Spatiotemporal measurements of flame stretch and propagation rates for lean and rich CH4/air premixed flames interacting with a turbulent-wake

I. F. Huang, S. S. Shy, C. C. Chang, S. C. Li, C. M. Huang

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations

Abstract

A 1.5 m long turbulent-wake combustion vessel with a 0.15 m × 0.15 m cross-sectional area is proposed for spatiotemporal measurements of curvature, strain, dilatation and burning rates along a freely downward-propagating premixed flame interacting with a parallel row of staggered vortex pairs having both compression (negative) and extension (positive) strains simultaneously. The wanted wake is generated by rapidly withdrawing an electrically-controlled, horizontally-oriented sliding plate of 5 mm thickness for flame-wake interactions. Both rich and lean CH4/air flames at the equivalence ratios Φ = 1.4 and Φ = 0.7 with nearly the same laminar burning velocity are studied, where flame-wake interactions and their time-dependent velocity fields are obtained by high-speed, high-resolution DPIV and laser-tomography. Correlations among curvature, strain, stretch, and dilatation rates along wrinkled flame fronts at different times are measured and thus their influences on front propagation rates can be analyzed. It is found that strain-related effects have significant influence on front propagation rates of rich CH 4/air (diffusionally stable) flames even when the curvature weights more in the total stretch than the strain rate does. The local propagation rates along the wrinkled flame front are more intense at negative strain rates corresponding to positive peak dilatation rates but the global propagation rate averaged along the rich flame front remains constant during all period of flame-wake interaction. For lean CH4/air (diffusionally unstable) flames, the curvature becomes a dominant parameter influencing the structure and propagation of the wrinkled flame front, where both local and global propagation rates increase significantly with time, showing unsteady flame propagation. These experimental results suggest that the theory of laminar flame stretch can be applicable to a more complex flame-wake interaction involving unsteadiness and multitudinous interactions between vortices.

Original languageEnglish
Pages (from-to)1755-1762
Number of pages8
JournalProceedings of the Combustion Institute
Volume32 II
Issue number2
DOIs
StatePublished - 2009
Event32nd International Symposium on Combustion - Montreal, QC, Canada
Duration: 3 Aug 20088 Aug 2008

Keywords

  • Curvature and strain rate
  • Dilatation rate
  • Flame-wake interaction
  • Front propagation rate
  • High-speed DPIV

Fingerprint

Dive into the research topics of 'Spatiotemporal measurements of flame stretch and propagation rates for lean and rich CH<sub>4</sub>/air premixed flames interacting with a turbulent-wake'. Together they form a unique fingerprint.

Cite this