• 오토저널
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• 제13권6호
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• pp.82-89
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• 1991

In order to investigate the characteristics of flow around the intake around the intake valve exit, discharge coefficient and the velocity near the valve exit in steady state were measured using X-type hot-wire. Valve and valve seat insert used in experiment were constructed as the same shape of production engine and the flow characteristics at various flow rates and valve lifts were investigated. From the results of discharge coefficient measurements, it is observed that there exists a similarity between the flow characteristics around the production engine valve and the typical poppet valve. Measurement of the velocity at the valve exit shows that the normalized radial velocity between the primary direction of flow and the valve angle is large, but the difference becomes smaller as the flow rate increases.

• 한국자동차공학회논문집
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• 제4권1호
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• pp.218-228
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• 1996

The behaviors of the mixture at the downstream of throttle valve in a TBI type gasoline engine plays a greater role in design of intake system. A good mixture has been influencing directly not only on the engine power but also on the pollutant emission. The mixture flow in an intake manifold is very complex, and the flow characteristics are varied with the valve type, valve angle, inlet air flow rate, and the other flow factors. Three kinds of valve are chosen in this study, and the informations of the mixture flow are observed experimentally using a PIV apparatus. Perforate valve has a smaller recirculation zone than the case of solid valve with a lower valve loss coefficient, and iti is verified that the perforated valve is also suitable to control the flow rate in a mixture flow system.

• International Journal of Fluid Machinery and Systems
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• 제5권3호
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• pp.109-116
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• 2012

Water hammer pumps can effectively use the water hammer phenomenon for water pumping. They are capable of providing an effective fluid transport method in regions without a well-developed social infrastructure. The results of experiments examining the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. However, these conventional studies have not fully evaluated pump performance in terms of pump head and flow rate, common measures of pump performance. The authors have focused on the effects on the pump performance of various geometric form factors in water hammer pumps. The previous study examined how the hydrodynamic characteristics was affected by the inner diameter ratio of the drive and lift pipes and the angle of the drive pipe, basic form factors of water hammer pumps. The previous papers also showed that the behavior of water hammer pump operation could be divided into four characteristic phases. The behavior of temporal changes in valve chamber and air chamber pressures according to the air volume in the air chamber located downstream of the lift valve was also clarified in connection with changes in water hammer pump performance. In addition, the effects on water hammer pump performance of the length of the spring attached to the drain valve and the drain pipe angle, form factors around the drain valve, were examined experimentally. This study focuses on the form of the lift valve, a major component of water hammer pumps, and examines the effects of the size of the lift valve opening area on water hammer pump performance. It also clarifies the behavior of flow in the valve chamber during water hammer pump operation.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.801-808
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• 2021

In this paper, a numerical analysis was conducted on the effect of the flow control valve of a oscillation water column(OWC) type wave power generator turbine. The OWC wave power turbine operates with compressed air in the air chamber according to the change of wave height. When the wave height changes rapidly, a flow control valve is required due to overload of the turbine and reduced efficiency. Therefore, in this paper, a flow control valve with an opening angle of 60 degrees was installed in the front of the turbine, and the pressure drop, torque, and overall performance were calculated according to the change of turbine RPM and flow rate of turbine inlet. In conclusion, the flow control valve with an opening angle of 60 degrees affects when the turbine rotates at low rotation and the inlet flow rate is large. But it does not have a significant effect on overall turbine performance and it is necessary to find the optimal angle in the future works.

• 한국분무공학회지
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• 제1권1호
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• pp.55-62
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• 1996

In a fuel injection engine, atomization of liquid fuel and mixture formation process has influenced(or affected) directly on the engine performance and pollutant emission. In this study, the characteristics of fuel spray and the behaviors of secondary atomization developed at the downstream of the valves were investigated using an image processing method. Solid and perforated valves are chosen in order to evaluate the valve performance in terns of air flow rate, valve opening angle and valve shape. Experimental results clearly indicate that the spray atomization quality can be improved by increasing the perforated rat io and the blockage rat io in the perforated valve, the characteristics of spray atomization is improved by using the perforated valve with high perforated rat io and blockage ratio.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.587-591
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• 2011

To improve the performance of the control butterfly valve seals are used to eccentric shaft. In this case, vertical opening gas of the butterfly valve is non-symmetrical, which will change the flow pattern around the valve. In this study, the eccentric drive shaft of the butterfly valve to change flow characteristics are performed numerically. Flow pattern and pressure drop are investigated as the valve opening angle increases for a given mass flow rate. The valve flow coefficient is compared to the without eccentric shaft.

• Journal of Advanced Marine Engineering and Technology
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• 제38권10호
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• pp.1263-1268
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• 2014

In this study, the variations of swirl center according to evaluating position have been investigated in a steady flow bench of SI engine. For the experiments, two engine heads with different intake valve angles ($11^{\circ}$ and $26^{\circ}$) were tested in the flow bench by varying the evaluating position (1.75~6.0B) and valve lift (2~10 mm). Particle image velocimetry was used to measure the velocity field inside the engine cylinder. The swirl center position is found with a critical point theory and the intensity of turbulence is calculated from PIV velocity data. The results show that the center of swirl is located closer to the center of cylinder and turbulence intensity is lower, when the intake valve angle is the smaller. It is conventional to evaluate the swirl ratio at 1.75B position in the steady flow bench of SI engine. At this position, however, the distance of swirl center from the cylinder center scatters significantly for the variation of valve lift, and the turbulence intensity is much stronger regardless of the valve angle. Thus, to estimate the flow at the end of compression stroke in a real engine from the data in the steady flow experiments, the evaluation position should be moved further downstream more than 4.5B.

• Journal of Magnetics
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• 제22권1호
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• pp.7-13
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• 2017

The magnetoresistance (MR) properties of antiferromagnetic (AFM) IrMn based giant magnetoresistance-spin valve (GMR-SV) was investigated in view point of the artificial rotation effect of ferromagnetic (FM) layer in the plane induced by an applied field during the post annealing temperature. The MR curves measured with an azimuthal angle region of ${\phi}=0^{\circ}-360^{\circ}$ are depended on the annealing temperature and the magnetization easy axis of two free NiFe layers and two pinned NiFe layers in dual-type GMR-SV film. Especially, the annealing temperature and sample rotation angle(${\theta}$ ) maintained to the magnetic sensitivity (MS) of 1.4 %/Oe with an isotropic region angle of $110^{\circ}$ are $100^{\circ}C$ and $90^{\circ}$, respectively.

• 대한기계학회논문집B
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• 제32권1호
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• pp.39-46
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• 2008

The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk.

• 대한기계학회논문집
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• 제19권10호
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• pp.2690-2698
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• 1995

Fuel atomization and mixture formation in an gasoline engine has influence on the engine performance and pollutant emission. The throttle valve installed in an intake system plays a greater role in control of mixture quantity in accordance with engine drive condition. In this study, the characteristics of secondary atomization developed at the downstream of the valves were observed using an image processing method. Two major kinds of valves, solid and perforated ones, are chosen in order to compare the valve performance with the experimental parameters of air flow rate, valve opening angle, and valve shapes. For the perforated valve, we can obtain the relatively small sized droplets, and nearly uniformed and dense distributed sprays with low loss coefficient than for the solid valve.