• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.77-83
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• 2009

In this study, we conducted resistance and propulsion performance test of ship composed of the Resistance Test, Propeller Open Water Test and Self Propulsion Test using the CFD(Computational Fluid Dynamics). We used commercial RANS(Reynolds Averaged Navier Stokes equation) solver, as a calculating tool. The unstructured grids were used in a bow and stern of ship, having complex shape, for a convenience of generating grids, and the structured grids were adopted in a central hull and rest of hull having a relatively simple shape which is called hybrid grid method. In addition, The sliding mesh method was adopted to rotate a propeller directly in the Propeller Open Water and Self Propulsion Test. The Resistance Test and Self Propulsion Test were calculated using Volume of Fluid (VOF) model and considering a free surface. And all The three cases were applied realizable k-epsilon model as the turbulence model. The results of calculations were verified for the suitability of calculations by comparing MOERI's EFD results.

• 한국전산유체공학회지
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• 제15권1호
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• pp.81-87
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• 2010

In this study, we conducted resistance and propulsion performance test of ship composed of the Resistance Test, Propeller Open Water Test and Self Propulsion Test using the CFD(Computational Fluid Dynamics). We used commercial RANS(Reynolds Averaged Navier Stokes equation) solver, as a calculating tool. The unstructured grids were used in a bow and stern of ship, having complex shape, for a convenience of generating grids, and the structured grids were adopted in a central hull and rest of hull having a relatively simple shape which is called hybrid grid method. In addition, The sliding mesh method was adopted to rotate a propeller directly in the Propeller Open Water and Self Propulsion Test. The Resistance Test and Self Propulsion Test were calculated using Volume of Fluid (VOF) model and considering a free surface. And all The three cases were applied realizable k-epsilon model as the turbulence model. The results of calculations were verified for the suitability of calculations by comparing MOERI's EFD results.

• 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.

• 한국항공우주학회지
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• 제39권3호
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• pp.201-209
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• 2011

NREL Phase VI 수평축 풍력터빈 주위의 3차원 유동에 대하여 미끄럼 격자 기법을 사용한 비정상 RANS 해석을 수행하였다. 블레이드/타워의 간섭영향을 해석하기 위하여 로터단일과 로터/타워/나셀의 2가지 해석 모델을 구축하였다. 로터/타워/나셀의 해석 결과를 NREL의 실험데이터와 비교하여 CFD 해석모델의 유용성을 확인하였다. 두 모델에 의한 해석 결과의 비교를 통하여 비록 상풍형 풍력터빈으로서 작기는 하지만 타워/나셀의 영향이 확실히 나타나는 것을 확인하였다. 다른 가시화 결과와 토크를 포함한 적분 공력하중 등도 구축한 CFD 모델의 비정상 유동해석 능력이 효과적임을 보여주고 있다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.256-261
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• 2008

A CFD analysis of helicopter flowfield in forward flight is considered as non-trivial issue because of the complexity of vorticity-dominated flowfield. In this work, a study on the selection of the proper location for the installation of the Pitot probe is conducted using a CFD code which can deal with the interaction of rotor blade vortex and body. To describe the flow patterns for rotating rotor blades and body, the sliding mesh scheme is utilized. Pressure distributions and flow patterns are also analyzed to identify regions free from the interaction of body and wake induced from rotor blades.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.256-261
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• 2008

A CFD analysis of helicopter flowfield in forward flight is considered as non-trivial issue because of the complexity of vorticity-dominated flowfield. In this work, a study on the selection of the proper location for the installation of the Pitot probe is conducted using a CFD code which can deal with the interaction of rotor blade vortex and body. To describe the flow patterns for rotating rotor blades and body, the sliding mesh scheme is utilized. Pressure distributions and flow patterns are also analyzed to identify regions free from the interaction of body and wake induced from rotor blades.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1406-1411
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• 2009

Stirred tanks are widely used in various industries for mixing operations and chemical reactions for single- or multi-phase fluid systems. In this study, a numerical study was conducted to predict the mixing characteristics in a simple stirred tank. The flow in the model stirred tank was calculated utilizing the multiple reference frame (MRF) and the sliding mesh (SM) capabilities of a commercial CFD code (Fluent 6.2). The results of the flow simulation were analyzed in terms of the mixing efficiency, and the applicability of MRF and SM methods was also discussed.

• Wind and Structures
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• 제14권5호
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• pp.435-447
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• 2011

A Computational Fluid Dynamics model is presented in this study for the simulation of the complex fluid flows with free surfaces inside the Tuned Liquid Column Dampers in horizontal motion. The characteristics of the fluid model of the TLCD in horizontal motion include the free surface of the multiphase flow and the horizontal moving frame. In this study, the time depend unsteady Standard ${\kappa}-{\varepsilon}$ turbulent model based on Navier-Stokes equations is chosen. The volume of fluid (VOF) method and sliding mesh technique are adopted to track the free surface of water inside the vertical columns of TLCD and treat the moving boundary of the walls of TLCD in horizontal motion. Several model solution parameters comprising different time steps, mesh sizes, convergence criteria and discretization schemes are examined to establish model parametric independency results. The simulation results are compared with the experimental data in the dimensionless amplitude of the water column in four different configured groups of TLCDs with four different orifice areas. The predicted natural frequencies and the head loss coefficient of TLCDs from CFD model are also compared with the experimental data. The predicted numerical results agree well with the available experimental data.

• 한국항공우주학회지
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• 제33권2호
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• pp.11-21
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• 2005

3차원 비정렬 격자를 이용한 로터-동체 공력 상호작용에 대한 수치적 해석을 수행하였다. 로터와 동체간의 상대적인 운동을 모사하기 위하여 해석 유동장을 회전하는 부분과 정지된 부분으로 나누어 계산하였다. 블레이드 끝단에서 생성되는 끝단 와류를 포착하기 위하여 준 비정상 적응 격자 기법을 도입하였다. 또한 낮은 속도로 전진 비행하는 헬리콥터 해석을 위해서 저 마하수 예조건화 기법을 적용하였다. 로터-동체 공력 간섭현상에 대한 검증을 위해 Georgia Tech 형상과 NASA에서 실험한 ROBIN 형상에 대한 실험 결과와 비교하여 본 연구 해석 기법이 타당함을 보였다.

• 한국항공우주학회지
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• 제42권1호
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• pp.59-66
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• 2014

프로펠러 추진 항공기의 경우, 프로펠러 power-on 효과는 항공기의 비행성능 및 조종안 정성에 직간접적으로 커다란 영향을 미친다. 본 연구에서는 CFD 기반의 multiple reference frame과 sliding mesh model을 이용하여 power-on 효과가 항공기의 공력특성에 미치는 영향을 해석하였다. 프로펠러 power-on 효과에 의해 양력이 미소하게 증가하고 최대양력이 증가되며 실속이 지연된다. 반면, 프로펠러 power-on 효과에 의해 항력이 크게 증가하여 양항비가 감소된다. 또한, 프로펠러 power-on 효과에 의해 기수내림 피칭 모멘트가 감소하여 종방향 정안정성이 감소된다. 본 연구를 통해 획득한 프로펠러 power-on 해석결과는 항공기 성능 및 조종안정성 해석에 중요한 자료로 활용되어 추진식 프로펠러 항공기 개발에 기여할 수 있을 것으로 기대된다.