• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.525-528
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• 2011

1400cc급 발전용 엔진 트로틀 바디의 최적화 및 성능 향상을 위하여 유동해석을 수행하였다. 베르누이 정리를 기본으로, 성능을 발휘하는 주요 설계인자인 트로틀 바디 내부의 트로틀 밸브 각도 및 흡기부 곡률 등을 설계 변수로 유동해석을 수행하였다. 벤튜리관 흡입부의 곡률을 증가시켜 트로틀 바디에서 소모되는 흡기저항을 줄였다. 감소된 흡기저항은 펌핑로스를 저감하여 연비향상에 도움이 될 것으로 기대된다. 결과적으로 해석결과 분석을 통하여 최적화된 모델을 제시하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.1
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• pp.139-147
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• 2015

This paper is the second investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous work, several assumptions used in the steady flow bench were examined and it was concluded that the assumption of the solid rotation might cause serious problems. In this study, intake valve angle is selected as a main parameter for the assessment because the main flow direction to cylinder governed by this angle has the strongest influence on the in-cylinder flow pattern. For this purpose, four heads, which have the different angle, are prepared and the flow characteristics are estimated both by the conventional impulse swirl meter and a particle image velocimetry at 1.75 times bore position apart from the cylinder head, which is widely used plane in the steady flow measurement. The results show that both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75 plane, however, the effects of two factors act in the opposite direction. In addition, the profile's influence is much greater than that of the eccentricity.

• 연구논문집
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• s.28
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• pp.49-58
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• 1998

In order to analyse the scavenging efficiency in a poppet valve type 2-stroke engine. visualization of scavenging flow and quantitative experiments for measuring scavenging efficiency were performed. The effect of shroud angle in RSSV which was developed by KIMM was evaluated under steady flow rig applying single-cycle method. Also dynamic simulator was used by using gas sampling with $CO_2$ and $O_2$gas. The $90^circ$ shroud RSSV was found to be the highest efficient system, and single-cycle and dynamic simulator test are very effective to save time and cost for the development of a 2-stroke engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.188-196
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• 1997

Many researchers have developed the measurement technique of in-cylinder flow characteristics and found the effect of intake port geometries on engine performance. The flow characteristics of four-valve cylinder head were examined in a steady flow rig for different intake ports. Tumble intensity of intake configurations with different entry angles were quantified with a tumble meter. The velocity and angular momentum distributions in the tumble adaptor were measured under steady conditions with PIV(Particle Image Velocimetry). We have obtained the results that flow structure becomes complicated by valve interference at low valve lift. As the valve interferences were reducing and the flow pattern changed to large vortex structure with tumble direction, intake ports with different entry angles have different tumble centers. Tumble eccentricity of intake port with low entry angle was large, so that the port had relatively much angular momentum compared to others which was expected to improve combustion performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.179-189
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• 2017

This paper is the fifth investigation on the methods of evaluating flow characteristics in a steady flow bench. In previous studies, several assumptions used in the steady flow bench were examined and it was concluded that the assumption of the solid rotation may lead to serious problems. In addition, though the velocity profiles were improved as the measuring position went downstream, the distributions were far from ideal regardless of the valve angle and evaluation position. The eccentricities were also not sufficiently small to disregard the effect on impulse swirl meter (ISM) measurement. Therefore, the effect of these distribution and eccentricity changes according to the positions needs to be analyzed to discuss the method of flow characteristics estimation. In this context, the effects of evaluation position on the steady flow characteristics were studied. For this purpose, the swirl coefficient and swirl ratio were assessed and compared via measurement of the conventional ISM and calculation based on the velocity by particle image velocimetry(PIV) from 1.75B, 1.75 times bore position apart from the cylinder head, to the 6.00B position. The results show that the swirl coefficients by ISM strictly decrease and the curves as a function of the valve lift become smooth and linear as the measuring position goes downstream. However, the values through the calculation based on the PIV are higher at the farther position due to the approach of the tangential velocity profile to ideal. In addition, there exists an offset effect between the velocity distribution and eccentricity in the low valve lift range when the coefficients are estimated based on the swirl center. Finally, the curve of the swirl ratio by ISM and by PIV evaluation as a function the measuring position intersect around 5.00B plane except at $26^{\circ}$ valve angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.169-182
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• 2016

