State-of-the-art of experimental methods for floating wind turbines

Floating wind turbines (FWTs) play a significant role in producing clean, renewable, and sustainable energy. Structural components of FWTs consist of the wind turbine, supporting floating platform, and mooring lines, which are subjected to coupled aerodynamic and hydrodynamic loads in the complex sea environment. Understanding the dynamic behavior of FWTs and validating their corresponding numerical simulation tools require reliable experimental methods to replicate various environmental loading conditions and realistic FWT dynamic responses. Conventional coupled wind-wave experiments have provided insight into the dynamic behavior of FWTs. However, scaling conflicts between the Froude and the Reynolds numbers are inevitable. Therefore, continuous efforts have been made to improve existing or develop new experimental methods of FWTs. To facilitate such development, this research aims to provide an overview of recent FWT laboratory tests of two broad categories (i.e., conventional wind-wave experiments and real-time hybrid simulation) with a focus on the testing specifics such as testing objectives, scaling factors, testing setups and laboratory limitations, instrumentations, and experimental related numerical simulations. Challenges of these two types of laboratory experiments are identified, and solutions addressing these challenges in the example tests are discussed. Finally, a geographically distributed real-time hybrid simulation method is proposed for FWTs aimed to overcome some of the challenges and further advance testing capabilities.