Extinction and flame bifurcations of stretched dimethyl ether premixed flames

Yiguang Ju, Yuan Xue

Research output: Contribution to journalConference articlepeer-review

17 Scopus citations

Abstract

Extinction limits and flame bifurcation of lean premixed dimethyl ether-air flames are numerically investigated using the counterflow flame with a reduced chemistry. Emphasis is paid to the combined effect of radiation and flame stretch on the extinction and flammability limits. A method based on the reaction front is presented to predict the Markstein length. The predicted positive Markstein length agrees well with the experimental data. The results show that flow stretch significantly reduces the flame speed and narrows the flammability limit of the stretched dimethyl ether-air flame. It is found that the combined effect of radiation and flow stretch results in a new flame bifurcation and multiple flame regimes. At an equivalence ratio slightly higher than the flammability limit of the planar flame, the distant flame regime appears at low stretch rates. With an increase in the equivalence ratio, in addition to the distant flame, a weak flame isola emerges at moderate stretch rates. With a further increase in the equivalence ratio, the distant flame and the weak flame branches merge together, resulting in the splitting of the weak flame branch into two weak flame branches, one at low stretch and the other at high stretch. Flame stability analysis demonstrates that the high stretch weak flame is also stable. Furthermore, a K-shaped flammability limit diagram showing various flame regimes and their extinction limits is obtained.

Original languageEnglish (US)
Pages (from-to)295-301
Number of pages7
JournalProceedings of the Combustion Institute
Volume30
Issue number1
DOIs
StatePublished - 2005
Event30th International Symposium on Combustion - Chicago, IL, United States
Duration: Jul 25 2004Jul 30 2004

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

Keywords

  • Bifurcation
  • Dimethyl ether
  • Extinction limit
  • Radiation
  • Stretch

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