• 융합신호처리학회논문지
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• 제24권2호
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• pp.97-102
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• 2023

방향타는 조선 분야에서 중요한 역할을 하기 때문에 방향타의 유체역학적 특성을 조사하기 위해 수치 시뮬레이션이 수행되었다. 유체역학적 힘과 같은 일부 값은 예인 탱크에서 쉽게 측정할 수 있지만, 실험을 통해 압력 분포, 속도 분포, 와류 발생과 같은 유동장에 대한 자세한 정보를 얻기는 어렵다. 본 연구에서는 전산유체역학(CFD)을 이용하여 방향타에 작용하는 유체역학 계수와 레이놀즈수가 미치는 영향을 연구하였다. 상용 전산유체역학 프로그램 Ansys Fluent를 이용하여 방향타 주위의 유동 특성을 연구하였고, 이때 k-epsilon 난류 모델이 사용되었다. 먼저 CFD 상용코드를 이용하여 KCS 방향타의 받음각에 따른 항력계수와 양력계수를 구하였다. 둘째, 동일한 조건에서 2차원 양력계수와 항력계수를 3차원 계수와 비교되었다. 셋째, 레이놀즈수가 유체역학적 힘에 미치는 영향이 연구되었다.

• 대한기계학회논문집B
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• 제20권7호
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• pp.2347-2355
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• 1996

Purpose of the present study is to develop a computational design program for shape optimization, combining the numerical optimization technique with the flow analysis code. The present methodology is then validated in three cases of aerodynamic shape optimization. In the numerical optimization, a feasible direction optimization algorithm and shape functions are considered. In the flow analysis, the Navier-Stokes equations are discretized by a cell-centered finite volume method, and Roe's flux difference splitting TVD scheme and ADI method are used. The developed design code is applied to a transonic channel flow over a bump, and an external flow over a NACA0012 airfoil to minimize the wave drag induced by shock waves. Also a separated subsonic flow over a NACA0024 airfoil is considered to determine a maximum allowable thickness of the airfoil without separation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.652-653
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• 2009

In this study, flow-induced vibration (FIV) analyses have been conducted for a 3D compressor blade model. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed dynamic responses of designed compressor blades. Fluid domains are modeled using the computational grid system with local grid deforming and remeshing techniques. Reynolds-averaged Navier-Stokes equations with $\kappa-\varepsilon$ turbulence model are solved for unsteady flow problems of the rotating compressor model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D compressor blade for fluid-structure interaction (FSI) problems. Detailed dynamic responses and instantaneous pressure contours on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating compressor blade.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.551-559
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• 2009

In this study, flow-induced vibration(FIV) analyses have been conducted for a 3D compressor blade model. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate detailed dynamic responses of designed compressor blades. Fluid domains are modeled using the computational grid system with local grid deforming and remeshing techniques. Reynolds-averaged Navier-Stokes equations with $\kappa-\epsilon$ turbulence model are solved for unsteady flow problems of the rotating compressor model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D compressor blade for fluid-structure interaction(FSI) problems. Detailed dynamic responses and instantaneous pressure contours on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating compressor blade.

• 한국콘텐츠학회논문지
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• 제16권12호
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• pp.1-9
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• 2016

전산유체역학은 유체현상을 기술하는 미분방정식의 근사해를 컴퓨터를 이용하여 풀고 해석하는 학문으로, 다양한 종류의 변수의 계산을 필요로 한다. 대용량의 유동해석 데이터의 경우, 스토리지의 제약으로 계산한 변수들 중 필수적인 변수만을 저장하고, 데이터 분석 시점에 필요한 2차 변수를 계산하는 경우가 많다. 본 논문에서는 전산유체역학 응용에서 많이 사용하는 2차 변수의 종류를 정리하고, 임의의 초기 변수가 주어졌을 때 최적의 2차 변수 계산 경로를 효율적으로 추정하기 위한 방법으로 2차 변수 종속 그래프를 일반적인 유향 그래프로 변환하는 기법과 이를 이용한 최단 경로 탐색 기법을 소개한다. 또한 제안하는 기법을 실제 데이터 분석 및 가시화 도구에 적용하여 효용성을 측정하였다.

• 한국전산유체공학회지
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• 제19권1호
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• pp.15-20
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• 2014

Accurate simulation of free-surface wave flows around a ship is very important for better hull-form design. In this paper, a computational fluid dynamics (CFD) code, termed SNUFOAM, which is based on the open source libraries, OpenFOAM, was developed to predict the wave patterns around a ship. Additional anti-diffusion source term for minimizing a numerical diffusion, which was caused by convection differencing scheme, was considered in the volume-fraction transport equation. The influence of the anti-diffusion source term was tested by applying it to free-surface wave flow around the Wigley model ship. In results, the band width of the volume fraction contours between 0.1 to 0.9 at the hull surface was narrowed by considering the anti-diffusion term.

• 한국전산유체공학회지
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• 제18권3호
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• pp.94-101
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• 2013

In the present study, a practical method to predict cavitation erosion, which caused a critical damage on hydraulic machineries, was developed. Impact and critical velocities were defined to develop a practical method for the prediction of cavitation erosion. To develope the practical method, the computational fluid dynamics (CFD) was introduced. Cavitating flows with erosion in a converging-diverging nozzle and around a hydrofoil were simulated by developed and validated code. Based on the CFD results, the cavitation erosion coefficient was derived by a curve fitting method. The cavitation erosion coefficient was formulated as the function of the cavitation and Reynolds numbers. A cavitating flow in an axisymmetric nozzle followed by radial divergence was simulated to validate the developed practical method. For the application to a propeller, a cavitating flow around a propeller was simulated. Predicted damage extent showed similar with damaged full-scale propeller blade.

• 한국전산유체공학회지
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• 제8권1호
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• pp.16-22
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• 2003

The present study introduces an architecture for performing efficient numerical analysis by using the Internet and three reconstructing methods of existing numerical analysis codes were presented in order to utilize the architecture. These methods were implemented into a computational fluid dynamics program for solving two-dimensional transient flow problems with free surface. The program was reconstructed with Java technologies and compared with the original one. This study will be a preparation for numerical analysis to participate in web services for engineering.

• 한국유체기계학회 논문집
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• 제18권2호
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• pp.54-59
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• 2015

The performance of UV reactor which is used in water treatment is strongly affected by UV fluence rate and water flow in the UV reactor. Therefore, CFD tools are widely used in designing process of UV reactors. This paper describes the development of a computational fluid dynamics (CFD) methodology that can be used to calculate the performance of open channel type UV reactor used in wastewater treatment plant. All computations were performed using commercial CFD code, CFX, by considering three dimensional, steady, incompressible flow. The Eulerian-Eulerian multi-phase method were used to capture the water-air interface. The MSSS model, provided by UVCalc3D, was used to calculate the UV intensity field. The numerical predictions and calculated UV Dose were compared with experimental dataset to validate the CFD methodology. The reactor performance based on MS2 log reduction was well matched with measurements within 6%.

• 한국기계가공학회지
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• 제21권5호
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• pp.53-60
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• 2022

In this study, the conceptual design and performance evaluation of a personal air vehicle (PAV) is presented, which is a potential futuristic individual transportation. The blade element theory (BET) is employed to compute a rotational velocity. A computational fluid dynamics (CFD) simulation is performed to investigate the difference in the thrust performance in the rotor axis distance of a quad-copter PAV in hovering. Modal analysis is performed to create a Campbell diagram to investigate critical speed. Consequently, a quad-copter PAV changes the aerodynamics thrust and critical velocity according to the rotor axis distance.