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Wind tunnel and numerical study of a small vertical axis wind turbine

Howell, R., Qin, N., Edwards, J. and Durrani, N. (2010) Wind tunnel and numerical study of a small vertical axis wind turbine. Renewable Energy, 35 (2). pp. 412-422. ISSN 0960-1481

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Abstract

This paper presents a combined experimental and computational study into the aerodynamics and performance of a small scale vertical axis wind turbine (VAWT). Wind tunnel tests were carried out to ascertain overall performance of the turbine and two- and three-dimensional unsteady computational fluid dynamics (CFD) models were generated to help understand the aerodynamics of this performance.

Wind tunnel performance results are presented for cases of different wind velocity, tip-speed ratio and solidity as well as rotor blade surface finish. It is shown experimentally that the surface toughness on the turbine rotor blades has a significant effect on performance. Below a critical wind speed (Reynolds number of 30,000) the performance of the turbine is degraded by a smooth rotor surface finish but above the turbine performance is enhanced by a smooth surface finish. Both two bladed and three bladed it, rotors were tested and a significant increase in performance coefficient is observed for the higher solidity rotors (three bladed rotors) over most of the operating range. Dynamic stalling behaviour and the resulting large and rapid changes in force coefficients and the rotor torque are shown to be the likely cause of changes to rotor pitch angle that occurred during early testing. This small change in pitch angle caused significant decreases in performance.

The performance coefficient predicted by the two dimensional computational model is significantly higher than that of the experimental and the three-dimensional CFD model. The predictions show that the presence of the over tip vortices in the 3D simulations is responsible for producing the large difference in efficiency compared to the 2D predictions. The dynamic behaviour of the over tip vortex as a rotor blade rotates through each revolution is also explored in the paper. (C) 2009 Elsevier Ltd. All rights reserved.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 Elsevier. This is an author produced version of a paper subsequently published in Renewable Energy. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: Wind turbine; VAWT; HAWT; Wind tunnel; CFD
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Mechanical Engineering (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 03 Dec 2009 16:19
Last Modified: 08 Feb 2013 16:59
Published Version: http://dx.doi.org/10.1016/j.renene.2009.07.025
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/j.renene.2009.07.025
URI: http://eprints.whiterose.ac.uk/id/eprint/10229

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