Application of a Reduced Mechanism by Computational Singular Perturbation Method to the Calculation of the Ignition Delays of a Turbulence Diffusion Flame CH4/H2/N2

Abstract

This work presents an application of a reduced chemical kinetic mechanism using computational singular perturbation (CSP) based on the significant indices of the modes on the evolution of species and the degree of participation of reactions. With this approach, the mechanism of Yang and Pope is reduced to 22 reversible reactions (RR22). In this study, the tabulation of ignition delays is made with Yang and Pope mechanism, GRI 3.0, and the reduced mechanism RR22; the results obtained show a good agreement among the three mechanisms. The “Modèle Intermittent Lagrangien” (MIL) necessary to calculate the chemical source term of the transport equation of the species requires the library of ignition delays determined above and a probability density function (PDF) of the mixture fraction presumed by a beta distribution. The scalar variance, one of the key parameters for the determination of the presumed beta function, is obtained by solving its own transport equation with the unclosed scalar dissipation rate modeled using either an algebraic model or a transport equation. All these models are introduced in the computational fluid dynamics “Code-Saturne” to simulate a turbulent CH4/H2/N2 jet flame (DLR Flame A) performed at the Deutsches Zentrum für Luft-und Raumfahrt (DLR), or German Aerospace Center. A set of comparisons is made and the results of simulations show a good agreement among the three mechanisms as well with the experimental data.