• 한국유체기계학회 논문집
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• 제5권4호
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• pp.32-39
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• 2002

The purpose of this 3-D numerical simulation is to calculate and examine the complex 3-D stall phenomena on the rotor blade and wake distribution of the wind turbine. The flow characteristics of 500kW Horizontal Axis Wind Turbine (HAWT) are compared with the calculated 3-D stall phenomena and wake distribution. We used the CFX-TASCflow to predict flow and power characteristics of the wind turbine. The CFD results are somewhat consistent with the BEM (Blade Element Momentum) results. And, the rotational speed becomes faster, the 3-D stall region becomes smaller. Moreover, the pressure distribution on the pressure side that directly gets the incoming wind grows high as it goes toward the tip of the blade. The pressure distribution on the blade's suction side tells us that the pressure becomes low in the leading edge of the airfoil as it moves from the hub to the tip. However, we are not able to precisely predict on the power coefficient of the rotor blade at the position of generating complex 3-D stall region.

• 한국유체기계학회 논문집
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• 제18권1호
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• pp.44-50
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• 2015

Labyrinth seals are commonly used in various kinds of turbomachinery to reduce leakage flow. In the present 3D CFD analysis of see-through-type labyrinth air seal, the methodology of determining leakage and rotordynamic coefficients is suggested with the relative coordinate system for steady-state simulation. The leakage flow and rotordynamic forces predicted by using different solvers and turbulent models of FLUENT are compared with the results of the existing bulk-flow analysis code LABYSEAL.FOR and experiment. The present CFD result of direct stiffness(K) shows only improvement in prediction. The results of leakage and rotordynamic coefficients as well as computing time are sensitive against the used solver and turbulent model.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.396-401
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• 2002

The purpose of this 3-D numerical simulation is evaluate the application of a commercial CFD code to predict 3-D flow characteristics of wind turbine. The experimental approach, which has been main method of investigation, appears to be its limits, the cost increasing disproportionally with the size of the wind turbines, and is hence mostly limited to observing the phenomena. Hence, the use of Computational Fluid Dynamics (CFD) techniques and Wavier-Stokes solvers are considered a very serious contender. The flow solver CFX-TASCflow is employed in all computations presented in this paper. The 3-D flow separation and the wake distribution of 2 bladed Horizontal Axis Wind Turbines (HAWTs) are compared to Heuristic model and visualized result by NREL(National Renewable Energy Laboratory). Simulated 3-D flow separation structure on the rotor blade is very similar to Heuristic model and the wake structure of the wind turbine is good agree with visualized results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.447-450
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• 2002

The purpose of this 3-D numerical simulation is to calculate and examine a 500 kW Horizontal Axis Wind Turbine (HAWT) power performance and 3-D rotor flow characteristics, which are compared to calculation data from Delft University. The experimental approach, which has been the main method of investigation, appears to be reaching its limits, the cost increasing relate with the size of wind turbines. Hence, the use of Computational Fluid Dynamics (CFD) techniques and Navier-Stokes solvers is considered a very serious contender. We has used the CFD software package CFX-TASCflow as a modeling tool to predict the power performance and 3-D flow characteristics of a wind turbine on the basis of its geometry and operating data. The wind turbine with 40m diameters rotor, it was scaled to compare with the calculation data from delft university. The HAWT, which has eight-rpm variations are investigated respectively. The pitch angle is $+0.5^{\circ}$and wind speed is fixed at 5m/s. The tip speed ratio (TSR) of the HAWT ranging from 2.89 to 9.63.

• 한국분무공학회지
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• 제17권2호
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• pp.77-85
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• 2012

The CFD simulation of diesel spray tip penetrations were compared with 0-D simulation for experimental data obtained with common rail injection system. The simulated four injection patterns include single, pilot and split injections. The CFD simulation of the spray penetration over these injection patterns was performed using the KIVA-3V code, which was implemented with both the standard KIVA spray and original gas jet sub-models. 0-D simulation of the spray tip penetration with time-varying injection profiles was formulated based on the effective injection velocity concept as an extension of steady gas jet theory. Both the CFD simulation of the spray tip penetration with the standard KIVA spray model and 0-D simulation matched better with the experimental data than the results of the gas jet model for the entire fuel injection patterns.

