Nonlinear Wave Load Response on Offshore Wind Turbine Structures

Cost reduction within offshore wind energy is central for achieving the 2020 goal of 50% wind share of the Danish electricity supply. DeRisk provides a key contribution by providing new design methods with reduced risk and uncertainty for extreme wave loads (ULS, Ultimate Limit State) which are often design-giving for the support structure.

DeRisk examines the design chain from met-ocean data to structural response. Joint-probability methods are developed for analysis of met-ocean data. Wave transformation over depth is computed with ground-breaking fully nonlinear, GPU-accelerated wave models. The detailed physical load effects of 3D wave spreading, bed-slope, wave-current interaction and formation of extreme irregular waves are quantified experimentally. Specialised tools for high-frequency ringing-type and breaking wave loads are developed. Advanced LES-based CFD methods are developed and applied to extreme wave impacts with wall friction.

The structural response for wind turbine structures of mono-pod and jacket type are examined through aero-elastic calculations and analysis of lab and field data. For the first time, new methods for numerical uncertainty quantification are applied to quantify the model sensitivity. The new tools and detailed investigations are sythesized into a de-risked design procedure for ULS wave loads. 

Project description:

This work package examines the response of the full wind turbine structure subject to simultaneous wind and wave forcing. Hereby, increased insight into the critical load cases is achieved. Comparison of response to field data and laboratory data for jacket structures is made and used for model validation.

Perspective:

  • Identification of critical load cases for jacket response to extreme waves.
  • Study of load effects from cyclic degradation of soil properties.
  • Analysis of full scale data to identify the extent of ringing loads.
  • Analysis and model formulation of current blockage effect for jacket structures.

Contact

Shaofeng Wang
Postdoc
DTU Wind Energy