Hydrodynamic Coefficients of Hexagonal Heave Plates for Floating Offshore Wind Turbine Platforms
Experiments were conducted on a 1:80 scaled column of the WindFloat semi-submersible floating offshore wind turbine platform. The structure was forced to oscillate at frequencies of up to 6 Hz and at various amplitudes to create a parameter space much larger than previously reported. The hydrodynamic coefficients of the column with a hexagonal heave plate were compared to the base case of a column with a circular heave plate. Results show remarkably similar behavior between the two cases over the range of parameters tested, but quite distinct from published data on square plates. At low Keulegan-Carpenter number, the hexagonal plate showed a slightly higher added mass, but the difference narrowed down with increasing KC. An opposite trend was noticed for the damping coefficients. Overall the maximum difference in damping was about 8%. The paper presents some of the challenges in experimenting over a large parameter range, and also analyzes the trends in data over the range. It is expected that the presented data will be of use with engineers attempting to use heave plates for stabilizing wind turbine platforms in range of wave and wind conditions to maximize wind energy generation efficiency.