Numerical study on vortex induced vibration responses of a circular cylinder attached by a free to rotate dartlike overlay
Abstract In the present paper, the two degree of freedom vibration responses of a circular cylinder attached by a free to rotate dartlike overlay with Reynolds number ranging from 1715.9 to 6851.6 are modeled in two dimensions by using the commercial CFD code "Fluent" The rotation of the dartlike overlay can disturb the flow around the cylinder and simultaneously convert hydrokinetic energy to mechanical energy. The URANS equations and SST k o turbulence model are employed to calculate the flow field, while a fourth order Runge Kutta method is applied to evaluate the motion of the system. It is found that the overlay rotates counterclockwise under the drive of fluid flow, resulting in 2S wake mode throughout the reduced velocity range. The boundary layer separation points move to the four tips of the overlay. Due to the shearing action of rotating overlay, small vortices are cut off from the vortices shedding from overlay tips. The rotation of overlay speeds up the migration of the vortices to the downstream. However, as the reduced velocity is larger than 6.7, the vibration of the system is enhanced. So this free to rate overlay can be used as power generation device at high reduced velocity.