  A modified Thickened Flame (TF) model based on Large Eddy Simulation
methodology is used to investigate premixed combustion and the model
predictions are evaluated by comparing with the piloted premixed stoichiometric
methane-air flame data (Chen et al., 1996) for Reynolds numbers Re = 24,000
(flame F3) and Re=52,000 (flame F1). The basic idea of Thickened-Flame approach
is that the flame front is artificially thickened to resolve on the
computational LES grid while keeping the laminar flame speed ( ) constant. The
artificially thickening of the flame front is obtained by enhancing the
molecular diffusion and decreasing the pre-exponential factor of the Arrhenius
law. Since the flame front is artificially thickened, the response of the
thickened flame to turbulence is affected and taken care of by incorporating an
efficiency function (E) in the governing equations. The efficiency function (E)
in the modified TF model is proposed based on the direct numerical simulations
(DNS) data set of flame-vortex interactions (Colin et al., 2000). The predicted
simulation results are compared with the experimental data and with
computations reported using RANS based probability distribution function (PDF)
modeling approach (Lindstedt, R. P. and Vaos, E. M., 2006, Transported PDF
modeling of high-Reynolds-number premixed turbulent flames, Combustion and
Flame, 145, 495) and RANS based G-equation approach (Herrmann, M., 2006). It is
shown that the results with the modified TF model are generally in good
agreement with the data, with the TF predictions consistently comparable to the
PDF model predictions and superior to the results with the G-equation approach.
