Gust Load Alleviation: Identification, Control, and Wind Tunnel Testing of a 2-D Aeroelastic Airfoil.

One important element in the progression of aircraft environmental impact reduction is to reduce their overall weight (without impacting other consumption-oriented performance index, such as drag). In addition to the numerous work conducted in material and structural engineering, from a control viewpoint, this challenge is strongly connected to the need of the development and assessment of dedicated load control strategies in response to gust disturbances. Indeed, the load factors due to gust are considered as sizing criteria during the aircraft conception steps and require specific verification according to the certification process. To this end, a dedicated experimental research program based on wind tunnel (WT) campaigns has been carried out. More specifically, this paper contributions are twofold: (1) to identify the gust load effect using two different versatile frequency-domain techniques, namely, the Loewner interpolation and a modified subspace approach and (2) to design and implement an active closed-loop control to alleviate the gust main effect. The entire procedure is validated in a WT setup, involving a gust generator device and a 2-D aeroelastic airfoil, for varying configuration traveling from sub to transonic airflow and varying angles of attack, emphasizing the effectiveness and robustness of the overall approach.