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M.Ing. / The purpose of this thesis was to gather experimental data of a stainless steel sleeve being formed into a convoluted tube. This convoluted tube, made from stainless steel ASTM 240 type 321 and with a wall thickness of 0,4mm, is the main part of an automotive exhaust bellow. The automotive exhaust bellow fits into a motor vehicle exhaust system. One of the functions of this bellow is to compensate for engine movement. The bellow is also used to damp the engine vibration to the vehicle chassis. Typical failures that occur during the production of a convoluted tube are identified. The data gathered are listed and the forming process, typical conditions and its effects discussed. The actual data and graphs are presented in the annexures at the end of this report. Plasticity theory for shells and cylinders is summarized in Annexure A and the solution of a related problem discussed. Experimental data were used to verify the result of a finite element model. The calculated values of the model compare well with the values of the experimental data. The model must still be developed further and the experimental data can be used to verify this developed model. Possible aspects, related to the forming and life-cycle prediction of an automotive exhaust bellow, that still need to be studied are identified and presented at the end of this report.

A common industrial ventilation and pollution problem results when a thermally buoyant polluted plume of air must be exhausted away from a work area to allow achievement of air pollution standards. Generally, a close fitting canopy hood is one of the most effective means of exhaust containment; however, physical restrictions or the operation itself often prevent such an arrangement, and a hood located to the side of the operation is required. This arrangement requires the exhaust to bend and contain the vertically rising plume with a horizontal sweep of exhaust air across the surface of the operation. A review of available literature revealed a lack of the necessary theory and data needed to design a side draft hood based on plume dynamics. The purpose of this study, then, is to develop the theory relating the side draft hood size and required exhaust volume to the hot source characteristics and to test the theory in the laboratory.

The purpose of this study is to develop and demonstrate a novel process for heat recovery from hot exhaust gases. This process involves direct contact of a hot gas with a countercurrently flowing vibrofluidized bed of cold solid. Based on a simple heat-transfer model, an "apparent" heat-transfer coefficient between the air and solid was calculated. The temperature profile of the air as a function of heat-exchanger length was used to determine the "apparent" area for heat transfer in the model. Analysis, based on factorial-design experiments, showed that increasing the airflow rate and applied vibrational intensity, as well as decreasing the baffle height of the system served to increase the "apparent" heat-transfer coefficient. Increasing the solid flow rate produced higher heat-transfer coefficients only when the baffle was lowered past a certain "critical" height. Under optimum conditions investigated, a gas-to-bed heat-transfer coefficient of about 270 W/m²-K was obtained with a heat exchanger length of 0.71 m. "Cold-flow" experiments of the system were used to explain the heat-transfer trends. A condition analogous to "flooding" determined the operating range of the "flowing" vibrofluidized-bed heat exchanger. As a result of this work, significant progress has been made on the evolutionary development of a vibrofluidized-bed heat exchanger to be used for future heat recovery. / M.S.

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This thesis is concerned with unsteady, one-dimensional flow, which closely mimics those found in the manifolds of internal combustion engines. The physical equations describing problems of this nature are presented and some of the important concepts introduced. These equations and concepts were verified by comparison to published results. The Method of Characteristics (MaC) for unsteady one-dimensional flow with friction and heat transfer was used to analyse the gas flow through the inlet and exhaust systems of an engine. The theoretical derivation of unsteady gas dynamic boundary conditions is presented and the integration with the unsteady pipe flow explained. A simulation flow model was developed to analyse the flow by using the Mae. Thisflow model was then incorporated into an engine simulation program, ESA,to simulate internal combustion engines and to predict the performance of a specific engine. A cam-profile model and an in-cylinder thermodynamic model are used to complete the ESAsoftware. Experimental work was done on a modified Nissan Z24/NA20 engine to evaluate the simulation model. The manifolds of the Nissan Z24/NA20 were modified to isolate one of the cylinders for a proper single cylinder model. More experimental work was done on a Volkswagen 1.6£ 8-valve and a 1.6£ 20-valve engine to obtain performance data on two inlet manifolds developed using the ESAsoftware. Performance data and pressure traces in the inlet manifold of the Nissan Z24/NA20 were recorded for comparison with the ESA software. Good correspondence was found between tested and modelled data and the differences varied between ±5% on engine performance data and pressure wave frequency predictions, and ± 10% on pressure pulse amplitudes. / AFRIKAANSE OPSOMMING: Hierdie tesis handeloor bestendige, eendimensionele vloei, wat die gasvloei in spruitstukke van binnebrandenjins naboots. Die nodige vergelykings wat hierdie tipe probleme beskryf asook van die belangrikste konsepte, word bespreek. Hierdie vergelykings en konsepte is met behulp van gepubliseerde data geverifieer. Die Metode van Karakteristieke (MVK) vir bestendige, eendimensionle vloei met wrywing en warmte oordrag, is gebruik om die gasvloei deur inlaat en uitlaat sisteme van 'n enjin te analiseer. Die teoretiese afleiding van bestendige gasdinamiese randvoorwaardes asook hul integrasie met die bestendige pypvloei, word verduidelik. 'n Simulasie vloeimodel is ontwikkelom die vloei met behulp van die metode van karakteristieke te analiseer. Hierdie vloeimodel is deel van 'n omvattende enjinsimulasie program, ESA. Dit word gebruik om binnebrandenjins te simuleer en enjinwerkverrigting te voorspel. 'n Nokprofielmodel en 'n termodinamiese ontbrandingsmodel word gebruik om die enjinsimulasie program af te rond. Eksperimentele toetse op 'n gemodifiseerde Nissan Z24/NA20 enjin is gebruik om die simulasie model te evalueer. Die spruitstukke van die Nissan Z24/NA20 is aangepas om een van die silinders te isoleer om so 'n geskikte enkelsilindermodel te skep. Verdere eksperimentele toetse is gedoen op Volkswagen 1.6£8- klep en 1.6£ 20-klep enjins. Werkverrigtingsdata is verkry op twee nuwe inlaatspruitstukke wat met behulp van die ESAsagteware ontwerp is. Werkverrigtingsdata en drukverdelingsdata in die inlaatspruitstuk van die Nissan Z24/NA20is aangeteken om te vergelyk met die resultate van die ESAsagteware. Goeie ooreenstemming is verkry tussen toets- en gemoduleerde data. Die verskille varieer tussen ±5% op enjin werkverrigtingsdata en drukpulsfrekwensie voorspellings, en ± 10%op drukpuls-amplitudes.

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