On structural loads and responses of monopile offshore wind turbines under typhoons: Numerical case study of Super Typhoon Chan-hom

Typhoons present a critical hazard to offshore wind turbines, particularly in the Northwest Pacific, where the extreme environmental conditions can compromise structural safety. This study aims to comprehensively evaluate offshore wind turbine performance under actual typhoon conditions, using Super Typhoon Chan-hom in 2015 as a case study. A high-fidelity numerical simulation framework was developed, integrating an advanced three-dimensional typhoon wind field model with the SWAN and ADCIRC models to simulate wind, wave, and storm surge fields. The simulation outputs were validated against field measurement data, confirming their accuracy. On this basis, the structural loads and responses of turbines installed at various radial positions around the typhoon center were analyzed, revealing that peak loads and responses occur for turbines located northeast and southwest at the radius of maximum wind speed. Then, the individual contributions of wind, waves, and storm surges were examined. The storm surge effects can be negligible in open seas, while the relative contributions of waves and winds on the blade and tower are location dependent. Finally, the yaw angle effect was examined. Remarkably, simply realigning the rotor plane perpendicular to the wind direction instead of the typhoon track could lead to a substantial decrease in blade and tower loads, with an 81% reduction in flapwise blade root moments and a 17% reduction in fore-aft tower base moments. These findings underscore the critical role of accurate environmental modeling and yaw control in enhancing offshore wind turbine resilience during typhoons.