Journal of the Korean Society of Combustion (한국연소학회지)

The Korean Society of Combustion (한국연소학회)
권호 표지

NOx Reduction by Acoustic Excitation on Coaxial Air Stream in Lifted Turbulent Hydrogen Non-Premixed Flame

부상된 수소난류확산화염에서 동축공기의 음향가진에 의한 NOx 저감

  • 허필원 (서울대학교 기계항공공학부 대학원) ;
  • 오정석 (서울대학교 기계항공공학부 대학원) ;
  • 윤영빈 (서울대학교 기계항공공학부)
  • Published : 2009.03.31
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Abstract

The effects of acoustic excitation of coaxial air on mixing enhancement and reduction of nitrogen oxides (NOx) emission were investigated. A compression driver was attached to the coaxial air supply tube to impose excitation. Measurements of NOx emission with frequency sweeping were performed to observe the trend of NOx emission according to the fuel and air flow conditions and to inquire about the effective excitation frequency for reducing NOx. Then, Schlieren photographs were taken to visualize the flow field and to study the effect of excitation. In addition, phase-locked particle image velocimetry (PIV) was performed to acquire velocity field for each case and to investigate the effect of vortices more clearly. Direct photographs and OH chemiluminescence photographs were taken to study the variation of flame length and reaction zone. It was found that acoustic forcing frequencies close to the resonance frequencies of coaxial air supply tube could reduce NOx emission. This NOx reduction was influenced by mixing enhancement due to large-scale vortices formed by fluctuation of coaxial air jet velocity.

Keywords

References

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