Combustion is important in many industrial and engineering applications, such as automotive engines and power plants. The goal of this research is to provide scientific knowledge that will be useful for developing the technology required for designing engines that make efficient use of fossil fuels and carbon-dioxide-neutral transportation fuels. The proposed effort involves both experiments, with whose results theoretical/mathematical analysis of the ignition phenomena can be validated. Graduate students working on the project contribute to the nation's STEM (science, technology, engineering, and mathematics) work force.
Autoignition is an inherent property of all long-chain hydrocarbons and some oxygenated fuels as they occur in engines. Efficient operation of engines depends crucially on this property. A comprehensive experimental, computational and analytical study will be carried out with the goal of obtaining a fundamental understanding of autoignition of n-heptane, iso-octane, ethanol, dimethyl ether, in laminar non-premixed flows. The alkanes n-heptane and iso-octane are selected because they are designated as primary reference fuels and are considered as surrogates of Diesel and gasoline. Critical conditions of autoignition will be measured. Computations will be performed using detailed chemistry. A significant part of the research will be devoted to employing rate-ratio asymptotic techniques to obtain analytical expressions that can be used to predict autoignition. The key outcomes are expected to be, experimental data on autoignition for the fuels, tested chemical kinetic mechanisms, and analytical expressions for predicting autoignition in the intermediate and high temperature regimes that can be employed in computational fluid dynamic codes.
The research will provide a clear fundamental understanding of autoignition as a chain-branching/chain-breaking process which involves the competition of the fuels for specific radicals in different temperature regimes. The research will provide new mathematical techniques for analyzing autoignition. These techniques have their foundation in boundary layer theory and singular perturbation analysis. Therefore they are expected to have a much wider use in analyzing problems in fluid mechanics, thermal sciences and chemical sciences.
