• 대한기계학회논문집B
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• 제27권1호
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• pp.9-16
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• 2003

According as the industry was developed, the pollution of the environment and atmosphere rose up to the surface. So, the focus is now concentrated on the engines of affinity for nature. And the investigators make more effort to the improvement in the performance of engines, depending to the prices of oil and the anxiety about the exhaustion of the fossil fuel go up. So the GDI engines head up for these necessities. In this experimental study, the spray flow characteristics for a commercial injector equipped in the present GDI engine were investigated, which had a strong influence on the engine performance and emissions. The experiment was performed at the injection pressures of 1, 3, 5 and 7MPa under the atmospheric condition. A PDPA system was used to specify the flow characteristics of the spray. Also, the global spray behavior classified into three regions as leading, main spray and vortex cloud region, was analyzed by using a visualization system. And the regions were compared with each other.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.100-106
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• 2006

The behavior of spray impinging on the inclined constant temperature flat plate was experimentally investigated. To clarify the wall effect of a high pressure DISI injector, a relative angle of the inclined wall to a spray axis was varied. Spray penetration along the wall was observed optically and it was compared with that of a Fan spray type and Swirl type spray. To evaluate various spray motion quantitatively, a spray path penetration which describe the development of a spray tip along the wall was newly introduced. To observe the structure of an impinging spray, it was visualized by a controlled stroboscope light and its visualized image was captured on an CCD camera. Using the digital image of impinging spray $H_x$ and $R_x$ was extracted to clarify the structure of impinging spray. The main parameter of the relative position of the wall was the inclined angle which was defined as the angle was varied from $0^{\circ}$ (vertical impingement) to $60^{\circ}$ at the same condition.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.9-18
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• 1995

The substitution of conventional fuel oil by alternative fuels is of immense interest due to liquid oil shortage and requirements of emission control standard. Among the alternative fuels, natural gas may be the most rational fuel, because of its widespread resource and clean est burning. Meanwhile, engine simulation is of great importance in engine development. Hence a zero-dimensional combustion model was developed for dual-fuel system. Natural gas was injected directly into the cylinder and small amount of distillate was used to provide the ignition kernel for natural gas burning. The intake air and exhaust gas flow was modeled by filling and emptying method. Although the single zone approach has an inherent limitation, the model showed promise as a predictive tool for engine performance. Its simulation was also made to see how the engine performance was influenced by the fuel injection timings and amount of each fuel.

• 동력기계공학회지
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• 제15권1호
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• pp.5-10
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• 2011

The spatial fuel vapor distribution of the homogeneous charge by a 6-hole injector was examined in a optically accessed single cylinder direct injection spark ignition(DISI) engine. The effects of in-cylinder charge motion, and fuel injection pressure, and coolant temperature were investigated using a planar LIF (Laser Induced Fluorescence) technique. It was confirmed that the in-cylinder tumble flow played a little more effective role in the spatial fuel vapor distribution than the swirl flow during the compression stroke at 10 mm and 2 mm planes under cylinder head gasket and the increased fuel injection pressure activated spatial distributions of the fuel vapor. In additions, richer mixtures were concentrated around the cylinder wall by the increase of the coolant temperature.

• Journal of Advanced Marine Engineering and Technology
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• 제26권3호
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• pp.362-374
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• 2002

For the purpose of development of a GDI engine, the in-cylinder phenomena, such as the spray behaviors, fuel distributions, unburned fuel, and flame characteristics were investigated in a single cylinder GDI engine. The GDI engine was equipped with a swirl type electronic injector and SCV(Swirl Control Valve). PLIF(Planar Laser Induced Fluorescence) system with KrF Excimer laser was used far the measurements of fuel distributions. The effects of the injector specifications, such as the spray cone angle and the offset angle on the in-cylinder phenomena were investigated. As a result, it was found that the injected fuel collided with the bottom of the bowl and moved upward along the exhaust side wall of piston bowl. This fuel vapor played an important role in the instance of spark ignition. The unburned fuel and flame characteristics were greatly influenced by the injector specifications.

• 한국산업융합학회 논문집
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• 제19권1호
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• pp.31-38
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• 2016

Since the oil shock of 1970's there was a strong upward tendency for the use of the high viscosity and poorer quality fuels. Therefore the misfiring engine occurs due to the decrease of quantity injected for lean burn and emission control in Compression Ignition Common Rail Direct Injection diesel engine. In this study, it is designed and used the test bed which is installed with fuel injector controller. In addition to equipped engine using CRDI by controlling the injection timing with mapping modulator, it has tested and analyzed the engine performance and combustion characteristics, as it is varied that they are the operating parameters: fuel injected quantity, engine speed and injection timing.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.33-38
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• 2002

An optical single cylinder diesel engine equipped with a common-rail injection system has been built to investigate diesel combustion and emission characteristics. Three optical widows (piston crown quartz for bottom view of the cylinder, upper piston quartz for allowing laser sheet and liner quartz for side view) have been placed in the optical engine to visualize spray characteristics and combustion process inside the cylinder. Before doing further research using various optical diagnostics with the optical engine, fundamental combustion experiments and flame visualization incorporating a high speed motion analyser have been carried out with a wide range of engine operating conditions.

• 한국분무공학회지
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• 제6권4호
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• pp.39-48
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• 2001

The Gasoline Direct Injection(GDI) system has been highlighted due to the improvement of fuel consumption and the control of exhaust emission from gasoline engines. Main purpose of the present study is to measure spray characteristics of GDSI for real engine application. We have investigated experimentally spray tip penetration, spray angle, tip velocity and spatial spray distribution. Counter-rotating vortex grown on the spray surface plays an important role in the spray characteristics. Accordingly the spray tip penetration and tip velocity do not excess 50mm, 20m/s respectively, under 0.6MPa ambient pressure. the spray cone angle of GDSI have a same tendency to a simplex swirl atomizer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.726-731
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• 2000

This study was experimentally analyzed to improve the performance and to reduce exhaust emissions in a turbochaged D.I. diesel engine of the displacement 9.4L. In generally, the system of intake port, fuel injection and turbocharger are very important factors which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. The optimum results which is tested as available factors fur better performance and emission are as follows; the swirl ratio is 2.43, compression ratio is 16, combustion bowl is $5^{\circ}$ re-entrant type, nozzle hole diameter is ${\phi}0.28*6$, injection timing is BTDC $13^{\circ}CA$ and turbocharger is GT40 model which are selected compressor A/R 0.58 and turbine A/R 1.19.

• 한국분무공학회지
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• 제25권2호
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• pp.51-59
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• 2020

The purpose of this study is to propose and compare methods for measuring individual spray cone angles using spray cross-section images. In direct injection gasoline engines, it was believed that the distribution of air-fuel mixture in the combustion chamber directly affected combustion performance and emission formation. However, since gasoline direct injection (GDI) injectors have a small injection angle, interference between individual spray plumes occurs. Therefore, GDI injectors have only measured the spray angle of the entire spray. To overcome these limitations, three methods of indirectly measuring the spray cone angles of individual spray plume were presented and compared by forming sheet beams using Nd:YAG laser and acquiring spray cross-section images. Each method currently has advantages and disadvantages, and research to apply the method suitable for various GDI injectors needs to be continued.