Show simple item record

dc.contributor.supervisor Popplewell, Neil (Mechanical and Manufacturing Engineering) en
dc.contributor.author Fleming, Patrick Hugh
dc.date.accessioned 2010-06-30T15:57:05Z
dc.date.available 2010-06-30T15:57:05Z
dc.date.issued 2010-06-30T15:57:05Z
dc.identifier.uri http://hdl.handle.net/1993/4017
dc.description.abstract Overhead transmission lines are prone to undergo large amplitude, low frequency vibrations when exposed to freezing rain and steady side winds. These vibrations are referred to as galloping. They involve a dominant vertical motion in addition to twisting and horizontal swaying. Field reports indicate that the majority of galloping cases are associated with lightly-iced lines with thin ice accretions. Previous studies have failed to explain this trend satisfactorily. The present thesis involves a series of wind tunnel experiments to understand the rotational effects in lightly-iced transmission line galloping. The work to restore and upgrade the wind tunnel used for the experiments are also reported. Aerodynamic loads are measured first on a stationary model of a short, representative section of a lightly-iced conductor. Subsequently, automated controls force the model to undergo rotational oscillations, and the aerodynamic loads measured from these dynamic tests are compared to the stationary results. The airflow in both sets of experiments is visualised by using a laser-based system. The stationary test shows that the well-established den Hartog criterion for predicting vertical galloping does not explain why lightly-iced lines gallop. The dynamic experiments however confirm the presence of rotation-induced lift, unaccounted for by quasi-steady theory and the den Hartog criterion. This additional lift force increases the coupling between the rotational and vertical directions and may promote coupled aerodynamic instability. Visualisations indicate that the surface irregularities of the ice and the rotational motion are jointly responsible for the rotation-induced lift forces observed in the aerodynamic measurements. en
dc.format.extent 33810762 bytes
dc.format.extent 846928 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/zip
dc.language.iso en_US
dc.rights info:eu-repo/semantics/openAccess
dc.subject galloping en
dc.subject conductor en
dc.subject wind en
dc.subject ice en
dc.subject flutter en
dc.subject transmission en
dc.title Wind tunnel studies on rotational effects in lightly-iced transmission line galloping en
dc.type info:eu-repo/semantics/masterThesis
dc.type master thesis en_US
dc.degree.discipline Mechanical and Manufacturing Engineering en
dc.contributor.examiningcommittee Tachie, Mark (Mechanical and Manufacturing Engineering) Gole, Aniruddha (Electrical and Computer Engineering) en
dc.degree.level Master of Science (M.Sc.) en
dc.description.note October 2010 en


Files in this item

This item appears in the following Collection(s)

Show simple item record

View Statistics