This paper presents a study of the influence of chemical mechanisms and turbulence models on RANS simulations of the CH4/H2/N2-air turbulent diffusion flame i.e., the so-called DLR-A flame. The first part of this work is focused on the assessment of the influence of four chemical models on predicted profiles of the DLR-A flame. The chemical mechanisms considered are: i) a C2 compact skeletal mechanism, which is derived from the GRI3.0 mechanism using an improved multi-stage reduction method, ii) a C1 skeletal mechanism containing 41 elementary reactions amongst 16 species, iii) the global mechanism by Jones and Lindstedt, iv) and a global scheme consisting of the overall reactions of methane and dihydrogen. RANS numerical results (e.g: velocities, temperature, species or the heat production rate profiles) obtained running the reactingFOAM solver with the four chemical mechanisms as well as the standard k – ε model, the partially stirred reactor (PaSR) combustion model and the P – 1 radiation model indicate that the C2 skeletal mechanism yields the best agreement with measurements. In the second part of this paper four turbulence models, namely, the standard k – ϵ model , the RNG k – ϵ model, Realizable k – ϵ model and the k – ω SST model are considered in order to evaluate their effects on the DLR-A flame simulation results obtained with the C2 skeletal mechanism. Results reveal that the predictions obtained with the standard k – ϵ and the RNG k – ϵ models are in very good agreement with experimental data. Hence, for simple jet flame with moderately high Reynolds number such as the DLR-A flame, the standard k-epsilon can model the turbulence with a very good accuracy.

The present work assesses the capabilities of a compact skeletal mechanism, derived using an in-house reduction code, to accurately model chemical processes in a turbulent CH4/H2/N2 flame. To this end, a numerical investigation of the DLR-A flame is performed using the free and open-source code openfoam with the derived mechanism. Specifically, the numerical investigation is performed using the Reynolds-averaged Navier–Stokes (RANS) approach and a compact skeletal mechanism consisting of 51 elementary reactions among 21 species. The skeletal mechanism is derived from the GRI3.0 mechanism using an improved multistage reduction method. The k − ɛ model is used as a closure for the RANS equations, while the source terms in the species and energy transport equations are closed by the partially stirred reactor (PaSR) model. The radiation term is modeled by the P-1 model. The numerical results show a good agreement with the experimental data.

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