Nonlinear effects in the extraction of laminar flame speeds from expanding spherical flames

A. P. Kelley, Chung King Law

Research output: Contribution to journalArticlepeer-review

480 Scopus citations


Various factors affecting the determination of laminar flames speeds from outwardly propagating spherical flames in a constant-pressure combustion chamber were considered, with emphasis on the nonlinear variation of the stretched flame speed to the flame stretch rate, and the associated need to nonlinearly extrapolate the stretched flame speed to yield an accurate determination of the laminar flame speed and Markstein length. Experiments were conducted for lean and rich n-butane/air flames at 1 atm initial pressure, demonstrating the complex and nonlinear nature of the dynamics of flame evolution, and the strong influences of the ignition transient and chamber confinement during the initial and final periods of the flame propagation, respectively. These experimental data were analyzed using the nonlinear relation between the stretched flame speed and stretch rate, yielding laminar flame speeds that agree well with data determined from alternate flame configurations. It is further suggested that the fidelity in the extraction of the laminar flame speed from expanding spherical flames can be facilitated by using small ignition energy and a large combustion chamber.

Original languageEnglish (US)
Pages (from-to)1844-1851
Number of pages8
JournalCombustion and Flame
Issue number9
StatePublished - Sep 2009

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • General Physics and Astronomy


  • Butane
  • Flame speed extrapolation
  • Laminar flame speed
  • Markstein length
  • Propagating spherical flame


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