Tödter, SimonSimonTödterSheshtawy, Hassan elHassan elSheshtawyNeugebauer, JensJensNeugebauerMoctar, O. elO. elMoctar2021-03-102021-03-102019-0911th International Workshop on Ship and Marine Hydrodynamics (IWSH2019), Paper 76http://hdl.handle.net/11420/9043Tower structures of wind turbines are often installed in various configurations at the port before being transported by ships. Vortex-induced vibrations may occur when the natural frequency of the structure is close to flow vortex shedding frequency. This leads to a considerable reduction of their fatigue life. The phenomenon is well-known for risers in the oil and gas industry. Here, we present an experimental study of vortex-induced vibrations (VIV) of a fully and partially submerged hollow cylinder in water. A circulating water channel generated the flow towards the test bodies. Two hollow cylinders with a length-to-diameter ratio (l/d) of 28.13 and 18.5 and an outer diameter of 32 mm were used. Each cylinder was equipped with three-dimensional accelerometers. From the acceleration data, a two-fold integration delivered the motion amplitudes of the cylinders at the location of the accelerometer. In addition, a speckle pattern was applied to the cylinders and captured with two high-speed cameras, arranged in different orientations to the cylinder. Three-dimensional Digital Image Correlation (DIC) was used to measure the motion trajectories for the areas of the cylinder, covered by a speckle pattern. First, decay tests for the test bodies were performed in air and water. From the motion trajectories, the natural frequencies and damping coefficients were evaluated. Second, tests in uniform flow were conducted under fully and partially submerged conditions for different flow velocities. Flow effects such as reduced velocity on vibration were assessed in terms of motion amplitudes and frequencies in longitudinal and transverse direction. The results from DIC and accelerometer measurements were compared and the suitability of DIC for VIV investigations was discussed.enhttp://rightsstatements.org/vocab/InC/1.0/Digital image correlationExperimental methodsVortex induced vibrationTechnikIngenieurwissenschaftenConference Paper10.15480/882.336810.15480/882.3368Fluiddynamik und Schiffstheorie M-8Conference Paper