http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Jeong, Chanyeong,Bae, Jinhyun,Kim, Taesung,Yoon, Jisu,Joo, Seongpil,Yoon, Youngbin Elsevier 2017 Proceedings of the Combustion Institute Vol.36 No.2
<P><B>Abstract</B></P> <P>This study investigated the flashback phenomenon coupled with self-excited combustion instability in turbulent premixed bluff-body flames using the pressure fluctuation measurement, high-speed OH-PLIF, and PIV techniques. Previous studies investigating flashback in a bluff-body have found that the flame moves back and forth around the trailing edge of the bluff-body; however, the phenomenon in which the flame propagates beyond the bluff-body has not been sufficiently studied. Therefore, this study focused on understanding a strong flashback, which can damage the upper section of a combustor and which is vulnerable to heat due to flame propagation over the front of the bluff-body.</P> <P>The combustion instability frequency resulting from changes in the combustion length occurred within the range of the resonance frequency of the combustor, thereby confirming that thermal-acoustic combustion instability occurred in the combustor. When the strong flashback occurs, an instantaneous adverse pressure gradient is formed within a combustion instability cycle. Consequently, the generated reverse flow pushed the flame attached at the trailing edge of the bluff-body to the upstream from the bluff-body. The flame propagated rapidly along the side of the bluff-body by the influence of the boundary layer flow and the decreased quenching distance. This propagated flame became the ignition source at the front tip of the bluff-body and generated the flame surface that propagated in all directions; thus, it was found to be the primary cause of the increase in the flashback distance. The flame flashback distance also varied depending on the combustor length and the initial flow condition. An attempt was made to concentrate the measured data of flashback distance under various conditions into a single line, and turbulence intensity and combustion instability frequency were the dominant factors that impacted the flashback distance.</P>
정찬영(Chanyeong Jeong),김태성(Taesung Kim),송진관(Jinkwan Song),윤영빈(Youngbin Yoon) 한국추진공학회 2012 한국추진공학회 학술대회논문집 Vol.2012 No.11
비-거터형 보염기가 장착된 덕트형 연소기에서 연소 불안정이 발생할 때 보염기 근처에서 나타나는 화염의 동특성에 대한 실험적 연구를 수행하였다. 연소기의 단면은 40 x 40 mm 이며, 연료는 천연도시가스를 사용하였다. 화염 구조를 가시화하기 위해서 고속 카메라를 이용한 자발광 계측과 PIV기법을 사용하였다. 연소 불안정이 발생하면 연소기 내부의 압력 구배에 변화가 생기면서 화염의 역화 현상이 일어나고, 역화의 진행거리는 당량비에 따라서 달라졌다. 역화의 진행거리와 구조에 따라 불안정 화염을 세가지 유형을 분류하였다. 일정 당량비 이상에서는 역화가 진행됨에 따라 보염기 앞쪽 끝단에서 새로운 화염 구조를 관측할 수 있었다. 순압력 구배에서 역화되었던 화염면은 뒤로 밀리고, 이때 보염기 안쪽에 형성된 와류로 인하여 재안정화가 이루어지는 것을 확인하였다. The characteristics of flame dynamics occurring near bluff body was experimentally investigated in a model combustor with V-gutter bluff body. The combustor has a long duct shape with cross section of 40 x 40 mm and Nature City Gas were used as fuel. Measurements of chemiluminescence with high speed camera and PIV was used for visualization of flame structure. Flashback occur due to the change of pressure gradient in the combustor, and flashback distance depend on equivalent ratio. Unstable flames can be classified into three types depending on the flashback distance and structure. When the flame goes over the bluff body, a new flame structure occur at the front of the bluff body. Re-stabilization takes place as the flame moves downstream. This process is supported by a strong vortex structure behind bluff body.
