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UBC Theses and Dissertations
Suppression of wind-induced torsional instability using partitioned nutation dampers Lim, Seng Boh
Abstract
The thesis aims at the development of partitioned rectangular and toroidal dampers for suppressing wind-induced instabilities in torsion of bluff bodies like bridge-decks and bundles of transmission line conductors. To begin with, energy dissipation of the dampers as affected by the system frequency and liquid height, in the presence of partitioning, is assessed. This is followed by a qualitative flow visualization study of the surface waves to provide better appreciation of the dissipation mechanism. Finally, a set of wind tunnel tests with a square prism is undertaken to determine the effectiveness of the dampers in suppressing torsional galloping instability. Results suggest that the optimum partitioning corresponds to the compartment length to width ratio of 1.2 for the rectangular damper, while for the double toroid, it represents the diameter ratios of 1.125 and 2 for the outer and inner rings, respectively. In general, for the rectangular damper, roll motion led to a higher damping compared to the pitch degree of freedom. From flow visualization, it appeared that wave breaking as well as collision of waves promote energy dissipation. During the wind tunnel tests, both rectangular and toroidal dampers proved to be quite successful in suppressing galloping instability in torsion. The information can be used to advantage in the design of bridgedecks and high voltage transmission lines, which are often susceptible to this form of instability.
Item Metadata
Title |
Suppression of wind-induced torsional instability using partitioned nutation dampers
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1996
|
Description |
The thesis aims at the development of partitioned rectangular and toroidal
dampers for suppressing wind-induced instabilities in torsion of bluff bodies like
bridge-decks and bundles of transmission line conductors. To begin with, energy
dissipation of the dampers as affected by the system frequency and liquid height,
in the presence of partitioning, is assessed. This is followed by a qualitative flow
visualization study of the surface waves to provide better appreciation of the
dissipation mechanism. Finally, a set of wind tunnel tests with a square prism is
undertaken to determine the effectiveness of the dampers in suppressing torsional
galloping instability.
Results suggest that the optimum partitioning corresponds to the
compartment length to width ratio of 1.2 for the rectangular damper, while for
the double toroid, it represents the diameter ratios of 1.125 and 2 for the outer
and inner rings, respectively. In general, for the rectangular damper, roll
motion led to a higher damping compared to the pitch degree of freedom. From
flow visualization, it appeared that wave breaking as well as collision of waves
promote energy dissipation. During the wind tunnel tests, both rectangular and
toroidal dampers proved to be quite successful in suppressing galloping instability
in torsion.
The information can be used to advantage in the design of bridgedecks and
high voltage transmission lines, which are often susceptible to this form of
instability.
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Extent |
7448802 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-02-17
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0080919
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1996-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.