Interaction of Floating Wind Energy System with Wind and Wave at Multiple Directions

Scotland boasts the world’s first floating wind farm. A floating wind farm has the advantage that offshore wind speeds are typically faster and steadier than on land and it is within easy reach of the densely populated coastal area. Field measurements by oceanographic buoys often indicate that wind field are not in the same direction as wave field. This misalignment between wind and wave direction can affect the performance and structural dynamics of an offshore floating wind energy system. The survivability and performance of floating wind turbine together with the functionality and reliability of platform and mooring systems are key components in the success of offshore wind developments for variable environmental loading of wind, wave and current. Modelling floating wind turbine systems, however, it is challenging due to the nonlinear coupling between the aerodynamic, hydrodynamics, structural, and controls problems. The current state-of-art coupled aero-hydro-servo-elastic numerical models for floating platforms is the FAST code developed by the National Renewable Energy Lab (NREL). The FAST code is a nonlinear time-domain simulator capable to perform an integrated loads analysis for a variety of wind turbine, support platform, and mooring system configurations. In this model, aero-servo-elastic models and hydrodynamic models are incorporated in the fully coupled simulation environment. FAST assumes linear hydrodynamics which implies that nonlinear wave-induced “slap” and “slam” loading, run-up and overtopping and other higher-order hydrodynamic effects are not accounted for. These higher-order hydrodynamic effects are critical for accurately capturing the dynamic behavior of floating wind turbine systems.

An air-water two phase flow 3-D Navier–Stokes solver with a hybrid Level-Set/VOF free surface capturing scheme will be used to examine the key physical mechanism for nonlinear coupling between the aerodynamics, hydrodynamics and structure. A novel Immersed Membrane Method (IMM) is used to track the immersed moving solid or elastic boundaries. This modelling framework consists of an integrated structural dynamics solver to perform Fluid Structure Interaction (FSI) simulations. The model is robust in capturing wind-wave interaction, the nonlinear wave interactions and motion response of a floating platform. The structural dynamics solver will be used to investigate how the shape, configuration and material of platform would affect its performance, stress, fatigue and reliability. This model is capable to resolve the highly nonlinear effects excluded in FAST, which is particularly important during extreme storms. The study results, therefore, it will improve the reliability of FAST’s performance as a turbine and platform design and optimization tool for both normal and high sea state with muiltiple wind and wave directions.

Informal enquiries should be directed to the primary supervisor, Professor Qingping Zou.

Applicants should have a first-class honours degree in a relevant subject or a 2.1 honours degree plus Masters (or equivalent). Scholarships will be awarded by competitive merit, taking into account the academic ability of the applicant.

Please complete our online application form and select PhD programme Civil Engineering within the application and include the project reference, title and supervisor on your application. Applicants who do not include these details on their application may not be considered.

Please also provide a written proposal, at least one side of A4, outlining how you would approach the research project. You will also be required to upload a CV, a copy of your degree certificate and relevant transcripts and one academic reference. You must also provide proof of your ability in the English language (if English is not your mother tongue or if you have not already studied for a degree that was taught in English). We require an IELTS certificate showing an overall score of at least 6.5 with no component scoring less than 6.0 or a TOEFL certificate with a minimum score of 90 points.

Applicants MUST be available to start the course of study in October 2019.