스월 및 연소실 형상에 의한 정상유동특성에 관한 연구

김대열(Dae Yeol Kim),한영출(Young Chool Han),박봉규(Bong Kyu Park) 한국생산제조학회 2006 한국생산제조학회지 Vol.15 No.4

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.

단기통 엔진 헤드에서 흡기포트의 정상유동에 관한 연구

김대열(Dae Yeol Kim),최수광(Soo Kwang Choi) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.4

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 1㎜ to 10㎜. 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.

흡입 밸브 각도에 따른 압축 행정 중 실린더 내 유동 특성

엄인용(Inyong Ohm),박찬준(Chanjun Park) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.4

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.

Orientation and deformation of FENE dumbbells in confined microchannel and contraction flow geometry

안경현,송선진,김주민,이승종,여종기 한국유변학회 2007 Korea-Australia rheology journal Vol.19 No.3

The orientation and deformation of polymer chains in a confined channel flow has been investigated. The polymer chain was modeled as a Finitely Extensible Nonlinear Elastic (FENE) dumbbell. The Brownian configuration field method was extended to take the interaction between the flow and local chain dynamics into account. Drag and Brownian forces were treated as anisotropic in order to reflect the influence of the wall in the confined flow. Both Poiseuille flow and 4 : 1 contraction flow were considered. Of particular interest was molecular tumbling of polymer chains near the wall. It was strongly influenced by anisotropic drag and high shear close to the wall. We discussed the mechanism of this particular behavior in terms of the governing forces. The dumbbell configuration was determined not only by the wall interaction but also by the flow type of the geometric origin. The effect of extensional flow on dumbbell configuration was also discussed by comparing with the Poiseuille flow.

직접분사식 가솔린 기관에서 흡입유동이 고압 11공 연료분사기의 분무형상에 미치는 영향

김성수(Seong Soo Kim) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.9

The effect of the intake flow on the spray structure of a high pressure 11-hole fuel injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing and in-cylinder charge motion were investigated using the 2-dimensional Mie scattering technique. It was confirmed that in the homogeneous charge mode, the in-cylinder swirl charge motion played a major role in the fuel spray distribution during the induction stroke rather than the tumble flow. But, in the stratified charge mode, the effect of the in-cylinder charge was not so large that the injected spray pattern was nearly maintained and the increase of in-cylinder pressure by the upward moving piston reduced the fuel spray penetration.

직접분사식 가솔린 기관용 고압 11공 연료분사기의 분무 특성 연구

김성수(Seong Soo Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

The spray characteristics of a high pressure 11-hole fuel 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 11-hole fuel injector had some advantage characteristics of larger spatial and more stable fuel distribution than 6-hole fuel injector. And the in-cylinder swirl charge motion played a major role in the fuel spray distribution during the induction stroke rather than the in-cylinder tumble flow.

Effect of Stiffness on Tumbling Dynamics of Short Worm-like Polymers under Mixed Flows

이주성,김주민 한국고분자학회 2011 Macromolecular Research Vol.19 No.3

This study examined the effects of the stiffness on the tumbling dynamics of short semi-flexible polymers in mixed flows varying from simple shear to pure rotation, as an extension of a previous study on rod-like polymers. A multi bead-rod model with bending potential was adopted and represented the stiffness or persistence length of the polymers. The rotational time and angular distribution of the semi-flexible chains were examined in mixed flows. These results were compared with previous theoretical predictions and numerical simulations of rod-like polymers. Furthermore, the angular distribution of the short semi-flexible polymers was strongly dependent upon the stiffness of the polymers. These results are expected to be helpful in the development of lab-on-a-chip applications, such as the separation of short DNA molecules.

CORRELATION STUDY OF THE MEASURED TUMBLE RATIOS USING THREE DIFFERENT METHODS: STEADY FLOW RIG; 2-DIMENSIONAL PIV; AND 3-DIMENSIONAL PTV WATER FLOW RIG

Kim, M.J.,Lee, S.H.,Kim, W.T. The Korean Society of Automotive Engineers 2006 International journal of automotive technology Vol.7 No.4

In-cylinder flows such as tumble and swirl play an important role on the engine combustion efficiencies and emission formations. The tumble flow, which is dominant in current high performance gasoline engines, is able to effect fuel consumptions and emissions under a partial load condition in addition to the volumetric efficiency under a wide open throttle condition. Therefore, it is important to optimize the tumble ratio of a gasoline engine for better fuel economy, lower emissions, and maximum volumetric efficiency. First step for optimizing a tumble ratio is to measure a tumble ratio accurately. For a tumble ratio measurement, many different methods have been developed and used such as steady flow rig, PIV, PTV, and LDV. However, it is not well known about the relations among the measured tumble ratios using different methods. The purpose of this research is to correlate the tumble ratios measured using three different methods and find out merits and demerits of each measurement method. In this research the tumble flow was measured, compared, and correlated using three different measurement methods at the same engine: steady flow rig; 2-dimensional PIV; and 3-dimensional PTV water flow rig.

CORRELATION STUDY OF THE MEASURED TUMBLE RATIOS USING THREE DIFFERENT METHODS: STEADY FLOW RIG; 2-DIMENSIONAL PIV; AND 3-DIMENSIONAL PTV WATER FLOW RIG

M. J. KIM,S. H. LEE,W. T. KIM 한국자동차공학회 2006 International journal of automotive technology Vol.7 No.4

In-cylinder flows such as tumble and swirl play an important role on the engine combustion efficiencies and emission formations. The tumble flow, which is dominant in current high performance gasoline engines, is able to effect fuel consumptions and emissions under a partial load condition in addition to the volumetric efficiency under a wide open throttle condition. Therefore, it is important to optimize the tumble ratio of a gasoline engine for better fuel economy, lower emissions, and maximum volumetric efficiency. First step for optimizing a tumble ratio is to measure a tumble ratio accurately. For a tumble ratio measurement, many different methods have been developed and used such as steady flow rig, PIV, PTV, and LDV. However, it is not well known about the relations among the measured tumble ratios using different methods. The purpose of this research is to correlate the tumble ratios measured using three different methods and find out merits and demerits of each measurement method. In this research the tumble flow was measured, compared, and correlated using three different measurement methods at the same engine: steady flow rig; 2-dimensional PIV; and 3- dimensional PTV water flow rig.

Investigation of In-Cylinder Flow Patterns in 4 Valve S. I. Engine by Using Single-Frame Particle Tracking Velocimetry

Lee, Ki-hyung,Lee, Chang-sik,Chon, Mun-soo The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.1

The in-cylinder flow field of gasoline engine comprises unsteady compressible turbulent flows caused by the intake port, combustion chamber geometry. Thus, the quantitative analysis of the in-cylinder flow characteristics plays an important role in the improvement of engine performances and the reduction of exhaust emission. In order to obtain the quantitative analysis of the in-cylinder gas flows for a gasoline engine, the single-frame particle tracking velocimetry was developed, which is designed to measure 2-dimensional gas flow field. In this paper, influences of the swirl and tumble intensifying valves on the in-cylinder flow characteristics under the various intake flow conditions were investigated by using this PTV method. Based on the results of experiment, the generation process of swirl and tumble flow in a cylinder during intake stroke was clarified. Its effect on the tumble ratio at the end of compression stroke was also investigated.