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An existing multidimensional in-cylinder flow code, KIVA, was modified to conduct port-and-cylinder gas flow, fuel spray, and combustion calculations in a port-fuel-injection engine. The effect of a moving valve with a stem was modeled using a novel internal obstacle technique in which the valve was represented by a group of discrete computational particles. Previously developed spray and combustion models were used to simulate fuel injection and combustion processes for a solid-cone shaped, pressure-atomized spray with isooctane as the fuel. The spray model was further modified to handle interactions between the spray drops and the valve. The model was applied to a generic port-fuel-injection engine with variations in port orientation, spray cone angle, and valve configuration (without and with a 180-degree shroud).

The comprehensive engine simulation code, WAVE, is extended to include a knock sub-model. A hydrocarbon autoignition model based on a degenerate chain-branching mechanism that constitutes the basic kinetic framework was modified and coupled with WAVE's engine thermodynamic environment for this purpose. Making use of this modified hydrocarbon autoignition model and the flow based in-cylinder heat transfer model in WAVE, the original rapid compression machine (RCM) experiments of Shell can be reproduced reasonably well. In addition, a spatially and temporally resolved end-gas thermodynamic model was developed to allow a more accurate calculation of the end-gas temperature over the combustion chamber wall. The developed end-gas thermodynamic-driven knock model further assumes the existence of a pseudo-boundary-layer temperature profile which is linearly distributed between the unburned end-gas and the wall.

Two-dimensional in-cylinder velocity distributions measured with Particle Image Velocimetry were compared with computed results from Computational Fluid Dynamics codes. A high-swirl, two-valve, four-stroke transparent-combustion-chamber research engine was used. Comparisons were made of mean-flow velocity distributions, swirl-ratio evolution during the intake and compression strokes, and turbulence distributions at top-dead-center compression. This comparison with the measured flows led to more accurate calculations by identifying code improvements including swirl in the residual gas, modeling of the gas exchange during the valve overlap, and improved numerical accuracy.

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.

The predictive capability of a phenomenological spray-combustion model was evaluated for diesel engine performance, combustion, and emissions. The data used for comparisons with the predictions resulted from tests on two single-cylinder research-type open-chamber diesel engines -- a 2.0-L per cylinder heavy-duty engine and a 0.52-L per cylinder light-duty engine. The data covered wide ranges of speed and overall air-fuel ratio. Such global performance quantities as indicated mean effective pressure and indicated thermal efficiency predicted by the model agreed with experimental results from both engines within 5%. Pressure-time and heat-release rate predictions agreed within 5-15%. However, further improvements are needed before the model can be used reliably for emissions predictions. Specifically, predictions of nitric oxide (NO) and non-volatile particulate (soot) were in poor agreement with the measurements, especially for the light-duty engine.