The opposed-jets configuration is very used in industrial systems. The actual practical applications use clean fuels which in stead of classical hydrocarbons. The present work is a numerical simulation of opposed diffusion jets using FLUENT6.3.26. We have compared different turbulence models and combustion models and mechanisms to find which gives the best predictions for this type of flows. We have used methane and hydrogen fuels because they are considered as clean fuels. The comparison between k-ε, k-omega and RSM turbulent models shows that both of k-ε and RSM gives good results. The use of k-ε is more practical because it requires less long time to be implied. The comparison between the combustion models shows that EDC gives more realistic results than eddy dissipation and Finite rate models. In addition, the detailed chemical mechanisms are more adequate to this model. For both methane and hydrogen flames, the detailed mechanisms gives good results and temperatures.

Nomenclature a-large diameter of the sprayer aperture, mm; b-small diameter of the sprayer aperture, mm; Dlargediameter of the impacting zone, mm; Doverlapoverlapping zone width, mm; F-section area of the sprayer aperture, mm 2 ; g-fluid dispersion, mm 3 /mm 2 .s; g ̅-average dispersion, mm 3 /mm 2 .s; gmax-maximum fluid dispersion, mm 3 /mm 2 .s; gexp-fluid dispersion obtained by experiments, mm 3 /mm 2 .s; gthe-fluid dispersion obtained by summation law of both jets, mm 3 /mm 2 .s; H-distance between sprayer and plane surface, mm; Hoverlap-overlapping area height, mm; h-depth of the sprayer slit, mm; K-dimensionless number characterizes relation between dispersions; K1-hydrodynamic statistical parameter, kg/mm 2 .s; K2-geometrical statistical parameter, mm; L-Nozzles spacing, mm; n-integer represents number of points; R-inner radius of the sprayer channel, mm; Ssection of the recovery tube, mm 2 ; V-volume of recovered fluid, mm 3 ; xi-coordinate on the x axis; yi-coordinate on the y axis; xmax-radius of the impacting water along the x axis, mm; ymax-radius of the impacting water along the y axis, mm; Greek Symbols-AP-pressure variation, MPa; φ-opening angle of the sprayer, deg; δthickness of the bottom's sprayer, mm; τtime, s; ρ-mass density, kg/m 3 ; σxvariance; σyvariance; ξ-dimensionless geometrical parameter.

The opposed-jets configuration is very used in industrial systems. The actual practical applications use clean fuels which in stead of classical hydrocarbons. The present work is a numerical simulation of opposed diffusion jets using FLUENT6.3.26. We have compared different turbulence models and combustion models and mechanisms to find which gives the best predictions for this type of flows. We have used methane and hydrogen fuels because they are considered as clean fuels. The comparison between k-ε, k-omega and RSM turbulent models shows that both of k-ε and RSM gives good results. The use of k-ε is more practical because it requires less long time to be implied. The comparison between the combustion models shows that EDC gives more realistic results than eddy dissipation and Finite rate models. In addition, the detailed chemical mechanisms are more adequate to this model. For both methane and hydrogen flames, the detailed mechanisms gives good results and temperatures.