• 항공우주기술
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• 제4권1호
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• pp.39-44
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• 2005

로터의 성능 예측 검증을 위해 tilt rotor aeroacoustic model(TRAM)에 대한 3차원 CFD 해석을 수행하였고 로터 파워 효과에 의한 영향을 분석하기 위해 수치해석을 행하였다. 수치 기법은 multiple reference method(MRF)와 sliding mesh technique을 사용하였다. TRAM 실험치와 비교 결과 정지 비행시에는 수치해석이 실험보다 적은 추력을 예측하였고 전진 비행시에는 실험결과와 매우 유사한 결과를 예측하였다. 로터효과를 고려한 비행체의 양력은 감소하고 항력 및 피칭 모멘트는 거의 변화가 없는 것으로 판단된다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권1호
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• pp.65-71
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• 2011

Seakeeping analysis has progressed from the linear frequency-domain 2D strip method to the nonlinear timedomain 3D panel method. Nevertheless, the violent free surface flows such as slamming and green water on deck are beyond the scope of traditional panel methods based on potential theory. Recently, Computational Fluid Dynamics (CFD) has become an attractive numerical tool that can effectively deal with the violent free surface flows. ABS, as a classification society, is putting forth a significant amount of effort to implement the CFD technology to the advanced strength assessment of modern commercial ships and high-speed naval craft. The main objective of this study is to validate the CFD technology as a seakeeping tool for ship design considering fully nonlinear three-dimensional slamming and green water on deck. The structural loads on a large container carrier were successfully calculated from the CFD analysis and validated with segmented model test measurements.

• 대한기계학회논문집B
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• 제34권1호
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• pp.61-66
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• 2010

최근 본 연구그룹은 국소적인 종횡비 증가를 기반으로 수평 분리벽 없이 검체의 3 차원 집속을 구현하는 3 차원 유체역학 집속 미세유체 장치(3D-HFMD)를 제안한 바 있다. 본 논문에서는, 다양한 형상 및 유동 조건에 따른 3D-HFMD 의 3 차원 유체역학 집속 거동 영향에 대한 연구를 수행하였다. 이에 3 차원 전산유체역학(CFD) 시뮬레이션을 통해, 형상 및 유동 조건 변화에 대한 기존의 미세유체 장치와 본 연구 그룹이 제안한 3D-HFMD의 3 차원 유체역학 집속의 매개변수 연구를 수행하였다. 수행된 CFD 시뮬레이션 결과를 바탕으로 3 차원 집속을 위한 채널 형상 디자인 및 유동 조건을 제안하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.1-1
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• 2010

With the power of supercomputers increasing exponentially, there is an insatiable need for more advanced multi-disciplinary aerospace CFD simulations. A particular current interest is the 3D viscous turbulent simulation of the highly nonlinear aspects of aero-icing. The applications of CFD in that field are literally light-years behind aerodynamics, with a significant number of users still mired in correlations, or 2D, inviscid, incompressible, and, yes, Panel Methods simulations! Thus, the disparity of tools between aerodynamics and icing departments within an organization leads to a disconnect that makes ice protection a downstream isolated process that is not an integral part of the aerodynamic behavior of an aerospace system (aircraft, rotorcraft, jet engine, UAV, etc.). While 3D RANS has been recently introduced, it is still considered computationally too demanding for industry when wide parametric studies for certification are required. In addition, not unlike the situation in aerodynamics say 20 years ago, naysayers are at every corner claiming that CFD is not reliable and is of limited use.

• 한국도로학회논문집
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• 제19권4호
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• pp.19-25
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• 2017

PURPOSES : In this paper, the flow of construction material was simulated using computational fluid dynamics in a 2D axisymmetric condition to evaluate the effect of initial or varying material properties on the final shape of a specimen. METHODS : The CFD model was verified by using a well-known analytical solution for a given test condition followed by performing a sensitivity analysis to evaluate the effect of material properties on the final shape of material. Varying dynamic viscosity and yield stress were also considered. RESULTS : The CFD model in a 2D axisymmetric condition agreed with the analytical solution for most yield stress conditions. Minor disagreements observed at high yield stress conditions indicate improper application of the pure shear assumption for the given material behavior. It was also observed that the variation of yield stress and dynamic viscosity during curing had a meaningful effect on the final shape of the specimen. CONCLUSIONS : It is concluded that CFD modeling in a 2D axisymmetric condition is good enough to evaluate fluidal characteristics of material. The model is able to consider varying yield stress and viscosity during curing. The 3D CFD-DEM coupled model may be required to consider the interaction of aggregates in fluid.