• Wind and Structures
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• 제36권6호
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• pp.423-434
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• 2023

Aerodynamic force coefficients are generally obtained from traditional wind tunnel tests or computational fluid dynamics (CFD). Unfortunately, the techniques mentioned above can sometimes be cumbersome because of the cost involved, such as the computational cost and the use of heavy equipment, to name only two examples. This study proposed to build a deep neural network model to predict the aerodynamic force coefficients based on data collected from CFD simulations to overcome these drawbacks. Therefore, a series of CFD simulations were conducted using different geometric parameters to obtain the aerodynamic force coefficients, validated with wind tunnel tests. The results obtained from CFD simulations were used to create a dataset to train a multilayer perceptron artificial neural network (ANN) model. The models were obtained using three optimization algorithms: scaled conjugate gradient (SCG), Bayesian regularization (BR), and Levenberg-Marquardt algorithms (LM). Furthermore, the performance of each neural network was verified using two performance metrics, including the mean square error and the R-squared coefficient of determination. Finally, the ANN model proved to be highly accurate in predicting the force coefficients of similar bridge sections, thus circumventing the computational burden associated with CFD simulation and the cost of traditional wind tunnel tests.

• 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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.68-75
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• 2009

In this study, aeroelastic response analyses have been conducted for a 3D wind turbine 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 responsed of wind turbine blade. Vibration analyses of rotating wind-turbine blade have been conducted using the general nonlinear finite element program, SAMCEF (Ver.6.3). Reynolds-averaged Navier-Stokes (RANS)equations with spalart-allmaras turbulence model are solved for unsteady flow problems of the rotating turbine blade 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 turbine blade for fluid-structure interaction (FSI) problems. Detailed dynamic responses and instantaneous Mach contour on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating wind-turbine blade model.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.451-452
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• 2003

전산유체역학(CFD, Computational Fluid Dynamics)은 유동을 지배하는 편미분방정식을 근사적인 대수방정식으로 바꾸고 이를 수치적으로 풀어 유동을 해석하는 학문으로, 이학·공학의 여러분야에서 광범위한 유동관련현상이나, 산업계에서의 항공기나 로케트의 공력설계, 터보기계의 성능개선, 대기·수질·악취·소음·토양 등의 환경영향평가 등에 널리 이용되고 있는 바, 현재 주요 하이테크 기술 중의 하나로 인식되고 있다. (중략)

• 항공우주기술
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• 제7권2호
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• pp.27-30
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• 2008

풍동시험의 벽면효과 보정방법이 풍동시험 조건에서 수행된 전산해석결과에 적용되었다. 보정을 마친 양력계수는 벽면이 없는 조건에서 수행된 전산해석 결과와 잘 일치하지만 보정된 항력계수는 벽면효과가 제거된 결과와 약간의 차이를 보인다.

• Wind and Structures
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• 제34권3호
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• pp.259-274
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• 2022

The present paper is focused on analyzing a set of Computational Fluid Dynamics (CFD) simulation data on reducing orthogonal peak base moment coefficients on a high-rise rectangular building with wings. The study adopts an aerodynamic optimization procedure (AOP) composed of CFD, artificial neural network (ANN), and genetic algorithm (G.A.). A parametric study is primarily accomplished by altering the wing positions with 3D transient CFD analysis using k - ε turbulence models. The CFD technique is validated by taking up a wind tunnel test. The required design parameters are obtained at each design point and used for training ANN. The trained ANN models are used as surrogates to conduct optimization studies using G.A. Two single-objective optimizations are performed to minimize the peak base moment coefficients in the individual directions. An additional multiobjective optimization is implemented with the motivation of diminishing the two orthogonal peak base moments concurrently. Pareto-optimal solutions specifying the preferred building shapes are offered.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.212-215
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• 2008

e-AIRS, an abbreviation of 'e-Science Aerospace Integrated Research System,' is a virtual organization supporting CFD(computational fluid dynamics) simulations, remote experimental service, and collaborative and integrative study between computation and experiment. e-AIRS works on the e-Science environment and research process is accomplished through the web portal. By the system development since 2005, a stable education system with the full support on fluid dynamics is successfully established and utilized to various fluid dynamic lectures in universities. By using e-AIRS system during a lecture, students can conduct the full CFD simulation process on the web and inspect the wind tunnel experiment via Access Grid. This kind of interactive lecture makes students to have a deeper understanding on the physics of fluid, as well as the characteristics of numerical techniques. The current paper will describe system components of e-AIRS and its utilization on education.

• 한국소음진동공학회논문집
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• 제19권7호
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• pp.651-658
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• 2009

In this study, computer applied engineering(CAE) techniques are fully used to efficiently conduct structural and dynamic analyses of a huge composite rotor blade using super-element. Computational fluid dynamics(CFD) is used to predict aerodynamic loads of the rotating wind-turbine blade. Structural vibration analysis is conducted based on the non-linear finite element method for composite laminates and multi-body dynamic simulation tools. Various numerical results are presented for comparison and the structural dynamic behaviors of the rotor blade are investigated herein.

• KIEAE Journal
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• 제10권2호
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• pp.63-69
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• 2010

Diverse problems in wind environment has occurred through rapid urbanization and growth of high-rise building numbers, This study aims to propose the CFD (Computational Fluid Dynamics) simulation method and evaluation standard of wind environment in site planning of high rise apartment housing. The CFD simulation method proposed in this study is not existing detail simulation, but it is the method that a designer can correct and develop the design through immediate evaluation of design options in concept design phase. Therefore, the proposed CFD simulation method of wind environment in this study uses the BIM based CFD tool in which the 3D model in concept design phase can be used as for the CFD simulation. In this paper, the study examines existing evaluation standards of comfortableness level in wind environment for pedestrian near buildings, and selects new evaluation method which is possible to apply to the proposed CFD simulation method. In addition, it is to examine calculation time-spending and appropriate mesh division method for finding CFD result which is useful to find the best design options in aspect of wind environment in concept design phase. Furthermore, it proposes the wind environment evaluation method through BIM based CFD simulation.

• Wind and Structures
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• 제1권4호
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• pp.303-315
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• 1998

Full-scale measurements have been made to determine the increase in wind speed over two exposed embankments, one of $23^{\circ}$ slope and 4.7 m in height, the other of $24^{\circ}$ slope and 7.3 m in height. Measurements were made at heights of 5, 10 and 15 m above the upper edge of each embankment and at the same heights approximately 100 m upwind in the lower-level approach fetch. Despite the modest sizes of the embankments, the maximum recorded increase in mean wind speed was 28% and the minimum was 13%; these increase relate to increases in wind loads on structures erected at the top of the embankments of 64% and 28% respectively. The associated increases in gust speeds are estimated at 33% and 18%, which imply increases in gust loading of 77% and 39% respectively. These experimental results are compared with predictions obtained from a computational fluid dynamics (CFD) analysis, using three high Reynolds number eddy-viscosity models and estimates from the UK wind loading code, BS 6399: Part 2. The CFD results are generally in agreement with the experimental data, although near-ground effects on the embankment crest are poorly reproduced.