A dynamic SGS model for LES of turbulent premixed flames

Numerical simulations are carried out for transient turbulent premixed flames using large eddy simulations (LES) technique. The sub-grid scale (SGS) mean chemical reaction rate is calculated using a simple algebraic relation for flame surface density (FSD), with a dynamic formulation for the model coefficient. The dynamic model is derived based on fractal theory and a flame wrinkling factor and implemented in compressible LES code. The developed model is used to simulate turbulent premixed flames of stoichiometric propane/air mixture in a vented combustion chamber, propagating over built-in solid obstacles. The fractal dimension is dynamically calculated by viewing the flame front as a fractal surface, using the SGS velocity fluctuations and the strained laminar burning velocity. The model predictions are validated against experimental measurements where good agreements are obtained.