Electronic Theses and Dissertations (Masters)
Permanent URI for this collectionhttps://hdl.handle.net/10539/37972
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Item Assessment of Quality Management in Major Projects in the Mining Industry in Botswana(University of the Witwatersrand, Johannesburg, 2024) Pitswe, Odirile Boniface; Sunjka, BernadetteWhile project performance is generally evaluated in terms of schedule, cost and quality performance, guidelines for project quality management are lacking, (Steyn and Nicholas, 2008). The Botswana mining industry is faced with problems of engineering projects which don’t meet the expected outcomes and most of the problems emanate around quality management and quality defects. This research project involved the assessment of quality management in major engineering projects in the Botswana mining industry by evaluating the level of adoption and implementation of quality management systems in major engineering projects, identifying the major causes of project failure, and evaluating the effectiveness of quality management system as employed in major capital projects. The research was focused mainly on Debswana Diamond Mining company as the major mining house in the country, with an objective to assess the maturity level of the company’s quality management system (QMS) and identify opportunities for improvement. A mixed method approach was used which involved archival research and survey research, the results of which were triangulated to corroborate the findings and remove bias. Archival research was conducted using the company document repository to review project retrospect reports, (Lessons learnt reports) and identify problems experienced during the implementation of different projects. These were correlated with common causes of project failures as identified in the critical literature review and cross referenced against survey results to further confirm them. The results indicated that the maturity level of the Quality Management system is at level 4 (quantitatively managed), where processes are measured and controlled. Gaps were identified that if rectified would move the maturity to level 5 (optimizing), where the focus would now be on process improvement. The gaps are mainly around operationalisation, lower-level employees training on quality management, optimisation of shared resources especially subject matter experts like project engineers, key stakeholder management, involvement and participation from end users and operational teams. The study came up with the top five (5) major causes of project failure being: 1. Shared resources and subject matter experts get overstretched between different projects and end up neglecting quality assurance. 2. Poor stakeholder management. 3. Lack of stakeholder involvement and participation in the project. 4. Inexperienced project team. 5. Unclear statements of expected quality outcomes.Item Measurement of combustion airf low into burners in coal fired plants(University of the Witwatersrand, Johannesburg, 2024) Manqele, Gladwell Sizwe; Schmitz, WalterThis research study is aimed at achieving accurate measurement of mass flow rates in large square industrial square ducts at Eskom’s boiler plants. For safe and efficient operation of Fossil Fuel Firing Boiler Plants, the utility has put in place the Fossil Fuel Firing Regulation Standard which requires that the Total Combustion Air flow be measured at exit from the air heaters, into the ducts. In this study, a sophisticated airflow measuring probe was acquired, herein the current study referred to the 14-hole Omniprobe. The accuracy was found to be within 5% in a free stream flow field. A Five-hole probe was calibrated in the free-stream wind tunnel. The calibration process enabled the derivation of the probe specific polynomials of Pitch, Yaw, Total Pressure, Static Pressure coefficients and velocity components. A prototype air duct was designed for the study to simulate air flow through square ducts with a 90⁰ bend as an abrupt flow disturbance. To achieve the objectives of the study, 6 planes were identified where air flow velocity profiles were generated using the equal area method. The modeling of the velocity profiles was conducted numerically, using CFD (Ansys Fluent), and experimental, using Pitot-static probe, Omniprobe, and a Five-hole probe. The mass flow rates as measured by the Pitot-static tube were found to be consistent at planes 1, 2, 5, and 6. The mass flow rate as calculated from the Pitot-static probe varied by 2.1% through the duct. This justified the selection of the Pitot-static probe as the reference for this study. The velocity profiles generated from the traverse measurements using the 14-hole Omniprobe showed an error in velocity measurements which are in the proximity of the wall. This can be attributed to the the wall effect. The mass flow rates of air calculated from the Five- hole probe measurements were found to be within 4% of the mass flow rate as calculated from the results of the reference probe in the 1st and 2nd planes upstream of the bend. After the 90⁰ flow disturbance bend, the accuracy drops to 13% at plane 5 and improved slightly at plane 6 to 11.7%. This is attributed to complex flow pattern at these planes. The study concludes that the Pitot-static tube remains the preferred instrument for use in measuring flow rates using the equal area method in large square ducts. The Five-hole probe can be applied where the flow field is not distorted in conjunction with CFD. The Omniprobe’s accuracy in measuring the velocity magnitude, and the angularity of the flow field was verified in an open stream wind tunnel. This study recommends exploring the use of an L-type 14-hole Omniprobe for application in large square industrial ducts.Item Distributed Electric Propulsion on a Joined-Wing Air-Taxi(University of the