In order to investigate the coupling mechanisms of bottom fixed offshore wind turbines (OWTs) under environmental loads, the scaled physical model of DTU 10-MW wind turbine with jacket substructure is designed. The geometry scale ratio is selected as 1/75 in the study, and the joint Froude number and elastic similarity is applied to design the scaled model of the support system. Meanwhile, the airfoil of SD7032 is applied and the sectional geometries are updated in the design of blade model, in order to ensure the similarity of aerodynamic loads. Meanwhile, the drivetrain and mechanical control system developed accordingly. Then the performance scaled RNA model is developed. The simulation accuracy of the RNA model is primarily validated. Sequentially, the dynamic tests of the scaled OWT model under different wind speeds are conducted. The coupling mechanisms are obtained from the experimental data, such as the coupling effects between the rotor and support system. It can be seen the remarkable influence of the rotational frequencies on the structural responses of an operation OWT, besides the OWT fundamental frequency. The fundamental and blade collective flap modes dominate the responses of OWT in the parked state. Therefore, it proved the necessity of applying coupled numerical model in the analysis of OWTs.
According to the Global Wind Energy Council (GWEC), more than 235GW of new offshore wind capacity would be installed worldwide in the next decade. At the end of 2021, China became the world's largest offshore wind power market. The offshore regions with a depth of 25-50 m is one of the most potential areas for the development of China's offshore wind power, with a wind energy development potential of 400GW. Compared with the other fixed substructures, the jacket-type substructure is the preferred for the offshore wind farms in the depth of 30 - 50 m, because of its advantages, such as relative small hydrodynamic loads and deformations.
