• Journal of Advanced Marine Engineering and Technology
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• 제32권7호
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• pp.1019-1029
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• 2008

In this study, visual investigation of sprays and flames has been performed and soot formation in Diesel and GTL fuels has been compared in a specially designed Rapid Charging Combustion Vessel (RCCV) under various ambient gas $O_2$ concentrations and two injection pressures. It has been concluded that soot in the mixing-controlled combustion of Diesel and GTL fuels has similar tendency to be formed in the leading portion of the jet boundaries. Auto-ignition delay for GTL fuel is shorter than that for diesel fuel. The temporal and special variation of soot concentration in the diesel flame jets at various $O_2$ concentrations was correlated with the heat release rate. Soot concentration appears in the regions when diffusion combustion starts, and its concentration reaches maximum at the peak of heat release curve and then decreases due to oxidation. Visualization by shadowgraph method showed that soot decreases with lower $O_2$ concentration, and higher injection pressure.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.133-134
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• 2014

The full transport equation approach for laminar non-premixed flame with detailed chemistry, soot and radiation has an advantage in accuracy and describing for emission pathway, but this approach requires the excessive computational cost especially for a higher-order hydrocarbon fuel flames. On the other hand, the standard flamelet model has an efficiency and accuracy for non-premixed flame, though this model is not suitable for simulating slow processor like soot and radiation in laminar non-premixed flame situation. To overcome this limitation, modified transient flamelet model is developed which coupled with two-equation soot model involved in soot formation and evolution mechanism such as nucleation, surface growth, oxidation and agglomeration.

• 대한기계학회논문집
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• 제16권8호
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• pp.1583-1594
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• 1992

본 연구에서는 동층류 축대칭 확산화염에서 이전까지의 화염해석 방법들을 면 밀히 고찰하여 층류 확산화염 방식의 연소문제를 해결하는데 있어서 접근이 용이하고 타당성을 가지는 화염해석 방법을 찾아내는데 있으며 매연 입자에 관한 생성및 산화모 델을 총체적으로 연결하여 실험결과와의 비교를 통해 적절한 모델인수를 결정하며 복 사효과와 열영동효과를 고려하여 화염해석과 화염내의 매연입자의 분포를 예측하는데 있다.

• 대한기계학회논문집
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• 제13권5호
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• pp.962-978
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• 1989

본 연구에서는 저자들이 이미 발표한 난류 화염에서의 매연 농도 분포 해석을 포함한 화염 구조 및 복사 열전달의 해석에 대한 연구와 관련하여, 난류 화염에서의 생성된 매연 입자의 재연소 속도에 관한 새로운 모델을 제시한다.구체적인 방법 으로, 난류 화염에 대한 난류 지배 방정식의 매듭(closure) 문제로서 문제가 되고 있는 난류 모델과 반응 속도 모델에 대해서는 비교적 잘 정립되어 있다고 할 수 있는 축대칭 분류 유동을 선택하여, 난류 모델과 난류 연소 속도 모델을 고정하고, 난류 화염에서의 매연 생성 및 연소 모델을 검토하였다.

• 한국연소학회지
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• 제7권3호
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• pp.9-15
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• 2002

Soot generation by combustion process has been investigated with objective of understanding of chemical reaction responsible for its formation in a coaxial laminar propane jet diffusion flame. For the direct photos, as the coflowing air flow rate is reduced, the area of soot luminous zone increases at first, then becomes smaller and smaller, and even disappears. The aspects of soot deposition can be acquired by using nine $15{\mu}m$ thin SiC fibers are positioned horizontally across the flame. Deposited soots on SiC fibers show the soot inception point and growth and soot oxidation zone in a typical propane diffusion. Soot is not generated anymore in a oxidizer deficient conditions of near-extinction and flame is fully occupied by transparent blue flame. It suggests that nonsooting pyroligneous blue reaction is being dominant in a oxidizer deficient ambience. In comparison with luminosities of SiC fibers and flame itself, indirect evidence is found that the process of soot nucleation and growth is endothermic reaction. It is remarkable that there exists two adjacent regions to have antithesis characteristics; one is exothermic reaction of blue flame and another endothermic reaction zone of soot formation.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.19-26
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• 2003

Experimental measurements of flame structure and soot characteristics were performed for ethene inverse diffusion flames (IDF). IDF has been considered as the excellent flow field to study the incipient soot because soot particle do not experience the oxidation process. In this study, LIF image clarified the reaction zone of IDF with OH signal and PAH distribution. laser light scattering technique also identified the being of soot particle. To address the degree of soot maturing, C/H ratio and morphology of soot sample were investigated. From these measurements, the effect of flow residence time and temperature on soot inception could be suggested, and more details on soot characteristic in the IDF was determined according to fuel dilution and flame condition. The fuel dilution results in a decrease of temperature and enhancement of residence time, but the critical dilution mole fraction is existed for temperature not to effect on soot growth. Also, the soot inception evolved on the specific temperature and its morphology are independent of the fuel dilution ratio of fuel.

• 대한기계학회논문집B
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• 제21권5호
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• pp.659-669
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• 1997

The effects of exhaust gas recirculation on diesel engine combustion and soot/NOx emissions are numerically studied. The primary and secondary atomization is modelled using the wave instability breakup model. Autoignition of a diesel spray is modelled using the Shell ignition model. Soot formation is kinetically controlled and soot oxidation is represented by a model which account for surface chemistry. The NOx formation is based on the extended Zeldovich NOx model. Effects of injection timing and concentration of $O_{2}$ and CO$_{2}$ on the pollutant formation and the combustion process are discussed in detail.

• 한국해양공학회지
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• 제10권4호
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• pp.128-140
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• 1996

To analyze a formation process of the soots in spray flame in the combustion chamber, an optically accessible DI Diesel engine was used for visualization. The images of the flames and soots were visualiaed with high speed camera by Schlieren method and Light extinction method. The spray flame and soot images on the films were analyzed at the various engine operating conditions. Soot distributed widely in spray flame and its concentration was about $100g/m^3$ at the position close by nozzle tip of spray flame region, however it decreased below $20g/m^3$ at the corner of combustion chamber due to soot oxidation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.183-193
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• 2000

Soot formation and oxidation is closely related to the combustion phenomena inside a diesel engine. Laser-based diagnostics provide a means for improving our understanding of diesel combustion, because they have highly temporal and spatial ability. To understand the soot behavior we did preliminary study by taking flame luminosity photographs and 2-D images of soot distribution using Laser Elastic Scattering(LIS) and Laser-Induced Incandescence(LII). From the data we found that soot concentration was high in the bowl and disappeared from the central region in the late combustion stage and that soot exists in the flame using luminosity, LIS and LII.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.162-167
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• 2000

Soot formation and oxidation is closely related to the combustion phenomena inside a diesel engine. Laser-based diagnostics provide a means for improving our understanding of diesel combustion, because they have highly temporal and spatial ability. To understand the soot behavior we did preliminary study by taking flame luminosity photographs and 2-D imaging soot distribution using Laser Elastic Scattering(LIS) and Laser-Induced Incandescence(LII). From the data we found that soot concentration was high in the bowl and disappeared from the central region in the late combustion stage.