동축이중 공기분류중의 난류확산화염에 관한 실험적 연구 II

An Experimental Study on Turbulent Diffusion Flame in Double Coaxial Air Jets(II)

본 연구에서는 선회가 없는 중심기류와 주위기류의 난류 전단층에서 형성되는 난류확산화염의 천이영역(transition region)에 주목하여 전단층내의 혼합작용과 화염 구조와의 상호작용을 규명하기 위해 거시적 및 순간적인 화염구조에 대해 실험적으로 조사 연구한 결과를 보고한다.

Double coaxial are jets(annular and coaxial air jets) between which propane gas is fed was selected to study the structure of diffusion flames in turbulent shear flow. Schlieren and direct photographs are taken to visualize the flame structure. Mean and fluctuating temperatures and ion currents were measured to investigate the macroscopic and the instantaneous flame structure. The objective of this study is to understand the interaction between combustion and mixing process especially in the transition region of turbulent shear flow. The investigation reported in this paper focuses on the macroscopic and the instantaneous structures of three flames obtained. The increased mixing effect resulting from increase of Reynolds number of central air jet makes the flame bluish and short. When the velocity of surrounding air stream is higher than that of central air jet, the instantaneous flame structure is composed of coherent structure. It is considered that the flame structure of transitional region of mixing layer depends on the structure of mixing layer of non-reacting conditions.