The response of a propane-air counter-flow diffusion flame subjected to a transient flow field

Eric J. Welle, William L. Roberts*, Campbell D. Carter, Jeffrey M. Donbar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


OH planar laser-induced fluorescence (PLIF) and particle image velocimetry have been used to study the frequency response of laminar C3H 8-air counterflow diffusion flames to assess the adequacy of the steady-flamelet models. Particle image velocimetry was used to determine the flame strain rate, while OH PLIF was used both to measure temperature at the flame front, using the two-line PLIF technique, and the reaction-zone width. Both measurements demonstrate that the frequency response of flames subjected to a time-varying flow field is diffusion-limited. At the 30-Hz and 50-Hz forcing frequencies, the maximum reaction-zone temperature and width were found to respond quasi-steadily. However, at higher forcing frequencies-i.e., 100 and 200 Hz-transient behavior is evident from the phase relationship between the imposed sinusoidal strain rate and the resulting peak temperature and reaction-zone width. The measured values of the OH-field widths were well fit by an offset sine function. In all cases when the oscillation amplitude is normalized by the cycle mean strain rate and plotted against the non-dimensional flow field frequency, the results collapse onto a single line having a steep negative slope.

Original languageEnglish (US)
Pages (from-to)285-297
Number of pages13
JournalCombustion and Flame
Issue number3
StatePublished - Nov 2003
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the Army Research Office, under ARO Grant DAAG55 to 98-1 to 0222 (Dr. David Mann, technical monitor), the Air Force Office of Scientific Research (Dr. Julian Tishkoff, technical monitor), and the Propulsion Directorate of the Air Force Research Laboratory, Wright-Patterson AFB.


  • Diffusion flame
  • PIV
  • PLIF
  • Stokes parameter
  • Transient flame
  • Unsteady flame

ASJC Scopus subject areas

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


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