Flow-Induced Vibration Characteristics of a Fix-Supported Elastic Wing

Abstract

The aerodynamics and responses of an elastic high-aspect-ratio (AR = 9) NACA0012 airfoil with two-end-fixed supports were experimentally investigated. The chord-based Reynolds number is 1.5 × 10⁵ and the angle of attack (α) of the wing varies from 0° to 90°. The lift, drag coefficients (C_l and C_d), deformation (A^*, where the asterisk denotes normalization by the chord) of the wing, as well as the velocity fluctuation (u) in the wake were measured simultaneously. Based on the behaviors of C_l, C_d and A^*, and their spectral coherences with u, four regimes are identified, i.e. α = 0º − 4º, 6º − 8º, 10º − 50º and 60º − 90º, respectively. In the regime of α = 0º − 4º, the wing keeps stable, while the dramatic structural vibration emerges for α in the range of 6º − 8º because of the occurrence of the flutter. As α is increased to stall angle (α = 10º), a rapid drop is observed in the RMS value of lift, drag and displacement. Beyond the stall angle, the fluctuation of lift and drag forces increases slowly with α in the range of 14º < α < 50º while the vibration of the displacement hardly changes. In this range, one pronounced peak corresponding to the vortex shedding occurs in their spectral coherences. As α overs 60º, the fluctuations in lift, drag and structural response are impaired, becoming negligibly small. The peak associated with vortex shedding in the spectral coherences is not distinct.