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Energies 2016, 9(2), 73; doi:10.3390/en9020073

Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine

Center for Ocean Renewable Energy, University of New Hampshire, 24 Colovos Rd., Durham, NH 03824, USA
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Academic Editor: Sukanta Basu
Received: 1 November 2015 / Revised: 14 January 2016 / Accepted: 15 January 2016 / Published: 26 January 2016
(This article belongs to the Special Issue Wind Turbine 2015)
View Full-Text   |   Download PDF [1593 KB, uploaded 26 January 2016]   |  

Abstract

Experiments were performed with a large laboratory-scale high solidity cross-flow turbine to investigate Reynolds number effects on performance and wake characteristics and to establish scale thresholds for physical and numerical modeling of individual devices and arrays. It was demonstrated that the performance of the cross-flow turbine becomes essentially R e -independent at a Reynolds number based on the rotor diameter R eD ≈ 106 or an approximate average Reynolds number based on the blade chord length R ec ≈ 2 × 105 . A simple model that calculates the peak torque coefficient from static foil data and cross-flow turbine kinematics was shown to be a reasonable predictor for Reynolds number dependence of an actual cross-flow turbine operating under dynamic conditions. Mean velocity and turbulence measurements in the near-wake showed subtle differences over the range of R e investigated. However, when transport terms for the streamwise momentum and mean kinetic energy were calculated, a similar R e threshold was revealed. These results imply that physical model studies of cross-flow turbines should achieve R eD ∼ 106 to properly approximate both the performance and wake dynamics of full-scale devices and arrays. View Full-Text
Keywords: Reynolds number; cross-flow turbine; turbine performance; marine hydrokinetic energy; wind energy; vertical-axis wind turbine (VAWT); scale model Reynolds number; cross-flow turbine; turbine performance; marine hydrokinetic energy; wind energy; vertical-axis wind turbine (VAWT); scale model
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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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MDPI and ACS Style

Bachant, P.; Wosnik, M. Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine. Energies 2016, 9, 73.

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