Wind tunnel and wave flume testing on directionality dynamic responses of a 10 MW Y-shaped semi-submersible wind turbine

Y-shaped semi-submersible platforms are typical supporting structures for floating wind turbines. The incompletely symmetric platforms may generate directionality dynamic responses in different wind/wave directions, and unfavorable responses will affect structural safety. Integrated and fine tests should be considered to find the dynamic response mechanisms in wind tunnel and wave flume (WTWF) laboratories. In this paper, the model test scheme of a 10 MW Y-shaped semi-submersible wind turbine with a 1:70 scale ratio is designed in WTWF; besides, the aero-hydro-elastic-servo dynamic numerical model is established on the open-source platform OpenFAST to verify the test results. First, the quality of the wind and wave fields is calibrated. Then, hydrostatic tests, wind-induced tests, wave-induced tests, and wind wave combined tests are carried out. Finally, the dynamic responses and service performances of the floating wind turbine in different wind/ wave directions are analyzed and compared in detail. The results show that the excellent wind and wave fields provide a successful basis for high-accuracy model tests. Wave/wind directions certainly affect the directionality dynamic responses of floating wind turbines. Specifically, the responses of the pitch, tower base loads, and nacelle acceleration in the 0 degrees and 60 degrees wave directions should be paid extra attention to, for its higher responses, which are related to structural safety and power generation efficiency. The directional dynamic responses should be fully determined before structural designs to benefit the operation and maintenance of Y-shaped semi-submersible wind turbines.