highlighting of ambient turbulence impact on the interaction effects between tidal turbines

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  • Highlighting of ambient turbulence impact on the interaction effects between tidal turbines

    Youen KERVELLA

    Open Ocean, Marine Energy Consultancy

    15 rue Kepler, Brest, France

    Grgory GERMAIN

    Benot GAURIER

    Jean-Valry FACQ

    Thomas BACCHETTI

    Ifremer, Marine Structures Laboratory

    Boulogne-sur-Mer, France

    GCGC Dunkerque July, 2014

  • 22/07/2014 Open Ocean 2014 All right reserved 2

    Context: Future tidal turbines areas: intense currents and high

    turbulence level Need to know the turbulences impact on turbines

    Need to estimate the environmental impact of tidal

    farms

    Numerical models to be calibrated

    Study: Previous measurements with 1 then 2 tidal turbines: # Experimental study of the turbulence intensity effects on marine current turbines behaviour. Part I: One single turbine. Mycek et al., 2014, Renewable energy. # Experimental study of the turbulence intensity effects on marine current turbines behaviour. Part II: Two interacting turbines. Mycek et al., 2014, Renewable energy.

    Understanding interactions between 3 turbines in various configurations

    Identify the ambient turbulence impact on performance and wake development

    Numerical modeling of currents energy extractions by 6 tidal turbines (with and without TEC) in Raz Blanchard area

    (Open Ocean)

    Introduction Experimental Features Results Conclusion Setup | configurations Config 1 | Config 2

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    Pool : # dimensions: 18 x 4 x 2 m # currents, waves, free surface # Input current velocity: from 0,1 to 2,2 m/s # Measurement: LDV, PIV, torque, ..

    Experiment: # Input current velocity: 0,8 m/s # Turbulence intensity (TI): 3 and 15% # Measurement system: LDV, torque

    Tidal turbines: # 3 horizontal axis three-bladed turbines of 700 mm diameter # TSR=R/U fixed at 4 (maximum power, Carlier et al., 2014) # torque and balance => Cp et Ct

    Introduction Experimental Features Results Conclusion device | configuration Performances | Washes

  • 22/07/2014 Open Ocean 2014 All right reserved 4

    2 turbines side by side (2D spaced) upstream and one turbine centred downstream

    Over speed recovery created between both upstream turbines

    Turbine downstream is instrumented (performance)

    2 inter-rows distances (DIR) tested: 4D and 6D

    Measurements LDV at -1D, 2D and 4D of the second row (wakes)

    Introduction Experimental Features Results Conclusion device | configuration Performances | Washes

  • 22/07/2014 Open Ocean 2014 All right reserved 5

    Maximum power at TSR = 4

    Soft differences for

    DIR= 4D and DIR= 6D Global curves form

    similar for both TI

    30 % Cp decrease for TI=15% compared to TI=3%

    Introduction Experimental Features Results Conclusion device | configuration Performances | Washes

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    Small differences for DIR 4D and DIR 6D downstream turbine position, except for -1D profil

    No speed increase at

    the center of the flume behind the 1st row for TI=3%.

    Speed decrease at the center of the flume behind the 1st row for TI=15%

    Speed decrease behind

    turbines is smoothed when TI increases (from 45 to 70 % for TI=3% and from 10 to 30% for TI=15%)

    Introduction Experimental Features Results Conclusion device | configuration Performances | Washes

    Wakes

  • Obvious role of the ambient turbulence on performance and wakes development:

    - TI increase Cp et Ct decrease (30%)

    - TI increase Wakes limited development and smaller speed decrease

    Turbulence is key in tidal farm development areas such as Raz-Blanchard, TI between 15 and 25% estimated

    Need to consider TI in numerical modeling

    Study = test tank and in-situ database used to the numerical modeling validation

    22/07/2014 Open Ocean 2014 All right reserved 7

    Introduction Experimental Features Results Conclusion device | configuration Performances | Washes

  • www.openocean.fr

    Email : [email protected]

    Open Ocean Paris 27 rue du Chemin Vert

    75011 Paris, France

    Open Ocean Brest 15 rue Johannes Kpler

    Technople Brest Iroise

    site du Vernis

    29200 Brest, France

    THANK YOU FOR

    YOUR ATTENTION

    wwz.ifremer.fr/manchemerdunord

    Email : [email protected]

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