Effects of partial premixing on pollutant emissions in swirling methane jet flames

T. S. Cheng, Y. C. Chao, D. C. Wu, H. W. Hsu, T. Yuan

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


Experimental measurements of visible flame heights, temperatures, and pollutant emission indices in partially premixed swirling flames with a broad range of central fuel tube equivalence ratios (ΦF) are reported. Two cases of partially premixed swirling flames are studied; one with a constant fuel tube exit velocity and the other with an increased exit velocity. With increasing partial premixing, the visible flame height decreases and the overall flame color changes from yellow to blue. Temperature measurements indicate that the flame structures become thinner and temperatures increase continuously with increasing partial premixing. Emission index, EINOx and EICO, values decrease with increasing levels of partial premixing and reach a minimum value at ΦF ≈ 3, followed by an increase as ΦF approaches the blowoff limits. The reduction in EINOx and EICO at optimum partial premixing (ΦF ≈ 3), as compared with that for the non-premixed swirling flame is at least 23% and 77%, respectively. The emission index for NOx scales very well with the fuel mass fraction and the fuel-air momentum flux ratio. Good agreement is achieved between the predictions and measured results.

Original languageEnglish
Pages (from-to)865-878
Number of pages14
JournalCombustion and Flame
Issue number1-2
Publication statusPublished - 2001

All Science Journal Classification (ASJC) codes

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


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