Experimental study of temperature and CH radical location in partially premixed CH4/air coflow flames

Linda G. Blevins, Michael W. Renfro, Kent H. Lyle, Normand M. Laurendeau, Jay P. Gore

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


As part of an ongoing investigation of an exhaust NO(x) emission index minimum measured for partially premixed fames, radial temperature profiles and CH radical locations were measured in atmospheric-pressure, partially premixed, coflow, methane/air flames with fuel-side equivalence ratios of 1.6, 2.0, and 3.5, at three axial heights above the burner. The work was undertaken because of the importance of temperature and CH radical behavior in NO formation chemistry. Thin-filament pyrometry was found to be more appropriate than thermocouple thermometry for temperature measurements in partially premixed flames. Results demonstrated that the 1.6-equivalence- ratio flame exhibited classical double-flame structure, the 2.0-equivalence- ratio flame was a merged flame, and the 3.5-equivalence-ratio flame exhibited diffusion-flame structure. Signals from CH* chemiluminescence and CH laser- induced fluorescence provide evidence that, for the present measurement locations, double flames exhibit single CH peaks which can be associated with their premixed component flames. Double CH radical peaks, which were predicted to occur in low-strain-rate flames, were not found for the limited number of flame conditions and locations studied. In the near-burner region, the premixed and nonpremixed component flames of the Φ(B) = 1.6 double flame diverge radially with increasing downstream distance and merge together for larger values of Φ(B).

Original languageEnglish
Pages (from-to)684-696
Number of pages13
JournalCombustion and Flame
Issue number4
StatePublished - Sep 1999

Bibliographical note

Funding Information:
Financial support for this work was provided by National Science Foundation Grant CTS-915720, by the Office of Naval Research Grant N00014-94-0624, and by a Clare Boothe Luce graduate fellowship administered by Purdue University for the Henry Luce Foundation. Guidance provided by Mr. Anil Kelkar and Mr. Ramakrishna Chakka was invaluable during the TFP and LDV measurements. The assistance of Mr. Spencer Pack during the LIF measurements is pleasingly acknowledged.

ASJC Scopus subject areas

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


Dive into the research topics of 'Experimental study of temperature and CH radical location in partially premixed CH4/air coflow flames'. Together they form a unique fingerprint.

Cite this