Experimental study on vortex induced vibration responses of a flexible cylinder in sheared current

The vortex induced vibration responses of a flexible cylinder in sheared current were studied experimentally. The relative sheared currents were simulated by rotating the cantilever in the experiment. Based on the modal analysis method, the displacement responses could be obtained by the measured strain. The results indicate that the response frequency involves in the vibration all the time at low reduced velocity. However, at high reduced velocity, response frequency involves in the vibration intermittently. Vortex induced vibration response has only one lock-in region in the CF direction, but two lock-in regions in the IL direction. The first lock-in region in the IL direction coincides with the lock-in region in the CF direction.