Dynamic responses of a 10 MW semi-submersible wind turbine at an intermediate water depth: A comprehensive numerical and experimental comparison

Abstract

A series of experiments and numerical simulations were conducted to investigate the dynamic responses of a 10 MW floating wind turbine concept named SPIC, at an intermediate water depth of approximately 60 m. A fully coupled numerical model was established using the aero-hydro-servo-elastic-moor method. The experimental and numerical dynamic responses under operational conditions, including irregular waves, steady and turbulent winds, and combined wind–wave conditions, generally agree well. The mean values are well predicted, and the powers at motion resonant frequencies, wave frequency and tower vibration frequency are captured. Discrepancies between the numerical and experimental results are further addressed by in-depth numerical analyses. Under turbulent winds, the discrepancies of dynamic responses at 1P and 2P frequencies are induced mainly by individual blade installation error, while the discrepancies at 3P components are caused mainly by the nonuniformity of the wind field. In addition, in the turbulent wind case with variable blade pitch angles and rotor speed control system, the mean tower-base bending moment is smaller, and the low-frequency responses are larger than those in the case with fixed blade pitch angles and a constant rotor speed. The reveal of uncertainties is helpful for further guiding the model test of floating wind turbines.