Zone conditional modeling of premixed turbulent flames at a high Damkohler number

Abstract

The zone conditioning approach is applied to generic mass and momentum conservation equations in unburned and burned gas. Conditionally averaged equations include additional source terms with flame surface density to reflect interfacial transports between two zones. Zone conditional averaging does not involve countergradient diffusion, which is due to description in terms of mixture properties in Favre averaging. Asymptotic analysis shows that flame propagation characteristics are determined by gradient diffusion by turbulence and an externally imposed pressure gradient at the leading edge. Two-dimensional CFD simulations are performed for two typical premixed turbulent flames stabilized in an impinging jet. With adjusted constants to match the (c) over bar profiles, conditional axial velocities show good agreement with experimental data for the two test flames. The zone conditional model provides an intuitive set of governing equations suitable for a solution procedure of premixed combustion devices at a high Damkohler number. (C) 2004 Published by Elsevier Inc. on behalf of The Combustion Institute.