Faculty of Engineering, Built Environment and Information Technology
School of Engineering
Department of Mechanical and Aeronautical Engineering
Selected Highlights from Research Findings
Mechanical engineers have developed a more objective way of ascertaining flow patterns in heat exchangers during condensation and evaporation. They use the frequency response of the pressure signal measured along a heat exchanger to pinpoint the local flow pattern. This method has been tested using a variety of tubular condensers and three refrigerants used in modern industrial heat pumps. The accuracy and repeatability of the so-called 'power spectral density of pressure fluctuations' method has been proven without doubt, and the work will now be extended with leading researchers from the Swiss Federal Institute of Technology, the University of Maryland, the University of Illinois at Urbana-Champaign, and the USA's National Institute of Standards and Technology.
Contact person: Prof JP Meyer.
The classic compromise between vehicle ride comfort and handling is well-known. Sports cars usually have stiff suspension for excellent handling, but ride comfort suffers over bad roads. For off-road vehicles again, it is especially difficult to achieve a good compromise due to the fact that these vehicles are also used on highways at high speeds. Controllable suspension systems offer the possibility to change the spring and damper characteristics while the vehicle is moving, thereby adapting to different terrains and speeds. The Dynamic Systems Group in the Department embarked on a project that includes the design, manufacture and testing of a two-state semi-active hydro-pneumatic spring, combined with a two state semi-active damper and ride height control. A prototype suspension unit was built and characterised to obtain all the parameters required for mathematical modelling as well as vehicle dynamics simulation. A mathematical model of the suspension unit was developed and the predicted results correspond very well to the measured characteristics. A multi-body dynamics model of the baseline vehicle was developed in ADAMS software and verified against road tests results. Control system development for ride and handling control are currently under investigation, and vehicle implementation is scheduled for 2005.
Contact person: Prof PS Heyns.
'Single-crystal' blades for turbines for the aeronautical industry are manufactured from a single crystal, which are grown within a specially manufactured ceramic mould. Of paramount importance to the time taken to manufacture the blade as well as its quality, is the process in which the mould is dried (correct temperatures and airflow, in the shortest possible time). Customised computational software technology developed together with Prof Roland Lewis of the University of Wales-Swansea, a world leader in the field of computational fluid dynamics technology, has now enabled effective modelling of the complex drying process and surrounding fluid flow to fine-tune the drying time and simultaneously ensure increased blade quality. The developed simulation software offers a very high degree of accuracy and could be applied to wherever it is useful to model the drying of complex materials – from construction materials to foodstuffs.
Contact person: Dr AG Malan.
Acute hepatic failure (AHF) or liver failure is a devastating condition with a very high associated mortality rate. A team of researchers is currently undertaking research towards the development of a bio-artificial liver support system (BALSS) that will bridge AHF patients to transplantation or spontaneous liver generation. The system uses blood plasma from the patient and carries out the liver's essential functions, such as synthesis, metabolic activities, detoxification and excretion before reintroducing the blood plasma into the patient's body. The research is a multi-professional collaboration between this Department, the Department of Internal Medicine and CSIR's Manufacturing & Materials Technology.
Contact person: Mr AJ van Wyk.
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