Influence of bracings on the hydrodynamic modelling of a semi-submersible offshore wind turbine platform

摘要

This paper discusses the consequences of using a simplified 3D geometric model for a semisubmersible offshore wind turbine platform in terms of hydrodynamics. A full 3D geometric model of the platform and a second model that simplifies the modelling process by leaving out the connecting braces of the columns are evaluated. The added masses, potential damping coefficients and wave exciting forces are compared in between these two models, considering only the platform. The modes of motion that lead to significant deviations are identified and used in full system evaluation in order to understand how much this change in hydrodynamic coefficients reflects in the full behaviour of the wind turbine. Comparative simulation results are presented for the platform under different loading conditions. These loading conditions include free decay motions, incoming waves without wind and wind - wave combined condition. The study aims to understand how accurate are the simplified 3D models that may be considered at initial design stages of offshore wind turbines.