Hostname: page-component-745bb68f8f-mzp66 Total loading time: 0 Render date: 2025-01-09T22:13:10.266Z Has data issue: false hasContentIssue false
  • English
  • Français

A free-surface and blockage correction for tidal turbines

Published online by Cambridge University Press:  10 April 2009

J. I. WHELAN ,
J. M. R. GRAHAM  and
J. PEIRÓ
J. I. WHELAN*
Affiliation:
Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
J. M. R. GRAHAM
Affiliation:
Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
J. PEIRÓ
Affiliation:
Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The effects of free-surface proximity on the flow field around tidal stream turbines are modelled using actuator disc theory. Theoretical results are presented for a blocked configuration of tidal stream turbines such as a linear array that account for the proximity of the free surface and the seabed. The theoretical results are compared to open channel flow experimental results in which the flow field has been simulated using a porous disc and strip. These results are complemented by more detailed measurements of the performance of a model horizontal-axis turbine carried out in a water flume and a wind tunnel. The two sets of experiments represent highly blocked and effectively unblocked cases, respectively. The theoretical model of the effects of free-surface proximity provides a blockage correction for axial induction that can be incorporated in blade element momentum codes. The performance predictions obtained with such a code are in good agreement with the experimental results for CP and CT at low tip-speed ratios. The agreement weakens with increasing tip-speed ratio, as the wake of turbine enters a reversed flow state. A correction following the philosophy of Maskell is applied to CT in this region, which provides a better agreement.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 624 , 10 April 2009 , pp. 281 - 291
Copyright
Copyright © Cambridge University Press 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Antheaume, S., Maître, T. & Achard, J. 2008 Hydraulic Darrieus turbines efficiency for free fluid flow conditions versus power farm conditions. J. Renewable Energy 33, 2186–2198.CrossRefGoogle Scholar
Betz, A. 1920 Das Maximum der theoretisch möglichen Ausnützung des Windes durch Windmotoren. Zeitschr. Gesam. Turbinenwesen 26, 307–309.Google Scholar
Carbon Trust 2005 Variability of UK Marine Resources. Environmental Change Institute.Google Scholar
Drela, M. 1989 XFOIL: an analysis and design system for low Reynolds number airfoils. In Proceedings of the Conference on Low Reynolds Number Aerodynamics, Nôtre Dame, Indiana.CrossRefGoogle Scholar
Garrett, C. & Cummins, P. 2007 The efficiency of a turbine in a tidal channel. J. Fluid Mech. 588, 243–251.CrossRefGoogle Scholar
Glauert, H. 1933 Wind tunnel interference on wings, bodies and airscrews. ARC R&M 1566.Google Scholar
Maskell, E. 1963 A theory of the blockage effects on bluff bodies and stalled wings in a closed wind tunnel. ARC R&M 3400.Google Scholar
Myers, L. & Bahaj, A. S. 2007 Wake studies of a 1/30th scale horizontal axis marine current turbine. J. Ocean Engng 34, 758–762.CrossRefGoogle Scholar
Wilson, R. E. & Lissaman, P. B. S. 1974 Applied aerodynamics of wind power machines, Oregon State University.Google Scholar