File(s) under permanent embargo
Vortex-induced motion of a free-standing riser below the critical mass ratio
conference contribution
posted on 2023-05-23, 13:11 authored by Florager, C, Balash, CThe presented work studied the vortex-induced motion (VIM) response of a free-standing riser (FSR) with varied riser length and buoyancy can (BC) mass with an ultimate aim to find a combination that would reduce the motion of the system. Specifically, four model configurations were experimentally tested in a flume tank over a range of flow velocities, with the BC motion recorded by a submersible camera positioned directly above the model; consequently, inline (IL) and crossflow (CF) amplitudes were estimated with a motion tracking software. In the pre-resonant flow regime, non-dimensionally, minimal differences were observed between the CF amplitudes, and the IL motion was reduced with a longer riser. Given the extreme length of full-scale FSRs and inherent low natural frequency, it is impractical to increase the riser tension to a point where VIM would not occur under normal environmental conditions. Alternatively, increasing the mass ratio of the BC so that it is above the critical mass ratio of 0.54 (the ratio of the mass of the body to the mass of the fluid) would limit the resonant flow velocities to a finite range, but a larger BC may not be an economically viable solution, and because of the increased diameter, it would experience a larger CF amplitude during resonance. Further study into the prevention of VIM of an FSR by varying the riser length and BC mass is unlikely to be beneficial.
History
Publication title
Proceedings of the ASME 2017 36th International Conference on Ocean, Offshore and Arctic EngineeringPagination
V002T08A032-039ISBN
978-0-7918-5764-9Department/School
Australian Maritime CollegePublisher
American Society of Mechanical EngineersPlace of publication
USAEvent title
ASME 2017 36th International Conference on Ocean, Offshore and Arctic EngineeringEvent Venue
Trondheim, NorwayDate of Event (Start Date)
2017-06-25Date of Event (End Date)
2017-06-30Rights statement
Copyright 2017 ASMERepository Status
- Restricted