• Journal of Environmental Science International
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• v.18 no.8
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• pp.911-918
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• 2009

Electromagnetic interference (EMI) is defined as the interaction phenomena of electromagnetic waves scattered from a large structure or complex terrain. In this study, the propagation of linear wave is modeled with ray theory, direct simulation Monte Carlo (DSMC), and some classical theories on flat plates. The wave physics of reflection, refraction, and diffraction are simulated for the investigation of front and back scattering of the one-dimensional plane wave from a tower with ray theory and DSMC, respectively. The effect of rotating disk idealized from the real wind-turbine blades is modeled with a simplified version of the classical electromagnetic theory as well as DSMC based on the ray theory.

• Journal of computational fluids engineering
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• v.19 no.4
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• pp.94-99
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• 2014

The aerodynamic performance of a modified NACA64-418 with blunt trailing edges of irregular shape was investigated. As the trailing edge of the airfoil was thickened, the drag of the airfoil was increased due to development of a re-circulation bubble in the wake region. To reduce the drag of the airfoil with a blunt trailing edge, the optimum shape of the trailing edge for a modified NACA64-418 was investigated. The numerical results showed that the drag of the protruding shape was much more decreased than that of the retreating shape, but the lift was almost the same regardless of shape. In addition, the pitching moment of the modified NACA64-418 with a protruding sharp trailing edge was the smallest at the given angle of attack.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.72-75
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• 2005

Recently, as the global warming by fossil fuels become social issues. the interest of renewable energy producing system is increasing rapidly. Among these, wind turbines are most highlighted because of its economic competitiveness. The tower occupying about $20\%$ of overall turbine costs, is one of the main components of wind turbine. Tower access door located to base part of the tower, is used to enter the tower. This is the main structural weak point because of door hole, weldment, etc. In this study, by FEM, we retrieved the maximum van Mises stress at door location and carried out fatigue analysis using stresses at weld toe locations of tower access door part.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.63.2-63.2
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• 2011

The objective of this study is to investigate the aerodynamic characteristics of a small vertical axis wind turbine with dual blade type. The Wind turbine with dual blade has various angle of attack. so this turbine improve starting characteristics. The various arrangement of the vertical axis wind turbine with dual blade is designed. Among them, it shows superior quality that is arranged in three rows. Among arrangement in three rows, we use general computational fluid dynamics program CFX to find out the optimal arrangement. By comparing the predicted results of the aerodynamic characteristics of the different arrangement of the blades, an appropriate arrangement of the blade is suggested to design the small wind turbine blade.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.414-419
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• 2007

This paper describes the prediction of aerodynamic performance and wake of HAWT in normal and yawed flow operation using potential based methods. In order to analyze aerodynamic performance of wind turbine WINFAS program is used, which is based on VLM(Vortex Lattice Method) and CVC(Constant vorticity contour) Free wake model. Some problems of CVC vortex filament method are investigated arid to improve these problems vortex ring wake are introduced in behalf of CVC vortex filament. The prediction results using the vortex lattice wake are compared to experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.90-95
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• 2014

In order to investigate low frequency swishing noise of wind turbines, singularity in circular motion with large radius is introduced as a noise source model. By employing Lowson's acoustic analogy, simple exact solution is obtained. The solution shows that time histories of acoustic pressure at receiver points varied significantly according to receiver's directional location, even when the retarded time distributions are similar. However, the corresponding spectra of sound pressure for the receiver locations where the retarded time distributions are almost the same are not significantly different. It can be inferred from these results that the time-averaged sound pressure spectra which cannot take into account the detailed difference in the time-variation of wind turbine noise may not represent the sound quality of wind turbines due to its swishing.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.241-244
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• 2006

The present paper describes the scale effect correction method for wind turbine by using CFD(computational fluid dynamics). For the correct ions of wind turbine scale effect, various researches on the helicopter rotor scale effect were Investigated and feasibility study of methods was performed to correct wind turbine scale effect The present paper also introduces new scale effect correction method based on two dimensional lift slope modification. In order to test the Present method, performance analyses of NREL Phase VI wind turbines under various scale conditions were carried out by using CFD. The present method showed reasonable results when applied to NREL Phase VI wind turbine.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.265-268
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• 2006

Performed fatigue strength analysis for Hub to get the targeted service life of 20 years. ANSYS is used to analysis. The major structure of bearing which connect the hub and blades is modeled using the element of LINK10. To represent the stiffness of LINK10 element, initial strain and diameter of LINK10 element is applied. Prior to calculating the fatigue damages, the influence matrix is extracted from the unit loads. The target service life of 20 years is achieved from the Analysis results.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.269-272
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• 2006

Load analysis software enables to design wind turbines effectively and exactly. In this paper, Bladed software developed by Garrad Hassan and Partners is used for load analysis. When using Bladed software, many time is requested to input data which is called by pre-processing. So in this paper, pre-processing Is automated by in-house software(BX) With this BX software, we can reduce the total time for pre-processing about 90%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.8
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• pp.75-82
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• 2013

We propose a fiber grating sensor system for condition monitoring of large scale wind turbine blades. For the feasibility test of the proposed sensor system, a down-scaled wind turbine has been constructed and experimented. Fiber grating sensors were attached on a blade surface for distributed strain and temperature measurements. An optical rotary joint was used to transmit optical signals between the FBG sensor array and the signal processing unit. Instead of broadband light source, we used a wavelength-swept fiber laser to obtain high output power density. A spectrometer demodulation is used to alleviate the nonlinear wavelength tuning problem of the laser source. With the proposed sensor system we could measure dynamic strain and temperature profiles at multi-positions of rotating wind turbine blades.