• The KSFM Journal of Fluid Machinery
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• v.16 no.6
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• pp.12-18
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• 2013

This paper presents the performance characteristics of a centrifugal blower using the design parameters of an impeller blade. Two design variables, the bending length from the blade trailing edge and bending angles of an impeller blade, are introduced to analyze the effects on the blower performance. Three-dimensional Navier-Stokes equations with shear stress transport turbulence model are introduced to analyze the performance and internal flow of the blower. Relatively good agreement between experimental measurements and numerical simulation at the design flow condition is obtained. Throughout present study, it is known that pressure increases as the bending length from the trailing edge and bending angle increase while efficiency decreases. But efficiency is decreased. Detailed flow field inside the centrifugal blower is also analyzed and compared.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.252-256
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• 1999

In this research, the performance predictions of the submersible mixer were investigated. The variation of the performance characteristics by changing the impeller design parameters were discussed through the flow calculation results by using a commercial program, FLUENT. The performance of the submersible mixers is related to the velocity diffusion profiles downstream of the impeller and also the required input motor power to mix the fluid. In this study, the various design parameters such as the number of blade, the hub and tip diameters, the impeller blade profiles and revolution speed of the blades were taken for the fixed values. The blade sweep direction, the chord length distribution along with the radius of the blade and the inlet blade angle were changed to make different testing models. The flow calculation results show the effect of the changed design parameters on the performance of the submersible mixers and also give some helpful information for designing more efficient submersible mixers.

• Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.27-32
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• 2011

The purpose of this study was to suggest 10 kinds of case and perform Mixed-flow pump optimum design and performance analysis depending on the shape of the impeller for suitable to water jet propulsion system. H20 was applied to the material properties, to analysis conditions for water jet axial impeller 1000 rpm given analysis was performed. Interpretation for each case as a result of speed, pressure, flow rate, calculate the thrust at the Inlet Angle $30^{\circ}$ and Outlet Angle $30^{\circ}$ could see a persistence of optimal performance.

• Korean Journal of Computational Design and Engineering
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• v.20 no.3
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• pp.312-319
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• 2015

The grinding and furbishing process as the finishing process for molds include the works such as the grinding, buffing, lapping and polishing among others. A finishing tool unit is applied to this finishing process for the burr, lapping, polishing and others of molds. A finishing tool unit can carry out the flexible machining, depending on the machining allowance for objects to be cut on the basis of the instrumental driving mechanism which enables the up, down, left and right floating, which is applied in link with the dedicated cutters and robot machining systems. This study selected the shape to increase the rotatory force of an impeller when air is discharged during the driving of a finishing tool unit, and reflected it to the impeller designing. In addition, the study analyzed each flow velocity and pressure distribution per air pressurization value and finally analyzed the rotating torque to suggest the optimal conditions in designing impellers.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.3
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• pp.132-139
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• 2003

The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-sized centrifugal compressor are investigated. Especially, numerical analyses are conducted for the centrifugal compressor with both a circular casing and a volute one. The optimum design for each element (i.e., impeller, diffuser and casing) is important to develop an efficient and compact compressor using alternative refrigerant as working fluids. Typical rotating speed of the compressor is in the range of 40,000∼45,000 rpm. The impeller has backswept blades due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside an entire impeller, vaneless diffuser and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For computations of compressible turbulent flow fields, the continuity and time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained for various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. The static pressure around the casing and pressure difference between the inlet and outlet of the compressor are measured for the circular casing.

• International Journal of Fluid Machinery and Systems
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• v.7 no.3
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• pp.86-93
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• 2014

This paper describes performance enhancement of a regenerative blower used for a 20 kW fuel cell system. Two design variables, bending angle of an impeller and blade thickness of an impeller tip, which are used to define an impeller shape, are introduced to enhance the blower performance. Internal flow of the regenerative blower has been analyzed with three-dimensional Navier-Stokes equations to obtain the blower performance. General analysis code, CFX, is introduced in the present work. SST turbulence model is employed to estimate the eddy viscosity. Throughout the numerical analysis, it is found that the thickness of impeller tip is effective to increase the blower efficiency in the present blower. Pressure is successfully increased up to 2.8% compared to the reference blower at the design flow condition. And efficiency is also enhanced up to 2.98 % compared to the reference one. It is noted that low velocity region disturbs to make strong recirculation flow inside the blade passages, thus increases local pressure loss. Detailed flow field inside the regenerative blower is also analyzed and compared.

