Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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Effects of Multi-hole Baffle Thickness on Flow and Mixing Characteristics of Micro Combustor

다공배플 두께가 마이크로 연소기의 유동 및 혼합특성에 미치는 영향

  • Kim, Won Hyun (School of Mechanical Engineering, Kyungpook Nat'l Univ.) ;
  • Park, Tae Seon (School of Mechanical Engineering, Kyungpook Nat'l Univ.)
  • 김원현 (경북대학교 기계공학부) ;
  • 박태선 (경북대학교 기계공학부)
  • Received : 2017.04.10
  • Accepted : 2017.06.14
  • Published : 2017.09.01
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Abstract

Flow structure and mixing characteristics in a micro combustor with a multi-hole baffle were numerically studied using the Reynolds stress model. The multi-hole baffle has geometrical features to produce multiple three-dimensional vortices inside combustion chamber. When the thickness of the baffle's geometrical factors changes, variations of vortical structures occur variously. Among these vortices, the vortex generated from the fuel stream exerts a critical influence on the mixing enhancement. The three-dimensional vortical structure, in its development state, was strongly dependent on the baffle thickness. In particular, as the baffle thickness decreases to values less than the diameter of the fuel hole, the jet stream in baffle holes changes from the parabolic to saddleback profile type. The sizes of recirculation zones inside combustion chamber and the mixing state were closely affected by the structure of the jet streams.

다공배플을 가진 마이크로연소기에 레이놀즈응력 난류모형을 이용하여 난류유동 및 혼합특성에 대한 수치해석 연구를 수행하였다. 다공배플은 연소실 내부에 다수의 3차원 와유동을 발생시키는 기하학적 특징을 가지고 있다. 그러한 형상특징 중에서 배플두께를 변화시킬 경우 와유동구조의 다양한 변화가 얻어졌다. 여러 와유동중에서 연료유동으로부터 생성된 와유동은 혼합도 증가에 결정적 역할을 하였다. 연소실 내부의 3차원 와유동구조는 배플두께 변화에 따른 유동의 발달상태에 의존하였다. 특히, 배플두께가 연료유입구 직경보다 작을수록 배플구멍 제트유동의 속도분포는 포물선형태에서 안장모양의 형태로 변하였다. 연소실내부의 재순환영역크기 및 혼합도는 이러한 제트유동구조에 밀접한 상관관계를 가졌다.

Keywords

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