challenges and solutions for modelling of tidal turbines
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Challenges and solutions for modelling of tidal turbinesAll Energy 2012Lloyd’s RegisterMarine Renewable Energy Research
Peter DaviesRenewable Energy Global Technology LeaderMay 2012
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Your local, global expert
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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 variation
Turbulence Wave simple
Irregular Wave
Random walk spreadsheet
No Simple Yes
TurbSim + spreadsheet
No Complex Yes
Custom programme
Yes Complex Yes
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Custom programme – developed by LR
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ConclusionsQuestions Conclusions
Is BEM software for HAWT valid for horizontal axis tidal turbines ?
Yes, but with some caution due to physical differences in operating regime
Can open source software for horizontal axis tidal turbines be used for tidal turbines ?
Yes, using FAST / Aero_Dyn has been demonstrated for tidal turbines
Are results from open source software reliable ?
Yes, but cavitation may be an issue
Can tidal resource be modelled ? Yes, several options are available
Are simple tidal resource models reliable ?
Yes for initial design studies
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ANY QUESTIONS ?
Thank you for listening
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Peter Davies Renewable Energy Global Technology Leader
Lloyd’s Register Group Services LtdDenburn House, 25 Union TerraceAberdeen, AB10 1NN
T +44 (0)1224 267771E [email protected] www.lr.org/renewables