Influence of Tower Inclination on the Dynamic Behavior and Fatigue Damage of Twin-Rotor Floating Offshore Wind Turbines

Twin-rotor floating offshore wind turbines (TwinFOWTs) exhibit significant potential for reducing the cost of floating wind technology, emerging as an advantageous alternative to conventional large-scale wind turbines. This study proposes a 10 MW floating TwinFOWT concept consisting of two inclined 5 MW wind turbines and the OO-Star prototype platform. To explore the effects of tower inclination on the dynamic behavior of the TwinFOWT and the fatigue damage at the tower base, the hydrodynamic responses of six TwinFOWT models with different tower inclination angles ranging from 35° to 45° are evaluated in SESAM under various environmental scenarios. The results indicate that larger tower inclination causes a slight reduction in the average power output for the below-rated wind conditions. The tower inclination angle significantly affects platform motions in operational states. The maximum relative differences in platform pitch and yaw among the six models are 32.73% and 58.58%, respectively. The uneven gravity distribution due to tower inclination results in notable local stress concentration, posing a potential risk for structural strength failure. Fatigue damage will decrease with increasing tower inclination angle. The accumulated fatigue damage of the 45° tower-inclination model is reduced by up to 28.84% compared to that of the 35° model. This study is expected to provide a reference for the design and improvement of the TwinFOWT concept with inclined towers.