中国物理B ›› 2014, Vol. 23 ›› Issue (3): 34704-034704.doi: 10.1088/1674-1056/23/3/034704

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Flow characterization and dilution effects of N2 and CO2 on premixed CH4/air flames in a swirl-stabilized combustor

韩乐a, 蔡国飙a, 王海兴a, Renou Brunob, Boukhalfa Abdelkrimb   

  1. a School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100191, China;
    b UMR 6614 CORIA, INSA de Rouen, Avenue de l’Université, BP 08, 76801 Saint-Etienne du Rouvray, France
  • 收稿日期:2013-10-21 修回日期:2013-12-26 出版日期:2014-03-15 发布日期:2014-03-15
  • 基金资助:
    Project supported by the China Scholarship Council.

Flow characterization and dilution effects of N2 and CO2 on premixed CH4/air flames in a swirl-stabilized combustor

Han Yue (韩乐)a, Cai Guo-Biao (蔡国飙)a, Wang Hai-Xing (王海兴)a, Renou Brunob, Boukhalfa Abdelkrimb   

  1. a School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100191, China;
    b UMR 6614 CORIA, INSA de Rouen, Avenue de l’Université, BP 08, 76801 Saint-Etienne du Rouvray, France
  • Received:2013-10-21 Revised:2013-12-26 Online:2014-03-15 Published:2014-03-15
  • Contact: Han Yue E-mail:hanyue@sa.buaa.edu.cn
  • Supported by:
    Project supported by the China Scholarship Council.

摘要: Numerically-aided experimental studies are conducted on a swirl-stabilized combustor to investigate the dilution effects on flame stability, flame structure, and pollutant emissions of premixed CH4/air flames. Our goal is to provide a systematic assessment on combustion characteristics in diluted regimes for its application to environmentally-friendly approaches such as biogas combustion and exhaust-gas recirculation technology. Two main diluting species, N2 and CO2, are tested at various dilution rates. The results obtained by means of optical diagnostics show that five main flame regimes can be observed for N2-diluted flames by changing excess air and dilution rate. CO2-diluted flames follow the same pattern evolution except that all the domains are shifted to lower excess air. Both N2 and CO2 dilution affect the lean blow-out (LBO) limits negatively. This behavior can be counter-balanced by reactant preheating which is able to broaden the flammability domain of the diluted flames. Flame reactivity is degraded by increasing dilution rate. Meanwhile, flames are thickened in the presence of both diluting species. NOx emissions are significantly reduced with dilution and proved to be relevant to flame stability diagrams: slight augmentation in NOx emission profiles is related to transitional flame states where instability occurs. Although dilution results in increase in CO emissions at certain levels, optimal dilution rates can still be proposed to achieve an ideal compromise.

关键词: dilution effect, premixed combustion, swirl flow, optical diagnostics

Abstract: Numerically-aided experimental studies are conducted on a swirl-stabilized combustor to investigate the dilution effects on flame stability, flame structure, and pollutant emissions of premixed CH4/air flames. Our goal is to provide a systematic assessment on combustion characteristics in diluted regimes for its application to environmentally-friendly approaches such as biogas combustion and exhaust-gas recirculation technology. Two main diluting species, N2 and CO2, are tested at various dilution rates. The results obtained by means of optical diagnostics show that five main flame regimes can be observed for N2-diluted flames by changing excess air and dilution rate. CO2-diluted flames follow the same pattern evolution except that all the domains are shifted to lower excess air. Both N2 and CO2 dilution affect the lean blow-out (LBO) limits negatively. This behavior can be counter-balanced by reactant preheating which is able to broaden the flammability domain of the diluted flames. Flame reactivity is degraded by increasing dilution rate. Meanwhile, flames are thickened in the presence of both diluting species. NOx emissions are significantly reduced with dilution and proved to be relevant to flame stability diagrams: slight augmentation in NOx emission profiles is related to transitional flame states where instability occurs. Although dilution results in increase in CO emissions at certain levels, optimal dilution rates can still be proposed to achieve an ideal compromise.

Key words: dilution effect, premixed combustion, swirl flow, optical diagnostics

中图分类号:  (Flames; combustion)

  • 47.70.Pq
47.70.Fw (Chemically reactive flows) 47.50.Ef (Measurements) 47.27.ep (Large-eddy simulations)