This paper is the third investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous works, several assumptions used in the steady flow bench were examined and the flow characteristics were estimated both by the conventional impulse swirl meter and a particle image velocimetry at 1.75B position. From these works, it was concluded that the assumption of the solid rotation might cause serious problems and both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75B plane. Therefore, the understanding of the detail velocity profiles is very important to keep discussing the issues about the steady flow evaluation method. For this purpose, the planar velocity profiles were measure at 1.75B position by particle image velocimetry and the characteristics were examined according to the valve angles and lifts. The results show that the planar velocity profiles of 11, 16, $21^{\circ}$ valve angle heads according to the lift are similar to each other, however, that of $26^{\circ}$ angle is an exceptional case in the all aspects. In addition, the swirl behaviors are not apparent up to 6~8 mm lift under the $21^{\circ}$ angle and somewhat arranged motions are observed over the whole plane near the highest lift. At this point, the narrower the angle, the lower the lift at which the swirl motions become clear. On the other hands, when the angle is $26^{\circ}$, the center of swirl is always farthest from the cylinder center and only the indistinct swirl is observed even if at the highest lift. Also, all the swirl centers are quite apart from the cylinder center so that the effect of eccentricity may not be negligible at 1.75B regardless the valve angle. Related to the tangential velocity along with the radial direction, the bands of the velocity distribution are very wide and the mean velocities of cylinder center basis are lower than the velocity which is assumed in the ISM evaluation. Lastly, the mean tangential velocity profiles of swirl center basis are sometimes higher than that of ISM-assumed up to 0.6 non-dimensional distance less than 6mm lift, however, as the lift increases the profiles are different according to the angles and profile $11^{\circ}$ is the most closed to the ideal profile. Consequently, the real velocity profile is far from the assumption of ISM evaluation.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.242-254
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• 2016

This paper is the forth investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous works, it was concluded that the assumption of the solid rotation might cause serious problems and both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75B plane. Also particle image velocimetry (PIV) measurement at this position showed that the real velocity profile was far from the assumption of ISM evaluation. In this paper, the planar velocity profiles were measure from 1.75B to 6.00B position by PIV and the characteristics were examined according to the valve angles and lifts for further investigations about the effect of the position on the velocity profile. The results show that $26^{\circ}$ valve angle is always an unique exceptional case in all aspects. If the valve angle is $21^{\circ}$ and below, the planar velocity profiles according to the lift and the position are similar to each other, however, the tangential velocity curves along with the radial direction have common tendencies up to $16^{\circ}$ angle. Also the well arranged swirl behaviors are generally observed at the position above 3.00B and the velocity contour lines come closer to the concentric circle as the valve lift increases. In addition, the gradient of tangential velocity along with the radial direction from the swirl center becomes stable and constant as the position goes downstream. Concurrently the velocity gradient is larger to the eccentric direction of the center. In the meantime the tangential velocity curves along with the radial direction are irregular and various at 1.75B, however, they become regular and reach higher level as the evaluation position goes downstream. At this time the curves of 4.50B are the best fitted to the ideal one. On the other hand in an exceptional case, $26^{\circ}$, the velocity contours are very complicated over 6mm valve lift regardless the position and the gradient increases to the opposite direction of the eccentric center. Also, 6.00B is a best fitting position in the geometrical cylinder center base. With respect to the swirl center, the distribution range of centers for 1.75B is different to that for the other positions and the eccentricities of this plane are larger regardless the valve angle. After 1.75B, there is no certain tendency in the center position change according to the valve angle and lift. Additionally, the eccentricities are not sufficiently small to neglecting the effect on ISM measurement.