Lifted methane-air jet flames in a vitiated coflow

R. Cabra, J. Y. Chen*, Robert Dibble, A. N. Karpetis, R. S. Barlow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

252 Scopus citations

Abstract

The present vitiated coflow flame consists of a lifted jet flame formed by a fuel jet issuing from a central nozzle into a large coaxial flow of hot combustion products from a lean premixed H2/air flame. The fuel stream consists of CH4 mixed with air. Detailed multiscalar point measurements from combined Raman-Rayleigh-LIF experiments are obtained for a single base-case condition. The experimental data are presented and then compared to numerical results from probability density function (PDF) calculations incorporating various mixing models. The experimental results reveal broadened bimodal distributions of reactive scalars when the probe volume is in the flame stabilization region. The bimodal distribution is attributed to fluctuation of the instantaneous lifted flame position relative to the probe volume. The PDF calculation using the modified Curl mixing model predicts well several but not all features of the instantaneous temperature and composition distributions, time-averaged scalar profiles, and conditional statistics from the multiscalar experiments. A complementary series of parametric experiments is used to determine the sensitivity of flame liftoff height to jet velocity, coflow velocity, and coflow temperature. The liftoff height is found to be approximately linearly related to each parameter within the ranges tested, and it is most sensitive to coflow temperature. The PDF model predictions for the corresponding conditions show that the sensitivity of flame liftoff height to jet velocity and coflow temperature is reasonably captured, while the sensitivity to coflow velocity is underpredicted.

Original languageEnglish (US)
Pages (from-to)491-506
Number of pages16
JournalCombustion and Flame
Volume143
Issue number4
DOIs
StatePublished - Dec 1 2005

Keywords

  • Computational modeling
  • Laser spectroscopy
  • Multiscalar measurements
  • Reactions in flames
  • Vitiated flow

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy(all)

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