Abstract
Direct numerical simulation of a three-dimensional spatially-
developing turbulent Bunsen flame has been performed at three
different turbulence intensities. The simulations are performed
using a reduced methane-air chemical mechanism which is specifically
tailored for the lean premixed conditions simulated here. A
planar-jet turbulent Bunsen flame configuration is used in which
turbulent preheated methane-air mixture at 0.7 equivalence ratio
issues through a central jet and is surrounded by a hot laminar
coflow of burned products. The turbulence characteristics at the jet
inflow are selected such that combustion occurs in the thin reaction
zones (TRZ) regime. At the lowest turbulence intensity the
conditions fall on the boundary between the TRZ regime and the
corrugated flamelet regime. At the highest turbulence intensity the
conditions correspond to the boundary between the TRZ regime and the
broken reaction zones regime. The data from the three simulations is
analyzed to understand the effect of turbulent stirring on the flame
structure and thickness. Statistical analysis of the data shows that
the thermal preheat layer of the flame is thickened due to the
action of turbulence, but the reaction zone is not significantly
affected.
