Minimising the effects of scour on wind turbine foundations

Russell Mayall, Oxford University DEng student, with the monopile test equipment in the Fast Flow Facility at HR Wallingford
Russell Mayall, Oxford University DEng student, with the monopile test equipment in the Fast Flow Facility at HR Wallingford
HR Wallingford’s Fast Flow Facility project team
HR Wallingford’s Fast Flow Facility project team
Industry Database

UK independent engineering and environmental hydraulics organisation HR Wallingford has completed a ten week project working with Oxford University’s Department of Engineering Science and energy company E.ON, examining different forms of scour protection to assure the stability of offshore wind turbine monopiles.

The project has also helped identify which scour remediation strategies are the most effective in maintaining foundation performance.  E.ON and HR Wallingford are jointly funding the research including the experiments at HR Wallingford’s physical laboratory test facilities as part of the research project: ‘Foundation Response to Scour Protection’.

All monopile founded wind turbine structures vibrate to some degree during operation, with the frequency of resonant vibration determined by the monopile, tower, nacelle and blade dimensions and interactions of the foundation with the soil.  The design process addresses this system behaviour, and yields optimised installation depths for each monopile installation.

Erosion around the foundation due to the process of seabed scour causes the exposed length of the monopile at the seabed to change, and can alter the frequency at which the system resonates.  If the turbine structure begins to vibrate excessively due to this behaviour, it will need to be shut down, leading to loss of revenue and potentially significant remediation costs.

Prof Byron Byrne from the Department of Engineering Science at the University of Oxford, said: “Oxford University is applying its expertise in geotechnical engineering and structural analysis to this research for which we have appropriately scaled the monopile and turbine structure and exposed it to scour and erosion processes.  In the experiments, we are measuring the structural dynamic responses, quantifying the amplification of the vibration as it changes with erosion at the base of the monopile, and for different scour protection systems.”

The physical modelling tests, at a scale of 1:20, are being carried out in HR Wallingford’s Fast Flow Facility, which at 75m long and 8m wide, can hold a million litres of water, and can generate waves up to 1m high and flows of over 2m/second.

Prof Richard Whitehouse, Chief Technical Director, Sediment Dynamics, at HR Wallingford, said: “We are using our Fast Flow Facility to test the response of a monopile foundation employing different scour protection measures including rock protection and tyre filled nets. We have designed the local and global scour scenarios for the project with a fully mobile sediment bed model and worked closely with Oxford University to deliver world class experiments on the interaction between scour and structural response.”

Philippa Cassie, Offshore Foundations Engineer at E.ON Climate and Renewables, said: “E.ON has invested more than €10 billion in renewable energy since 2007 and is responsible for about 5.3 GW of renewable generation capacity in Europe and North America.  Our portfolio includes one of the world’s largest onshore wind parks in Roscoe, Texas, and with partners DONG Energy and Masdar we operate London Array off the coast of Kent, one of the world’s largest offshore wind parks. By conducting this research, we are aiming to quantify the contribution of scour and scour protection measures in structural terms to inform proactive management of the operational fleet and designs on future projects.”

For this project, Oxford University’s DEng student Russell Mayall is being co-supervised by the University, E.ON and HR Wallingford as part of the UK Engineering and Physical Sciences Research Council’s Centre for Doctoral Training in Renewable Energy Marine Structures, a collaboration between Oxford University and Cranfield University.

By Jake Frith

Latest Press Releases

Iskes Towage names twin Damen ASD Tugs 3212 Mars and Mercurius

Two of Iskes Towage’s vessels, the Damen ASD Tugs 3212 Mars and Mercurius, have been officially name... Read more

A Huge Success for Datum Electronics’ Cutting-Edge Marine Shaft Power Meter at SMM Hamburg

SMM Hamburg, the biggest maritime fair of 2018, ended recently and Datum Electronics, together with ... Read more

Damen supplies DOP150 submersible dredge pump for new power plant project in Brazil

Damen has supplied a DOP150 submersible dredge pump to Brazilian civil engineering contractor BELOV.... Read more

Damen performs tank testing of new FCS 7011

Damen Shipyards Group has carried out tank testing of its 70-metre Fast Crew Supplier (FCS) 7011. Th... Read more

Damen Shipyards Galati opens historical exhibition as part of continuing 125 year anniversary celebrations

Displaying an extensive collection of historical maritime memorabilia, Damen Shipyards Galati has op... Read more

Damen Chairman meets Romanian Minister of Economy

3 September 2018: Chairman and owner of Damen Shipyards Group Kommer Damen has held a meeting with t... Read more

View all