2019 Volume 75 Issue 2 Pages I_539-I_549
In the coupled aero-hydro-servo-elastic analysis to predict the response of the floating offshore wind turbines, two models are widely used for the estimation of the hydrodynamic loadings; the Morison’s equation, and the potential flow theory. In this study, a semi-submersible type floating offshore wind turbine was analyzed with both hydrodynamic models with the same flexible structure, and obtained responsed were compared to each other. It is shown that while both models predicted the floater motion well, both underpredicted the pitch natural frequency components. For tower-base moment, the Morison’s equation overpredicted tower 1st mode component, while the potential flow theory underpredicted wave excitation components for wind turbine operating condition. For the shear force and bending moment in the horizontal brace in air of the floater and the bending moment in the horizontal brace in water, the same frequencies with towerbase moments were excited, and the Morison’s equation predicted larger valules for all components than the potential flow. For the shear force in the horizontal brace in water, only the wave excitation frequency were excited and the two models showed similar results.
