Moss, J. B.De Castro, F. L. J.2024-01-162024-01-161989-05https://dspace.lib.cranfield.ac.uk/handle/1826/20653In the present work a zero-dimensional model of turbulent combustion has been developed for the spark ignition engine. In addition to the prediction of thermodynamic state properties, the model includes the following elements: heat transfer from the combustion chamber, a geometrical model of turbulent spherical flame propagation and detailed post flame chemical equilibria. The model is responsive to such engine operating parameters as spark timing, equivalence ratio, engine speed and also to such design parameters as compression ratio, spark plug position and combustion chamber geometry. Two different geometries were studied extensively with the program, namely the disc chamber and the bowl-in-piston chamber. Ethanol and isooctane were investigated as fuels during the numerical simulations at variable conditions of spark advance, equivalence ratio, engine speed and compression ratio The model was employed in a partly diagnostic role to predict the engine performance using different correlations for a critical model parameter, the flame speed ratio. These were taken from the work of different researchers and included both empirical correlations, derived from engine experiments, and correlations derived from more fundamentally-based turbulent combustion studies. Comparison between prediction and experiment was made possible by a diagnostic investigation of the expanding flame front into the combustion chamber of a homogeneous charge spark ignition engine, performed in a Ricardo E6 research engine. The turbulent flame speed was determined experimentally by a dual-beam laser deflection technique. The measurement of flame transit times was performed using a specially designed and built system incorporating equipment for data acquisition based on a microcomputer. The results obtained experimentally and those obtained by the numerical simulation in general show good agreement. In the absence of detailed in-cylinder turbulence information the more fundamentally-based turbulent flame propagation models often do not perform as satisfactorily as those developed specifically for zero-dimensional ( or thermodynamic ) engine simulation.enTurbulent combustionspark ignitionthermodynamicheat transferturbulent spherical flame propagationpost flame chemical equilibriaThesis