SuperGen UK Centre for Marine Energy Research Annual Assembly 2012

X-MED: EXTREME LOADING OF MARINE ENERGY DEVICES DUE TO WAVES, CURRENTS, FLOTSAM

AND MAMMAL IMPACT

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Consortium of the Universities of Manchester, Edinburgh and Plymouth and the Scottish Association for Marine Sciences (SAMS) led by Professor Peter Stansby of University of Manchester Manchester : Peter Stansby, Tim Stallard, Ben Rogers, David Apsley, Alistair Revell Edinburgh : Ian Bryden, Tom Bruce Plymouth : Deborah Greaves, Alison Raby SAMS : Ben Wilson

Aim :

To identify and improve understanding of extreme loading on tidal stream turbines and wave energy devices by modelling and experiments

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• WAVE ENERGY DEVICES design sea states in waves and currents for a taut moored floating body representative of a wave energy device or support structure

Objectives: • TIDAL STREAM TURBINES 1. extreme swell waves and breaking waves 2. tidal turbulence 3. impact of flotsam (containers) and marine mammals

Experiments 1. Manchester wide current/wave flume – 5m x 15m x 0.5m deep. Use existing model turbines, 1:70 scale. Preliminary debris/mammal impacts on turbines. 2. Plymouth wave basin – 35m x 15.5m x 3m deep. Use taut moored floating body, 1:20 scale 3. Edinburgh wave/current basin FloWave TT – 30m diameter x 2m deep , current speed 0.8 m/s. New turbines,1:15 scale, taut moored floating body as Plymouth. Debris/mammal impact on turbines

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ETI ReDAPT field data - flow kinematics

Numerical Models 1. Code-SATURNE – CFD LES or RANS model

for turbines developed in ReDAPT. Loading due to upstream wakes.

2. STAR-CCM – commercial CFD VOF code for floating bodies,

assess use for debris/mammal turbine impact.

3. SPHysics – SPH model for floating bodies, assess use for debris/mammal turbine

impact 4. BLADED – commercial Blade Element

Momentum model of GL Garrad Hassan.

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Calender year 2012 2013 2014

Work year 1 2 3

Quarter 1 2 3 4 5 6 7 8 9 10 11 12

Manchester flume – tidal turbines √ P P

Plymouth basin – moored body

Plymouth CFD - STAR-CCM - moored body

SAMS – mammal literature review

Design and fabrication to be re-distributed

Edinburgh ReDAPT data analysis

Edinburgh basin – tidal turbines , moored body

Manchester code-SATURNE – tidal turbines R R R R R R

Manchester SPH – floating body and turbine

impacts from flotsam and mammals

Plymouth basin commissioning date X

Edinburgh basin commissioning date X

8 work packages

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P : ETI PerAWAT R : ETI ReDAPT

DEVIATIONS SAMS 12 months PDRA time to be reduced to one for literature review 11 months to be re-distributed for design and fabrication of marine mammals Fabrication costs to be re-distributed Edinburgh EVOPOD not suited to FloWave TT facility New turbine is being designed Manchester SPH to concentrate on modelling flexible Minke Whale and Basking Shark ReDAPT (Edinburgh and Manchester) Some data on tidal turbulence alone available but delay with waves due to deployment

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CHOICE OF MARINE MAMMAL Minke Whale and Basking Shark common and next size down from Sperm Whales which are less common and likely to cause turbine destruction. Report on Killer Whales for OpenHydro.

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Both about 10m long

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SPH Numerical Wave Tank

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SPH with 6 DoF best agreement

Plymouth –

taut moored floating body

• 2mm Mild Steel Construction

• Taut, flexible, inelastic mooring –

Nylon, Polyester, Dyneema or

Kevlar?

CFD modelling – Star CCM+ Proposal:

• Volume-of-fluid (VoF) approach

• Allows free surface and body motion

• Applied to simulate interactions between the floating buoy and waves

Progress:

• Licence agreement signed

• Training booked (9th – 11th November)

Cell generated to model Manchester Bobber in Star-CCM+.

Westphalen, J. (2010), Extreme wave loading on Offshore Wave

Energy Devices using CFD, PhD thesis, University of Plymouth.

[1] Westphalen, J., Greaves, D.M, Williams, C.J.K., Hunt-Raby,

A.C, Zang, J. (2012), ‘Focused waves and wave-structure

interaction in a numerical wave tank’,Ocean Engineering 45, 9-21.

Thanks and Questions

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