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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.

A new material system was developed for fabricating the combustion engine of an unmanned aerial vehicle. The material system consisted of a mixture of nanoscale and microscale particles of silicon nitride. Magnesia and yttria were used as sintering additives. The powders were mixed with a paraffin binder system. The binder-powder was analyzed for its properties and molding attributes. The study involved several steps of the development and processing. These steps include torque rheometery analysis, mixing scale-up, property measurements of binder-powder, injection molding, binder removal, sintering, scanning electron microscopy analysis and mechanical properties measurements. Simulations of the injection molding process were conducted to assess the feasibility of manufacturing a ceramic engine and to determine its optimal process parameters. The model building required for the simulation was based on flow and solidification behavior data compiled for the binder-powder mixture. The simulations were performed using the Moldfow software package. A design of experiments approach was set up in order to gain an understanding of critical process parameters as well as identifying a feasible process window. Quality criteria were then analyzed in order to determine the optimal production parameters. The study resulted in the successful development of design parameters that will enable fabrication of silicon nitride engine components by powder injection molding. / Graduation date: 2012