Norwegian Deepwater Program: Damping of Vortex-Induced Vibrations

摘要

Vortex-induced vibration (VIV) of a long riser in sheared current is often considered as an energy balance problem: Excitation forces in the power-in region add an equal amount of energy to the system as is dissipated by damping forces outside this region and by structural damping. A riser may have different excitation and damping regions depending on the actual oscillation frequency, cross-section properties and local flow velocity. A damping model must hence be able to handle higher and lower flow velocities than the excitation velocity range. in this paper the fluid damping models proposed by Venugopal are compared tih the experiments conducted by Gopalkrishnan and Vikestad. The results show that the models are conservative at high and low reduced velocities.