Title: Numerical modelling of the pressure dependent reaction source term for premixed turbulent methane/air flames

Authors: S.P.R. Muppala, F. Dinkelacker

Addresses: Lehrstuhl für Technische Thermodynamik, Am Weichselgarten 8, 91058 Erlangen, Germany. ' Lehrstuhl für Technische Thermodynamik, Am Weichselgarten 8, 91058 Erlangen, Germany

Abstract: Effects of pressure are studied numerically for premixed turbulent flames under varied turbulence conditions up to 1.0 MPa. In order to model the pressure dependency of the reaction source term, a set of available experimental Bunsen flame data for methane/air mixtures from Kobayashi et al. are used as reference for a numerical optimisation study, where three parameters of a generalized algebraic closure relation for a reaction progress variable approach are determined. This approach is based on the algebraic turbulent flame speed closure model proposed by Zimont, which is subjected to modifications for influence of pressure and for low turbulence conditions. The net pressure dependency of the turbulent flame speed is slightly above zero, similar to the experimental fit of Kobayashi. Dependency of turbulent velocity is found proportional to u|0.55, similar to several experimental data fits by Bradley et al. If the resulting flame angles are represented in terms of sT/sL vs. u|/sL, then the fitted curve of the calculated results is closely related to that of the experiments. Both are showing a nonlinear bending behaviour especially at low turbulence intensities, which seems to be related to the influence of laminar flame instabilities.

Keywords: numerical combustion; premixed flame; turbulent flame velocity; high-pressure; reaction source term.

DOI: 10.1504/PCFD.2004.004605

Progress in Computational Fluid Dynamics, An International Journal, 2004 Vol.4 No.6, pp.328 - 336

Published online: 24 May 2004 *

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