Three facets of turbulent combustion modelling: DNS of premixed V-flame, LES of lifted nonpremixed flame and RANS of jet-flame

Abstract

Three aspects of turbulent combustion modelling are discussed to provide an overview of numerical simulation of turbulent flames. The three examples reported concern direct numerical simulation (DNS), large eddy simulation (LES) and Reynolds average Navier–Stokes (RANS) calculations. Recent developments in DNS deal with the possibility of performing a full simulation of a premixed turbulent V-flame evolving in grid turbulence. The DNS data are useful to improve modelling of turbulent micromixing, in terms of the scalar dissipation rate of a reaction progress variable. Many combustion systems operate with reactants that have been partially premixed by unsteady large-scale motions. In this context, LES of partially premixed turbulent-lifted flame bases are reported, with a subgrid procedure that accounts for the combination of premixed and nonpremixed combustion regimes observed in such flames. Then, some developments are proposed to improve the prediction capabilities of RANS methods applied to complex combustion systems. Specifically, RANS is introduced to capture mean temperature and major pollutants' fields. Along these lines, a novel approach combining a flame tabulated chemistry with presumed conditional moments is proposed. The results are compared with laser diagnostic measurements of a nonpremixed turbulent jet flame of a methane–air mixture (Sandia D-flame).

This paper was chosen from Selected Proceedings of the Third International Symposium on Turbulence and Shear Flow Phenomena (Sendai, Japan, 24–27 June 2003).

Also with SNECMA, Villaroche, France.

Notes

Also with SNECMA, Villaroche, France.