A 6DOF/Hil setup for wind tunnel hybrid tests on a 1/75 scale model of a 10 MW floating wind turbine

This paper deals with the design of a 6 degrees-of-freedom (DoF) robot for Hardware-In-The-Loop wind tunnel tests of floating offshore wind turbines (FOWT) and its experimental implementation. This setup allow to perform wind tunnel tests with a physical scale model of a wind turbine and to provide the motion at the base of the tower thanks to a 6-DoF Hexaslide robot with parallel kinematics. The motion is given consistently with real time combination of measurements (aerodynamic forces) and computations (hydrodynamic forces). The paper presents an overview of the design process of the robot as well as a description of the corresponding integrated numerical model based on MSC-Adams/Adwimo/MATLAB-Simulink co-simulation environment to account for the complete dynamic system (robot, wind turbine, control, HIL algorithm). The structural model of the wind turbine has been verified against the experimental modal analysis on the scale model. The complete model has been validated against a reduced order experimental setup (2-DoF), in terms of the aerodynamic forces computed in dynamic conditions (imposed motion tests) as well as HIL methodology effectively implemented for various conditions (free decay in still water and air, irregular sea state with wind). The main results of such a validation are reported showing promising extension outputs considering the ongoing extension to 6-DoF, making this tool valuable of numerical benchmark and wind tunnel design of experiments (DoE).