• 한국자동차공학회논문집
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• 제12권6호
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• pp.119-126
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• 2004

In order to elucidate the modes of double-droplet combustion speed in premixed spray flame, the difference between flame propagation speed and droplet cluster disappearance speed are experimentally investigated using a premixed spray burner system, It was confirmed that flame speed concerned with premixed-mode combustion in the spray flame was approximately 2.0 m/s in average while mean disappearance speed of droplet clusters, which were dominated by diffusion-mode combustion in downstream of the flame, was evaluated as much as 0.45 m/s. It was clarified that both characteristics of premixed-mode and diffusion-mode combustion in spray flames are of much difference in nature, even though both speed, which are supposed to depend on local properties of the spray itself and flow conditions surrounding droplet clusters, are scattered in experiments.

• 에너지공학
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• 제14권4호
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• pp.259-267
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• 2005

예혼합 분무화염의 상세한 연구기구를 관찰하기 위하여 예혼합 분무화염 중의 분무단면상의 확대촬영과 또한 연소시의 순간적 이차원 유동장을 얻기 위해 미소시간차를 가진 2연속 분무단면 화상에 대해 상호 상관 PIV를 적용하였다. PIV에 통상 사용되어지는 펄스 레이저가 아닌 연속발진 레이저를 PIV에 적용하는 기법 등을 나타내었다. 또한 통계적 PIV 해석법을 이용하여 얻은 상호상관 PIV의 결과를 PDA에 의해 측정된 결과와 비교하여, 상호상관 PIV는 PDA의 계측에 의한 결과와 잘 일치한다는 결론에 이르렀다. 연속발진 레이저를 이용한 상호상관 PIV를 예혼합 분무화염에 적용하여 본 연구에서 적용한 기법이 분무화염의 구조를 관찰하는데 매우 유용함을 검증하였다.

• 한국산업융합학회 논문집
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• 제7권3호
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• pp.265-271
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• 2004

A light collecting probe named Multi-colored Integrated Receiving Optics (MICRO) is experimentally examined to verify its performance. For these purposes, the time-series signals of MICRO probe is compared with those of electro-static probe and light-guided probe by monitoring, for example. such as OH radical chemiluminescence. CH radical band and droplet Mie scattering In addition, the experiment was conducted by using laminar premixed Bunsen flame, turbulent premixed Bunsen flame and premixed spray flame, respectively. It was confirmed that the performance of MICRO probe was very useful and convenient to obtain the chemiluminescence signals from local regions in turbulent premixed Bunsen flame and premixed spray flame.

• 센서학회지
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• 제13권5호
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• pp.335-341
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• 2004

A light collecting probe named Multi-colored Integrated Receiving Optics (MICRO) is experimentally examined to verify its performance. For these purposes, the time-series signals of MICRO probe is compared with those of electrostatic probe and light-guided probe by monitoring, for example, such as OH radical chemiluminescence, CH radical band and droplet Mie scattering. In addition, the experiment was conducted by using laminar premixed Bunsen flame, turbulent premixed Bunsen flame and premixed spray flame, respectively. It was confirmed that the performance of MICRO probe was very useful and convenient to obtain the chemiluminescence signals from local regions in turbulent premixed Bunsen flame and premixed spray flame.

• 한국분무공학회지
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• 제3권4호
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• pp.43-49
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• 1998

In order to clarify the effect of equivalence ratio and kinds of fule in flame structure, a numerical simulation of triple flame developed in a co-flowing methane-air and air stream was carried out by the elementary chemical reaction mechanism. The following conclusions were obtained. Equivalence ratio at which the apparent burning velocity is maximum is a little larger than that of the one-dimensional premixed flame. Apparent burning velocities are two times higher than that of the one-dimensional premixed flame for the methane-air. The flame thrusts out forward in the downstream of the boundary between mixture and air stream, and a part of the flow is bent and forks out in this protruding flame so that a triple flame is originated; this triple flame is composed of fuel rich and lean premixed flame branches and a diffusion flame branch. Near the equivalence ratio at which the burning velocity of rule-dimensional premixed flame is the largest the effect of one-dimensional premixed flame becomes large and the fuel rich premixed flame advances and becomes vertical to the flow direction.

