• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.880-885
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• 2000

Flow patterns and steady flow characteristics of an intake 3valve cylinder head are not obviously declared. Thus, in the study, the characteristics and limitation of intake flow coefficient which applied to multi intake valve engine are introduced. The flow coefficient and tumble characteristics are investigated by means of the steady flow test and flow visualization method. As the results, it is found that the intake flow rate is dominated by effective valve open area. In addition, this paper shows that the mass flow rate of intake 3valve engine is greater than that of intake 2valve engine and tumble flow of intake 3valve engine is superior to that of intake 2valve engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.107-115
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• 1999

Hydrocarbon emission from spark ignition engines deeply relates with fuel evaporation mechanism. Therefore, fuel evaporation on the back of the intake valve is very important to understand fuel evaporation mechanism during engine warm up period. Intake valve heat transfer model was build up to estimate the amount of fuel evaporation on the intake valve back . Intake valve temperature was measured intake valve temperature is increased rapidly during few seconds right after engine start up and it takes an important role on fuel evaporation. The liquid fuel evaporation rate on the intake valve back proportionally increases as valve temperature increases, however its contribution slightly decreases as intake port wall temperature increases. The fuel evaporation rate on the valve back is about 40∼60% during engine warm-up period and it becomes about 20∼30% as intake port wall temperature increases. The estimation model also makes possible model also makes possible to review the effect of valve design parameters such as the valve mass and seat area on fuel evaporation rate through intake valve heat transfer.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.933-938
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• 2001

A 5-valve(intake 3-valve) engine has been developed to increase engine performance. These vehicles have a high power caused by the decrease of inertia mass of an intake valve and the increase of intake effective area. In this study, velocity profiles at near intake valves were inspected by using a two-color PIV and laser sheet method with tumble control valve(TCV). In addition, steady flow tests were performed to quantify tumble ratio on flow-fields generated with a TCV. These experimental results show that the tendency of the tunble ratio in intake 3-valve engine is different from the one in intake 2-valve engine. From this results, the intake flow characteristics around intake valves were made clear.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.93-100
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• 2009

Intake/exhaust valve timing and exhaust cam lift were changed to control the internal exhaust gas recirculation (IEGR) and combustion phase of homogeneous charge compression ignition (HCCI) engine. To measure the IEGR rate, in-cylinder gas was sampled during from intake valve close to before ignition start. The lower exhaust cam made shorter valve event than higher exhaust cam and made IEGR increase because of trapping the exhaust gas. IEGR rate was more affected by exhaust valve timing than intake valve timing and increased as exhaust valve timing advanced. In-cylinder pressure was increased near top dead center due to early close of exhaust valve. Ignition timing was more affected by intake valve timing than exhaust valve timing in case of exhaust valve lift 8.4 mm, while ignition timing was affected by both intake and exhaust valve timing in case of exhaust valve 2.5 mm. Burn duration with exhaust valve lift 2.5 mm was longer than other case due to higher IEGR rate. The fuel conversion efficiency with higher exhaust valve lift was higher than that with lower exhaust valve lift. The late exhaust and intake maximum open point (MOP) made the fuel conversion efficiency improve.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.238-244
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• 2002

A 5-valve(intake 3-valve) engine has been developed to increase engine performance. These engines have a high power caused by the decrease of inertia mass of an intake valve and the increase of intake effective area. In this study, in-cylinder flow patterns were visualized with laser sheet method and velocity profiles at near intake valves were inspected by using a two-color PIV. In addition, steady flow tests were performed to quantify tumble ratio of flow-fields generated by a tumble control valve(TCV). Experimental results of steady flow test show that the cure of tumble ratio in intake 3-valve engine farmed as a S shape with valve lift changes. This tendency is different from the one in intake 2-valve engine. Using laser sheet method and two color PIV method, we can find that the intake flow through upper valve increases and the velocity gradient also slightly increases as valve lift increases. From this study, the in-cylinder flow characteristics around intake valves were made clearly.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.51-66
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• 1997

A heat transfer model of the intake valve in a spark ignition engine is presented, which is calibrated with a number of the valve temperature profiles measured during engine warm-up for the gaseous fuel(propane). The valve is divided into four identical elements for which the assumption of lumped thermal mass is applied. The calibration is made so that the difference between the measued and simulated valve temperatures becomes minimal. Then the model is applied to the cases of the liquid fuel(indolene) to estimate the amount of the liquid fuel vaporized from the intake valve by assuming that fuel evaporation accounts for the deficit of the heat balance budget. The results of the model show quantitative contribution of each heat transfer source to the heat balance. The behavior of the calculated mass fraction of the fuel vaporized from the intake valve explains how the liquid fuel evaporate during engine warm-up. The mass fraction at warmed-up condition is closely related with the fraction directly targeted on the valve back by the fuel spray geometry.

• Journal of ILASS-Korea
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• v.21 no.1
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• pp.7-12
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• 2016

In this study, to research in-cylinder flow characteristics of spark-ignited engine with intake valve closing timing change for Miller cycle. 3D simulation study were used 6 different intake valve profile with $CAD10^{\circ}$ gap for retard intake valve closing timing. Comparison of In-cylinder flow pattern characteristic were accompanied between Base and LIVC. And the efficiency of volume and the work of compression were analyzed with simulation study. When intake valve closing angle was retarded in $CAD50^{\circ}$, the pressure in cylinder was decreased about 12~13 bar and volume efficiency was reduced about 16%. The efficiency of volume and the work of compression were reduced on LIVC.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.157-169
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• 1997

The effects of intake port eccentricity on the characteristics of in-cylinder swirl ratio in a 4-valve diesel engine having the two intake ports; one is a helical intake port and the other is a tangential intake port were investigated by using the ISM(impulse swirl meter) in steady flow test rig. Swirl ratio($R_s$) and mean flow coefficient($C_{f(mean)}$) with valve eccentricity ratio($N_y$) and axial distance(Z/B) were measured. As the results from this experiment, the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by intake port eccentricity. There is a difference in the mass flowrate through the two intake ports, and the mass flowrate through the tangential intake port is 19% more than that of the helical intake port. Therefore, we could know that the effects of the mass flowrate ratio through each intake port besides intake port shape should be conidered.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1097-1102
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• 2001

For the purpose of development of high performance gasoline engine, the design technique of the 5-valve(3 intake valves) combustion chamber for a subcompact vehicle has been studied. 3 intake valves cylinder heads were designed by using a 3-dimension CAD program, and steady state flow experiments have been performed with these model. The 5-valve engines, which have larger valve opening areas, have larger intake flow rates and higher flow coefficient than the 4-valve engines. The effects of intake port design parameters of a 5-valve engine on the intake flow rate and bore size were studied, and the design guidelines for the 5-valve engine were established.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.42-48
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• 2009

This paper is the second of 2 companion papers which investigate in-cylinder swirl generation characteristics according to inlet valve angle. Two DOHC 4 valve engines, one has wide intake valve angle and the other has narrow valve angle, were used to compare the characteristics of swirl motion generation in the cylinder. One intake port was deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. The results show that the flow patterns of narrow valve engine are much more stable and well arranged compared with the normal engine over the entire intake and compression stroke except early intake stage, and very strong swirl motion is generated at the end of compression stage in this engine nevertheless using straight port which is unfavorable for swirl generating. In the wide valve angle one, however, strong swirl motion induced during intake stroke is destroyed as the compression progresses.