정찬영(Chanyeong Jeong),신재익(JaeIk Shin),윤영빈(Youngbin Yoon) 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.5
보염기가 장착된 덕트형 연소기에서 화염의 희박 날림 현상을 이해하기 위해 화염의 동특성에 대한 실험적 연구를 수행하였다. 연소기는 길이방향으로 긴 덕트형 모양을 가지고 있고 단면은 정사각형이다. 보염기는 정삼각형 구조를 가지고 있다. 연료로는 메탄이 주성분인 도시가스를 사용했다. 화염 날림 현상이 발생하는 당량비는 레이놀즈수와 비례하여 증가하게 되며, 재순환 영역의 규모에 따라서 당량비 값이 변화한다. 화염이 날림에 가까워질 때, 재순환 영역과 화염은 상당한 변화를 겪지만, 이러한 현상이 바로 날림 현상으로 이어지지는 않는다. 날림 현상이 발생하기 적전에는 미연 가스가 재순환 영역으로 강하게 유입된다. 이로 인해 화염의 국소 소멸이 발생하고 보염기 후류의 재순환 영역은 완전히 붕괴된다. 결국 연소반응물은 다시 점화되지 못하고 날림 현상이 발생하게 된다. The dynamic characteristics of flame closed to lean blowoff are investigated in the ducted combustor with the bluff body. The combustor has a long duct shape and rectangular cross-section. Bluff body takes the shape of an equilateral triangle. Methane was used as fuel. The blowoff equivalence ratio increase with the Reynolds number. And blowoff equivalence ratio change depending on the extent of the recirculation zone. When the flame closed to blowoff, recirculation zone and flame undergoes a considerable change, but this phenomenon is not directly connected to the blowoff. Shortly before the blowoff, the unburned gas strongly penetrate into the recirculation zone. The flame is disconnected at bluff body downstream and recirculation zone is completely collapsed. The combustible mixture eventually do not ignite and the blowoff occurs.
정찬영(Chanyeong Jeong),김태성(Taesung Kim),송진관(Jinkwan Song),윤영빈(Youngbin Yoon) 한국추진공학회 2013 한국추진공학회지 Vol.17 No.5
The characteristics of flame dynamics occurring near the bluff body was experimentally investigated in a model combustor with V-gutter bluff body. Measurements of chemiluminescence with high speed camera and PIV were performed for visualization of flame structure. Flashback occurs due to the change of pressure gradient in the combustor, and the flashback distance depends on equivalent ratio. Unstable flames can be classified into three types depending on the flashback distance and structure. When the flame goes over the bluff body, an unusual flame structure occurs at the front of the bluff body. Re-stabilization takes place as the flame moves downstream of the combustor. This process is supported by a strong vortex structure behind the bluff body.
보염기가 존재하는 덕트형 연소기에서 화염의 동적 특성에 관한 연구
정찬영(Chanyeong Jeong),김태성(Teasung Kim),송진관(Jinkwan Song),윤영빈(Youngbin Yoon) 한국연소학회 2012 KOSCOSYMPOSIUM논문집 Vol.- No.45
The characteristics of flame dynamics occurring near bluff body was experimentally investigated in a model combustor with V-gutter bluff body. Flashback occurs due to the change of pressure gradient in the combustor, and flashback distance depends on equivalent ratio. Unstable flames can be classified into three types depending on the flashback distance and structure. Re-stabilization takes place as the flame moves downstream. This process is supported by a strong vortex structure behind bluff body.
V-gutter형 보염기에서 발생하는 화염의 역화 및 재점화 구조에 관한 실험적 연구
정찬영(Chanyeong Jeong),김태성(Taesung Kim),송진관(Jinkwan Song),윤영빈(Youngbin Yoon) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.11
V-gutter형 보염기가 장착된 모델 연소기에서 연소불안정이 발생할 때 보염기 근처에서 나타나는 화염의 역화 및 재점화 구조를 조사하였다. 연소기는 단면이 40 x 40 mm인 긴 덕트 형태이며 연료는 천연도시가스(CNG)를 사용하였다. 화염 구조를 가시화하기 위해서 고속 카메라를 이용한 자발광 계측을 하였다. 연소불안정이 발생하면 화염의 역화가 발생하며, 역화의 진행거리는 당량비에 따라서 달라졌다. 일정 당량비 이상에서는 역화가 진행됨에 따라 보염기 앞쪽 끝단에서 새로운 화염면이 형성된다. 흡입되는 혼합기의 속도가 증가하면서 역화되었던 화염면은 뒤로 밀리게 되고, 이때 보염기 안쪽에 형성된 재순환 영역으로 혼합기가 유입되면서 재점화가 이루어지는 것을 확인하였다. Structure of flashback and reignition occurring near flameholder was experimentally investigated in a model combustor with V-gutter flameholder. The combustor has a long duct shape with cross section of 40 x 40 mm and City Nature Gas(CNG) were used as fuel. Measurements of chemiluminescence with high speed camera was used for visualization of flame structure. In the lean case, flashback distance depend on equivalent ratio. New flame occurred at the front tip of flameholder when flashback. Flashback flame moved toward downstream direction of combustor because mixture flow velocity had increased, and then re-ignition was caused by entering flow into recirculation zone that is formed behind the flameholder.