Wind tunnel testing of scaled wind turbine models: Beyond aerodynamics

An aeroelastically scaled model of a wind turbine is described, featuring active individual blade pitch and torque control. The model, governed by supervision and control systems similar to those of a real wind turbine, is capable of simulating steady conditions and transient maneuvers in the boundary layer test section of the wind tunnel of the Politecnico di Milano. Expanding the classical scope of wind tunnel models, the present experimental facility enables applications ranging from aerodynamics to aeroelasticity and control.After a description of the model design and of its main characteristics, several applications are presented. Results are shown for the validation of a wind misalignment observer, for the optimization of the open-loop pitch profile used during emergency shutdowns, for the control in wake interference conditions of two models, and for active load alleviation by higher harmonic individual blade pitch control. Results demonstrate the potential of the proposed experimental facility to enable non-standard observations in the controlled environment of the wind tunnel, beyond the classical purely aerodynamic ones.