Ultra-lean combustion through the backflow of burned gas in rotating counterflow twin premixed flames

Makihito Nishioka, Zhenyu Shen, Akane Uemichi

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Rotating counterflow twin premixed flames of methane-air were numerically simulated with detailed chemistry based on a similarity solution to explore the leanest extinction limit without preheating and to elucidate the mechanism of " ultra-lean" combustion. We focused on high rotation rate cases in which unrealistic backflow from infinity is allowed to occur since ultra-lean combustion was found to be realized in such a situation. It was found that the reaction zone is in the backflow zone, where the flame's apparent burning velocity is negative, and that the flame zone width is much smaller than that of a 1-D planar premixed flame due to an inversion of the convexity directions of the profiles of temperature and main species concentrations. The decrease of the flame width seems to make the flame less extinguishable. The equivalence ratio of the leanest flame obtained neglecting radiative heat loss is 0.32, while that obtained with an optically thin radiation model is 0.42, which is still much leaner than the ratio of 0.49 for a 1-D planar premixed flame generated using the same radiation model.

Original languageEnglish
Pages (from-to)2188-2198
Number of pages11
JournalCombustion and Flame
Volume158
Issue number11
DOIs
Publication statusPublished - 2011 Nov
Externally publishedYes

Keywords

  • Burned gas backflow
  • Extinction limit
  • Negative burning velocity
  • Rotating counterflow twin flame
  • Ultra-lean combustion

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy(all)

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