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A Wind-Tunnel Simulation of the Wake of a Large Wind Turbine in a Weakly Unstable Boundary Layer

Hancock, PE, Zhang, S and Zhang, S (2015) A Wind-Tunnel Simulation of the Wake of a Large Wind Turbine in a Weakly Unstable Boundary Layer Boundary-Layer Meteorology, 156 (3). pp. 395-413.

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Abstract

© 2015, Springer Science+Business Media Dordrecht. Measurements have been made in the wake of a model wind turbine in both a weakly unstable and a baseline neutral atmospheric boundary layer, in the EnFlo stratified-flow wind tunnel, between 0.5 and 10 rotor diameters from the turbine, as part of an investigation of wakes in offshore winds. In the unstable case the velocity deficit decreases more rapidly than in the neutral case, largely because the boundary-layer turbulence levels are higher with consequent increased mixing. The height and width increase more rapidly in the unstable case, though still in a linear manner. The vertical heat flux decreases rapidly through the turbine, recovering to the undisturbed level first in the lower part of the wake, and later in the upper part, through the growth of an internal layer. At 10 rotor diameters from the turbine, the wake has strong features associated with the surrounding atmospheric boundary layer. A distinction is drawn between direct effects of stratification, as necessarily arising from buoyant production, and indirect effects, which arise only because the mean shear and turbulence levels are altered. Some aspects of the wake follow a similarity-like behaviour. Sufficiently far downstream, the decay of the velocity deficit follows a power law in the unstable case as well as the neutral case, but does so after a shorter distance from the turbine. Tentatively, this distance is also shorter for a higher loading on the turbine, while the power law itself is unaffected by turbine loading.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Authors :
AuthorsEmailORCID
Hancock, PEUNSPECIFIEDUNSPECIFIED
Zhang, SUNSPECIFIEDUNSPECIFIED
Zhang, SUNSPECIFIEDUNSPECIFIED
Date : 6 September 2015
Identification Number : 10.1007/s10546-015-0037-5
Additional Information : The final publication is available at Springer via http://dx.doi.org/10.1007/s10546-015-0037-5
Depositing User : Symplectic Elements
Date Deposited : 27 Oct 2015 09:33
Last Modified : 06 Sep 2016 01:08
URI: http://epubs.surrey.ac.uk/id/eprint/809034

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