Date of Award
Master of Science (MS)
Experiments and simulation work were conducted to explore the conditions that influence ignition events in a constant volume environment. Experiments were conducted in a Fuel Ignition Tester, produced by CFR Engines, Inc., and in a prototype combustion chamber to observe the combustion of diesel fuels and primary reference fuels. These experiments attempted to isolate experimental conditions that would provide repeatable pressure measurements. These experiments showed that the fuel spray properties and the environmental conditions, such as initial temperature and initial pressure, are significantly influential in these results. Simulation work was conducted in Converge 2.2.0 to explore these conditions further. The simulations were focused on the examination of the effects of the injected fuel mass, the geometry of the chamber, and temperature inhomogeneities on the ignition delay results for n-dodecane, a well-defined diesel surrogate fuel. These simulations revealed that combustion events are sensitive to the initial temperature of the environment and slightly sensitive to fuel mass. It was found that geometry effects have significant effects on fuel-air mixing, which in turn has large effects on the intermediate reactions in low-temperature combustion of hydrocarbons. Ultimately, it was concluded that conditions should be sought to reduce the system’s sensitivity to slight changes in fuel mass in order to produce a reliable direct correlation between ignition delay and cetane number. This study acts to further the development of an optimal CVCC experimental setup to measure ignition quality of diesel fuels. Based on the results from this thesis, a reliable direct correlation between ignition delay and cetane number could be developed through iterations on the conditions in CVCC experiments, through further simulation and experimental work. Simulation work from this study could be extended to explore incremental changes in fuel mass at different fuel mass conditions. This would provide insight into which fuel mass conditions are least sensitive to slight changes on an experiment-by-experiment basis. These simulation results could then be applied to further experiments to determine the repeatability of the pressure results at those fuel mass conditions.