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LARGE EDDY SIMULATION OF AN UNSTEADY LIFTED FLAME

Christophe Duwig
Department of Energy Science, Division of Fluid Mechanics, Lund University, LTH, Box 118, 22100 Lund, Sweden; and Haldor Topsøe, A/S, DK-2800 Lyngby

Laszlo Fuchs
Department of Mechanics, KTH, CICERO, SE-10044 Stockholm; Division of Fluid Mechanics Lund University Lund, 22363, Sweden

Abstrakt

A lifted turbulent flame in a vitiated co-flow is studied using Large Eddy Simulation together with a perfectly stirred reactor based closure. The closure generates chemical look-up tables that are further used to close the filtered temperature equations and to compute local radical concentrations throughout the computational domain. The two-scalar approach has been used to simulate a lifted turbulent flame. The numerical predictions are compared to detailed experimental data obtained by Cabra et al. (2002). The agreement between the two sets of data is very good indicating that the present approach predicts successfully the flame lift-off and the combustion process.
The LES data is also used to study the unsteady flame stabilization. The influence of the large scale turbulent structures on the fuel/air mixing as well as on the combustion is highlighted.