Journal of the Korean Society for Aeronautical & Space Sciences (한국항공우주학회지)

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
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An Experimental Study of Acoustic Excitation Effect on Blowoff Mechanism for Premixed Flame

예혼합 화염 날림 메커니즘에 음향 가진이 미치는 영향에 대한 실험적 연구

  • Shin, Jaeik (Department of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Jeong, Chanyeong (Department of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Yoon, Youngbin (Department of Mechanical and Aerospace Engineering, Seoul National University)
  • Received : 2013.12.27
  • Accepted : 2014.09.29
  • Published : 2014.12.01
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Abstract

In this study, blowoff was investigated in a ducted combustor with the bluff body when acoustic excitation was forced. To observe the flame structure, OH radical chemiluminescence was used and the image was analyzed by using POD (Proper Orthogonal Decomposition) algorithm. Natural gas mainly composed of methane was used as fuel. Blowoff occurred when the equivalence ratio was reduced. Equivalence ratio causing blowoff was measured by changing air flow rate, excitation frequency and sound pressure. Blowoff equivalence ratio was varied depending on the experimental conditions. Vortex frequency behind the bluff body and resonance effect in combustor are the main factors that affect the blowoff equivalence ratios with the excitation.

본 연구에서는 보염기가 장착된 덕트형 연소기에 음향 가진을 주었을 때 화염의 날림 현상을 이해하기 위한 실험을 수행하였다. 화염 구조를 관측하기 위한 촬영기법으로는 $OH^*$ 자발광이 적용되었고 POD (Proper Orthogonal Decomposition) 알고리즘을 이용하여 이미지를 분석하였다. 연료는 메탄이 주 성분인 도시가스를 사용했으며 당량비를 낮춤으로써 화염 날림이 발생하도록 하였다. 공기 공급 유량, 가진 주파수 및 음압에 변화를 주며 실험을 하여 화염 날림이 발생하는 당량비를 측정하였다. 실험 조건에 따라 화염 날림 당량비 값이 크게 달랐으며 이러한 당량비 값에 변화를 주는 요인은 보염기 후류의 와류 주파수와 연소기 공진 효과의 영향으로 판단된다.

Keywords

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