The extinction of unsteady counterflow diffusion flame without the retardation effect of a mixing layer
혼합층의 지연효과를 배제한 비정상 대향류 확산 화염의 소화
- Lee, Uen-Do ;
-
Oh, Kwang-Chul
;
- Lee, Ki-Ho ;
-
Lee, Chun-Bum
;
- Lee, Eui-Ju (NIST) ;
- Shin, Hyun-Dong
- 이은도 (한국과학기술원 기계공학과) ;
-
오광철
(한국과학기술원 기계공학과) ;
- 이기호 (현대자동차 연구소) ;
-
이춘범
(자동차 부품연구소) ;
- 이의주 ;
- 신현동 (한국과학기술원 기계공학과)
- Published : 2003.05.30
Abstract
The extinction of unsteady diffusion flame was experimentally studied in an opposing jet counterflow burner using diluted methane. The stabilized flame was perturbed by linearly varying velocity change that was generated by pistons installed on both sides of the air and fuel stream. As the results, the extinction of unsteady flame is dependent not only on the history of unsteadiness, but also on the initial condition. We found that there are several unsteady effects on the flame extinction. First, the extinction strain rates of unsteady cases are extended well beyond steady state extinction limits. Second, as the slope of the strain rate change increases, the unsteady extinction strain rate becomes larger. Third, the extension of unsteady extinction strain rate becomes smaller as the initial strain rate increases. We also found that the extension of the extinction limit mainly results from the unsteady response of the reaction zone because there is no retardation effect of a mixing layer for our experimental condition.
Keywords
- Counterflow diffusion flame;
- Unsteady flame extinction;
- Linearly varying strain rate;
- Retardation of a mixing layer