Experimental evaluation of the vortex-induced vibration suppression of catenary flexible riser with helical strakes

This study experimentally investigates the vortex-induced vibration (VIV) suppression of a catenary flexible riser equipped with helical strakes subjected to sheared flows. The performances of different coverage ratios and arrangements are compared in the reduced velocity U r m range of 6.05–36.89. The experimental results indicate that helical strakes can effectively reduce the dominant vibration mode and response amplitude. Nevertheless, the coupling between the in-plane and out-of-plane responses is enhanced. A uniform arrangement with 60 % coverage is recommended, considering both response amplitude and mode reduction. • The performance is tested under the superposition of shear flow and catenary layout. • The coverage ratio and spatial arrangement of helical strakes are examined. • VIV suppression is comprehensively evaluated through the amplitude and dominant mode. • The coupling of in- and out-of-plane responses is enhanced with attachment of strakes.