Study on the marine growth effect on the dynamic response of offshore wind turbines

Jacket foundation is regarded as a suitable solution for wind turbines in the intermediate water depths ranging from 30 to 80 m. Numerous types of marine fouling organisms may be found on the submerged members of jacket. Marine growth is found to influence loading of offshore structures by increasing tube diameters, drag coefficient, mass and hydrodynamic added mass and structural weight. In this paper, the types and distribution of marine growth are mentioned. We aimed to investigate the effects of marine growth with different thicknesses, densities and hydrodynamic coefficients values on characteristics of an offshore wind turbine with jacket foundation. The eigen analysis shows that the marine growth has a little effect on the first order natural frequencies while it has higher effect on second and third order natural frequencies of the support structure. Thickness and density have a strong effect on hydrodynamic loads. To obtain the properties of marine growth and hydrodynamic coefficients in the design of offshore wind turbines, full-scale measurements are needed.