• Journal of KSNVE
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• v.8 no.6
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• pp.1150-1157
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• 1998

In this Paper, we present an efficient method for finite element vibration analysis of constantly rotating structures with cyclic symmetry, which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A structure with cyclic symmetry is composed of circumferentially repeated substructures with the same geometry. Being only one substructure modeled. the dynamic characteristics of the structure can be analyzed systematically. rapidly and exactly using discrete Fourier transform by means of a computer with small memory.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.416-421
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• 2011

Recently there has been increase in need for high precision and high speed machining due to economic and environmental reasons. It is a very important issue that determines the optimal preload that is to be applied to bearings in order to satisfy the performance required in bearings according to its operation conditions. This study introduces a variable preload device that can automatically adjust the preload applied in a machine tool spindle using centrifugal force as opposed in existing rubber instrument. In this study, the deformation of the rubber device by the centrifugal force is analyzed and it is discussed that the proposed device can be worked properly through changes of the collar density.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.179-190
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• 2000

The main object of this study was to investigate experimentally the characteristics of electrostatic cyclone-bag filter with upper tangential inlet in order to overcome the low collection efficiency for the submicron particle and high pressure drop which were main problems of general fabric bag filters. The experiment was carried out for the analysis of collection efficiency and pressure drop of electrostatic cyclone-bag filter comparing to those of fabric bag filter with various experimental parameters such as the inlet velocity(filtration velocity) and applied voltage etc. In the results the upper tangential inlet type showed higher collection efficiency for submicron particles below 2 ${\mu}{\textrm}{m}$ in diameter than that of center inlet and over 99.9% for overall collection efficiency. Pressure drop reduction ratios were shown as 40-50% for the applied voltage 0kV by centrifugal force and 70-90% for 20k V by the centrifuga and electrostatic force with the tangential inlet velocity (12-21m/s)

• The KSFM Journal of Fluid Machinery
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• v.7 no.3 s.24
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• pp.32-38
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• 2004

Shape of a multi-blades centrifugal fan is optimized by response surface method based on three-dimensional Navier-Stokes analysis. For numerical analysis, Reynolds-averaged Navier-Stokes equations with standard $k-{epsilon}$ turbulence model are transformed into non-orthogonal curvilinear coordinate system, and are discretized with finite volume approximations. Due to the large number of blades in this centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models for economic calculations. Optimizations with and without constraints are carried out. Design variables, location of cur off, radius of cut off, expansion angle of scroll and width of impeller were selected to optimize the shapes of scroll and blades. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, the efficiency was successfully improved. The correlation of efficiency with relative size of inactive zone at the exit of impeller is discussed as well as with average momentum fluxes in the scroll.

• Journal of Environmental Science International
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• v.10 no.5
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• pp.351-358
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• 2001

The main purpose of this study was to investigate the characteristics of cylindrical electrostatic precipitator with centrifugal effect in viewpoints of pressure drip and collection efficiency, experimentally. The experiment was carried out for the analysis of current-voltage, pressure drop and collection efficiency with various experimental parameters such as the applied voltage, inlet velocity, inlet size and inlet type(upper and bottom), etc. In the results, the pressure drops were estimated as 27~54, $34~63mmH_2O$ for inlet size $15mm{\tiems}30mm$ and $30mm{\tiems}60mm$, respectively. The collection effeciencies were shown over 90% with the small inlet size($15mm{\tiems}30mm$) for the applied voltage 40kV, inlet velocity(15~21m/s), and 51~89% with the large inlet size ($30mm{\tiems}60mm$). Moreover, in the applied voltage 0kV and inlet size $15mm{\tiems}30mm$, the collection efficiency induced by centrifugal force was represented as about 35% with inlet velocity 15 - 21m/s.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2157-2161
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• 2003

In this paper, the response surface method using three-dimensional Navier-Stokes analysis to optimize the shape of a forward-curved blades centrifugal fan, is described. For numerical analysis, Reynolds-averaged Navier-Stokes equations with standard k-e turbulence model are transformed into non-orthogonal curvilinear coordinate system, and are discretized with finite volume approximations. Due to the large number of blades in forward-curved blades centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models for economic calculations. Linear Upwind Differencing Scheme(LUDS) is used to approximate the convection terms in the governing equations. SIMPLEC algorithm is used as a velocity-pressure correction procedure. Design variables, location of cur off, radius of cut off, expansion angle of scroll and width of impeller were selected to optimize the shapes of scroll and blades. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, the efficiency was successfully improved. It was found that the optimization process provides reliable design of this kind of fans with reasonable computing time

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.455-460
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• 2012

In this paper, an experimental and numerical investigation of transition characteristics in a square-sectional curved duct flow under Centrifugal force is presented. The experimental study is carried out to measure axial velocity profiles by using Laser Doppler Velocimeter (LDV) system. Computational fluid dynamic (CFD) simulation was performed using the commercial CFD code FLUENT to investigate the transition characteristics. The flow development is found to depend upon Dean number and curvature ratio. The velocity profiles in center of the duct have lower value than those of the inner and outer walls because of the centrifugal forces.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.385-390
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• 2003

Shape of a multi-blades centrifugal fan is optimized by response surface method based on three-dimensional Navier-Stokes analysis. For numerical analysis, Reynolds-averaged Wavier-Stokes equations with standard $k-{\varepsilon}$ turbulence model are transformed into non-orthogonal curvilinear coordinate system, and are discretized with finite volume approximations. Due to the large number of blades in this centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models for economic calculations. Optimizations with and without constraints are carried out. Design variables, location of cur off, radius of cut off, expansion angle of scroll and width of impeller were selected to optimize the shapes of scroll and blades. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, the efficiency was successfully improved. The correlation of efficiency with relative size of inactive zone at the exit of impeller is discussed as well as with average momentum fluxes in the scroll.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.228-233
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• 1992

The objective of this report is to investigate the effect of factors on the centrifugal compaction of concrete piles with design of experiments. The analysis of sludge and measurement of compressive strength of specimens compacted by centrifugal of vibration were performed. As a result, there were some effective factors like unit content of cement, high and middle centrifugal force and time. It was considered that the process of centrifugal compaction of concrete piles could be optimized with these results.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.48-53
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• 2001

A centrifugal fan design code was developed and included in $DasignFan^{TM}$. This program generates forward -curved and backward-curved bladed centrifugal fan data. With the inverse design concept used in the code, the period of designing a fm, which has given aerodynamic performance with minimal acoustic noise, is significantly shortened.. A centrifugal fan design code, developed in this study and included in $DasignFan^{TM}$, predicts the aerodynamic performance by using mean-line analysis and various loss models. In the period of design a lift force distribution between pressure side and suction side of blade is calculated. And then it is used to calculate steady loading noise from the impeller.