• 대한기계학회논문집B
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• 제30권11호
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• pp.1057-1065
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• 2006

In order to figure out the physical meaning of 3-D angular flow index for in-cylinder bulk motion, CFD analysis for the swirl and tumble steady flow test rig were made using commercial package STAR-CD. Computer simulations and rig tests on some kinds of induced flow conditions were carried out. Finally, based on the comparison between the simulated results and measured results, the physical meaning of 3-D angular flow index $|\longrightarrow_{N_B}|$, $\beta$ composed of swirl and tumble coefficients measured by steady flow test rig was described.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.99-105
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• 2007

It is very important to clarify the 3-D angular flow characteristics of in-cylinder bulk motion in the developing process of variable induction system. In-cylinder flow induced by variable induction system is very complex, so we can not describe the in-cylinder bulk flow characteristics using the conventional swirl or tumble coefficient. In this study, we introduced the new 3-D angular flow index, angular flow coefficient($N_B$), for in-cylinder bulk flow characteristics. And also, to confirm the index, we carried out the steady flow rig test for intake port of test engine varying valve lift on the test matrix.

• 대한기계학회논문집B
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• 제30권11호
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• pp.1066-1073
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• 2006

Recently, because the variable induction systems are adopted to intake system, in-cylinder flow induced by induction system is very complex. Therefore it is very difficult to describe the in-cylinder bulk flow characteristics using the conventional swirl or tumble coefficient. In this study, in order to clarify the 3-D angular flow characteristics of in-cylinder bulk motion in the developing process of variable induction system, we introduced the new 3-D angular flow index, angular flow coefficient($N_B$) Finally, to confirm the index, we carried out the steady flow rig test for intake port of test engine varying valve lift on the test matrix.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3306-3310
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• 2007

Many researches have been studied on in-cylinder flow as one of dominant effects for an engine combustion. Specially because the combustion flame speed is mainly determined by the turbulence at the end of compression process. Tumble and Turbulence ahead of combustion is very important phenomenon. As this phenomenon make research certainly, combustion condition will effectively be improve. This paper describes analytical results of the tumble flow, intensity, turbulence inside the cylinder of maritime engine. 3-D computation has been performed by using STAR-CD v3.26 solver and es-ice

• 한국자동차공학회논문집
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• 제7권9호
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• pp.82-88
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• 1999

The object of this study is to find new evaluation index for in-cylinder flow chracteristics istead of current swirl, tumble coefficient using steady flow test rig on intake port system. To this end, port flow system. To this end, port flow rig test was conducted on DOHC head varying intake valve lift respectively. Finally combination angular coefficient and inclination angle were introduced as new evaluation index for in-cylinder angularflow characteristics instead of swirl and tumble coefficient.

• 한국자동차공학회논문집
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• 제4권5호
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• pp.197-205
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• 1996

The flow characteristics of five different 4-valve cylinder heads were investigated in a steady flow rig using laser-Doppler velocimetry. The tumble flow of each head with pentroof combustion chamber was quantified by nondimensional tumble number using a tumble adaptor. The formation of tumbling vortex was examined in an optical single-cylinder engine which has windows for in-cylinder LDV measurements. Tumble vortex ratio was estimated from the tumble flow measurement. The four-valve cylinder heads with pent-roof combustion chamber showed the tumble vortex from the intake process, which was investigated in the steady flow test. The tumble adaptor which converts the tumble into swirl flow was found to be feasible in predicting the tumble flow in the real engine. The tumble strength in the steady flow test coincides with that in the real engine experiment within 15%. It was found that the steady flow test on the four-valve cylinder heads provides the tip for a better design of cylinder head.

• 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.

• 대한기계학회논문집
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• 제19권3호
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• pp.763-770
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• 1995

Gas flow characteristics within the cylinder is important factors in impoving lean combustion stability. This paper shows the effects of various flow fields generated by a swirl control valve(SCV) on combustion process in a 4-valve spark ignition engine. An impulse swirl/tumble meter was used to elucidation the steady-state flow characteristics, and a rotating grating type LDV was developed to measure the mean velocity and tunbulence intensity in relation to the crank angle. These methodologies were applied to clarify the correlation between gas flow characteristics and combustion stability at a lean air fuel ratio. An analysis of the correlation revealed the gas flow conditions required to optimize a lean-burn system.

• 대한기계학회논문집B
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• 제32권11호
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• pp.878-883
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• 2008

The spray characteristics of a high pressure 6-hole injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing, in-cylinder charge motion, fuel injection pressure and coolant temperature were investigated using the 2-dimensional Mie scattering technique. It was confirmed that the in-cylinder charge motion played a major role in the fuel spray distribution during the induction stroke while the propagation of fuel spray was restrained during the compression stroke by the increasing pressure and the upward moving piston. In additions, it was confirmed that the liquid fuel droplets existing at the sprays edges were vaporized by the increase of the coolant temperature.

• 동력기계공학회지
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• 제12권6호
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• pp.64-69
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• 2008

The spatial fuel distribution of the stratified charge of a high pressure 6-hole injector was examined in a single cylinder optical 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 more effective role in the spatial fuel distribution of the stratified charge than the swirl flow during the compression stroke and the fuel distribution area increased due to the activation of the fuel vaporization by the increase of the coolant temperature. But, the increase of the fuel supplying pressure could not change the pattern of the fuel vapor distribution against the expectation.