Shock-induced flow through a pipe gap

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 2016An 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.MT201

a comparative analysis of CDM in South Africa and China

Both South Africa and China are emergent economies heavily dependent on fossilfuel based energy sources, and the potential to leverage the Clean Development Mechanism (CDM) is significant in both countries. However, experience to date with CDM indicates South Africa has significantly lagged behind China in the uptake of the CDM, accounting for only 0.9% of the worldwide registered annual Certified Emission Reductions (CERs) while China has dominated the market, generating over 54% of the annual worldwide CERs. Thus, an opportunity exists to redefine the role of CDM in South Africa to better incentivise a lower carbon development trajectory. This paper provides a comparative analysis of the CDM experience in China and South Africa in order to identify the underlying drivers and obstacles to CDM in both countries. It is the authors’ objective to analyse the lessons learnt from marketleading China and laggard South Africa to better understand the structures and policies necessary within host CDM countries to unlock the potential of CDM in a post 2012 regime

Internationalization of higher education and emerging national rationales : comparative analysis of the Global North and South

This paper provides a comparative analysis of national rationales to higher education internationalization in the global north and south countries using content analysis. The results reveal that the socio-economic rationales are dominant across most of the 27 sampled countries. However, they manifest differently across the global north and global south as countries interpret the benefits and effects of internationalization in line with their national priorities. These variations are being shaped by an increasingly complex, competitive, and multipolar higher education internationalization landscape with new global south actors acquiring agency despite the deepening global inequalities. As a result, political rationales are becoming an important driver to internationalization. The current geopolitical environment associated with global conflicts, health pandemics, and increased nationalistic, anti-immigrant, and anti-globalization sentiments is also adding more uncertainty and complexity. Due to increased concerns about this multipolar and self-centred internationalization, a few countries are starting to promote inclusive approaches to internationalization.Open access funding provided by University of Pretoria.https://link.springer.com/journal/41307hj2024Future AfricaSDG-04:Quality Educatio

Investigating business' contribution to climate change governance in areas of limited statehood: the case of South Africa and Kenya

Climate change and the related social and economic challenges present society with problems at multiple levels. There is a diverse range of actors who are contributing to climate change governance, including those who are going to be affected by the impacts. In areas of limited statehood were states have varying degrees of deficits in their abilities to steer effective climate change mitigation and adaptation, private actors such as business organisations are expected to step in. This research set to investigate how and why companies in South Africa and Kenya contribute to climate change governance. South Africa and Kenya are selected because they represent areas which have varying levels of limited statehood. The results from the content analysis and the case studies reveal that companies’ climate change governance contributions can be characterised into four configurations: laggards, emergent planners, efficiency drivers and visionaries. The laggards display very limited responses and if anything adopt cosmetic initiatives. The majority of Kenyan and South African firms are in this cluster. Emergent planners are in the early stages of implementing self-regulatory initiatives mostly at the firm level. The efficiency drivers which consist of mostly energy intensive companies engage in co-regulation which involves partnering with the state to set and implement rules in energy efficiency accords in both countries. The firms, in turn, self-regulate themselves by internally implementing the energy efficiency accord guidelines. The final configurations, the visionaries, make more comprehensive mitigation and adaptation governance contributions focusing on collective self-regulation and adopting the role of the “inspector” along their supply chain. On the basis of these empirical findings, the research identifies different ways in which the institutional, organisational and issue specific drivers interact to explain the variations in firms’ governance contributions between countries, sectors and different companies. First, corporate climate change governance contributions vary between South Africa and Kenya as a result of the countries’ different levels of statehood. South African firms are more responsive to climate change than Kenyan companies because they are more exposed to the shadow of hierarchy. Statehood is a significant factor in the context of possible alternative explanations. Second, the climate change governance contributions vary between sectors due to the combined effect of the shadow of anarchy and the task complexity associated with securing energy or water supply among “high salience” sectors. Furthermore, carbon intensive sectors have strong associations which enable them to address collective problems linked to climate change. Lastly, there are significant levels of variance in the governance contributions between the different types of companies, that is, between large, multinational companies and smaller, domestic firms. The large firms engage in more comprehensive mitigation and adaptation efforts due to organisational factors which include “asset specificity” and organisational resources

Thesis

Water is an essential resource in everyday life and if managed properly can help alleviate the day to day struggles that most South Africans face. The transition to democracy in South Africa required a process of law reform that saw old acts abolished to make way for new legislation that encapsulate the principles of equity, sustainability, and efficiency. In terms of the National Water Act (NWA) strategies including the national water resource strategy (NWRS) have been developed to facilitate the proper management of water resources. South Africa has been divided into nineteen water catchment management areas, identified in the strategy, and new water management institutions have been designed to help address the problems of water provision, management, conservation and participation by stakeholders in these processes (DWAF, 2004b). This project seeks to analyse and evaluate these new water management arrangements, especially relating to the water user association (WUA). A key focus will be the role that socio-cultural issues, particularly the role of traditional leadership and cultural and religious practices play in determining water management outcomes

Is there a role for traditional governance systems in South Africa’s new water management regime?

The transition to democracy in South Africa in 1994 catalysed new forms of governance in all sectors of society including water resource management. This paper examines the extent to which traditional governance systems have been acknowledged and incorporated into these new water management institutions and approaches. The research focused on understanding the cultural, religious and customary practices and rules relevant to water resource management as well as the roles of traditional leaders in 2 water user associations in the Eastern Cape Province. Findings from the research reveal that bothstate governance systems and traditional governance systems are relevant to water resource management in the study areas. However, management is predominantly guided by state-driven strategies which are based on statutory legal systems. Yet, traditional governance systems, including customary laws and cultural and religious practices, have an important role to play in achieving the purposes of the water user associations. Failure to acknowledge and incorporate aspects of these traditional governance systems may undermine the ability of government to achieve the objectives of the National Water Act