• 한국분무공학회지
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• 제22권2호
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• pp.55-61
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• 2017

This study has investigated the relationship between heat release fluctuations and the flow perturbations in a partially premixed gas turbine combustor using a commercial CFD code. Special focus of the current work is placed on the effect of equivalence ratio on the flame dynamics in a partially-premixed system. As the first step for this combustion dynamics study in the non-perfectly premixed combustor, flame behaviors are modeled and then compared with measured results under both steady and unsteady conditions. The calculated results of the flame transfer function with equivalence ratio fluctuation are found to well capture the main qualitative characteristics of the combustion dynamics for the partially-premixed flames.

• 한국분무공학회지
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• 제7권4호
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• pp.42-49
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• 2002

In this study, quantitative measurement of nitric oxide concentration distributions were investigated in the laminar CH4/O2/N2 premixed flame by laser-induced fluorescence (LIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and O2 fluorescence. The measurements were taken in CH4/O2/N2 premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flowrate of 5slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to NO formation in CH4/O2/N2 premixed flame. Furthermore, this trend was well matched with previous works.

• 한국분무공학회지
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• 제20권3호
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• pp.135-140
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• 2015

Flame transfer function is used to determine the relationship between flow fluctuations and heat release perturbations in a lean premixed gas turbine combustor. The characteristics of flame transfer function are known to depend greatly on flame geometries in addition to other various flow conditions. However, it is not easy to experimentally measure the flame transfer function under various actual combustor operating conditions in terms of time and cost. The current research tries to model the flame transfer function using CFD(Computational Fluid Dynamics). From the results, it is shown that the calculated steady flame geometry can be exactly captured with consideration of the wall heat transfer and radiations. Also, unsteady analysis results show the close characteristics of the flame transfer function to the measured one in both gain and phase.

• 한국분무공학회지
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• 제8권4호
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• pp.9-16
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• 2003

The Purpose of this study is to investigate the relationships between the local heat release rate and CH concentration have been investigated by numerical simulations of methane-air premixed flames. And simultaneous CH and OH PLIF(Planar Laser Induced Fluorescence) measurement has been also conducted for lean premixed flame as well as for laminar flames. Numerical simulations are conducted for laminar premixed flames and turbulent ones by using PREMIX in CHEMKIN and two dimensional DNS code with GRI mechanism version 2.11, respectively. In the case of laminar premixed flame, the distance between the peak of heat release rate and that of CH concentration is under $91{\mu}m$ for all equivalence ratio calculated in present work. Even for the premixed flame in high intensity turbulence, the distribution of the heat release rate coincides with that of CH mole fraction. For CH PLIF measurements in the laminar premixed flame burner, CH fluorescence intensity as a function of equivalence ratio shows a similar trend with CH mole fraction computed by GRI mechanism. Simultaneous CH and OH PLIF measurement gave us useful information of instantaneous reaction zone. In addition, CH fluorescence can be measured even for lean conditions where CH mole fraction significantly decreases compared with that of stoichiometric condition. It was found that CH PLIF measurements can be applicable to the estimation of the spatial fluctuations of heat release rate in the engine combustion.

• 한국연소학회지
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• 제16권1호
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• pp.58-65
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• 2011

Thermal spray technology has been used in many industrial application. Especially, thermal spray coating have been employed with the purposes of achieving better resistances in abrasion, heat and corrosion. In the previous studies on the thermal spray coating, thermal spray characteristics from the perspective of combustion engineering have not been investigated sufficiently, while the material characteristics of the coated substrates have been investigated widely. In this study, the effect of spray particles on the flame behavior was experimentally investigated. The amount of the injected particles was measured using the light scattering method and the temperature of the particles was estimated using a two-color method. Various flame-spray interactions were observed and it was found that the high temperature zone near the flame is elongated by particles density. Based on these results, the applicability of the light scattering method and the two-color method was discussed.