The Influence Of Damping On The Viv Suppression Of A Circular Cylinder Fitted With Flexible Shrouds

Experiments have been carried out with a circular cylinder fitted with four different models of flexible shrouds with variable values of structural damping. Shroud models were derived from the geometry of the suppressor called "ventilated trousers". VIV responses are presented in a range of reduced velocities from 2 to 15 and Reynolds number from 2,000 to 25,000. Influence of structural and hydrodynamic damping is considered and, since the meshes generate more hydrodynamic damping than a bare cylinder, this effect on VIV suppression is analyzed. With the minimal structural damping, the VT mesh reduced about 55% of the amplitude peak of bare cylinder; while the thick-sparse, thin-sparse and thin-dense meshes reduced about 50%, 45% and 50%, respectively. For the case with similar levels of total damping (structural plus hydrodynamic) the same models reduced about 50%, 25%, 40% and 50%, respectively. The results show that the effect of increasing the structural damping has an important role in the VIV suppression of the thick-sparse mesh. For the other models, this effect is less significant.