Dynamics of long flexible cylinders at high-mode number in uniform and sheared flows

The primary objective of this thesis is to characterize the response of risers at high-mode numbers in sheared and uniform ocean currents. As part of this thesis work, three separate experiments have been planned and executed. The objective of these tests was to create a set of model tests at high-mode numbers, the first test was in uniform currents and the other tests in sheared currents. In the experiments, Vortex-Induced Vibrations (VIV) happened at one frequency at one time, rather than at many frequencies simultaneously. The single VIV frequency varied with time, but the VIV frequencies did not co-exist. The major impact of time-sharing frequencies is that it increases the damage rate and fatigue of the pipe. The high density of the sensors on the pipe allowed for analysis that had not previously been done. Two methodologies are presented to locate the area of the power-in region. Once the region where the vibration originated has been found, the different phenomena that effect the location of the power-in region that were discovered are shown. Four different factors are presented that effect the locations of the power-in region: the incidence angle of the current, the gradient of the current direction, the current profile, and the end effects at high mode number.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Swithenbank, Susan B. (Susan Brenda)

Advisor dc:contributor.advisor

• J. Kim Vandiver.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/38543

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/38543