NOxPrediction in 3-D Turbulent Diffusion Flames by Using Implicit Multigrid Methods

Abstract

Abstract Modeling of the nitric oxide formation in the turbulent nonpremtxed methane and syngas (CO/H2/N2) diffusion flame is studied using an implicit time-stepping and multigrid technique. The chemical kinetic model for both methane-air in a sudden-expansion combustor and syngas-air combustion in a laboratory combustor as well as in a gas turbine combustor is assumed to have 49 species and 229 finite-rate, reversible reaction steps. The standard k - e turbulence model and the algebraic correlation closure model are applied to close the time-averaged Navier-Stokes and species equations (Liao et al., 1995) respectively. The computation requires about 250 time steps to reduce the residual by 3 orders of magnitude for the 3-D turbulent methane-air diffusion flame case on a 34 × 18 × 18 grid, which shows convergence rate is much faster than conventional iterative methods. Computational results with detailed chemistry are exhibited and some of them are compared with experimental data. Qualitative agreement be...