An experimental and theoretical investigation of the dilution, pressure and flow-field effects on the extinction condition of methane-air-nitrogen diffusion flames

H. K. Chelliah, C. K. Law, Toshihisa Ueda, M. D. Smooke, F. A. Williams

Research output: Contribution to journalArticle

146 Citations (Scopus)

Abstract

Velocity fields, and extinction conditions for methane-air diffusion flames are measured for an opposed-flow nozzle-type burner system and calculated by a numerical-integration, routine for pressures from 0.25 to 2.5 atm and for dilutions having fixed stoichiometric mixture fractions with oxidizer-stream oxygen mass fractions from 0.233 to 0.190. Imposition of boundary conditions ranging from potential flow to plug flow reveals that changes on the order of a factor of two in the oxidizer-side strain rate at extinction can be produced by changes in opposed-flow burner design. It is shown that the maximum velocity gradient, however which occurs on the fuel side of the main reaction zone, achieves a value at extinction that is relatively insensitive to the boundary conditions of the flow. The results explain differences found by different investigators on influences of dilution on extinction strain rates and show that most counterflow burners are closer to the plug-flow limit than to the potential-flow limit. Strain rates at extinction without dilution are shown to increase with increasing pressure over the above-stated range, countrary to previously observed behaviors with dilution or at very high pressures. This behavior is explained as a consequence of decreasing peak radical concentration with increasing pressure.

Original languageEnglish
Pages (from-to)503-511
Number of pages9
JournalSymposium (International) on Combustion
Volume23
Issue number1
DOIs
Publication statusPublished - 1991
Externally publishedYes

Fingerprint

diffusion flames
Methane
pressure distribution
Dilution
dilution
Flow fields
flow distribution
extinction
Nitrogen
methane
Fuel burners
burners
nitrogen
Strain rate
Potential flow
air
strain rate
Air
potential flow
oxidizers

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes
  • Physical and Theoretical Chemistry

Cite this

An experimental and theoretical investigation of the dilution, pressure and flow-field effects on the extinction condition of methane-air-nitrogen diffusion flames. / Chelliah, H. K.; Law, C. K.; Ueda, Toshihisa; Smooke, M. D.; Williams, F. A.

In: Symposium (International) on Combustion, Vol. 23, No. 1, 1991, p. 503-511.

Research output: Contribution to journalArticle

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AU - Williams, F. A.

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