Peter Davies’ (Renewable Energy Technology Leader) paper looks at the potential for using existing wind turbine modelling software to model tidal turbines. While there are obvious differences between air and water, the difference in velocity makes it possible.

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Challenges and solutions for modelling of
tidal turbines
All Energy 2012
Lloyd’s Register
Marine Renewable Energy Research
Peter Davies
Renewable Energy Global Technology Leader
May 2012

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Can horizontal axis wind turbine software
be used for tidal turbines?
• Reynolds number is in the same range for wind and tidal
turbines
• W/T BEM software has been used for tidal turbines
• Some of the problems
• Different velocity profiles
• Wake expansion may be restricted
• Cavitation may be an issue

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NREL software – used in project
See paper by Buhl – 2005 The NWTC
Design-Codes Suite: An Overview

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Validation 1 - using data from BAHAJ et al 2007.
Power and thrust measurements of marine current turbines under various
hydrodynamic flow conditions in a cavitation tunnel and a towing tank. Renewable
Energy, 32(3), pp. 407-426

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Validation 2 - using data from BAHAJ et al 2007.
Power and thrust measurements of marine current turbines under various
hydrodynamic flow conditions in a cavitation tunnel and a towing tank. Renewable
Energy, 32(3), pp. 407-426

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Reasons for discrepancies
• Cavitation
• Wake expansion
• 2D v 3D lift and drag coefficients

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Other options 1 – Harp_Opt see paper by SALE, D., NWTC Design
Codes (HARP_Opt by Danny C. Sale). http://
wind.nrel.gov/designcodes/simulators/HARP_Opt/.

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Other options 2 – MB Dyn & Aero Dyn
• Not tested for tidal but as using in AeroDyn should be OK
• Open source
• Multi Body (rather than modal model)
• Status of control system model unclear
• See paper “Free/Open Source Multibody and Aerodynamic
Software for Aeroelastic Analysis of Wind Turbines” Fanzhong
Meng / Pierangelo Masarati / Michel van Tooren

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Issues to consider in modelling the tidal
energy resource
• Turbulence (horizontal and vertical)
• Wave influence on velocity (horizontal and vertical)
• Wave spectrum
• Tidal variation
• Length of simulation

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Options for modelling resource tested by LR
Description Tidal Turbulence Wave Irregular
variation simple Wave
Random walk No Simple Yes
spreadsheet
TurbSim + No Complex Yes
spreadsheet
Custom Yes Complex Yes
programme

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Custom programme – developed by LR

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Conclusions
Questions Conclusions
Is BEM software for HAWT valid for Yes, but with some caution
horizontal axis tidal turbines ? due to physical differences in
operating regime
Can open source software for Yes, using FAST / Aero_Dyn
horizontal axis tidal turbines be used has been demonstrated for
for tidal turbines ? tidal turbines
Are results from open source Yes, but cavitation may be an
software reliable ? issue
Can tidal resource be modelled ? Yes, several options are
available
Are simple tidal resource models Yes for initial design studies
reliable ?

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Thank you for listening
ANY QUESTIONS ?

16. For more information, please contact:
Peter Davies
Renewable Energy Global Technology Leader
Lloyd’s Register Group Services Ltd
Denburn House, 25 Union Terrace
Aberdeen, AB10 1NN
T +44 (0)1224 267771
E peter.davies@lr.org
w www.lr.org/renewables
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