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Energies 2015, 8(4), 2438-2453; doi:10.3390/en8042438

Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades

1
Department Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada
2
Department Mechanical and Materials Engineering, Queen's University, Kingston, ON K7L 3N6, Canada
*
Author to whom correspondence should be addressed.
Academic Editor: Frede Blaabjerg
Received: 27 January 2015 / Revised: 17 March 2015 / Accepted: 19 March 2015 / Published: 26 March 2015
(This article belongs to the Collection Wind Turbines)
View Full-Text   |   Download PDF [582 KB, uploaded 26 March 2015]   |  

Abstract

To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases. View Full-Text
Keywords: flat plate lift and drag; PV (photovoltaic) wind loads; small wind turbines; unsteady aerodynamic forces flat plate lift and drag; PV (photovoltaic) wind loads; small wind turbines; unsteady aerodynamic forces
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Ortiz, X.; Rival, D.; Wood, D. Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades. Energies 2015, 8, 2438-2453.

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