• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.269-272
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• 2006

Numerical analysis of wind turbine scale effect was performed by using computational fluid dynamics. For the numerical analysis of wind turbine. Three dimensional Navier-Stokes solver with various turbulence models was tested and realizable k-e turbulence model was selected for the simulation of wind turbines. To validate the present method, performance of NREL (National Renewable Energy Laboratory) Phase VI wind turbine model was analyzed and compared with experiment and blind test data. Using the present method, numerical simulations for various size of wind tunnel model were carried out and characteristics were observed in detail. The power loss due to the interference between wind turbine and nacelle was also computed for relatively larger nacelle installation in wind tunnel test. The present results showed good correlations with experimental data and reasonable trends of scale effect of wind turbine.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.600-605
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• 2009

A general purpose viscous flow solver Ansys CFX is used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank. This paper presents the results of a computational fluid dynamics (CFD) analysis of the effect of blade configuration on the performance of 3 bladed Savonius rotors for wave energy extraction. A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves. A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated. The flow over the rotors is assumed to be two-dimensional (2D), viscous, turbulent and unsteady. The CFX code is used with a solver of the coupled conservation equations of mass, momentum and energy, with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces. Turbulence is modeled with the k.e model. Simulations were carried out simultaneously for the rotor angle and the helical twist. The results indicate that the developed models are suitable to analyze the water flows both in the chamber and in the turbine. For the turbine, the numerical results of torque were compared for all the cases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.06a
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• pp.75-86
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• 1996

Three-Dimensional finite element analysis is performed using PAM-STAMP for design evaluation of automotive back door inner panel die. Gravity process by blanks own weight, binder-wrap process, and drawing process in the forming operations are sequentially simulated with Virtual Manufacturing Method. The most valuable result in this research is that 3-D FEM analysis can be applied to the design evaluation of draw die in the die try-out, though effects of mesh size and drawbead resistance force on the numerical accuracy are much sensitive. For the intensive application to draw-die design and try-out, the experimental know-hows about the forming variables such as friction coefficient, punch velocity, drawbead force, etc are necessary.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.69-73
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• 2005

Three-dimensional density distributions of an impinging and eccentric flame have been analyzed numerically and experimentally by a combined optical system with a digital speckle tomography. The flame has been ignited by premixed butane/air from air holes and impinged vertically against a plate located at the upper side of tile burner nozzle. In order to compare with experimental data, computer synthesized phantoms of impinging and eccentric flames have been made and reconstructed by a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique has been developed for the analysis of speckle displacements to investigate wall jet regions of the impinging flame including sharp variation of the flow direction and pressure gradient. The reconstructed temperatures have been compared with a temperature photography by an infrared camera and results of numerical analysis using a finite-element method.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.709-729
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• 2008

This paper describes a three-dimensional dynamic finite element analysis of two/multiple shots impacting on a metallic component. The model is validated against a published numerical study. An extensive parametric study is conducted to investigate the effect of shot impacting with overlap on the resulting residual stress profile within the component, including time interval between shot impacts, separation distance between the impacting points, and impacting velocity of successive shots. Several meaningful conclusions can be drawn regarding the effect of shot impacting with overlap.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.652-657
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• 2008

A stress distribution of composite laminates patches is obtained by using the Kantorovich method when the substrate is under uniaxial load. The analysis is based on the stress function approach and uses the complementary virtual work principle. The three-dimensional stresses satisfy the traction free conditions at the free edges and the top surfaces of the patch. The stress of the bottom surfaces of the patch is obtained from equilibrium equation of patch and substrate. To demonstrate the efficiency and validity of the proposed analysis, numerical examples for cross-ply and quasi-isotropic laminates are included. The present method provides accurate stresses in the interior and near the free edges of composite laminate patches.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.8
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• pp.850-857
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• 1992

Design sensitivity analysis is proposed for the optimal shape design of three-dimensional magnetostatic problems. The direct differentiation method is introduced for design sensitivity analysis and the boundary element method with reduced magnetic scalar potential as the state variable is used to analyze the magnetic characteristics. In the direct differentiation method, the design sensitivity, defined as the total derivative of the objective function with respect to the design variables, is calculated based on the variation of the state variable with respect to the design variable. And the variation of the state variable is calculated by differetiating the both sides of the system matrix equation obtained by applying boundary element method. Through the numerical example with simple electromagnet, the usefulness is proved.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.1-6
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• 2003

Steady flow bench test is a practical, powerful and widely used in most engine manufacturers to give a design concept of a new engine. In order to use steady data as a performance index, it is necessary to build some database, which can correlate the port characteristics with engine data. However, it is very difficult to investigate all port shapes with experimental tools. The steady flow scheme is relatively simple and its results are bulk ones such as flow rate and momentum of flow. Therefore a CFD code can be easily applied to the port evaluation. In this study, the steady flow test was simulated through three-dimensional analysis on intake port design for comparing with experimental data and confirming the feasibility of applying analytic method . for this purpose, the effect of valve curvature on flow rate was estimated by a CFD code. Numerical results were compared with those of real steady flow tests. As a result, the results of 3-D analysis were almost consistent with experimental data.

• Structural Engineering and Mechanics
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• v.3 no.1
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• pp.11-23
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• 1995

The examined model consists of two substructures linked by a right angle rigid line joint. One element is a wall loaded externally along its upper edge by an uneven vertical load. The other element, defined as a plate, is not loaded. Stresses and displacements in the vicinity of the joint are analysed, considering the lateral distribution which leads to three-dimensional effects. The proposed solution combines classical approach with numerical means, using appropriate stress distribution polynomial functions along the joint. Space structure constructions supply cases of interest.

• Structural Engineering and Mechanics
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• v.61 no.5
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• pp.563-576
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• 2017

This paper is a continuation of the investigations started in the paper by Akbarov, S.D., Guliyev, H.H and Yahnioglu, N. (2016) "Natural vibration of the three-layered solid sphere with middle layer made of FGM: three-dimensional approach", Structural Engineering and Mechanics, 57(2), 239-263, to the case where the three-layered sphere is a hollow one. Three-dimensional exact field equations of elastodynamics are employed for investigation and the discrete-analytical method is employed for solution of the corresponding eigenvalue problem. The FGM is modelled as inhomogeneous for which the modulus of elasticity, Poison's ratio and density vary continuously through the inward radial direction according to power law distribution. Numerical results on the natural frequencies are presented and discussed. These results are also compared with the corresponding ones obtained in the previous paper by the authors. In particular, it is established that for certain harmonics and for roots of certain order, the values of the natural frequency obtained for the hollow sphere can be greater (or less) than those obtained for the solid sphere.