Hydrodynamic response behavior of ribbon fairing

Ribbon fairings were developed to mimic the effectiveness of marine growth in changing the frequency response behavior of marine cables and there are a variety of practical designs that are used in oceanographic applications. An experimental investigation was conducted in a model basin to study the basic nature of suppression of flow-induced vibrations by ribbon fairing. The flexible test cylinder model with an L/D ratio of approximately 760 was towed in a horizontal orientation at speeds reflecting uniform current velocities ranging from .18 m/s to .43 m/s. The objective here is to understand the migration of flow-induced vibrations in terms of frequency content, mode shapes and modal contributions that can be used to reconstruct the original time series measurements. Spectral analysis of the data revealed the multi-modal excitation that in these experiments was typically dominated by two to three dominant spectral peaks. The increase in current velocity and introduction of the fairings resulted in the mitigation of the energy associated with each of the spectral peaks and a shifting of the remaining spectral response peaks. The ability to reconstruct the original time series measurements is shown to be sensitive to the frequency response range and the number of sensors.