Dynamic response and stability of a flexible foil with special emphasis on the flutter mechanism via the reduced-order model

The objective of this paper is to study the dynamic response and stability of a flexible foil with emphasis on flutter mechanism. The hybrid coupled fluid-structure algorithm is applied to investigate the effect of solid-to-fluid mass ratio on the dynamic response and stability of a 2-D flexible foil. The results show that, with increase of the solid-to-fluid mass ratio, the failure will be triggered in turn, such as the static divergence, the dynamic divergence, and the flutter divergence. The predicted divergence velocity boundary, increasing with the increase of solid-to-fluid mass ratio, is in accordance with the experimental results. The reduced-order model (ROM) is applied to investigate the flutter mechanism. The flutter boundary estimated by the ROM-based FSI model shows good agreement with the experimental and numerical results. The results obtained from the complex eigenvalue analysis show that the instability depends on the fluid mode and the structural mode, which consist of plunging mode and pitching mode. Flutter is triggered by the unstable pitching mode, meanwhile the fluid mode and plunging mode are stable.