Experimental investigation of spring stiffness effect on Vortex Induced Vibration of a flexibly mounted cylinder

Vortex induced vibration (VIV) is a well-known flow phenomenon studied in many engineering fields. VIV happens when a current flows over a bluff body. During this process, vortices generate and shed on the downstream side of the bluff body. Vortex shedding alternates from one side to the other side, thereby inducing alternating forces on the body, generating an up and down movement. A potential exists to harness this phenomenon for electrical energy generation from low velocity currents. Our Towing-Tank set-up includes an elastically-mounted rigid circular cylinder, with low system damping that is carried inside a ۱۴m long water channel. The cylinder is limited to one degree of freedom and VIV cause it to oscillate transverse to the movement’s direction. This system shows the potential of harnessing hydrokinetic energy of water currents by converting it to mechanical energy using VIV. The most important advantage of this Towing-Tank system is the lack of turbulence intensity during the experiments. At this paper VIV have been studied experimentally with emphasis put on spring stiffness and Reynolds number effects. Experiments are carried out in the subcritical Reynolds regime (۱×۱۰۴VIV happens in a wide range of spring stiffness’. The maximum amplitude of oscillation happens at a specific stiffness. Accordingly, by reducing and increasing natural frequency of system, the maximum amplitude ratio decreases. Also for lower stiffness cases, the synchronization occurs at lower Reynolds numbers.

کلیدواژه ها:

VIVACE ، VIV ، Towing-Tank ، Ocean Energy