Experimental Investigation on Vortex-Induced Vibration of Risers With Staggered Buoyancy

In this paper, model tests of a riser with an aspect ratio of 263 were performed in a towing tank by towing the model with constant speeds. The riser was tested with various configurations of buoyancy, including 0% coverage, 25% coverage, 50% coverage and 100% coverage of the buoyancy modules. Furthermore, for the 25% and 50% coverage conditions, the portion without buoyancy modules of the model was covered with helical strakes of 17.5D/0.25D (pitch/height). In the experiments, the strain information in cross-flow (CF) direction was measured using Fiber Bragg Grating (FBG) sensors. The VIV characters of flexible risers with different buoyancy configurations were studied and compared with each other in detail.