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The work presented describes the development of an interactive model to simulate a direct injection diesel engine under both steady and transient conditions, based on the application of concurrent process computing methods. Starting with the modelling of the engine under steady operating conditions, in which induction, injection, air entrainment, fuel air mixing, combustion, emission and mechanical friction processes are considered, the fuel pump, governor, engine crankshaft and external load dynamics are also investigated to model the transient behaviour of the engine and its associated load.

Homogeneous charge combustion in a four stroke cycle spark-ignition engine was studied using through-piston-photography with a gated-intensified CCD camera. Analysis of computer stored multiple exposed flame front images was carried out for various engine conditions, in conjunction with the test data and cylinder pressure signals. Representative turbulence scales were inferred from the flame propagation and cylinder pressure data. Fractal analysis of flame edge contours resulted in a fractal dimension D3 in the range 2.12 to 2.23 corroborating data presented elsewhere. A correlation is presented here between the standard deviation of peak cylinder pressure and the fractal dimension D3.

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This dissertation examines the suitability of Computational Fluid Dynamics (CFD) modelling for the production of realistic flowfields and temperature fields within a series of vortex combustion chambers of differing geometries and operating under various conditions. Initial validation of the CFD predictions was obtained through modelling of a series of isothermal vortex chambers for which a comprehensive set of experimental data was available. It was observed that CFD did indeed produce representative flowfield predictions for chambers of various geometries and operating conditions. A vortex unit used for the incineration of sewage sludge (US Navy Waste Incinerator) was subsequently investigated, and it was shown that due to the high moisture content of the waste material used, temperature profiles obtained with a modified coal combustion model were similar to those obtained with a more straightforward and computationally less expensive spray drier model. Results from both models were similar to experimentally observed conditions. However, comprehensive validation was not possible. In order that full validation could be provided for a CFD model of a vortex combustion unit, a model was developed of a commercial thermal oxidiser used for the incineration of liquid and gaseous wastes. CFD temperature predictions for the BASF Thermal Oxidiser were validated by a series of experimental measurements obtained from the operating unit. In general, it was found that the Reynolds Stress Model for turbulence produced the most representative velocity flowfields, with the less computationally demanding k-e model being applicable only under certain limited circumstances. Furthermore, insufficient grid refinement resulted in significantly distorted velocity profiles.

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No description available.