• 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.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2233-2238
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• 2003

It is well known that organized vortex rotations swirl and tumble greatly affect the mixing, the combustion and heat transfer processes in engine cylinder. We have developed 3 dimensional numerical simulation codes whose predictions make good agreement with the experimental data. Large eddy simulation based on Smagorinsky subgrid scale model was adopted to describe the turbulence of in-cylinder flows. The tumble motions generated by different inclination angles between valve-port and cylinder head have been calculated. The results show that the angles between direction of induced flow and cylinder walls which the flow collides with play a great role in the formation and generation of tumble motions. Therefore, it is inferred that seat angle and inclination angle are important factors of engine design. In addition, the numerical results of different engine speed -1000 rpm and 3000 rpm are very similar in the flow structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.7-13
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• 2003

The purpose of this study is to investigate the effect of the in-cylinder flows and different injection timings on fuel behavior in the cylinder of a GDI engine. Three different flows types induced by using masked port, unmasked port, and port deactivation were tumble, swirl&tumble, and high swirl respectively. LIEF technique was applied to investigate the mixture formation and fuel distribution at ignition time in the transparent engine with optical access through the piston top and upper part of cylinder liner. Injection timings of 180,90, and 60 degrees before TDC were examined. It was found that tumble flow was more effective on the homogeneous mixture formation than other flow and swirl flow transported more fuel vapor to the exhaust side at early injection mode, and swirl and swirl & tumble flow made fuel vapor concentrate around the cylinder center at late injection mode.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.2
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• pp.166-174
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• 1999

The flow characteristics of 2-valve and 4-valve cylinder heads with various blocked-valve were experimentally investigated in a steady flow rig. Effects of the blocked-valve configurations on flow coefficient, swirl and tumble intensity are studied. Compared to the conventional valve, the blocked valve in both cylinder heads have the much lower flow coefficient and the much higher intensity of swirl and tumble. Under the same size of blockage, the value of flow coefficient and swirl(or tumble) intensity were varied according to the position of blockage. Throughout these steady flow test the optimized positions of blockage in both cylinder heads were determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.17-23
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• 1999

This paper presents the characteristics of the gas flow in the engine cylinder under various intake flow conditins. The particle tracking velovimetry(PTV) was used to anlayze the gas flow pattern and flow field in the cylinder. Effects of tumble intensifying valve(TIV), swirl intensifying valve(SIV) and one-valve deactivated condition on in-cylinder flow patterns were compared with the baseline engine udner 600rpm motoring condition. In addtion, tumbel ration was estimated rwith results of in -cylinder flow fields. Base on experimental results, the tumble ration of in-cylinder flow field has the maximum value at the bottom dead center for the different four inlet conditions. In TIV condition, the tumble ration is 1.35 times larger than that of baseline engine and 1 intake valve deactivated condition is effective to improve in-cylinder swirl motion.

• 연구논문집
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• s.23
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• pp.63-71
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• 1993

To improve flow in-cylinder flow in a 2-valve gasoline engine, various geometries of combustion chambers are modified. Air flow rate, swirl and tumble flow are measured and analyzed by swirl impulse meter and LDV in a steady state flow measuring rig. The results of LDV experiment are compared with the data of swirl impulse meter.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.43-49
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• 2006

Optimizing in-cylinder flow such as tumble or swirl is one of the key factors to develop better internal combustion engines. Especially, the tumble, which is more dominant flow in current high performance gasoline engines, has significant effects on the fuel consumptions and exhaust emissions under part load conditions. The first step for the tumble optimization is to find an accurate but cost-effective way to measure the tumble ratio. From this point of view, tumble ratios from three different measuring methods were compared and correlated in this research. Steady flow rig, water rig, and PIV were utilized for that purpose. Engine dynamometer test was also performed to find out the effect of the tumble. The results show that the tumble ratios from those methods are well correlated and that the steady flow rig is the effective method to measure the tumble despite its limitations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.920-932
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• 1994

The combustion phenomena of a reciprocating engine is one of the most important processes affecting performance and emissions. One effective way to improve the engine combustion is to control the motion of the charge inside a cylinder by means of optimum induction system design, because the flame speed is mainly determined by the turbulence at compression(TDC) process in S.I. engine. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence in the compression stroke of the cycle. However, the exact nature of their relationship is not well known. This paper describes cycle resolved LDV measurement of turbulent flow inside the cylinder of a 4-valve engine under motoring(non-firing) conditions, and studies the effect of intake port configurations on the turbulence characteristics using following parameters ; Eulerian temporal autocorrelation coefficient, turbulence energy spectral density function, Taylor micro time scale, integral time scale, and integral length scale.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.49-57
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• 2005

In this study, in-cylinder flow of the swirl chamber type diesel engine numerically simulated by VECTIS code. The flow fields during the intake and compression process were also investigated in detail. Numerical results revealed that the generation and distortion of the swirling, tumbling vortices and those influences on turbulence kinetic energy by shape of the jet passage, angle and area. It was also found that flow characteristics were affected by inflow velocity that depends on change of the jet passage shape. Swirl ratio was increased according to decrease of jet passage area, and was affected by piston motion according to increase of jet passage angle. Tumbling vortices had the similar in various cases, but tumble ratio was increased with the inflow velocity. The generation of turbulence kinetic energy was considerably influenced by complex effects of swirling and tumbling vortices.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.219-228
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• 2010

A two-dimensional mathematical model was developed to predict the temperature and moisture-content profiles of a tumble dryer during infrared drying. The model is based on the movements of liquid water and moisture in the object and on the fluid and heat transfer in the drying air. The model was solved by the finite volume analysis for the fluid, temperature, and radiation intensity fields. After deriving the governing equations and developing the two-dimensional tumble dryer models, numerical investigations were carried out to examine the effects of various parameters such as the heater temperature and the heating patterns on the drying mechanism of the tumble dryer. All the results show that the drying time can be reduced by using the IR heater.