• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.66-75
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• 1999

Many researchers have developed the measurement technique of in-cylinder flow. Recently, there are lots of studies on steady flow with different SCV geometries. In this study the flow characteristics of four-valve cylinder head were examined in a steady test rig for different SCV open ratios. Each swirl ratio of several SCV angle was quantified by swirl impulse meter and 2D-LDV measurement. The results showed that the swirl ratio was controlled between 2.3 and 3.8 based on SCV angles. The velocity distributions of in-cylinder flow field were measured by 2-D LDV test and visualized swirl and tumble flow pattern at different positions. In this engine , we found out that the swirl was dominant flow.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.13-21
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• 2007

This paper presents characteristics of steady flow by variation of a combustion chamber and an intake port. Gas flow field inside a combustion chamber is the important factor in improving combustion stability and reduction of emission level. The flow characteristics such as flow coefficient, tumble ratio and swirl ratio are measured by the steady flow rig test with an impulse meter in this study. In the measuring, the valve lifts are varied between 1mm to 10mm. The three combustion chambers and two intake ports were applied to the steady flow apparatus in order to investigate the effect of swirl and tumble on the in-cylinder flow. As a result, tumble ratio were found to be different by variation of the combustion chambers and the intake ports. The data from the present study can be applied to design of a similar engine as basic data.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.69-79
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• 1997

This paper deals with the measurement and analysis on the scavenging performance of the oppet-valve type two-stroke engine with different shroud system. The scavenging flow characteristics is investigated by flow visualization under steady condition, in which a dye is introduced into single-cycle method using the difference of specific gravity between two working fluids is used to evaluate the scavenging efficiency and the trapping efficiency. The 90° shroud system was found to be the highest efficiency system through both flow visualization and single-cycle test, as well as the shroud system to generally be efficient for reducing a short-circuiting flow during scavenging process in a two-stoke engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.76-82
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• 1999

The object of this study is to find new evalution index for in-cylinder flow characteristics insteady of current swirl, tumble coefficient using steady flow test rig on intake port 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 angular flow characteristics.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.81-88
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• 2008

Flow characteristics have one of the effects in the process of engine. The numerical analysis makes it possible to predict the flow fields. This paper presents characteristics of steady flow according to variation of valve lift in a gasoline engine. The numerical computations have been made to observe the pressure distribution in accordance with the variable valve lift. Characteristics of tumble flow and swirl flow according to the variable valve has also been investigated. We could find that tumble ratio and swirl ratio is different between with/without PDA valve. The steady flow test was simulated through three-dimensional analysis on intake port design for comparing with experimental data and confirming the feasibility of applying analytic method. As a result, this study shows the possibility of the usage of numerical simulation to predict the flow characteristics for gasoline engine.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.74-82
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• 2006

This paper describes the steady flow characteristics due to PDA and tumble control valve in combustion chamber. We also investigated the flow inclination angle defined as the inverse tangent of non-dimensional rig tumble(NRT) devided by non-dimensional rig swirl(NRS) to find dominant flow direction. So we adapted two different types of PDA valve(port deactivation valve) to strengthen a swirl flow. The in-cylinder swirl flow different tendency between with/without PDA valve. It might be thought to be affected by swirl flow. We could find that tumble ratio and swirl ratio is different by PDA valve. The comparison are taked account of the swirl, the tumble ratio comparison in same mass flow rate. As a result, PDA valve is better than tumble control valve both in steady flow condition and swirl, tumble ratio. The data from present study are available for design of engine as the basic data.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.77-83
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• 2006

A PIV(Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during compression stroke. Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle, were used to compare real compression flow. The results show that the flow patterns are well arranged compared with intake flow and the basic tumble flow structures are maintained until end compression stage regardless of valve angle. Also the results show that the tumble motion is intensified by momentum conservation during compression in normal engine. In the normal engine, the bulk shape of flow pattern is "Y" type at the top of cylinder and reverse "Y" type at the bottom of cylinder and weak reverse flow exists at the top of cylinder along cylinder center line. Otherwise, the other engine's flow pattern changes from "Y" type to "T" type at the top of cylinder during compression.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.142-149
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• 2006

A PIV(Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle, were used to compare real intake flow. The results show that the intake flow pattern of conventional engine is more complicated than that of narrow angle one in horizontal plane and the vertical component of in-cylinder flow is rapidly decayed at the end stage of intake. On the other hand, the flow pattern of narrow angle one is relatively well arranged in horizontal plane and the vertical velocity component remains so strongly that forms large-scale strong tumble. Two engines also form commonly three tumble; two are small and bellow the intake valve and one is large-scale. The center of large scale tumble moves to bottom of cylinder as the vertical velocity increases.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.153-162
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• 1997

The effects of tumble and swirl flows on the flame propagation were investigated experimentally in a 4-valve optical gasoline engine. The tumble flow patterns, generated by various intake ports of different entry angle; $25^{\circ}$ , $20^{\circ}$ and $15^{\circ}$ , were characterized under motored conditions with laser Doppler velocirnetry. Inclined tumble(swirl) flows were induced by three different swirl control valves. The initial flame propagation was visualized by an ICCD camera and its image were analyzed to compare the enflamed area and displacement of initial flames. It was found that there is a correlation between the stronger tumble during induction and turbulence levels at the time of ignition resulting in faster flame development. Inclined tumble was proved to be more beneficial than the pure tumble for faster and stable combustion under lean mixture conditions, which was confirmed by faster propagating flame images.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.1-8
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• 2001

The flow field inside a cylinder of four-valve Sl engine was investigated quantitatively using a three-dimensional Laser Doppler Velocimetry system, to determine how stroke changes affect the flow field. The purpose of this work was to develop quantitative methods which correlate in-cylinder flows to engine performance. For this study, the sane intake manifold, engine head, cylinder, and the piston were used to examine the flow characteristics in different strokes. Quantification of the flow field was done by calculating three major parameters which are believed to adequately characterize in cylinder motion. These quantities were TKE, tumble and swirl ratios. The LDV results reveal that flow patterns are similar, the flow velocities scale with piston speed but another parameters such as TKE, and tumble and swirl numbers are not the same for different stroke systems.