• 연구논문집
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• s.24
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• pp.107-117
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• 1994

In aerodynamic design of centrifugal compressors, impellers are designed through preliminary design and blade profile generation. In order to find out faults of the initially designed impellers, the detailed informations about internal flow phenomena such as pressure distribution, flow separation, blade loading, etc are essential. These informations can be acquired with flow measurements or computational flow analyses. In this study, we calculated 3-D viscous flow in 4 back-swept impellers which were designed in our laboratory, and analyzed the flow characteristics which influence the performance of impellers.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.672-677
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• 2001

This study has been conducted to design the high efficiency centrifugal compressor for a HFC-134a. The 2-stage centrifugal compressor consists of inlet guide vanes, two impellers with splitters, a deswirler, a vaneless diffuser and a volute casing. We have designed the high efficiency centrifugal compressor by applying the repeated design procedure including a meanline design, a 3D geometry generation of 1st and 2nd impellers etc. Also, a fluid dynamic calculation of impellers and deswirler have been conducting using a commercial code STAR-CD.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1129-1138
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• 1999

This paper presents a systematic two-zone modeling for reliable performance prediction of centrifugal compressors. In order to improve the predictive capability, a modified jet slip factor is developed and new corrections for the wake flow deviation and mass fraction are suggested based on the comprehensive experimental data of the three Eckardt impellers. The proposed two-zone modeling is tested against nine sets of measured data of centrifugal compressors. The results are also compared with those obtained by the mean streamline analysis. It was found that the predictions by the present two-zone modeling agree fairly well with experimental data for a variety of centrifugal compressors over the wide operating conditions.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.506-511
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• 2009

In order to improve the bacterial cellulose(BC) production yield, centrifugal and inclined centrifugal impellers were developed. A 6 flat-blade turbine impeller was used as a control system. The flow pattern in the fermenter and volumetric oxygen transfer coefficient($k_La$) of these fermentation systems were studied. Fermentations were carried out for the production of BC by G. hansenii PJK in a 2-L jar fermenter equipped with new impellers. Liquid medium was circulated from the bottom, through the cylinder of the impeller and to the wall. The volumetric oxygen transfer coefficients, $k_La$, of inclined centrifugal and centrifugal impeller systems at 100 rpm were 23 and 15% of the conventional turbine impeller system, respectively. However, the conversion of microbial cells to cellulose non-producing mutant decreased and this results in the increase in BC production at low rotating speed of impellers.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.464-468
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• 2003

A general program of three dimensional profile design of impellers for centrifugal/fixed-flow compressors is successfully commercialized using Bezier curves and quasi-3D flow analysis methods. Control points for meridional hub and shroud contours and blade camberline angles are arbitrarily changed to give smooth Bezier curves. With specified blade normal thicknesses, contructed geometry is instantly analyzed using flow analysis methods to be checked.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.240-243
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• 2008

In this paper, the design of Centrifugal Compressor which is used in sizes 50 horse power has 8 pressure ratio and numerical analysis of the flow within compressor varying tip clearance length are performed. To get high pressure ratio with low power the exit height of impellers is low but compressor has very high speed of revolution. So compressor has high specific speed although mass flow rate is very small. The shape of impellers at the first stage is carried out. Flow and performance characteristics of impellers has been analyzed by using a commercial CFD program, $Fine^{TM}$/turbo. The result shows that loss coefficient is affected by tip clearance length and compressor has proper tip clearance length. It is possible to decrease loss by selecting apt tip clearance length.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.5
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• pp.321-327
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• 2016

This paper presents the application of airfoil impeller for enhancement of aerodynamic performance of a high speed centrifugal fan. Three airfoil impellers are proposed, considering the maximum thickness and the location of maximum thickness of the airfoil. C4 airfoil thickness distribution is applied to the three airfoil impellers. The impellers are evaluated using CFD (computational fluid dynamics) and suction power test. From the results, it is confirmed that flow separations on the pressure side of the impeller blades and the pressure side of diffuser blades are reduced when airfoil blade is applied to the impellers. It is also confirmed that with the centrifugal fan having airfoil impellers, there is an increase in fan efficiency by approximately 3% and reduction in specific sound level by approximately 1.3 dB(A).

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1869-1875
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• 2001

The paper presents computational and flow visualization results on a centrifugal blood pump. 4 impeller designs were tested at a rotational speed of 2000 rpm using blood analog as working fluid. All impellers have seven blades but of different geometry (Impellers A3, A4, B2 and R7). Flow visualization within the impeller passages was conducted using an image de-rotation system. A pair of large scale vortices was found within the blades of impeller R7 while a single vortex was found in most of the passages of backward facing impellers (Impellers A3, A4 and B2). To establish the effects of blade geometry on blood cells, CFD was used to simulate the blade to blade flow to provide an estimate of the maximum shear stress. The results showed that though most of the stresses within the blade passages are below a threshold level of 150 N/m$^2$for extensive erythrocyte damage to occur, there are some regions near to the leading edge of the pressure side where the shear stresses a abode threshold level.

• Journal of computational fluids engineering
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• v.3 no.1
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• pp.30-36
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• 1998

The three dimensional Navier-Stokes equations in rotational coordinate are solved using a multigrid algorithm for the calculations of turbulent flows in centrifugal compressor impellers. Some numerical studies are made in applying the multigrid algorithm for the turbulent flow calculations with the standard κ-ε equations. The present method is used to calculate the flow fields of Mizuki's B-type and Niigata Ms. 350 centrifugal compressor impellers. Fast convergent steady-state solutions are carefully examined, comparing the static pressure distributions along the impeller flow passage and also in the diffuser with experimental data. Performance of a centrifugal compressor system is also numerically validated by comparing the performances of the impeller and the diffuser individually.

• International Journal of Fluid Machinery and Systems
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• v.8 no.2
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• pp.94-101
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• 2015

To investigate the influence of blade profiles on cavitation behavior in impeller of centrifugal pump, a centrifugal pump with five different blade profiles impellers are studied numerically. The impellers with five different blade profiles (single arc, double arcs, triple arcs, logarithmic spiral and linear-variable angle spiral) were designed by the in-house hydraulic design code using geometric parameters of IS 150-125-125 centrifugal pump. The experiments of the centrifugal pump have been conducted to verify numerical simulation model. The numerical results show that the blade profile lines has a weak effect on cavitation inception near blade inlet edge position, however it has the key effect on the development of sheet cavitation in impeller, and also influences the distribution of sheet cavitation in impeller channels. A slight changing of blade setting angle will induce significant difference of cavitation in impeller. The sharp changing of impeller blade setting angle causes obvious cavitation region separation near the impeller inlet close to blade suction surface and much more flow loss. The centrifugal pump with blade profile of setting angle gently changing (logarithmic spiral) has the super cavitation performance, which means smaller critical cavitation number and lower vapor cavity volume fraction at the same conditions.