CFD modelling of a turbulent CH4/H2/N2 jet diffusion flame with detailed chemistry

A CFD model based on the Reynolds Averaged Navier-Stokes (RANS) approach combined with a detailed chemical kinetic mechanism to investigate a turbulent CH4/H-2/N-2 jet diffusion flame is developed. The CFD governing equations of momentum, mass, and energy in the turbulent field were solved in conjunction with the standard k - epsilon turbulence model. The laminar flamelet concept that views the turbulent diffusion flame as an ensemble of laminar diffusion flamelets is adopted. The coupling between turbulence and chemistry is achieved by the statistical description of three parameters namely (1) mixture fraction (Z), (2) variance of mixture fraction (Z("2)) and (3) scalar dissipation rate (chi). The flamelet model consists of two steps namely (a) the generation of a set of laminar flamelet solutions and (b) the integration of the laminar flamelet solutions with presumed-shape Probability Density Function (PDF). The GRI Mech-3.0 mechanism that involves 53 species and 325 reactions is adopted. The effect of various parameters such as C-1 epsilon constant in the turbulent dissipation transport equation on the numerical solution is highlighted. Also, the comparison between the CFD model results and the experimental data of velocity, temperature and mass fractions of species (CH4, H-2, N-2, H2O, CO2, O-2 and CO) along the centreline as well as on the radial position of x/D = 5, 40 are presented. Generally, the CFD results show a good agreement with the experimental data, and the presented approach in this paper is an accurate promising alternative to LES and DNS approaches for the modelling of non-premixed turbulent configurations.