The near field jet of a self-igniting methane-air diffusion jet flame is studied by means of Direct Numerical Simulation (DNS) and a Flamelet/Progress-Variable (FPV) model to include detailed chemistry. Hence, all flow and transport scales are resolved and chemical reactions are assumed to take place in thin layers. Key aspects in the creation of the flamelet database, prior to the DNS simulation, are considered. Inclusion of differential diffusion effects are discussed by analysing the S-shaped curve and autoignition delay times. Similarly, the influence on these parameters of two detailed mechanism, the GRI2.11 and GRI3.0, is assessed. The definition of the progress-variable used in the FPV is analysed and a new definition is proposed. Results of the near jet, up to 20 jet diameters, are shown for the two detailed mechanism.

Peer Reviewed