burnt gas show large heat release, while those concave toward the burnt side show relatively low heat release. In the range of small curvatures, local heat releases increase linearly with the increase of curvature. Local heat release can be represented as a linear function of strain rate tangential to the flame front. Mean tangential strain rate at the flame fronts shows positive value, which results in the larger mean heat release than that of the laminar flame. The change of local heat release in turbulence can be explained by the modification of local flame structures due to difference of diffusion coefficients of O2 and H2.