Aeroacoustics of large wind turbines

Abstract

This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling effects for the low frequencies in the downwind direction are illustrated. Special topics such as distributed source effects in prediction and the role of building dynamics in perception are also included.

The Beat is Getting Stronger: The Effect of Atmospheric Stability on Low Frequency Modulated Sound of Wind Turbines

“…See, e.g., the studies by Lowson [3] and Grosveld [4], and the reviews by Hubbard and Shepherd [5] and Wagner et al [6]. A short introduction on wind aeroacoustics will be given to elucidate the most important sound producing mechanisms.…”

Turbulent Inflow Noise Prediction from Wind Turbine Blades

“…During the yawing operation of turbine, the blade velocity is found to be reduced when the blade reaches the top position than when the blade is at bottom. It can be noted that for power production during yaw operation is higher compared when the turbine is not yawing, The SPL (dB) levels for different observer azimuth angle are plotted in fig.9 which indicates that at 90 deg in cross wind direction, the sound pressure level is lower compared to 0 deg/180 deg downwind /upwind directions.The tower wake produces rotor in-plane velocity gradients and it also causes the impulse noise to be produced in the form of acoustic pulses [6,7]. The pulses are transient in nature and vary in amplitude.…”

“…The frequency spectra are evaluated using the scaling factor function which establishes the relationship between the convective wave number, K shed from the blade. Low frequency correction factor which takes account of compressible flow characteristic is expressed in terms of Mach number and compressible Sears function as proposed by Lowson [6].…”

“…The tower effect [8] is modeled in BEM code and calculated for wind speeds range of 20 m/s. The shear effect [5,6,8], is also modeled in BEM using the surface roughness parameter at the site location.…”

Analysis of aerodynamic sound noise generated by a large-scaled wind turbine and its physiological evaluation

“…However, there are some concerns on the aerodynamic noise, which is generated from a wind power plant, for the technicians who work in close proximity to the wind turbine (Hubbard and Shepherd 1991;Giguere and Selig 1997;Hansen 2007; Van den Berg 2008;Jaskelevicius and Užpelkiene 2008;Genescà et al 2009;Watson et al 2010;Lee et al 2011). A local resident has the right to live quietly within the limits of the environmental standards (Lercher 1996;Japanese-Government 1998;Waye and Ohrstrom 2002).…”