Behaviors of Premixed Flames and Triple Flames with its Concentration Difference in a Slot Burner

슬롯버너에서 농도차이에 따른 예혼합화염과 삼지화염의 거동

  • 김태권 (계명대학교 기계자동차공학부) ;
  • 장준영 (계명대학교 산업기술연구소) ;
  • 박정 (순천대학교 기계자동차공학부) ;
  • 전성화 (경북대학교 공학설계연구원) ;
  • Published : 2004.11.26

Abstract

We have presented characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. The experimental apparatus consisted of a slot burner and a contraction nozzle for a lifted flame. As concentration difference of the both side of slot burner increases, the shape of flame changed from a premixed flame to a triple flame, and the liftoff height is decreased to the minimum value and then increase again. Around this minimum point, it is confirmed a transition regime from premixed flame to triple flame. Consequently, the experimental results of the liftoff height, flame curvature and luminescence intensity showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame. In the visualization experiment of smoke wire, the flow divergence and redirection reappeared in premixed flame as well as triple flame. Thus we cannot express the flame front of lifted flame has a behavior of triple flame with only flow divergence and redirection. To differentiate triple flame and premixed flame, ${\Phi}$ value of partially premixed fraction is employed. The partially premixed fraction ${\Phi}$ was constant in premixed flame. In critical flame small gradient appears over the whole regime. In triple flame, typical diffusion flame shape is obtained as parabolic distribution type due to diffusion flame trailing.

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