Vim suppression for a fsr with a co-centric porous sheath around the buoyancy can: Effects of mesh orientation and diameter ratio
Abstract
Here, we experimentally studied the vortex-induced motion (VIM) of a free-standing riser (FSR; 1:65 scale model) with and without a porous metal screen (‘sheath’) placed co-centrically around the buoyancy can (BC). Specifically, we investigated the effects of mesh orientation (square and square rotated 45° in its own plane) and screen-BC diameter ratio (1.1 and 1.2) over a range of flow velocities. BC motions were recorded with a submersible camera; and inline (IL) and cross-flow (CF) amplitudes were then estimated with a motion tracking software. As expected, the installation of the screen changed the natural frequency of the models. Furthermore, the screen increased the reduced velocity at which the lock-in occurred, delaying it by a factor of ∼1.2 and ∼1.4 for the CF and IL respectively. All sheathed models had a prominent reduction in IL amplitudes compared to the bare/unsheathed BC; and at smaller flow velocities, the sheathed models also exhibited significantly lower CF motions, particularly those with a greater screen-BC diameter ratio.
Keywords
Vortex-induced motion (VIM), buoyancy can (BC), mesh orientation
Document Type
Conference Proceeding
Date of Publication
2018
Publisher
American Society of Mechanical Engineers
School
School of Engineering
RAS ID
29521
Copyright
subscription content
Comments
Crosswell, J., & Balash, C. (2018, June). VVim suppression for a fsr with a co-centric porous sheath around the buoyancy can: Effects of mesh orientation and diameter ratio. In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering (pp. V002T08A053-V002T08A053).
Available here.