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Turbulence in vertical axis wind turbine canopies

Kinzel, Matthias and Araya, Daniel B. and Dabiri, John O. (2015) Turbulence in vertical axis wind turbine canopies. Physics of Fluids, 27 (11). Art. No. 115102. ISSN 1070-6631.

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Experimental results from three different full scale arrays of vertical-axis wind turbines (VAWTs) under natural wind conditions are presented. The wind velocities throughout the turbine arrays are measured using a portable meteorological tower with seven, vertically staggered, three-component ultrasonic anemometers. The power output of each turbine is recorded simultaneously. The comparison between the horizontal and vertical energy transport for the different turbine array sizes shows the importance of vertical transport for large array configurations. Quadrant-hole analysis is employed to gain a better understanding of the vertical energy transport at the top of the VAWT arrays. The results show a striking similarity between the flows in the VAWT arrays and the adjustment region of canopies. Namely, an increase in ejections and sweeps and decrease in inward and outward interactions occur inside the turbine array. Ejections are the strongest contributor, which is in agreement with the literature on evolving and sparse canopy flows. The influence of the turbine array size on the power output of the downstream turbines is examined by comparing a streamwise row of four single turbines with square arrays of nine turbine pairs. The results suggest that a new boundary layer forms on top of the larger turbine arrays as the flow adjusts to the new roughness length. This increases the turbulent energy transport over the whole planform area of the turbine array. By contrast, for the four single turbines, the vertical energy transport due to turbulent fluctuations is only increased in the near wake of the turbines. These findings add to the knowledge of energy transport in turbine arrays and therefore the optimization of the turbine spacing in wind farms.

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Additional Information:© 2015 AIP Publishing LLC. Received 10 February 2015; accepted 20 October 2015; published online 9 November 2015. The authors gratefully acknowledge funding from the Gordon and Betty Moore Foundation through Grant No. 2645, the National Science Foundation Energy for Sustainability program (Grant No. CBET-0725164), and the Office of Naval Research through Grant No. N000141211047.
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Gordon and Betty Moore Foundation2645
Office of Naval Research (ONR)N000141211047
Record Number:CaltechAUTHORS:20151116-090115067
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Official Citation:Turbulence in vertical axis wind turbine canopies Kinzel, Matthias and Araya, Daniel B. and Dabiri, John O., Physics of Fluids, 27, 115102 (2015), DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62111
Deposited By: Tony Diaz
Deposited On:18 Nov 2015 00:20
Last Modified:18 Nov 2015 00:20

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