Study on Passive Flutter Control of a High-Aspect-Ratio Flexible Wing

The aerodynamic performance and structural safety of high-aspect-ratio flexible wings can be dramatically unstable once the flutter occurs. In this study, an experimental investigation is performed to understand the mechanism of fluid–structure interactions on a flexible cantilever wing with a high aspect-ratio of 7.5, and develop a passive control method based on bionic leading-edge protuberances. The pitch and plunge deformations of the wing are measured by strain gauges and fiber Bragg grating (FBG) sensors, respectively. With the protuberance, the lift-to-drag ratio is improved in the no limit cycle oscillation (LCO) regime. And the flutter regimes are greatly concentrated. Even in the stall flutter regime, the amplitudes of pitch and plunge are dramatically reduced. Particle image velocimetry measurement shows that the flow separation at high angles of attack is suspended by the protuberances induced streamwise vortices.