EXPERIMENTAL INVESTIGATION OF MULTI-MODAL VIBRATION CHARACTERISTICS IN FLEXIBLE WING

This paper presents an experimental exploration of the aeroelastic response exhibited by a NACA0006 wing characterized by low natural frequency within a low-speed wind tunnel. The experiments encompass a range of angles of attack(AoA) (5^◦, 10^◦, 15^◦, 20^◦) and incoming flow velocities spanning from 10 m/s to 50 m/s. The dynamic responses of the wing are captured using four laser sensors. The analysis delves into both average and instantaneous modal features of the responses, revealing distinctive multi-modal characteristics as incoming flow velocity increases and AoA changes. At low incoming flow velocities, pure bending modal predominates, while higher-order modes become prominent as incoming flow velocity increases, transitioning from bending-torsional coupling to pure torsional with AoAs. Experimental and finite-element analysis (FEM) modal characteristics are compared, highlighting the response frequencies of the three vibration modes. Notably, the torsional mode shows the most significant deviation between experimental and FEM frequencies. Moreover, an examination of the variation in modal shape for the torsional mode reveals substantial differences, particularly at the rear part of the wing in comparison with FEM analysis under specific conditions.