• International Journal of Fluid Machinery and Systems
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• v.5 no.3
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• pp.117-125
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• 2012

In the present experimental study, the authors try to clarify the characteristics of the flow around and inside a cross-flow impeller in a typical geometry, over a wide parameter range of an aspect ratio $L/D_2$. In order to eliminate the complicated casing factors, the impeller rotates in open space without any casings. As a result, by using hot wire anemometer measurements and by conventional flow visualisations with a particle image velocimetry technique, the authors show that both the outflow rate and the maximum vorticity attain the maximum for $L/D_2$ = 0.6. In order to investigate the aspect-ratio effect, we further reveal minute fluctuating pressures on an impeller end wall for a singular $L/D_2$ = 0.6. Especially in these pressure measurements, the eccentric vortex is prevented to revolute by the insertion of a tongue, in order to consider the spatial structure of flow more precisely.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.3
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• pp.43-51
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• 1994

The design technique of turbo pumps has been developed due to an increasing demand from related industrial fields. But infant stage of turbomachinery in the domestic industry needs more fundamental design method. Among various types of pumps, centrifugal pump was chosen because of its wide industrial application. It is difficult to decide the correct specification of centrifugal impeller, because of its complex flow analysis at the inlet, passage and outlet. This study is limited on the impeller blade design and its related performance analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3262-3271
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• 1996

Flow patterns were measured in a shrouded centrifugal impeller. The flow rate in measurements was fixed at the value corresponding to a nearly zero incidence at the blade inlet. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes from the inlet to the outlet of impeller rotating at 700 rpm, and the static pressure distribution along flow passage and the slip factor at impeller outlet were calculated from the measured values. From these measured data, the primary and secondary flows, the wake production and the static pressure rise in the impeller passage were investigated. Furthermore, the secondary flow patterns and the wake's location in this impeller passage were compared with those of the unshrouded impeller.

• 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.

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.29-38
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• 2010

This paper presents a procedure for the design optimization of a centrifugal compressor. The centrifugal compressor consists of a centrifugal impeller, vaneless diffuser and volute. And, optimization techniques based on the radial basis neural network method are used to optimize the impeller of a centrifugal compressor. The Latin-hypercube sampling of design-of-experiments is used to generate the thirty design points within design spaces. Three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model are discretized by using finite volume approximations and solved on hexahedral grids to evaluate the objective function of the total-to-total pressure ratio. Four variables defining the impeller hub and shroud contours are selected as design variables in this optimization. The results of optimization show that the total-to-total pressure ratio of the optimized shape at the design flow coefficient is enhanced by 2.46% and the total-to-total pressure ratios at the off-design points are also improved significantly by the design optimization.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.18-25
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• 1996

Power input in stirred vessel is especially important in the design of mixers, as well as the evaluation of mixing processes. A type of baffles in mechanically agitated vessels and power employed are major factors that determine the stirring efficiency in a large scale, multi-step processes. In the present study, power input in the totally baffled agitated vesseles was compared systematically in connection with several previous studies and adequate power input correlation was found to be : $Np_{(pitch)}=({\theta}/90^{\circ})Np_{(90^{\circ})}$ Power number correlation was dependent upon the distance of among the impeller in the agitated vesseles, as follows : $$Np=7.09(n_p)^{0.7}(\frac{b_(double)}{d})(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$<2 $$Np=8.73\{(n_p)^{0.7}(\frac{b_{(double)}}{d})\}^{0.7}(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$>2.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.21-26
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• 2016

The objective of present study is to assess the performance of the first stage compressor in a total 3-stage 5000 HP-level turbo compressor. CFD commercial code, CFX has been used to predict three-dimensional flow characteristics inside of the impeller. Shear Stress Transport (SST) model has been used to simulate turbulent flows through Reynolds-averaged Navier-Stokes (RANS) equations. Grid dependency has been also checked to get optimal grid distribution. Numerical results have been compared with the experimental test results to elucidate performance characteristics of the present compressor. In addition, flow characteristics of the impeller only have been studied for various blade configurations. Angular offset in leading edge of the blade has been selected for the optimal blade design. Performance characteristics in region of low mass flow rate and high pressure ratio between the impeller entrance and exit have been investigated for the selection of optimal blade design. Also, flow instability such as stall phenomena has been studied and anti-stall characteristics have been checked for various blade configurations in the operational window.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.7
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• pp.445-453
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• 2017

This paper presents the hydraulic design an impeller and radial diffuser of a high-pressure multistage pump for reverse osmosis. The flow distribution and hydraulic performance for the meridional design of the impeller were analyzed numerically. Optimization was conducted based on the response surface method by varying the hub and shroud meridional curvatures, while maintaining the impeller outlet diameter, outlet width, and eye diameter constant. The analysis results of the head and efficiency with the variation in the impeller meridional profile showed that angle of the front shroud near the impeller outlet (${\varepsilon}Ds$) had the highest effect on head increase, while the hub inlet length ($d_{1i}$) and shroud curvature (Rds) had the highest effect on efficiency. From the meridional profile variation, an approximately 0.5% increase in efficiency was observed compared with the base model (case 25).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3272-3281
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• 1996

The flow analysis method which had been developed for the numerical calculation of 3-dimensional, incompressible and turbulent flow within an axial compressor was extended to the flow field within centrifugal impeller. In this method based on the SIMPLE(Semi Implicit Method Pressure Linked Equations) algorithm, the coordinate transformation was adopted and the standard k-.epsilon. model using wall function was used for turbulent flow analysis. The calculated flow fields have agreed very well with measurement results. Especially, 3-dimensional and viscous flow characteristics including secondary flows, jet-wake flow and decreased pressure rise along impeller passage, which can't be predicted by inviscid Q3D calculation were predicted very reasonably.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.89-94
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• 2002

A commercial CFD code is used to calculate the 3-D viscous flow field within the centrifugal pump impeller. Design conditions are changed by impeller inlet(9.3mm, 12.2mm) and outlet breadth(6.65mm, 6.85mm). Numerical calculation was performed by changing flow rate from 8 to 26m$^{3}$/hr. Computation results shows that total head is increased at the larger inlet and outlet breadth than the others. And when the flow rate is increasing, the total head was decreased. The maximum efficiency of pump is shown at the design flow rate(16m$^{3}$/hr). In this study shows that the calculated results are good agreements with analysis results of design condition.