The Effects of Non-Unity Lewis Numbers on Turbulent Premixed Flame Interactions in a Twin V-Flame Configuration

Abstract

The influence of Lewis number on turbulent premixed flame interactions is investigated using automatic feature extraction (AFE) applied to high-resolution flame simulation data. Premixed turbulent twin V-flames under identical turbulence conditions are simulated at global Lewis numbers of 0.4, 0.8, 1.0, and 1.2. Information on the position, frequency, and magnitude of the interactions is compared, and the sensitivity of the results to sample interval is discussed. It is found that both the frequency and magnitude of normal type interactions increases with decreasing Lewis number. Counternormal type interactions become more likely as the Lewis number increases. The variation in both the frequency and the magnitude of the interactions is found to be caused by large-scale changes in flame wrinkling resulting from differences in the thermo-diffusive stability of the flames. During flame interactions, thermo-diffusive effects are found to be insignificant due to the separation of time scales.

Keywords:

• Data registration
• Flame stretch
• Flame surface density
• Turbulent flame modeling

ACKNOWLEDGMENTS

The authors would like to thank Professor R. S. Cant for the use of SENGA2. EPSRC funding through grant number EP/F028741/1, and funding from Rolls-Royce, are acknowledged.

Notes

For all flames T _in  = 600K, and τ = (T _ad  − T _in )/T _in  = 2.52.

For all flames Re _{l 0}  = 82 and (ms⁻¹)

The numbers of interactions identified are 196, 192, and 192 with increasing Δt. The missing interactions are a result of two interaction types occurring in very rapid succession at the same location. This is unavoidable to some degree but constitutes only 2% of the total, and therefore does not affect the analysis.