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Due to increasing problems with corrosive wear in marine Diesel Engines, caused by sulphuric acid, it is necessary to understand the mechanism of corrosion. Based on experience with large marine diesel engine operation, a mechanism model is proposed and verified by comparison with practical experience. From operation of engines it is known that the corrosion problem is most severe where the lubrication of the liner is most unsatisfactory. Therefore, most effort is put into modelling the formation and transportation of acid in the lubricant film area. Results from modelling the risk of corrosion during different engine operation conditions are presented.

A quasi-steady gas-jet model was applied to examine the spray penetration and deflection in swirling flow during the ignition-delay period in an open-chamber diesel engine timed to start combustion at top dead center. The input to the gas-jet model included measured values of ignition delay and mean fuel-injection velocity. Attempts were made to correlate measured fuel-consumption and soot-emissions data with mixing parameters based on calculated spray penetration and deflection. The engine parameters examined were piston-bowl geometry, compression ratio, speed, and overall air-fuel ratio. Four empirical correlations proposed in the literature were examined. The correlations, which were based on spray penetration and deflection in the swirl direction, represented overall degrees of fuel distribution in the combustion chamber and of utilization of the cylinder air.

Tests were performed on a single-cylinder direct-injection (DI) research diesel engine to investigate the influence of elevated combustion-chamber temperature on combustion performance. The test program examined the low-heat-rejection (LHR) approach by removing the coolant but without employing heat-insulated parts. Heat-release characteristics calculated from pressure-time histories were correlated with measured exhaust emissions. It was found that increasing temperature level decreases the ignition delay and consequently decreases the fraction of total fuel that burns in the premixed-combustion phase. Exhaust hydrocarbon, NOx and particulate emission were found generally to increase with increasing temperature. The premixed-combustion fraction is concluded not to be the main source of the increased emissions.

A theoretical model has been developed describing the propagation of a laminar, one-dimensional flame in a combustion chamber. The model aims specifically at illuminating the processes surrounding the flame propagation in the vicinity of the combustion chamber wall and the extinction of the flame (the quenching). The model assumes constant pressure for a two-reaction scheme with 6 chemical components (CnHm, O2, CO2, CO, H2O and N2). The equations describing the conservation of energy, mass, and species constitute a system of coupled parabolic differential equations, which are solved through a finite difference scheme with 9 grid-points. The boundary conditions specify the propagation or quenching situation. Temperature as well as concentration profiles through the flame are computed. Flame velocities and quenching distances are computed for a range of air-fuel ratios, physical constants and properties, both for methane and iso-octane.