Research on the sound generation by flow around vortex-induced vibrated aerofoil

In order to reduce efficiently the vortex-induced noise, the sound generation by viscous flow around vortex-induced vibrated aerofoil is studied. The fluid-structure coupled system of aerofoil in two dimensions is described by using Navier-Stokes equations. The reversing force and movement induced by body deformation are simulated by spring system. There are two degrees of freedom in aerofoil movement, that is the vibration vertical with incoming flow and the turning vibration. The initial attacked angle is so large that periodic vortex shedding and dynamic force could be produced. The latter is coupled with the spring system and vortex-induced vibration could be introduced. By using Lighthill' acoustic analogy, the sound generation induced by the viscous flow around the vortex-induced vibrated aerofoil in two dimensions is studied. The results show that lock phenomenon happens and the sound generation is the largest when the vortex-shedding frequency is coincided with the natural frequency of the aerofoil system