Physical Characteristics and Perception of Low Frequency Noise from Wind Turbines

Shepherd, Kevin P.; Hubbard, Harvey H.

doi:10.3397/1.2827777

Cited by 17 publications

(26 citation statements)

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“…It is generally agreed that these so-called thumping noises are related to the unsteady interaction between the blades and the unsteady wake behind the tower. [1][2][3] The large variation in the fi eld measurements indicate that the phenomenon is critically dependent on the exact nature of the interaction. As is evident from the present results as well as the UAE experiment, the highest fl uctuations in the blade loading occurred when the blade experienced a direct encounter with a vortex of positive vorticity (type 2).…”

Section: Tower Responsementioning

confidence: 99%

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Wind Turbine Rotor-Tower Interaction Using an Incompressible Overset Grid Method

Zahle¹,

Johansen²,

Sørensen³

et al. 2007

45th AIAA Aerospace Sciences Meeting and Exhibit

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In this paper, 3D Navier-Stokes simulations of the unsteady flow over the NREL Phase VI turbine are presented. The computations are carried out using the structured grid, incompressible, finite volume flow solver EllipSys3D, which has been extended to include the use of overset grids. Computations are presented, firstly, on an isolated rotor, and secondly, on the downwind configuration of the turbine, which includes modelling of the rotor, tower and tunnel floor boundary.The solver successfully captures the unsteady interaction between the rotor blades and the tower wake, and the computations are in good agreement with the experimental data available. The interaction between the rotor and the tower induces significant increases in the transient loads on the blades and is characterized by an instant deloading and subsequent reloading of the blade, associated with the velocity deficit in the wake, combined with the interaction with the shed vortices, which causes a strongly time-varying response. Finally, the results show that the rotor has a strong effect on the tower shedding frequency, causing under certain flow conditions vortex lock-in to take place on the upper part of the tower.

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Section: Tower Responsementioning

confidence: 99%

“…One of the reasons why the downwind concept was abandoned was that several fi eld tests showed that considerable low frequency noise was generated when the blades pass through the tower wake. [1][2][3] The large variation in the measured data was attributed to the interaction of the blades with the unsteady tower wake.…”

Section: Introductionmentioning

confidence: 99%

Wind Turbine Rotor-Tower Interaction Using an Incompressible Overset Grid Method

Zahle¹,

Johansen²,

Sørensen³

et al. 2007

45th AIAA Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

show abstract

“…Wind turbine noise became an issue with the erection of wind turbines with down-wind rotors. These down-wind turbines generated a"thumping noise" with a considerable proportion of lowf requencies [1]. With the next generation of wind turbines and with the rotor placed up-wind, the problem of lowfrequencynoise wassolved; however, mechanical noise from the gearbox, often comprising tones, became anew source of disturbance [2].…”

Section: Introductionmentioning

confidence: 99%

Wind Turbine Noise Propagation over Flat Ground: Measurements and Predictions

Forssén¹,

Schiff²,

Pedersen³

et al. 2010

Acta Acustica united with Acustica

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Noise from wind turbines is of concern in the planning process of newwind farms, and accurate estimations of immission noise levels at residents nearby are required. Sound propagation from wind turbine to receivercould be modelled by as implified standard model assuming constant meteorological conditions, by an engineering method taking atmospheric and ground propagation conditions into account, or by amore exact model. Epidemiological studies have found ahigher frequencyofannoyance due to wind turbine noise than to other community noise sources at equal noise levels, indicating that the often used simplified model is not sufficient. This paper evaluates the variation of immission sound levels under the influence of meteorological variation and explores if the prediction of levels could be improvedbytaking the effect of wind speed on sound propagation into account. Long-term sound recordings and measurements at ad istance of 530 mf rom aw ind turbine showt hat the simplified standard model predicts the average sound pressure levels satisfactorily under downwind conditions, and that amore complexpropagation model might not be needed for wind turbine noise at arelatively short distance. Large variations of sound immission levels at the same wind speed were howeverp resent. Statistical analysis revealed that these variations were influenced by meteorological parameters, such as temperature, static pressure and deviation from ideal downwind direction. The overall results indicate that meteorological factors influence the noise generated by the wind turbine rather than the sound propagation. PACS no. 43.28.-g, 43.50.x, 43.58.e ACTA ACUSTICA UNITED WITH ACUSTICA Forssén et al.:W ind turbine noise propagation over flat ground Vol. 96 (2010)

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“…A summary of the low frequency noise results from 8 different turbines in US was presented by Sheperd and Hubbard 5 . They also present measurements of low frequency noise from two turbines with an upwind rotor and with a diameter of 43 m and 95 m, respectively.…”

Section: Introductionmentioning

confidence: 99%

Low Frequency Noise from Wind Turbines Mechanisms of Generation and its Modelling

Madsen¹

2010

Journal of Low Frequency Noise, Vibration and Active Control

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SUMMARYThe objective of the present paper is to present an overview of LFN characteristics of modern MW turbines based on numerical simulations. Typical sizes of modern turbines are from 1-3 MW nominal generator power and a rotor diameter ranging from 80-100 m but larger prototypes up to 5 MW and with a rotor diameter of 126 m have now been installed. The numerical investigations comprise the common upwind rotor concept but also the turbines with a downwind rotor are considered. The reason to include the downwind rotor concept is that this turbine design has some advantages which could lead to future competitive designs compared with the upwind threebladed rotor. The simulation package comprises an aeroelastic time simulation code HAWC2 and an acoustic low frequency noise (LFN) prediction model. Computed time traces of rotor thrust and rotor torque from the aeroelastic model are input to the acoustic model which computes the sound pressure level (SPL) at a specified distance from the turbine. The influences on LFN on a number of turbine design parameters are investigated and the position of the rotor relative to the tower (upwind or downwind rotor) is found to be the most important design parameter. For an upwind rotor the LFN levels are so low that it should not cause annoyance of neighbouring people. Important turbine design parameters with strong influence on LFN are the blade tip speed and the distance between rotor and tower.

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Physical Characteristics and Perception of Low Frequency Noise from Wind Turbines

Cited by 17 publications

References 0 publications

Wind Turbine Rotor-Tower Interaction Using an Incompressible Overset Grid Method

Wind Turbine Rotor-Tower Interaction Using an Incompressible Overset Grid Method

Wind Turbine Noise Propagation over Flat Ground: Measurements and Predictions

Low Frequency Noise from Wind Turbines Mechanisms of Generation and its Modelling

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