Vortex-Excited Vibrations of Marine Cables

Recent experiments to study vortex-excited cable strumming in towing basins and at field sites are compared in this paper to small-scale laboratory experiments. The resonant cable strumming displacements and frequencies measured during the towing basin experiments with several 4.4-m long cables are in good agreement with laboratory experiments conducted with vibrating cylinders and cables. The field experiments were conducted with cables 23m long under spatially uniform flow conditions in a tidal current, for modes up to n = 7. The results from these field experiments also are in good agreement with basic laboratory-scale measurements of the strumming phenomenon. A strumming analysis of the SEACON II cable structure is briefly considered. Measured and calculated deflections of the cable structure are in excellent agreement when cable strumming effects are taken into account.