The aerodynamic interference effects of a floating offshore wind turbine experiencing platform pitching and yawing motions

Generally, a floating offshore wind turbine experiences larger motions than onshore or ground fixed wind turbines because of its free motions of the platform on the water. The accurate prediction of unsteady aerodynamic performances and loads for the rotating blades installed on a floating offshore wind turbine is a numerically complex problem and it is still challenging works. In this study, both the conventional numerical methods based on an unsteady blade element momentum theory and the advanced computational fluid dynamic method have been applied for the rotating blades with oscillating motions. Unsteady aerodynamic characteristics of the rotating blades with the platform pitching and yawing motions are numerically investigated in detail. It is shown that there are flow interaction phenomena between the rotating wind turbine blades with oscillating motions and generated blade-tip vortices. Finally, the unsteady aerodynamic blade loads for the pitching motion are also calculated and the results are compared for each rotating blade in order to show the effect of aerodynamic load variations during its oscillating motion.