• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.320-327
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• 2005

An experimental study was performed to investigate the effects of partially premixing, varying the equivalence ratios from $1.36{\sim}{\infty}$, and swirlers with swirl numbers of 0, 0.28, 0.64, and 1.32, on the characteristic of radical ($OH^{\ast}$, $CH^{\ast}$, and $C_2^{\ast}$) and pollutant emission in partially premixed swirling flames. The signal from the electronically excited state of $OH^{\ast}$, $CH^{\ast}$, and $C_2^{\ast}$ was detected through a band pass filter with a photo multiplier tube, and flow fields images were detected through a schlieren system. The results demonstrated that the flame height decreases and jet spreading angle increase with increasing a swirl number. The more momentum ratio and swirl number increase, the more decrease flame height, and the generation of sooting flame is promoted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.36.2-36.2
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• 2005

• 대한기계학회논문집B
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• 제29권2호
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• pp.263-270
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• 2005

An experimental study was performed to investigate the effects of partially premixing, varying the equivalence ratios from $0.79{\sim}{\infty}$, on NOx emissions and chemiluminescence of excited $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ radicals in laminar partially premixed flames. the signal from the electronically excited state of $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ was detected through a band pass filter with a photo multiplier tube, which are processed to the intensity ratio ($C_2^{\ast}/CH^{\ast},\;C_2^{\ast}/OH^{\ast},\;and\;CH^{\ast}/OH^{\ast}$) to reveal the correlation with local equivalence ratio. And measurements of NOx emission were made to investigate the relationship between visible flame appearance, chemiluminescence, and EINOX. The results demonstrated that (1) the flames at ${\phi}<1.59$ exhibited classical double flame structure, at ${\phi}>4.76$, the flames exhibited diffusion flame structure, and the intermediate flames at $1.59<{\phi}<4.76$ was a merged flame, (2) the $OH^{\ast}$ peak was located inside the $CH^{\ast}\;and\;C_2^{\ast}$ radical for all measured conditions and the emission intensity ratio of $C_2^{\ast}/CH^{\ast}\;and\;C_2^{\ast}/OH^{\ast}$ were identified as good marker for local equivalence ratio over a range of ${\phi}=0.79{\sim}1.2\;and\;CH^{\ast}/OH^{\ast}\;is\;0.79<{\phi}<1.9$. However, it was difficult to predict the equivalence ratio in partially premixed flames using this system for ${\phi}>2.38$, (3) the minimum NOX emission index (EINOx) is obtained for a equivalence ratio of 3.19 in the intermediate flames.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1116-1121
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• 2004

In this study, the effect of central fuel injection on a coaxial laminar $CH_{4}/air$ flame was experimented at the defined premixing condition(${\Phi}=1.90$, ${\sigma}=50/75/100%$, x/D=10). The partial premixing parameter are the equivalence ratio that total fuel is fixed at 200cc/min, the fuel split degree which means the percentage of fuel entering the outer tube to the total amount, and the mixing distance indicating the nonreactant mixture's homogeneity between inner tube top and burner exit. The object is to investigate the flame structure and chemiluminescence characteristics of laminar partial premixed flame as changing mixing parameters. The radical signal was acquired from ICCD camera and PMT. Each intensity was compared with Abel inverted value for measuring the effect of background light on the peak signal location and the intensity at central preheat zone. The results show that the peak location of each radical was broaden as the fuel split degree increasing because the mixing quality was enhanced. and $OH^{\ast}$ is a good indicator for flame front between reaction and preheat zone. At last $CH_{2}^{\ast}$ has the same tendency with $CH^{\ast}$ but a thinner reaction zone than $CH^{\ast}$ due to a rapid decay on the burned gas side.

• 대한기계학회논문집B
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• 제33권11호
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• pp.849-857
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• 2009

The experimental study was performed to investigate the effects of partial premixing, varying the equivalence ratio, mixing degree, swirl intensity, mixing length on the characteristics of flame structure and NOx emission. Experiments were conducted in a dump combustor at 1 bar using methane as fuel. Inlet air temperature was 570K. OH chemiluminescence images were acquired with an ICCD camera. As a result of the experimental investigation of characteristics of flame and NOx emission in partial premixed combustor, we can conclude the results as below. With the increase of swirl number, The flame length decreases and the flame width increases and it helps flame stabilization. It means that lean flammability limit is extended. With the increase of mixing of fuel-air length ratio, Flame goes to be stabilized and NOx emission and $OH^{\ast}$ intensity decrease. Through the comparison of preceding results, It is possible that the exhausted NOx emission from a gas turbine combustor will be able to predict through the $OH^{\ast}$ intensity.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.259-264
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• 2005

연소불안정과 밀접한 관련이 있는 열방출의 측정은 연소불안정을 제어하는데 매우 중요하다. 따라서 본 연구에서는 희박예혼합연소에서 반응영역의 위치와 전체, 국소 열방출률의 지표로 많이 사용되는 $OH^{\ast}$ 이미지를 ICCD를 이용해 취득하였다. 본 연구의 목적은 당량비가 전체 열방출률과 국소 레일라이 지수 분포에 미치는 영향을 알아보는 것이다. 국소 레일라이 지수 분포는 선적분된 이미지를 아벨 역변환 시켜서 화염의 중앙 단면 정보를 통해 얻을 수 있었다. 각 당량비 조건에서, 한 주기 동안의 열방출의 평균값은 당량비가 증가함에 따라 지수 함수적으로 증가하였다. 국소 레일라이 지수 분포 결과로부터, 연소불안정을 증폭시키거나 소멸시키는 영역을 분명히 알 수 있었다. 이것은 넓은 당량비 조건에 대한 화염구조와 연소불안정 영역에 대한 통찰력을 제공한다.