Effect of Lewis number on flame propagation through vortical flows

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Abstract

The premixed gas flame spreading through an array of large-scale vortices is studied numerically. It is found that the flame speed is a nonmonotonic function of the stirring intensity. At sufficiently low Lewis numbers (Le<1) the system becomes bistable with a hysteretic transition between possible propagation modes. In the presence of volumetric heat losses the stirring invariably promotes extinction (reduces the flammability limits), provided Le>1. At Le<1 this holds only for sufficiently strong stirring, whereas moderate stirring actually expands the flammability limits. At Le>1 the deficient reactant is fully consumed up to the very quenching point. At Le<1, prior to the total extinction, part of the deficient reactant escapes the reaction zone and remains unconsumed.

Original languageEnglish
Pages (from-to)235-240
Number of pages6
JournalCombustion and Flame
Volume142
Issue number3
DOIs
StatePublished - Aug 2005

Keywords

  • Flame-flow interaction
  • Flammability limits
  • Turbulent flames

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