Eunkuk Son - Academia.edu (original) (raw)
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Papers by Eunkuk Son
Current Applied Physics, 2010
Characteristics of noise propagation from wind turbine have been studied by using the integrated ... more Characteristics of noise propagation from wind turbine have been studied by using the integrated numerical methods based on Ray theory. There are two numerical approaches in this paper. Those are constructing noise sources of wind turbine and computing the noise level on the ground. First of all, the flow fields around the wind turbine blade are calculated using Wind Turbine Flow, Aeroacoustics and Structure analysis (WINFAS). WINFAS is an unsteady vortex lattice methods based on potential flow. The results of flow analysis are used for predicting tonal noise, turbulence ingestion noise, and airfoil self noise. Tonal noise is induced by the displacement of fluid and loading fluctuation of the blade and those are predicted by Farassat 1A equation. Moreover, semi-empirical formulas are used for the prediction of broadband noise such as the airfoil self noise and turbulence ingestion noise. Before the beginning of the next step, the acoustic pressure is integrated at the each point of virtual acoustic sphere considering retarded time. It also represents the noise directivity on wind turbine. Then, the noise level on the ground has been predicted including the effects of air absorption, ground reflection and diffraction.
Renewable Energy
Aerodynamic noise is one of the most serious barriers in wind energy development. To develop tech... more Aerodynamic noise is one of the most serious barriers in wind energy development. To develop technologies for wind turbine noise reduction and assessment, noise needs to be predicted precisely with special consideration given to blade flexibility. The numerical tool, WINFAS, which can simulate fluid estructure interaction, consists of three parts: the first part, the Unsteady Vortex Lattice Method, analyzes aerodynamics; the second part, the Nonlinear Composite Beam Theory, analyzes structure; and the third part uses a semi-empirical formula to analyze airfoil self-noise and the Lowson's formula to analyze turbulence ingestion noise. In this study, using this numerical tool, the change in the noise strength due to blade flexibility was examined. This research showed that elastic blades decreased broadband noise because pitching motion reduced the angle of attack.
Renewable Energy
This study investigates the effects of design parameters on the aerodynamic performance of a coun... more This study investigates the effects of design parameters on the aerodynamic performance of a counterrotating wind turbine. The counter-rotating wind turbine has two rotors rotating in opposite directions on the same axis. It has been proposed on the basis of the theory which states that a configuration of two rotors having the same swept area on the same axis has a higher maximum power coefficient than a conventional configuration of a wind turbine having a single rotor. More design parameters are involved in the description of the counter-rotating wind turbine than of a wind turbine using a single rotor because of the complex phenomenon arising from the aerodynamic interaction between its two rotors, but influences of these parameters is yet to be fully understood. In this study, a modified blade element momentum theory for the counter-rotating wind turbine is developed to investigate the effects of these design parameters such as the combinations of the pitch angles, rotating speeds and rotors' radii on the aerodynamic performance of the counter-rotating wind turbine.
Current Applied Physics, 2010
Characteristics of noise propagation from wind turbine have been studied by using the integrated ... more Characteristics of noise propagation from wind turbine have been studied by using the integrated numerical methods based on Ray theory. There are two numerical approaches in this paper. Those are constructing noise sources of wind turbine and computing the noise level on the ground. First of all, the flow fields around the wind turbine blade are calculated using Wind Turbine Flow, Aeroacoustics and Structure analysis (WINFAS). WINFAS is an unsteady vortex lattice methods based on potential flow. The results of flow analysis are used for predicting tonal noise, turbulence ingestion noise, and airfoil self noise. Tonal noise is induced by the displacement of fluid and loading fluctuation of the blade and those are predicted by Farassat 1A equation. Moreover, semi-empirical formulas are used for the prediction of broadband noise such as the airfoil self noise and turbulence ingestion noise. Before the beginning of the next step, the acoustic pressure is integrated at the each point of virtual acoustic sphere considering retarded time. It also represents the noise directivity on wind turbine. Then, the noise level on the ground has been predicted including the effects of air absorption, ground reflection and diffraction.
Renewable Energy
Aerodynamic noise is one of the most serious barriers in wind energy development. To develop tech... more Aerodynamic noise is one of the most serious barriers in wind energy development. To develop technologies for wind turbine noise reduction and assessment, noise needs to be predicted precisely with special consideration given to blade flexibility. The numerical tool, WINFAS, which can simulate fluid estructure interaction, consists of three parts: the first part, the Unsteady Vortex Lattice Method, analyzes aerodynamics; the second part, the Nonlinear Composite Beam Theory, analyzes structure; and the third part uses a semi-empirical formula to analyze airfoil self-noise and the Lowson's formula to analyze turbulence ingestion noise. In this study, using this numerical tool, the change in the noise strength due to blade flexibility was examined. This research showed that elastic blades decreased broadband noise because pitching motion reduced the angle of attack.
Renewable Energy
This study investigates the effects of design parameters on the aerodynamic performance of a coun... more This study investigates the effects of design parameters on the aerodynamic performance of a counterrotating wind turbine. The counter-rotating wind turbine has two rotors rotating in opposite directions on the same axis. It has been proposed on the basis of the theory which states that a configuration of two rotors having the same swept area on the same axis has a higher maximum power coefficient than a conventional configuration of a wind turbine having a single rotor. More design parameters are involved in the description of the counter-rotating wind turbine than of a wind turbine using a single rotor because of the complex phenomenon arising from the aerodynamic interaction between its two rotors, but influences of these parameters is yet to be fully understood. In this study, a modified blade element momentum theory for the counter-rotating wind turbine is developed to investigate the effects of these design parameters such as the combinations of the pitch angles, rotating speeds and rotors' radii on the aerodynamic performance of the counter-rotating wind turbine.