Characteristics of Turbulent Lifted Flames in Coflow Jet with Initial Temperature Variations

동축류 제트에서 초기 온도 변화에 따른 난류 부상화염 특성

  • 김길남 (서울대학교 대학원 기계항공공학부) ;
  • 원상희 (서울대학교 정밀 기계설계 공동 연구소) ;
  • 정석호 (서울대학교 기계항공학부)
  • Published : 2004.03.31


Characteristics of turbulent lifted flames in coflow jet have been investigated by varying initial temperature through the heating coflow air. In the turbulent regime, liftoff height increases linearly with fuel jet velocity and decreases nonlinearly as the coflow temperature increases. This can be attributed to the increase of turbulent propagation speed, which is strongly related to laminar burning velocity. Dimensionless liftoff heights are correlated well with dimensionless jet velocity, which are scaled with parameters determining local flow velocity and turbulent propagation speed. This implies that the turbulent lifted flames are stabilized by balance mechanism between local turbulent burning velocity and flow velocity. Blowout velocity can be obtained from the ratio of mixing time to chemical time. Comparing to previous researches, thermal diffusivity should be evaluated from the initial temperature instead of adiabatic flame temperature.