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Integrated numerical method for the prediction of wind turbine noise and the long range propagation
손은국,Hyunjung Kim,Hogeon Kim,Wooyoung Choi,이수갑 한국물리학회 2010 Current Applied Physics Vol.10 No.2
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.
Prediction of Aerodynamic Performance on Wind Turbines in the Far Wake
손은국(Son, Eunkuk),김호건(Kim, Hogeon),이승민(Lee, Seungmin),이수갑(Lee, Soogab) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
Although there are many activities on the construction of wind farm to produce amount of power from the wind, in practice power productions are not as much as its expected capabilities. This is because a lack of both the prediction of wind resources and the aerodynamic analysis on turbines with far wake effects. In far wake region, there are velocity deficits and increases of the turbulence intensity which lead to the power losses of the next turbine and the increases of dynamic loadings which could reduce system's life. The analysis on power losses and the increases of fatigue loadings in the wind farm is needed to prevent these unwanted consequences. Therefore, in this study velocity deficits have been predicted and aerodynamic analysis on turbines in the far wake is carried out from these velocity profiles. Ainslie's eddy viscosity wake model is adopted to determine a wake velocity and aerodynamic analysis on wind turbines is predicted by the numerical methods such as blade element momentum theory(BEMT) and vortex lattice method(VLM). The results show that velocity recovery is more rapid in the wake region with higher turbulence intensity. Since the velocity deficit is larger when the turbine has higher thrust coefficient, there is a huge aerodynamic power loss at the downstream turbine.
1.5 MW 풍력 터빈 소음 측정 및 저주파 소음 특성 분석
손은국(Eunkuk Son),이광세(Gwang-Se Lee),이진재(Jinjae Lee),강승진(Seungjin Kang),황성목(Sungmok Hwang),박사일(Sail Park),김석우(Seokwoo Kim) 한국신재생에너지학회 2018 신재생에너지 Vol.14 No.4
The noise from a 1.5 MW wind turbine was measured and the apparent sound power level, tonal audibility, and spectrum balance were analyzed. The apparent sound power level and tonal audibility were analyzed according to IEC 61400-11: ed3. (2012-11). The measured noise data at the turbine site was mainly in the north-west (NW) and north-north-west (NNW) directions, and approximately 500 and 250 samples of total noise and background noise data were obtained. Three tone components were observed in the low frequency region below 100 Hz. The tones in the low frequency critical band with a center frequency of 78.1 Hz were found to have a higher level than the hearing threshold. The possibility of wind turbine noise annoyance was also analyzed through the spectrum balance analysis.
Prediction of Wind Farm Noise with Atmospheric Stability
손은국(Son, Eunkuk),이승훈(Lee, Seunghoon),전민우(Jeon, Minu),이수갑(Lee, Soogab) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11
Noise generated from wind turbines has been predicted by numerical methods. Sound pressure level(SPL) on the turbines is predicted after aerodynamic analysis is carried out by Wind Turbine Flow, Aeroacoustics and Structure analysis (WINFAS) code. The level of each panel of acoustic sphere is determined by the sum of tonal, turbulence ingestion and airfoil self noise. With the noise source database, the acoustic sphere, SPL on the ground is calculated using the model based on acoustic ray theory. The model has been designed to consider the effects on the condition of terrain and atmosphere. The variations of SPL on the ground occur not only because of the different source level but also because of the nonuniform distributions of the sound speed along the height. Hence, the profile of an effective sound speed which is the sum of the contribution of sound speed to a temperature gradient and a wind speed variation is used by the theory based on atmospheric stability. With the integrated numerical method, the prediction of sound propagation on the wind farm is carried out with the states of the atmospheric stability.