In the Arrhenius law, the effects of turbulent fluctuations on rate of reactions are ignored. The model is generally inaccurate for turbulent flames due to highly non-linear Arrhenius chemical kinetics. Currently great deals of the CFD studies make use of the Eddy- Dissipation Model for investigation of turbulent combustion. Although CFD software such as Fluent allows multi-step reaction mechanisms applying the eddy-dissipation model, they will likely produce incorrect solutions. The reason is that multi-step chemical mechanisms are based on Arrhenius rates, which differ for each reaction. In this paper, a turbulent-chemistry interaction model is developed for numerical investigation of turbulent combustion according to Arrhenius law, which can be generalized to a wide range of complexity, from a single global reaction to a detailed reaction mechanism involving perhaps hundreds of species. It is achieved by introducing a correction turbulent factor (based on turbulent viscosity) added to temperature terms in Arrhenius law. Then, the modified Arrhenius law by this way is applied to simulate an air-methane diffusion flame. The results show that the modified Arrhenius model is in better agreement with the probability density distribution function (PDF) results than eddy-dissipation.

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