• 동력기계공학회지
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• 제19권2호
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• pp.40-48
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• 2015

As advantages of LPG-DI engine, LPG is directly injected into combustion chamber during compression stroke to reduce compression temperature, prevent knock and spontaneous combustion, and adjust engine output using the amount of directly injected fuel, thereby reducing pumping loss caused by throttle valve. Stratified charge can be supplied nearby spark plugs to allow for overall lean combustion, which improves thermal efficiency and can cope with problems regarding emission regulations. In addition, it is characterized by free designing of intake manifold. Despite the fact that LPG-DI has many advantages as described above, there is lack of detailed investigation and study on spray characteristics, combustion flame characteristics, and ignition probability. In this study, a visualization experiment system that consists of visualization combustion chamber, air supply control system, emission control system, LPG fuel supply system, electronic control system and image data acquisition system was designed and manufactured. For supply of stratified charge in the combustion chamber, alignment of injector and spark plugs was made linear.

• 한국가시화정보학회지
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• 제11권1호
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• pp.22-27
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• 2013

An investigation into the influence of ultrasonic standing wave on the structural behavior of propane/air premixed flame has been made to get a clue to the combustion reaction acceleration and combustion instability. Visualization technique utilizing the Schlieren photography was employed for the observation of structural variation of the flame reaction zone. Evolutionary characteristics of the flame front were caught by the high-speed Schlieren image, through which local flame velocity of the moving front were analyzed in detail.

• 한국분무공학회지
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• 제21권1호
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• pp.37-46
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• 2016

For the SI engines, at only full load, the pumping loss has a negligible effect, while at part load conditions, the pumping loss increases. To avoid the pumping loss, the spark-ignited engines are designed to inject gasoline directly into the combustion chamber. In the spark-ignited direct-injection engines, ignition probability is important for successful combustion and the flame propagation characteristics are also different from that of pre-mixed combustion. In this paper, a visualization experiment system is designed to study the ignition probability and combustion flame characteristics of spark-ignited direct-injection CNG fuel. The visualization system is composed of a combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. It is found that ambient pressure, ambient temperature and ambient air flow velocity are important parameters which affect the ignition probability of CNG-air mixture and flame propagation characteristics and the injected CNG fuel can be ignited directly by a spark-plug under proper ambient conditions. For all cases of successful ignition, the flame propagation images were digitally recorded with an intensified CCD camera and the flame propagation characteristics were analyzed.

• 동력기계공학회지
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• 제20권2호
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• pp.32-42
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• 2016

Under part load condition of spark-ignition engine, pumping loss had great effect on engine efficiency. To reduce pumping loss, the study designed spark-ignited engines to make direct spray of gasoline to combustion chamber. In spark-ignited direct-injection engines, ignition probability is important for successful combustion and flame propagation characteristics are also different from pre-mixed combustion. This study designed a visualization testing device to study ignition probability of spark-ignited direct-injection LPG fuel and combustion flame characteristics. This visualization device consists of combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. Ambient pressure, ambient temperature and ambient air flow velocity are important parameters on ignition probability of LPG-air mixture and flame propagation characteristics, and the study also found that sprayed LPG fuel can be directly ignited by spark-plug under proper ambient conditions. To all successful cases of ignition, the study recorded flame propagation image in digital method through ICCD camera and its flame propagation characteristics were analyzed.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.94-101
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• 2001

In this paper, the combustion improvement effects of alcohol-diesel oil blend fuel were investigated in a visualization engine. As a result of experiment, it was found out that the combustion chamber of deep dish type and re-entrant type at the same operation condition. However, when the con-tent of alcohol exceeded 10% of total fuel delivery, the combustion of alcohol-diesel oil blend fuel was worse than that of diesel oil. The maximum blend quantity of ethanol which is not ignited in the re-entrant type combustion chamber was estimated at approximately 40% of total fuel delivery. So, it is necessary to blend appropriate quantity of a volatility fuel such as alcohol in order to improve combustion.

• 대한기계학회논문집B
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• 제32권7호
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• pp.513-517
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• 2008

A parametric study was made to understand the fundamentals of combustion of CNG fuel in a constant volume chamber in the respect of swirl effect, and the numbers of spark ignition. Optical devices were applied for the visualization of the physics of combustion, and combustion pressures and exhaust emission were measured at several equivalence ratios by controlling speeds of a swirling motor. When the speed of a swirling motor was raised the combustion conditions were improved. The corresponding maximum combustion pressure and heat release rate were increased and the speed of flame propagation was getting faster. This research may contribute to improve the performance of CNG engine and reduce emissions in future.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.136-145
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• 1995

The aim of this study is to gain a better understanding of the effect of a flow motion on the flame development by means of an optically-accessible constant-volume combustion chamber and the visualization technique of a combustion flame. At first, the characteristics of a flame propagation are investigated in the combustion field of the two kinds of flow conditions such as a quiescent and a flowing condition, and methane-air mixture is used as fuel. Then the same investigation is performed in two flow configurations : bulk flow motion type and turbulence generating type. In this study, the combustion phenomena are analyzed by measuring the combustion pressure, flame propagation speed, mean velocity, turbulent intensity, and mass fraction burned.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.24-29
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• 2007

This study aims to provide a fundamental data for directly injected hydrogen fuel engines. Spray, ignition and combustion characteristics of hydrogen were studied using constant volume chamber. For spray visualization, hydrogen was vertically injected into a combustion chamber at various condition, for example, injection pressure, ambient pressure. And an argon laser was used for the shadowgraph photography by applying optical method. Also, to investigate heat-release rate and flame propagations, spark was ignited on hydrogen injected at the different time after injection and the duration of injection was also changed. Processes of ignition and combustion were analyzed by heat-release rate calculated by pressure history and were observed by shadowgraph photography The results gave much knowledge of spray, ignition and combustion characteristics of hydrogen.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.152-157
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• 2008

The biodiesel becomes one of the favorite alternative fuel applied to diesel engines. This research aims to understand the physics of spray and combustion characteristics of a biodiesel fuel in a constant volume chamber. For spray visualization, biodiesel was injected into a combustion chamber and a high speed camera was applied at various combustion conditions. To investigate heat-release rates and flame propagations, spark was ignited on a hydrogen fuel for the premixed combustion and then biodiesel was injected directly. In addition, parametric study was made by various geometries of combustion chambers and temperatures of fuels and injection pressures. This technology may contribute to improve the performance of bio-diesel engine and reduce emissions in future.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.191-193
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• 2012

The use of diesel engines has recently increased due to the need for internal combustion engines with a high thermal efficiency and low harmful exhaust gas. The PCCI(premixed charged compression ignition) technology has been studied specifically to simultaneously reduce NOx and PM. While the PCCI means has the merit of reducing NOx and PM, control of the combustion phase is difficult. In this study, Flame visualization was then performed with an endoscope system in order to compare combustion flame characteristics in an commercial diesel engine.