Extreme Loading on Floating Offshore Wind Turbines (FOWTs) under Complex Environmental Conditions

Lead Research Organisation: University of Plymouth
Department Name: Sch of Engineering

Abstract

The offshore wind industry has experienced significant growth in recent years, and continues to expand both in the UK and worldwide. Most of the offshore wind turbines installed to date are located in relatively shallow water and are mounted on fixed bottom support structures. Given the limitation of suitable shallow water sites available with high wind resources and also to reduce the environmental and visual impact of turbines, it is necessary to extend wind turbines to deeper water through the development of floating offshore wind turbine (FOWT) systems, which mount wind turbines on floating support platforms.

The project aims to fill an important gap in the design, manufacturing and testing of emerging FOWT techniques by specifically characterising extreme loading on FOWTs under complex and harsh marine environments. These are typically represented by storm conditions consisting of strong wind, extreme waves, significant current, rising sea level and complex interplay between these elements, through a coordinated campaign of both advanced CFD modelling and physical wave tank tests. This has direct relevance to the current and planned activities in the UK to develop this new technology in offshore wind.

In addition, the project aims to develop a suite of hierarchical numerical models that can be applied routinely for both fast and detailed analysis of the specific flow problem of environmental (wind, wave, current) loading and dynamic responses of FOWTs under realistic storm conditions. As an integral part of the project, a new experimental programme will be devised and conducted in the COAST laboratory at the University of Plymouth, providing improved understanding of the underlying physics and for validating the numerical models. Towards the end of the project, fully documented CFD software and experimental data sets will be released to relevant industrial users and into the Public Domain, so that they may be used to aid the design of future support structures of FOWTs and to secure their survivability with an extended envelope of safe operation for maximum power output.

Publications

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Title Hybrid modelling technique for testing of floating offshore wind turbine platforms 
Description During EP/T004150/1 a new hardware and software approach to physical scales testing of floating offshore wind energy devices in the University of Plymouth COAST laboratory Ocean Basin has been developed. This uses real time measurements of platform motion to control propellers attached to the top of the floating wind turbine model that emulate the thrust force applied by the turbine by the floating platform. A surrogate model, trained by numerical models of how the forces generated by the turbine change due to unsteady wind and platform motions, has been developed as the real time controller of the experiment. This method has several advantages over previous techniques. The surrogate modelling approach enables data from higher fidelity numerical models that can't be run in real time to be used to control the experiment. The hybrid modelling approach enables an effective way of testing different turbine types and at different scales without building new turbine models. The method will also enable testing into the impact of different turbine control strategies on floating platform response. 
Type Of Material Improvements to research infrastructure 
Year Produced 2022 
Provided To Others? Yes  
Impact This research tool has been used to collect the experimental data required in this project, which will form the numerical modelling validation to be published later this year. The tool has also been used in other ongoing research projects and will be used by industry developers in the next year as part of their research and development of new floating offshore wind platforms. 
 
Description IEA Wind Task 30 team 
Organisation International Energy Agency (IEA)
Country France 
Sector Charity/Non Profit 
PI Contribution - Contributed simulation data for a number of load cases in the (OC6 CFD) comparative study, which will lead to our inclusion on a paper in preparation. - Contributed to the virtual meetings including help steer the direction for the latest OC6 CFD phase of the project (i.e. supported continuation and progression towards floating cases etc.). - Helped to resolve an issue surrounding the definition of an OpenFOAM output which significantly altered the interpretation of the results (to be presented in the paper).
Collaborator Contribution - Involvement with IEA Wind Task 30 has given us access to the latest numerical modelling developments in Floating Offshore Wind by other international research groups - helping to insure the modelling developments on this project are state-of-the art. - Involvement with IEA Wind Task 30 provides a avenue for dissemination of our modelling developments to academic and commercial beneficiaries. - Allowed us to directly compare with a number of other CFD codes and experimental data, verifying that our hydrodynamic modelling techniques are both good and up-to-date. - Collaboration has improved our wave generation, propagation and absorption within our model
Impact Paper in preparation
Start Year 2020