Study of the Mechanism of Vortex-Induced Vibrations of a Marine Hydrokinetic Turbine Platform
Abstract
Vortex-induced vibrations (VIV) around bluff bodies, such as structural members, cables, conduits, and pipes, resulting in structural stresses due to the structural deformation. Marine hydrokinetic turbine platforms submerged in near-shore coastal areas and tidal zones are constructed with various geometric patterns using structural pipes which are positioned to experience VIV regularly. Cylinder structures in proximity to planar surfaces can undergo VIV when the gap between the cylinder surface and the planar surface is above a critical value (called the critical gap ratio when the critical gap distance is divided by the cylinder diameter). Even at very small gap ratios (sub-critical gap ratios) where vortex shedding is suppressed, streamwise and transverse accelerations of a cylinder in subcritical proximity to planar surfaces have been reported. This laboratory study centers on the mechanism of vibration and the effect of proximity to a planar surface on cylinder dynamics. With a better understanding of this mechanism and resulting cylinder dynamics, failures, or structural members that are at risk, can be predicted more accurately. A better understanding of the mechanism can lead to the development of countermeasures to protect the structural integrity of underwater marine hydrokinetic turbine platforms. Testing is conducted in an open return subsonic wind tunnel with a 9.2 to 1 contraction ratio, a 17.5" by 36" usable test-section, and a total length of 68.5 inches. The cylinder is mounted to permit 2 degrees of freedom using leaf springs in orthogonal directions. The results of this study will provide cylinder trajectories to document a mechanism of vibration for a cylinder in proximity to a planar surface which is directly applicable to the structural design of these marine turbine platforms.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMGC0860003C
- Keywords:
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- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSES;
- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 1635 Oceans;
- GLOBAL CHANGE;
- 4546 Nearshore processes;
- OCEANOGRAPHY: PHYSICAL