Assessment of an Increased-Fidelity Aeroelastic Experiment for Free Flying Wing Response to Gust Excitation

The paper proposes a methodology for increased-fidelity aeroelastic testing in a wind tunnel environment to improve the correlation between the aeroelastic response measured in a wind tunnel experiment and the aeroelastic response observed on an aircraft in flight. The focus of the current study is to assess the potential of the proposed methodology to improve load and response predictions by emulating the motion of a free flying aircraft at the root of the wing. For this purpose a numerical aeroelastic model of a free flying aircraft is used to obtain a reference aeroelastic response to gust excitation. The model is reduced to obtain an aeroelastic model comprising only the main wing of the aircraft which is clamped at the root as if it would be mounted in a wind tunnel. The wing is then subjected to five different motion profiles emulating the free flight to a various degree. The considered motion profiles are clamped boundary condition, heave-pitch motion of a free flying aircraft, motion profile following the angle of attack of the aircraft, and two modified heave-pitch motion profiles which match the angle of attack and the aerodynamic loads in the wind tunnel with those in free flight. The study shows that the considered motion profiles can significantly improve the correlation between the wind tunnel experiment and free flight. However, the effectiveness of each motion profile strongly depends on the gust length which indicates that the optimum motion profile depends on the gust length. Finally, the paper presents a conceptual design of a wind tunnel demonstrator to serve as a proof-of-concept for the proposed methodology.