Witwatersrand, Johannesburg, 2024) Brand, Darren Mark; Schekman, S.Urban Air Mobility (UAM) is a form of aerial transportation within urban areas with the main intention of easing traffic congestion. Electric Vertical Take-off and Landing (EVTOL) air-taxis are currently in development, but no single configuration has been identified as superior for UAM. There is still scope for alternate designs to be explored. A major obstacle to successful UAM operations is the combination of high energy requirements for VTOL and low battery energy densities, thereby affecting operational aircraft range. Aerodynamic efficiency has been identified as a critical factor for achieving maximum flight range while electric battery technology is matured. It is proposed that an air-taxi which combines Distributed Electric Propulsion (DEP) with a joined-wing may achieve superior aerodynamic efficiency compared to other air-taxi designs. A joined-wing air-taxi capable of carrying four passengers and a pilot has been developed with four alternative DEP configurations. These aircraft are herein investigated and compared against one another. A computational approach was followed using STAR- CCM+ to evaluate the flow characteristics and forces around the aircraft for both climb and cruise conditions. It was found that a “Non-DEP” configuration with four proprotors can achieve up to 5% higher aerodynamic efficiency than a DEP variant. However, this configuration suffers with poor lifting capability at high angles of attack. The sensitivity of aerodynamic efficiency to changes in the number of proprotors and their spacing was seen to be negligible according to this investigation.Item Aerodynamic Force Variation on a Trailing MotoGP Motorcycle in a Corner(University of the Witwatersrand, Johannesburg, 2024) Shaw, Craig Byrne; Boer, MichaelMotorcycle racing is a popular form of motor racing. The MotoGP category produces exciting and competitive races due to motorcycles following each other so closely. This has led to significant aerodynamic advancements being made in the MotoGP category over the past decade. Motorcycles and riders often race within the wake of a leading motorcycle as a result of this competitive racing. Racing in the wake provides an advantage on a straight due to the reduced drag force. This allows for greater acceleration and an opportunity to overtake the leading motorcycle. The effect of the wake on a trailing motorcycle in a corner has not been explored in depth. This research was focused on the aerodynamic force variation on a trailing motorcycle in the wake of leading motorcycle. The optimal position for the trailing motorcycle to gain an advantage over the leading motorcycle was determined subsequently. This was achieved using Computational Fluid Dynamics (CFD). The geometry of the motorcycle was obtained using 3D scans of a 1/18th scale model 2018 Repsol Honda RC213V. The geometry of the rider was drawn using CAD. Initial CFD models were created simulating the motorcycle and rider in a straight line to compare to existing published data for validation. The CFD cornering methodology was developed by Queens University in association with Siemens. The method makes use of rotating reference frames. This simulates the motorcycle and rider cornering at a constant velocity around a constant radius corner. Models were created for a singular motorcycle and rider at varying lean angles between 40 and 60 degrees with matched velocities and corner radii. The aerodynamic forces of drag, lift and side force were analysed on the motorcycle and rider for each case. The trends for these forces were determined relative to the changing lean angles. The drag on the motorcycle and rider increased non-linearly as the lean angle increased with the side force following a similar trend. The lift on the motorcycle and rider also increased non-linearly as the lean angle increased. These same CFD models were recreated with a second motorcycle and rider following a leading motorcycle to determine the effect the wake had on the aerodynamic forces. The second motorcycle and rider were positioned 1 characteristic length behind the leading pair on the same racing line. The drag on the trailing motorcycle and rider decreased as the lean angle increased. The lift on the trailing motorcycle and rider followed a similar trend to the leading pair with it increasing as the lean angle increased and the side force fluctuates as the lean angle increased. This resulted in the trailing motorcycle having a negative allowable change in forward acceleration relative to the leading motorcycle at lean angles lower than 60 degrees. The optimal position for a trailing motorcycle in a corner was determined by positioning the motorcycle and rider on various racing lines and following distances behind the leading motorcycle and rider. This created a grid pattern of the tested trailing positions. Two smaller racing line radii, three larger racing line radii and three different following distances were tested. The optimal trailing position at a 50 degree lean angle was found to be 1 characteristic length behind and on a racing line 1 characteristic width larger than the leading motorcycle. This position resulted in a positive allowable change in forward acceleration relative to the leading motorcycle around a corner radius of 125.86 m at 38.36 m/s. This iii position was tested around another two corner radii of 75 m and 150 m. This resulted in a negative allowable change in forward acceleration of around the 75 m radius corner and a greatly improved positive change in forward acceleration around the 150 m radius corner. From these results it was concluded that this optimal position is only viable around larger radius corners. It was approximated that this optimal position provides the trailing motorcycle an advantage around corner with radii larger than 86.8 m.