Offshore Code Comparison Collaboration within IEA Wind Annex XXIII: Phase II Results Regarding Monopile Foundation Modeling

摘要

Offshore wind turbines are designed and analyzed using comprehensive simulation codes that account for the coupled dynamics of the wind inflow, aerodynamics, elasticity, and controls of the wind turbine, along with the incident waves, sea current, hydrodynamics, and foundation dynamics of the support structure. This paper presents an overview and describes the latest findings of the code-to-code verification activities of the Offshore Code Comparison Collaboration, which operates under Subtask 2 of the International Energy Agency Wind Annex XXIII. In the latest phase of the project, a variety of project participants using an assortment of codes have modeled the coupled dynamic response of a 5-MW wind turbine installed on a monopile with flexible foundation in 20 m of water. Foundation models included the simple apparent fixity model, a coupled springs model, and the more complicated distributed springs model, all of which were tuned to ensure that the overall response of the monopile above the mudline would be the same under a given set of loading conditions. The code predictions from a set of load-case simulationseach selected to test different features of the modelswere compared. The comparisons, in general, agreed quite well. Differences that existed among the predictions were traced back to differences in the model fidelity, aerodynamic implementation, hydrodynamic load discretizations, and numerical difficulties within the codes.