• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.4
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• pp.56-62
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• 2008

This study presents the aerodynamic design and numerical analysis results on a transonic centrifugal compressor which is used for gas turbine systems. Mean-line analysis and quasi-3D analysis are used for the aerodynamic design, and Reynolds-averaged Navier-Stokes analysis is applied to flow analysis of the compressor. The aerodynamic parameters for a transonic compressor, such as pressure coefficient, swirl parameter, blade loading, are discussed, and flow characteristics in the impeller and diffuser are discussed.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.570-574
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• 2009

벽 근처에서의 흐름(near wall flow)을 해석하기 위한 낮은 레이놀즈수 수정(low-Reynolds number modification)을 포함하는 통계학적 난류모형을 이용한 3차원 비정상 레이놀즈-평균 나비어-스톡스 (URANS) 계산을 실시하여 사각형 수로에서의 중력류를 모의하였다. 3차원 계산 결과를 2차원 URANS 모의에 의한 계산 결과 그리고 실험결과와 비교하였다. 이 연구 결과는 적정 시 공간적 수치해상도를 가지고 벽 근처에서의 흐름을 주의 깊게 직접 해석하는 3차원 URANS 수치모의는 2차원 계산으로는 해석할 수 없는 대규모 Kelvin-Helmholtz 와구조 (vortical structure)의 붕괴(breakdown) 그리고 중력류 선단부에서 발달하는 Lobe-and-Cleft 흐름 불안정 등을 포함하는 중력류의 동적 특성을 높은 정확도로 재현할 수 있음을 보여준다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.17-25
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• 2020

In this study, three-dimensional fluid flow analyses have been performed in order to investigate the performance characteristics of a horizontal axis tidal turbine (HATT) by solving three-dimensional Reynolds-averaged Navier-Stokes equations utilizing the shear-stress-transport turbulence model. The computational domain for the flow analysis has been composed of hexahedral grids, and the grid dependency test has been carried out so as to determine the optimum grid size. Performance characteristics of the HATT have been investigated in consideration of the effects of hub nose geometry, inflow angle, and the tower. It has been found that the power output can be enhanced along with an increase of the ratio of the length to the diameter of the turbine nose, and the power of HATT has been reduced by approximately 10% when the primary fluid flow had an inflow angle of 15°. The power output of downstream HATT is found to be lower than that of the upstream HATT by about 1%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.3
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• pp.201-209
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• 2011

An unsteady RANS analysis study of the 3-D flow around the NREL Phase VI horizontal axis wind turbine(HAWT) was performed using sliding mesh approach. Two different analysis models such as rotor-only and rotor with tower/nacelle were constructed to investigate the blade/tower interaction. Analysis results for the rotor with tower/nacelle were compared with the corresponding NREL's experimental data which produced fairly good validation of the present CFD model. Comparison of flows around those two models also clearly showed the blade/tower interaction even it was small for upwind configuration. Other visualization results and integrated aerodynamic loads including torque of the blade demonstrated the effective unsteady flow simulation capability of the present CFD model.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.151-159
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• 2020

This study aimed to investigate the performance characteristics of vertical axis turbine of tidal energy convertor. Three-dimensional Reynolds-averaged Navier-Stokes equation with shear stress transport turbulence model has been solved to analyze the fluid flow of the vertical axis turbine. The hexahedral grids have been used to construct the computational domain and the grid dependency test has been performed to find the optimum grid system. Four steps have been carried out to design the vertical axis turbine of the 100 kW class tidal energy convertor.

• The KSFM Journal of Fluid Machinery
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• v.3 no.1 s.6
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• pp.19-27
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• 2000

A numerical study is presented for analysis of three-dimensional incompressible turbulent flows in a multi-blade centrifugal fan. Reynolds-averaged Navier-Stokes equations with a standard $k-{\espilon}$ turbulence model are discretized with finite volume approximations. The computational area is divided into three blocks; inlet core, impeller and scroll parts, which are linked by a multi-block method. The flow inside of the fan is regarded as steady flow, and the mathematical models for the impeller forces were established from a cascade theory and measured data. Empirical coefficients are obtained comparing between computational and experimental results for the case without scroll, and are employed to simulate the flow through the impeller with scroll. In comparisons with experimental data, the validity of the mathematical models for the impeller forces was examined. The characteristics of the flow in the scroll were also discussed.