서지주요정보
관내 예혼합 화염의 안정화와 축방향 유속변동에 의한 비정상 거동 = Stability of a premixed flame in a tube and its unsteady behavior induced by longitudinal velocity variation
서명 / 저자 관내 예혼합 화염의 안정화와 축방향 유속변동에 의한 비정상 거동 = Stability of a premixed flame in a tube and its unsteady behavior induced by longitudinal velocity variation / 김남일.
발행사항 [대전 : 한국과학기술원, 2001].
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8012512

소장위치/청구기호

학술문화관(문화관) 보존서고

DME 01050

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반납예정일

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초록정보

A stabilization condition for the premixed flame in a tube was investigated for the propane/air and methane/air flames. The stabilized flames were classified into two regimes, one-dimensional regime and two-dimensional regime, by both the shape and the mass consumption rate. In the case of propane/air premixed flame, the stabilized flame at the lean flammability regime (φ<0.6) has one-dimensional flame characteristics. In this regime the radius of curvature of the flame is sufficiently larger than the flame thickness, and the mean velocity of unburned mixture is similar to the laminar burning velocity of the previous research. In the case of methane-air flame, cellular shaped flame is observed in the one-dimensional regime when the equivalence ratio is larger than 0.61. And within some range of equivalence ratio both the one-dimensional and the two-dimensional stabilization conditions were satisfied at the same equivalence ratio. In this condition, a small increase in the mean velocity could cause a sudden transition from the one-dimensional flame to the two-dimensional flame and the flame skirt seemed to rotate azimuthally. A mean velocity variation larger than the burning velocity was introduced to the stabilized flame for a period longer than the reaction time scale in order to examine the unsteady behavior of flame propagation. The magnitude and period of the mean velocity variation were treated as experimental parameters. When the large velocity variation was introduced in the same direction as the initial mean velocity, the extinction behaviors were observed and systematically classified into two groups: extinction by boundary layer and extinction by acoustic instability. We found out that there exists a critical velocity variation and a critical time above which the extinction region develops to the center of the tube and extinguishes the flame. With the velocity variation in the opposite direction of the initial mean velocity, the flame was not extinguished near the wall and the characteristics of the flame propagation were similar to those of earlier studies on the flame propagation. The mechanism of the extinction near the wall is explained by the flame stretch theory, which provides a clue to the stretch effects on the finger flame. The effects of non-unity Lewis number on the flame extinction was negligible in the extinction by the boundary layer, but was important in the extinction by the acoustic instability. When the Lewis number is smaller than 1, it was found that there exists a critical velocity variation above which the eventual extinction takes place by the acoustic instability.

서지기타정보

서지기타정보
청구기호 {DME 01050
형태사항 xviii, 200 p. : 삽화 ; 26 cm
언어 한국어
일반주기 부록 수록
저자명의 영문표기 : Nam-Il Kim
지도교수의 한글표기 : 신현동
지도교수의 영문표기 : Hyun-Dong Shin
수록잡지명 : "Laminar premixed flame propagation using large axial velocity variation". Proceedings of the combustion institute, v.28, pp. 1867-1874 (2000)
학위논문 학위논문(박사) - 한국과학기술원 : 기계공학전공,
서지주기 참고문헌 : p. 136-139
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