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Effect of unsteady flow on wind turbine wake development and noise generation  

Author:  | Noise, Technology

«The results of this study show that underlying mechanism associated with the perceived noise in the far-field of the turbine blades is amplitude modulation due to partial stall on the blades or interaction of the blades with incoming turbulent structures. This is in contrast with the common belief of trailing edge noise to be the dominant source for the perceived noise and its amplitude modulation due to rotation of the blades. Moreover, it is observed that the majority of the locations in which the noise from whole turbines is perceived by the community, are in close proximity of the wake region. … Results revealed that, the highest noise level in the vicinity of a wind turbine corresponds to blade pass frequency and is due to amplitude modulation of the trailing edge noise caused by the rotation of the blade, as well as blade tower interaction. Results also showed that the emitted noise is refracted due to the wind shear in atmospheric boundary layer, as well as the wake and associated turbulent structures. The [computational fluid dynamics] outcomes showed that the wake breakdown occurs at a distance of 12 diameters downstream of the turbine with a strong downwash due to longitudinal vortices. Contours of sound pressure level at the breakdown location of the wake of the wind turbine showed refraction and modulation of the sound at this location. Results also revealed refraction of the noise towards the ground and wider areas due to existence of the longitudinal vortices.»

Schematic diagram of the typical vortex system downstream of a wind turbine

Nima Sedaghatizadeh
School of Mechanical Engineering, University of Adelaide, Australia
Thesis submitted in fulfilment of the requirements for the degree of Ph.D. in Mechanical Engineering

Download original document: “The effect of unsteady flow on wind turbine wake development and noise generation

This material is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

The copyright of this material resides with the author(s). As part of its noncommercial effort to present the environmental, social, scientific, and economic issues of large-scale wind power development to a global audience seeking such information, National Wind Watch endeavors to observe “fair use” as provided for in section 107 of U.S. Copyright Law and similar “fair dealing” provisions of the copyright laws of other nations. Send queries to query/wind-watch.org.

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