• 대한기계학회논문집B
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• 제24권12호
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• pp.1652-1661
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• 2000

A visualization study using the schlieren method is adopted in an optically-accessible, cylindrical constant volume combustion chamber to identify the mechanism of ignition energy and ignition system interaction in spark ignited, lean gasoline-air mixture. In order to research the effects of ignition system on flame propagation, two kinds of ignition system are designed, and several kinds of spark plugs are tested and evaluated. To control the discharge energy, the dwell time is varied. The initial flame development is quantified in terms of 2-D images which provides information about the projected flame area and development velocity as a function of ignition system and discharge energy. The results show that high ignition energy and extended spark plug gap can shorten the combustion duration in lean mixtures. The material, diameter and configuration of electrodes the flame development by changing the transfer efficiency from electrical energy to chemical energy and discharge energy. However these factors do not affect of flame development as much a ignition energy or extended gap does.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.75-83
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• 2001

This paper presents the evaluation of combustion characteristics of sing-hole plasma jet ignitions in comparison with conventional spark ignition for variable of swirl velocity. Plasma jet plugs are three types according to ejecting directions : center of chamber, positive and negative swirl flow direction. Experiments are carried out for equivalent ratio 1.0 of LPG-air mixture in a constant volume cylindrical vessel. Not only the flame propagation is photographed at intervals, but the pressure variation in the combustion chamber is also recorded throughout the entire combustion process. The results show that the plasma jet ignitions and spark ignition enhance the overall combustion rate by increasing the swirl velocity. The dependence of the combustion rate swirl velocity leade to the conclusion that the placma jet plug, which ejects plasma jet to the cwnter of combustion chamber is the most desirable ignitor than other plugs.

• 한국분무공학회지
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• 제27권4호
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• pp.203-210
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• 2022

Combustion and performance of a spark-ignition engine fueled with propane and butane were analyzed under different compression ratio. The electricity efficiencies of propane and butane increased with increasing the electricity production. The heat release rates of propane and butane were similar at a compression ratio of 9:1 because both fuels had similar optimal ignition timings without knocking combustion. Therefore, the difference in electricity efficiencies of engine generators was insignificant. However, at a higher compression ratio of 11:1, the butane engine generator had a lower electricity efficiency than the propane engine generator because its ignition timing retarded to suppress the knocking combustion.

• 한국연소학회지
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• 제1권1호
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• pp.65-73
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• 1996

Flame propagation in a four-valve spark-ignition optical engine was visualized under lean-bum conditions with A/F=18 at 2000rpm. The early flame development in a four-valve pentroof-chamber single-cylinder engine was examined with imaging of the laser-induced Mie scattered light using an image-intensified CCD camera. Flame profiles along the line-of-sight were also visualized through a quartz piston window. Two-dimensional flame structures were visualized with a Proxitronic HF-1 fast motion camera system by Mie scattering from titanium dioxide particles along a planar laser sheet generated by a copper vapor laser. The flame propagation images were subsequently analysed with an image processing programme to obtain information about the flame structure under different tumble flow conditions generated by sleeved and non-sleeved intake ports. This allowed enhancement of the flame images and calculation of the enflamed area, and the displacement of its center, as a function of the tumble flow induced by the pentroof-chamber in the vicinity of spark plug. Image processing of the early flame development quantified the correlation between flame and flow characteristics near the spark plug at the time of ignition which has been known to be one of the most important factors in cyclic combustion variations in lean-burn engines. The results were also compared with direct flame images obtained from the natural flame luminosity of the lean mixture.

• 오토저널
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• 제14권4호
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• pp.61-67
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• 1992

The ignition timing feedback control system was studied to enhance the engine power and to reduce the fuel consumption by optimizing the spark timing. The signal of a piezo-electric vibration transducer attached to the engine block was compared with that of a pressure transducer in order to determine the knock intensity. With the result of comparison the ignition timing feedback control system which detect the knock and correct the spark timing was set up. The ignition could be more advaced with this control system than the existing system without the continuous knocking, therefore the engine torque was increased.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.183-191
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• 1997

For the improvement of ignitability we need ignition energy and its discharge characteristics which are suitable for a part distribution of the mixture density around the ignition spark plug and the flow characteristics of the mixture in the combustion. Especially, for the solving of the instability of initial ignition and lean ignitability limit in the case of lean-burn combustion, the more powerful ignition energy is required. The conclusions from the observation can be summarized as follows: 1) The ignitability limit for HIS expands wider and the combustion is more stable than for CDI. 2) The combustion duration and ignition timing depend upon the distribution of local mixture density in the vicinity of ignition spark plug.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.65-77
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• 1996

A small-sized industrial diesel engine was converted to a spark ignited engine and then adapted for fuelling with natural gas. After conversion work, general combustion characteristics of the gas engine(such as ignition delay, main and total combustion durations, and heat release characteristics) were studied as a functio of major engine operating variables such as air to fuel ratio, spark timing, and spark plug type. Some other studies on cyclic variation characteristics in IMEP, Pmax and (dp/dφ)max, and also optimum combustion phasing angle were performed.

• 대한기계학회논문집B
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• 제23권2호
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• pp.288-298
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• 1999

In spark ignited engines, the electrical spark not only sets the time for the onset of combustion but also is able to greatly influence the character of the initial flame growth and the subsequent combustion, and thereby can influence engine performance. The relative importance of the ignition energy is particularly high under lean or high residual gas or exhaust gas recirculation (EGR). In this study, a modeling of flame Initiation and its development is proposed. Submodels consist in representing of cylinder pressure and temperature, heat transfer to cylinder wall, and flame kernel heat transfer to ambient air and to spark plug electrodes. The breakdown process and the subsequent electrical power input initially control the kernel growth while intermediate growth is mainly dominated by diffusion or conduction. Then, the flame propagates by the chemical energy, and laminar and turbulent flame velocity.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.37-44
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• 1998

Lean burn combustion is an important concept for improving the fuel consumption and exhaust emissions. However, the lean burning is associated with increased cycle-to-cycle combustion variations due to the ignition instabilities and redu- ced flame propagation rates. Engine stability under lean mixture conditions could be improved by increasing flame speed through enhanced flow characteristics and by securing ignitability with improvement of ignition systems. The effects of flow motion and ignition characteristics on the combustion performances were investigated in a 4-valve SI engine. Flow motions of tumble-swirl were varied with a swirl control valve attached at the inlet ports, while ignition energy and its distribution were controlled in a high -frequency ignition system by changing spark duration and spark frequency. The improvement of lean burn performance by the optimum flow motion and ignition characteristics is discussed.

• 한국가스학회지
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• 제14권3호
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• pp.14-20
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• 2010

본 논문은 리튬이온전지의 불꽃방전에 의한 폭발위험성에 관한 연구로서 휴대용기기의 전원으로 사용되는 리튬이온전지(일반용, 노트북용)를 시료로 선정하고, 폭발성 시험가스인 메탄, 프로판, 에틸렌, 수소를 대상으로 IEC형 불꽃점화 시험장치를 이용하여 불꽃점화실험을 실시하여 불꽃방전에 의한 폭발위험성을 규명하였다. 또한, 사고 시 단락전류에 의한 자체점화 가능성을 확인하고자 열화상카메라를 이용하여 온도변화를 측정하였다. 실험결과 리튜이온전지는 폭발성가스가 존재하는 폭발위험장소에서 사용할 때는 안전에 각별히 주의하여 사용 설계되어야 한다.