• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1222-1233
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• 1990

The formation and oxidation processes of soot particles in a diesel flame were investigated with a rapid compression machine. A cloud of soot particles was successfully visualized by means of the instantaneous laser shadow photographs technique and the equivalence ratio of the soot formation zone was estimated from a measured fuel concentration distribution in a nonevaporating spray. The temporal and spatial variation of soot concentration in the flame was also correlated with the rate of heat release. Soot particles appears first in a region near the flame tip when diffusion combustion period starts, and its concentration is a maximum at about the end of injection, then decreases due to oxidation. The reason for soot being formed in a fuel lean region near the flame tip is the evaporated fuel requires time to be pyrolized as it travels through the burning fuel rich zone towards the flame tip.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.389-395
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• 2017

This study was performed to provide the information of the soot formation behavior of octane single fuel droplet under the identical combustion conditions. To achieve this, this experimental study provide the results of the soot formation characteristics of octane droplet in accordance with different initial droplet diameter($d_0$), at the same time, experiment was conducted under the same combustion conditions which are 1.0atm of ambient pressure($P_{amb}$), 21% of oxygen concentration($O_2$) and 79% of nitrogen concentration($N_2$). Visualization of octane droplet combustion was performed by visualization system with high speed camera. The results of maximum soot volume fraction($f_{vmax}$) was almost the same under the equivalent ambient conditions regardless of initial droplet diameter. Furthermore, maximum soot volume fraction was showed the higher value in the measuring direction between $135^{\circ}$ and $315^{\circ}$ since the soot-tail is generated during two opposing igniters movement process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5980-5987
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• 2014

As a response to exhaust gas regulations, the electronic control system was applied to the diesel engine. The injected fuel mass and injection timing are accurately controlled using it, and the fuel efficiency and the engine output are significantly increased. In addition, the noise and the vibration of vehicles are decreased. To maintain the optimal performance of an electronic control diesel engine, it is important to control the fuel injection pressure accurately using the fuel pressure regulator. When the fuel pressure regulator is not worked normally, the failure phenomena (starting failure, staring delay, accelerated failure, engine mismatch et al.) occurred because the fuel pressure is not stabilized and controlled accurately. In this study, the effects on a fuel pressure, return fuel mass flow, and engine rotating speed according to the control rate of fuel pressure regulator were investigated to analyze the performance variation under the failure conditions of a fuel pressure regulator. As a result, when the control rate of a fuel pressure regulator decreased by 4%~6% compared to that of the standard condition, the variation of engine rotating speed and return fuel flow were increased greatly, and the abnormal condition occurred. In addition, it is possible to diagnose the failure of a fuel pressure regulator by monitoring these conditions.

• Fire Science and Engineering
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• v.24 no.6
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• pp.170-175
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• 2010

The effect of carbon dioxide addition on soot formation was investigated in jet diffusion flames in coflow. Flame temperature were measured with R-type thermocouple and the boundary temperature between blue and yellow flame was confirmed. Light-extinction method was introduced for the relative soot density (1-I/$I_0$) in the in-flame region. He-Ne laser with wave length at 632.8 nm was used for the light source, and the signal attenuated by absorption and scattering was detected directly. Oxidizer velocity effect on soot formation was studied to know that the thermal influence for soot formation. The results showed that the temperature of both blue and yellow flame were decreased according to the dilution of carbon dioxide but boundary temperature was nearly constant. The relative soot density was lower when carbon dioxide was added in oxidizer stream and oxidizer velocity increased. These were caused by the reduction of flame temperature and shorter residence time for soot growth. Also carbon dioxide addition enhanced the instability of jet flames like flickering, so the flame length was a little longer than pure ethylene/air flame.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.962-978
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• 1989

A new model of the combustion rates of soot particle in turbulent flames has been suggested. This model applies the combustion rate of soot particles in laminar flames and uses local time-averaged quantities in order to consider the effect of the chemical reaction on the soot combustion in turbulent flames. The proposed rate equation has been tested for two propane-air turbulent round-jet diffusion flames and gives better predictions for the soot concentration field of two flames than the model previously used, especially in low temperature regions. A modified Monte carlo Method for analyzing radiative heat transfer of a flame also has been suggested and tested, which reveals good results.

