WIND TUNNEL TESTS FOR GUST LOAD INVESTIGATION INTRANSONIC FLOWS – PART 2: EXPERIMENTAL RESULTS ANDCONTROL DEMONSTRATION

Aerodynamic loads are a recurrent topic in aeronautical research. Indeed, during a flight, a wing can endure a wide variety of load sources impacting significantly the aerodynamical performances of the aircraft. Regarding those problematics, aeronautical studies aim to understand and find ways to decrease the effects of those disturbances. The present work focuses on one of those sources: the vertical gust, a particularly common phenomenon, responsible for important alterations of the airflow around the wing profile. To reproduce its effects, a gust generator has been installed in the contraction section of the S3Ch transonic wind tunnel at the ONERA Meudon center. The present study first introduces the gust generator used in this wind tunnel experiment. It is composed of two wings located upstream of the model. The two wings oscillate, hence creating vortices that will be carried by the flow stream to the model. Then, the effects of the gust are described, in both subsonic and transonic (up to Mach 0.82), on the aerodynamics and the aeroelastic response of a heavy instrumented (accelerometers, pressure sensors, strain gages) half wing fuselage model. In addition, an optical methodology gives access to deformation measurements of the model, thus giving a global picture of the phenomenon. Finally, a gust load alleviation methodology based on an active feedback loop is presented. A real-time device has been used and linked to a movable aileron of the model. A control algorithm based on several input sensors is implemented in the real-time device to decrease the effects of the gust load on the structural dynamics of the model. The results of this active control experiment will be discussed. This work is part of the ”NACOR” project and has been funded within the frame of the Joint Technology Initiative JTI Clean Sky 2, AIRFRAME Integrated Technology Demonstrator platform ”AIRFRAME ITD”. The design and manufacturing of the innovative test rig is part of the associated project ”GUDGET”, with IBK-Innovation GmbH , Dream Innovation srl, Politecnico di Milano, Aviation Design and Cedrat Technologies SA as consortium partners.