Thesis (Ph. D.)--City University London, 1996. / Includes bibliographical references (p. 263-270).

Thesis (Ph. D.)--City University London, 1996. / Includes bibliographical references (p. 263-270).

Thesis (Ph.D.)--University of Tulsa, 1976. / Bibliography: leaves 96-98.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in ful lment of the requirements for the degree of Master of Science in Engineering. Johannesburg, April 2016 / An explosive event in an industrial gas transmission pipe stresses the pipe and can result in pipe rupture and separation at weak points. A shock wave results propagating from the high pressure section of the pipe, through the gap and to the low pressure section. The present study simulates numerically and experimentally the resulting ow eld at the position of pipe separation and propagation conditions in both pipe sections. The e ects of gap width, gap geometry and shock Mach number variation are investigated. Shock Mach numbers of 1.34, 1.45,1.60 and 2.2, gap widths of 40mm to 310mm were used. All variations of boundary conditions were found to have an e ect on the propagation conditions as well as the development of the ow features within the gap. The variation of the gap geometry was done for a pipe gap and a anged gap experimentally. Extended geometries were simulated numerically. For the pipe gap, the incident shock wave accelerated the gas in the upstream pipe to high subsonic speeds and continued in the downstream pipe at a much reduced strength. A strong expansion propagated into the ow in the upstream pipe causing a signi cant pressure drop from the initial post-shock pressure. Expansion waves at the out ow resulted in supersonic speeds as the ow entered the gap for Mach 1.45 and 1.6. A notable feature was the formation of a standing shock at the inlet to the downstream pipe. In addition to the standing shock, shock cells of alternating shocks and expansions developed within the gap essentially controlling the propagation conditions in the downstream pipe. For the lower Mach number of 1.3, no sharp discontinuities were noticed. The e ect of the gap width was found on the nature of the shock cells within the gap. The propagation conditions in the downstream pipe showed that the pressure is initially unsteady but becomes more uniform, controlled by the developed wave system in the gap. For the anged gap case, the ow within the gap is con ned for much longer and hence produced much more intense and complex ow feature interactions and an earlier transition of the ow to turbulence. Numerical investigations for a burst pipe gap, for a gap with a di erent diameter downstream pipe and a gap with a 90-degree bend downstream pipe produced peculiar ow features. / MT2016

"August 2002" / Bibliography: leaves 219-228. / xxix, 255 p. : ill., photos. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering. 2003

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / Wax deposition in sub-sea pipelines is a major concern in the oil industry. Wax precipitates in a pipeline when the temperature falls below a certain temperature called the Wax Appearance Temperature. As wax precipitates and deposits in a pipeline, the wax deposit can cause oil flow problems and reduce production efficiency. At critical conditions wax deposits in pipelines may damage production equipment or cause a production stoppage. In the past two or three decades, the challenge has been to develop and apply high-fidelity models for wax deposition. In this context, two promising models have recently been developed: that of Eskin et al. (2014) and that of Haj-Shafiei et al. (2014). This research report tries to solve and elucidate some of the key assumptions of these wax deposition models, through implementing them in the Python Programming Language. In investigating the significance of the shape of the Solubility Curve on wax deposition, a concave shaped solubility curve was found to exhibit the highest average deposition and the convex shaped solubility curve the lowest average deposition. The shape of the solubility curve also drastically affects the peak wax height with a concave shaped solubility curve forming the greatest wax peak. The results have shown that the description of the phenomenon of Wax deposition in undersea pipelines is difficult to grasp for anyone not familiar with the topic because of the complexity of the mechanisms involved. Often, the models are difficult to visualise owing to their multi-dimensional solution procedure and the interdependence of parameters. The resultant programs could be utilised to help illustrate the process of Wax deposition to Engineering students or professionals who do not have access to expensive proprietary software or who are less proficient with programming but interested in the field. / GS2016