Modelling floating offshore wind turbine systems under extreme storm conditions

The offshore wind industry has experienced significant growth in recent years, and continues to expand both in the UK and worldwide. 

Nearly all offshore wind turbines installed to date are located in relatively shallow water, mounted on fixed bottom support structures. However, the number of suitable shallow water sites with high wind resources are limited, and hence it is necessary to expand wind turbine technology for deployment at deeper water sites. 

Floating offshore wind turbine (FOWT) systems offer an opportunity to achieve this expansion, and can potentially play a vital role in providing affordable and sustainable energy for the UK as part of a broad and balanced energy system.

In order for cost-competitive and reliable FOWTs to be developed, it is crucial that the complex hydrodynamic and aerodynamic interactions with the system are well understood. 

The survivability in storm conditions is of particular importance, since the FOWTs will be subject to concurrent attacks from strong wind, steep waves, rising water levels due to storm surge as well as the effects from the complex interplay between the underlying flow processes, e.g. wind induced currents and wave breaking.

Therefore, the aim of the project is to characterize and quantify extreme loading on FOWTs in a complex and harsh marine environment with strong wind, rising water level, significant wind-driven current, steep swell and wind waves, and the interactions between each of these parameters.

This will be achieved through numerical and physical modelling following specific objectives:

• Increase understanding of the flow dynamics and interaction with FOWTs under complex environmental conditions, through a series of carefully configured wave tank tests.
• Further development and validation of an integrated CFD model for the fully coupled analysis of the hydrodynamics and aerodynamics of FOWT structures under the action of both wind, waves, and mooring.
• Optimization of the parallel efficiency of the hybrid CFD model through a new dynamic load balancing technique.
• Characterization of the coupled effects of wind, current, and rising water level on large-scale wave evolution and extreme wave events including the onset of wave breaking in storm conditions.
• Quantification of the extreme loading on FOWTs including effects of breaking waves and aeration under realistic environmental conditions through numerical and physical experiments.