• The KSFM Journal of Fluid Machinery
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• v.15 no.5
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• pp.32-36
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• 2012

The positive displacement pump and the regenerative pump are widely used in the range of low specific speed, $n_s{\leq}100$[rpm, m3/min, m]. The positive displacement pump is not suitable for miniaturization and operation in high rotational speed. The regenerative pump has a problem with large leakage flow and low efficiency. While the centrifugal pump has advantages of high efficiency, miniaturization and high rotational speed, efficiency drops sharply with decrease in specific speed. Therefore the purpose of this study is to design a new type of centrifugal pump that has advantages of centrifugal pumps in operation in low specific speed. The name of this new type of pump was called 'Pipe type centrifugal pump', since the flow path through the impeller is simple circular pipe. Due to the simple shape of impeller, the manufacturing process is simple and cost is low. There is strong jet flow at the outlet of the impeller. This jet induces flow path loss, meridional dynamic pressure loss and mixing loss. Large disk friction makes the efficiency be limitted in the range of low specific speed. Even though the loss and the low efficiency, 'Pipe type centrifugal pump' represents stable performance, affordable pressure ratio and efficiency better than that of other low specific speed pumps.

• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.57-61
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• 2020

Cooling by gas helium circulation can be used for various HTS (high temperature superconductor) magnets operating at 20~40 K, and a cryogenic blower is an essential device for circulating gas helium in the cooling system. The performance of the cryogenic blower is determined by various design parameters such as the impeller diameter, the blade number, the vane angle, the volute cross-sectional area, and the rotating speed. The trailing edge angle and the height of impeller vane are also key design factors in determining the blower performance. This study describes the design, fabrication and performance evaluation of cryogenic blower to produce a flow rate of 30 g/s at 5 bar, 35 K gas helium. The impeller shape is designed using a specific speed/specific diameter diagram and CFD analysis. After the fabrication of the cryogenic blower, a test equipment is also developed using a GM cryocooler. The measured flow rates and the pressure differences are compared with the design values at various rotating speeds and the results show a good agreement. Isentropic efficiency is also evaluated using the measured pressures and temperatures.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.435-441
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• 2015

In this study, a method for optimal design of impeller and diffuser blades in the centrifugal compressor using response surface method (RSM) and multi-objective genetic algorithm (MOGA) was evaluated. A numerical simulation was conducted using ANSYS CFX with various values of impeller and diffuser parameters, which consist of leading edge (LE) angle, trailing edge (TE) angle, and blade thickness. Each of the parameters was divided into three levels. A total of 45 design points were planned using central composite design (CCD), which is one of the design of experiment (DOE) techniques. Response surfaces that were generated on the basis of the results of DOE were used to determine the optimal shape of impeller and diffuser blade. The entire process of optimization was conducted using ANSYS Design Xplorer (DX). Through the optimization, isentropic efficiency and pressure recovery coefficient, which are the main performance parameters of the centrifugal compressor, were increased by 0.3 and 5, respectively.

• The KSFM Journal of Fluid Machinery
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• v.3 no.2 s.7
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• pp.31-35
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• 2000

In this research, the performance predictions of the submersible mixer were investigated. The variation of the performance characteristics by changing the impeller design parameters were discussed through the flow calculation results by using a commercial program, FLUENT. The performance of the submersible mixers is related to the velocity diffusion profiles downstream of the impeller and also the required input motor power to mix the fluid. In this study, the various design parameters such as the number of blade, the hub and tip diameters, the impeller blade profiles and revolution speed of the blades were taken for the fixed values. The blade sweep direction, the chord length distribution along with the radius of the blade and the inlet blade angle were changed to make different testing models. The flow calculation results show the effect of the changed design parameters on the performance of the submersible mixers and also give some helpful information for designing more efficient submersible mixers.