• 대한기계학회논문집B
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• 제31권7호
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• pp.611-619
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• 2007

In this study, the droplet size distribution of a slit injector at different surrounding conditions, such as air flow and fuel temperature, were investigated. Phase Doppler anemometry (PDA) was utilized to investigate the initial droplet size distribution and the effect of fuel temperature and air flow on droplet size distribution. The entrained air motion was also evaluated by the temporal velocity profile of droplets. When the air flow velocity increased, the small droplets were more entrained to the upper and central parts of the spray and this tendency was confirmed by plotting the temporal velocity profile of droplets. This entrainment of small droplets at high airflow velocities caused relatively small mean droplet size at upper and central parts of the spray and the large mean droplet size at downstream and edge of the spray, compared to that of low airflow velocities. The total mean droplet size, obtained by averaging the size of all droplets measured at all test locations, decreased when the high airflow velocities were applied. The increased fuel temperature, with an airflow velocity of 10m/s, caused reduced droplet size at all test locations. However, the decreased value of mean droplet size at high fuel temperatures was relatively higher at upper parts of the spray, compared to downstream, as a result of enhanced entrainment of small droplets to upper parts of the spray.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2239-2244
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• 2003

A new stratified charge combustion system has been introduced and developed for GDI engines. Before this new GDI system, the stratified mixture was formed by a high pressure swirl injector. But, the special feature of new system is employed of a thin fan-shaped fuel spray formed by a slit type nozzle. Also, this system has been adopted a shell-shaped piston cavity. We made high pressure gasoline injection system and investigated the fan-shaped spray characteristics such as spray tip penetration, spray angle, SMD and velocities of droplets using PDPA(Phase Doppler Particle Analyzer) system and spray visualization system to obtain the concept of the new design and the fundamental data for the next generation GDI system. The experiment was performed at the injection pressures of 5 and 9MPa under the atmospheric condition.

• 한국분무공학회지
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• 제10권3호
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• pp.38-44
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• 2005

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced from the injector of DIS(Direct Injection Spark Ignition) engine is of paramount importance in DISI engines. Fan-spray injector as well as swirl-spray injector was developed and utilized to the DISI engines. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engineer. The direct Mie scattered images presented the macroscopic view of the liquid spray fields interacted with crossflow. Particle sizes of fuel droplets were measured with phase Doppler anemometer(PDA) system. A faster cross-flow field made SMD larger and $D_{10}$ smaller. The experiments show the interaction of air flow field and the fuel spray field of fan-spray. The results can be utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.70-76
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• 2005

A new stratified charge combustion system has been introduced and developed for GDI engines. Before this new GDI system, the stratified mixture was formed by a high pressure swirl injector. But, the special feature of new system is employed of a thin fan-shaped fuel spray formed by a slit type nozzle. Also, this system has been adopted a shell-shaped piston cavity. We made high pressure gasoline injection system and investigated the fan-shaped spray characteristics such as spray tip penetration, spray angle, SMD and velocities of droplets using PDPA(Phase Doppler Particle Analyzer) system and spray visualization system to obtain the concept of the new design and the fundamental data for the next generation GDI system. The experiment was performed at the injection pressures of 5 and 9MPa under the atmospheric condition.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.103-111
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• 2006

The spray behavior of direct-injection spark-ignition(DISI) engines is crucial for obtaining the required mixture distribution for optimal engine combustion. The spray characteristics of DISI engines are affected by many factors such as piston bowl shape, air flow, ambient temperature, injection pressure and fuel temperature. In this study, the effect of fuel temperature on the spray and combustion characteristics was partially investigated for the wall-guided system. The effect of fuel temperature on the fan spray characteristics was investigated in a steady flow rig embodied in a wind tunnel. The shadowgraphy and direct imaging methods were employed to visualize the spray development at different fuel temperatures. The microscopic characteristics of spray were investigated by the particle size measurements using a phase Doppler anemometry(PDA). The effect of injector temperature on the engine combustion characteristics during cold start and warming-up operating conditions was also investigated. Optical single cylinder DISI engine was used for the test, and the successive flame images captured by high speed camera, engine-out emissions and performance data have been analyzed. This could give the way of forming the stable mixture near the spark plug to achieve the stable combustion of DISI engine.