• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.225-231
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• 1997

This paper reports on the theoretical study of the delivery pressure ripples of a positive displacement vane pump which is widely used for automobile power steering. Pressure ripples occur due to the flow tipples which induced cam ring profiles and reverse flow from the delivery ports. In this paper, the mathematical model for analyzing the pressure ripples has been presented, and set of the differential equationshave been solved using the Runge-Kutta method. As the results of analysis, instant ideal flow ripples, internal pressure, delivery pressure ripples, and delivery flow ripples have been presented. Internal pressure was related to delivery pressure variations, and amplitude of pressure tipples was increased with rotational speed and delivery pressure.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.572-578
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• 2011

The vane type air-motor hand-piece is used widely in the dental services. There are a lot of experimental studies about air-motor but eccentrically off not many numerical studies by using Computational Fluid Dynamics. An air-motor has rotor which rotates at the center of inner housing. The retractable vanes are installed on the rotor. As the rotor of the air-motor rotates, vanes move up and down straightly in the radial direction along the guide. Therefore we have to analyze the unsteady flow field by accurate time dependent marching technique. ANSYS 12.0 CFX is used to analyze unsteady vane-motor flow field Analysis of the changing control volume inside air-motor is implemented by user-defined functions and moving mesh options. Rotational speed of the rotor is approximately 23,000rpm.

• Journal of ILASS-Korea
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• v.9 no.2
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• pp.18-23
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• 2004

An experimental studies of conventional gasoline fuel pump were carried out to obtain fundamental data fur liquid phase LPG injection(LPLi) system. A regenerative type and a roller-vane type of pumps were investigated in various operational condition. The experiments were performed to obtain flow rate of LPG fuel as a function of pressure differences and temperatures. The regenerative pump had too low flow rate at some experimental conditions to use this pump system for LPLi fuel supply system. On the other hand, the roller-vane type pump can be applied to the system only if its check valve is modified. Cavitation might occur in this system which can result in system noise, flow rate variation, and pump durability problem. To solve these problems the system is needed to increase $NPSH_{re}$(required net positive suction head).

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1303-1308
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• 2008

This paper presents effects of impeller geometrical parameters on the performance of a centrifugal pump impeller. The effects of meridional parameters and vane plane development parameters on the performance of the impeller were numerically studied using a commercial CFD code and DOE(design of experiments) software. Geometrical parameters in a method of meridional view and vane plane development were selected and defined to generate the 3D impeller shape. The response variables are defined in a total head and efficiency curve with flow rate. The influences of selected design variables on the various objective functions were examined as a result of the calculation using 2k factorial.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.514-519
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• 2003

The objective of this study is to document the secondary flow and the total pressure loss distribution in the contoured endwall installed linear turbine nozzle guide vane cascade passage and to propose an appropriate contraction ratio of the contoured endwall which shows the best loss reduction among the simulated cases. In this study, three different contraction ratio of contoured endwalls have been tested. This study was performed by experimental method and when the contoured endwall has the contraction ratio of 0.17 on exit height the results showed the best loss reduction.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.1-7
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• 2004

This paper deals with the performance analysis of the impulse turbine for a owe type wave energy conversion device. Numerical analysis was performed using the commercially-available software FLUENT. This parametric study includes variation of the setting angle of the guide vane. Since parametric study at various flow coefficients requires a tremendous amount of computing time, two-dimensional cascade flow approximation was employed to determine the optimum principal particulars in a rather simple manner. A Full three-dimensional calculation was also performed for several cases to confirm the validity of the two-dimensional approach. Results were compared to other experimental data, such as Setoguchi et al. (2001)'s extensive set of data, and found that the usefulness of 2-D analysis was well demonstrated. The advantages of each method were also evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1267-1274
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• 2012

A guide vane plays a key role in controlling the flow rate of water supplied to the turbine of a hydropower plant. It has been reported that guide vane bearing bushings are subjected to considerable wear, which requires them to be maintained. An ancillary service such as frequency control and black start causes cyclic low opening operation of the guide vanes. It is empirically well known that such operation increases the wear rate of the guide vane bearing bushing. In this study, the effect of low opening operation on the increasing wear of the guide vane bearing bushing is quantitatively assessed via finite element flow analysis, finite element stress analysis, and relative wear evaluation. As a result of the assessment, it is identified that the pressure applied on the guide vane surface increases and the contact length between the outer surface of the guide vane stem and the inner surface of the bearing bushing decreases with a decrease in the opening of the guide vane. In addition, low opening of the guide vanes results in an increase in the relative wear owing to the generation of high contact pressure on the bearing bushing surfaces.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.277-285
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• 1998

This paper presents the deformation characteristics of the moving pressure plate in a balanced type vane pump that widely used automotive power steering systems. Moving pressure plate can control the clearance between rotor and plate in accordance with load pressure variation; it always guarantees that pump to have optimal volumetric efficiency. In this paper, firstly, we calculate the acting force on the pressure plate, which is used to determine the angular position and load condition for analyzing the deformation of pressure plate. Secondary, finite element method is used for the deformation analysis. As results of acting force analysis, it is found that maximum difference of forces occurs at angular position 28$\circ$ from the small arc center of cam ring and load pressure is a dominant factor to affect acting force variation. The deformation of pressure plate increases as load pressure increases. At high load pressure, the deformation of pressure plate becomes larger than the initial clearance between rotor and plate. Therefore, it is required to design the plate for controlling the deformation.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.391-398
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• 2000

The index properties of cohesive soils play an important role to examine entire tendency of soil properties. Especially, the Atterberg limits have a good correlation with compression and shear strength of cohesive soils. However, these values strongly depend on their testing methods. In this study, for Pusan clays the Atterberg limits were peformed under different conditions; for example, four kinds of specimen preparation, two kinds of testing equipment, and four kinds of estimating method. And a laboratory vane test was peformed to compare the undrained shear strength with that of the fall cone test. As experimental results, the value of liquid limit performed for oven-dried sample, followed in ASTM D4318, underestimated by about 10% compared to those of another three methods, irrespective to the used equipments. But the value of plastic limit was not influenced by sample preparation methods and equipments. The liquid limits by one-point methods(Leroueil et al., 1996; Nagaraj et al., 1981) were agreed well with those of different methods. Finally, the undrained shear strength by laboratory vane test was relatively larger than that of fall cone test, and the relationship between both showed a bad trend.

• Tribology and Lubricants
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• v.24 no.6
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• pp.374-377
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• 2008

Due to the environmental concerns, especially the greenhouse effect and GWP (Global Warming Potential), the carbon dioxide was investigated as an alternative natural refrigerant to replace HFCs (HydroFluoroCarbons) in refrigerator or air conditioning systems. Because new compressor with carbon dioxide is going to be operated under the high pressure, the tribology of sliding surfaces in the compressor becomes very important. To improve of wear resistance in compressor parts, especially rotary type, the friction and wear characteristics of improved sliding surfaces between vane and flange were evaluated in this paper. The method of reformed sliding surface, such as micro-dimple processes, was applied on surfaces in order to improve the tribological characteristics, and their performances were evaluated experimentally. The vane-on-flange type lubricated sliding tests were performed with a high pressure wear tester using carbon dioxide. Test results showed that the reformed surfaces were very effective to reduce the friction and the wear amounts of vane surfaces. The method of improved surfaces showed good tribological properties at vane and flange.