서지주요정보
대향류 확산 화염의 비정상 거동 = A study on the unsteady behaviors of counterflow diffusion flames
서명 / 저자 대향류 확산 화염의 비정상 거동 = A study on the unsteady behaviors of counterflow diffusion flames / 이은도.
발행사항 [대전 : 한국과학기술원, 2005].
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소장정보

등록번호

8016479

소장위치/청구기호

학술문화관(문화관) 보존서고

DME 05024

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리뷰정보

초록정보

Unsteady extinction behaviors of $(CH_4+N_2)$ /air diffusion flames were investigated in terms of the time history of the strain rate and initial conditions. A spatially locked flame in an opposing jet counterflow burner was perturbed by a linear velocity variation. To observe the whole process of the unsteady extinction, changes in a time-dependent flame luminosity and unsteady extinction points were measured by a high-speed ICCD camera. In addition, the transient maximum flame temperature ($T_{max}$) and the OH radical ($Y_{OH}$)were measured over time with the aid of the Rayleigh scattering method and OH laser-induced fluorescence, respectively. Unsteady flames survive at strain rates that are much higher than the extinction limit of steady flames, and unsteady extinction limits extend as the slope of the strain rate increases or the initial strain rate decreases. Changes in $T_{max}$ and $Y_{OH},_{max}$ with respect to the strain rate history provide details of the extinction process, and they show different characteristics for steady and unsteady flames. To investigate the difference between unsteady and steady extinction processes, the equivalent strain rate concept was used to subtract the time lag of the convective-diffusive zone. The process of the unsteady extinction then becomes almost identical to that of the steady extinction in the region where the velocity begins to change and the modified unsteady extinction limits become smaller than the original unsteady extinction limits. However, the modified unsteady extinction limits are still larger than the steady extinction limits. These results suggest that there exist the unsteady behavior of a diffusive-reactive zone near the extinction limit due to the chemical non-equilibrium states associated with unsteady flames. Consequently, the unsteady extinction limit is extended by the time lag of the convective-diffusive zone and the unsteady effect of the diffusive-reactive zone. The former is dominant in the starting region of the velocity change and the latter is dominant near the extinction limit. The results of this work help to explain the extension of the unsteady extinction limit and they have direct relevance to the understanding of the characteristics of turbulent combustion.

서지기타정보

서지기타정보
청구기호 {DME 05024
형태사항 xiii, 147 p. : 삽도 ; 26 cm
언어 한국어
일반주기 부록 : A, 스칼라 소산률. - B, 등가 변형률. - C, Rayleigh 산란 기법. - D, TFP를 이용한 온도 측정. - E, OH LIF 기법
저자명의 영문표기 : Uen-Do Lee
지도교수의 한글표기 : 신현동
지도교수의 영문표기 : Hyun-Dong Shin
학위논문 학위논문(박사) - 한국과학기술원 : 기계공학전공,
서지주기 참고문헌 : p. 117-120
주제 대향류 확산 화염
비정상 소화 과정
소화 한계 확장
Counteflow diffusion flame
unsteady extinction process
extinction limit extension
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