• Fire Science and Engineering
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• v.33 no.5
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• pp.13-18
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• 2019

In this study, the soot formation characteristics of Jet-A1 liquid fuel droplet flames were investigated by measuring the soot concentration under atmospheric conditions similar to the working environment of the Korea Space Launch Vehicle (KSLV) To obtain the desired atmospheric conditions, the oxygen concentration in the combustion chamber was maintained at 30% and the pressure was varied between 0.1 and 0.06 MPa. The full-field light extinction technique was used to measure the concentration of soot particles generated by applying the identical to 2-mm-diameter Jet-A1 fuel droplets. The soot concentration of the Jet-A1 droplet flames was the highest in the nitrogen-substituted atmosphere and the lowest in the carbon dioxide-substituted atmosphere, despite the pressure. the pressure was decreased the measured soot concentrations reduced as a function of Pⁿ.

• Fire Science and Engineering
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• v.26 no.5
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• pp.35-40
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• 2012

Numerical investigation was performed to study on the soot formation characteristics in the WSR according to the CO addition. Ethylene and pure air were used as a fuel and an oxidizer, respectively, and three different equivalence ratios (2.0, 2.5, 3.0) were used in the calculation. The resulted CO mole fraction of 10 % CO addition showed the maximum value in spite of the least CO supply. This means that the conversion of CO to soot and other carbon compounds is weakened under incipient soot formation. The soot volume fraction was decreased with increasing the CO addition because the important species for soot formation such as pyrene and acetylene, were decreased with the addition of CO. When the equivalence ratio was 2.5, the soot volume fraction shows the highest value, which results from the contribution of fuel rich condition and reacting temperature. Furthermore, surface growth rate and species concentrations justified the HACA mechanism for soot formation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1796-1804
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• 1992

Profiles of soot volume fraction, average diameter and particle number density have been measured using a light scattering and extinction technique in a coannular propane diffusion flame at atmosperic pressure. Temperature profiles were also obtained using a thermocouple technique. Measurements show that soot is first observed to form low in the flame in an annular region inside the main reaction zone. At higher locations this annular region widen until entire flame is observed to contain particles. Soot volume fraction and particle diameter profiles peak some 1mm on the fuel side of peak temperature and increase with height to oxidation region. Number density of the flame core drop steeply from formation region to growth region and relatively invariant to some height and decay out at flame tip.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.89-102
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• 1997

대향류 확산 화염의 매연 생성 특성에 대한 실험적 연구가 수행되었으며, 그 결과 에틸렌 ($C_2H_4$)-프로판($C_3H_8$) 혼합 연료의 경우 매연 생성 상승 효과 (synergistic effect)가 관측되었다. 프로판과 에틸렌의 PAH 생성 양상이 상이하게 나타났으며, 소량의 프로판을 에틸렌 확산 화염에 첨가할 경우 순수 연료에 비하여 매연 및 PAH (다중 고리 방향족 탄화수소; polycyclic aromatic hydrocarbon) 생성이 증대되었다. 단조적으로 변화하는 아세틸렌($C_2H_2$) 농도와 단열 화염 온도를 고려할 때, 이러한 결과는 HACA (H-abstraction-$C_2H_2$-addition) 반응만으로는 확산 화염에서의 매연 발생 및 성장을 설명할 수 없음을 의미한다. 수치해석과 실험 결과의 비교로부터 초기 PAH의 생성 과정을 규명하였으며 이 과정에서 C3 화학종의 재결합 반웅이 매우 중요함을 확인할 수 있었다. 또한, 이러한 C3 화학종과 C2 화학종의 상호 보완적인 역할에 의하여 에틸렌-프로판 혼합 연료에서 매연 생성이 증대됨을 밝혔다.

• Journal of ILASS-Korea
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• v.1 no.4
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• pp.1-7
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• 1996