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Energy exchange in an array of vertical-axis wind turbines

Kinzel, Matthias and Mulligan, Quinn and Dabiri, John O. (2012) Energy exchange in an array of vertical-axis wind turbines. Journal of Turbulence, 13 (38). pp. 1-13. ISSN 1468-5248. doi:10.1080/14685248.2012.712698.

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We analyze the flow field within an array of 18 counter-rotating, vertical-axis wind turbines (VAWTs), with an emphasis on the fluxes of mean and turbulence kinetic energy. The turbine wakes and the recovery of the mean wind speed between the turbine rows are derived from measurements of the velocity field using a portable meteorological tower with seven, vertically-staggered, three-component ultrasonic anemometers. The data provide insight to the blockage effect of both the individual turbine pairs within the array and the turbine array as a whole. The horizontal and planform kinetic energy fluxes into the turbine array are analyzed, and various models for the roughness length of the turbine array are compared. A high planform kinetic energy flux is measured for the VAWT array, which facilitates rapid flow recovery in the wake region behind the turbine pairs. Flow velocities return to 95% of the upwind value within six rotor diameters downwind from each turbine pair. This is less than half the recovery distance behind a typical horizontal-axis wind turbine (HAWT). The observed high level of the planform kinetic energy flux is correlated with higher relative roughness lengths for the VAWT array as compared to HAWT farms. This result is especially relevant for large wind farms with horizontal dimensions comparable to the height of the atmospheric boundary layer. As shown in recent work and confirmed here, the planform kinetic energy flux can be the dominant source of energy in such large-scale wind farms.

Item Type:Article
Related URLs:
Dabiri, John O.0000-0002-6722-9008
Additional Information:© 2012 Taylor & Francis. Received: 30 Mar 2012. Accepted: 07 Jul 2012. Version of record first published: 20 Sep 2012. The authors gratefully acknowledge funding from the National Science Foundation Energy for Sustainability program (Grant No. CBET-0725164) and the Gordon and Betty Moore Foundation.
Funding AgencyGrant Number
NSF Energy for Sustainability ProgramCBET-0725164
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:wind energy; energy transport; roughness length; turbulence
Issue or Number:38
Record Number:CaltechAUTHORS:20121108-104159367
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35355
Deposited By: Tony Diaz
Deposited On:08 Nov 2012 22:03
Last Modified:09 Nov 2021 23:14

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