Lift and drag forces on a submarine pipeline in steady flow

 

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dc.contributor.advisor Kilner, F A en_ZA
dc.contributor.author Kok, Nicolaas Johannes en_ZA
dc.date.accessioned 2014-10-11T12:00:00Z
dc.date.available 2014-10-11T12:00:00Z
dc.date.issued 1988 en_ZA
dc.identifier.citation Kok, N. 1988. Lift and drag forces on a submarine pipeline in steady flow. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/8315
dc.description Includes bibliography. en_ZA
dc.description.abstract This thesis describes an experimental investigation into the hydrodynamic forces induced on a cylinder placed transversely to a steady stream. Various cylinder locations near the bed of a water flume were considered. The work relates to pipeline design. The various flow phenomena around a cylinder are theoretically analysed and an explanation of the phenomenon of lift provided. A thorough literature review was undertaken regarding the classical theory, as well as experimental and theoretical studies carried out on the subject. This revealed that theoretical studies are virtually non-existent. Measurements have been done in intermediate water depths with both smooth and rough beds. Two different methods, comprising very simple yet novel techniques, were utilised in a water flume 18 m long x 600 mm wide x 450 mm deep. The methods involved a unique pressure determination method as well as the direct measurement of hydrodynamic forces, using a "weighing" method. Very ' accurate flow velocities were measured using a unique differential manometer. Experiments were performed in the Reynolds number range 6 000 to 26 000, using 30 and 50 mm diameter cylinders. comprehensive tests on cylinder roughening were carried out in a flow region which had not been well researched regarding this aspect. Cylinder locations were varied from a gap-to-cylinder diameter ratio of zero to 2,67. Results revealed that the force coefficients are not appreciably affected by bed roughness. Cylinder roughening produced somewhat contradicting results for the two different cylinders used. The influence on the lift coefficient was inconclusive, but the "rougher" 30 mm cylinder produced a slightly higher drag coefficient. Although the lift force was predominantly away from the bed, a downward lift force was measured on a few occasions with the cylinder situated further than one cylinder diameter away from the bed. A possible explanation is offered for this and other unexpected results. Flow visualisation tests were performed to confirm certain features of the flow around the cylinder. These as well as all the other results have been related to published work. en_ZA
dc.subject.other Civil Engineering en_ZA
dc.title Lift and drag forces on a submarine pipeline in steady flow en_ZA
dc.type Thesis / Dissertation en_ZA
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering & the Built Environment en_ZA
dc.publisher.department Department of Civil Engineering en_ZA
dc.type.qualificationlevel Doctoral en_ZA
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
uct.type.filetype Image


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