Flame Interactions in Turbulent Premixed Twin V-Flames

Abstract

Multiple flame–flame interactions in premixed combustion are investigated using direct numerical simulations of twin turbulent V-flames for a range of turbulence intensities and length scales. Interactions are identified using a novel automatic feature extraction (AFE) technique, based on data registration using the dual-tree complex wavelet transform. Information on the time, position, and type of interactions, and their influence on the flame area is extracted using AFE. Characteristic length and time scales for the interactions are identified. The effect of interactions on the flame brush is quantified through a global stretch rate, defined as the sum of flamelet stretch and interaction stretch contributions. The effects of each interaction type are discussed. It is found that the magnitude of the fluctuations in flamelet and interaction stretch are comparable, and a qualitative sensitivity to turbulence length scale is found for one interaction type. Implications for modeling are discussed.

Keywords:

• Data registration
• Dual-tree complex wavelet transform
• Flame stretch
• Wavelets

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 is acknowledged.

Notes

¹The interval used to evaluate χ _i is approximately 2 to 3 times the AFE interval Δt. This is done to compensate for the relatively small number of interactions occurring within each Δt, and within this range, the results are insensitive to the exact value used.