Fundamental and Applied Studies in Chemical Reacting Flows

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In keeping with the objectives of a Discovery Grant, the proposed work is program-based. It contains fundamental and applied research, as well as broadly addressing two core motivations for studying chemical reacting flows. This research is aimed at advancing the understandings needed to control and manage: (A) the environmental impacts of the combustion of hydrocarbon resources; and, (B) the rates of conversion of chemical energy to thermal energy associated with combustion processes. ******Project A Decarbonization of Natural Gas for Heating Applications: The world is transitioning away from fossilize fuels that primarily store their energy in the form of carbon (e.g., coal and oil, and to a lesser degree natural gas), which introduces “new” carbon dioxide into the atmospheric when it is burned, to a system with net-zero carbon cycle. A process is being explored, specifically for heating applications, to see if the elements in the alkanes in natural gas can be economically partitioned through thermal decomposition in a zero-oxygen environment into black carbon and hydrogen. These components can then be easily separated based on their density, capturing the carbon as a solid while sending the hot hydrogen off for combustion where its products are needed at their typical temperatures. The net result is that twice as much natural gas is processed as originally burned for the heating application, but there are no carbon dioxide emissions. This project also involves the characterization of the captured black carbon to see if it has value for tires, rubber, paint, inks, or electrodes.******Project B - Role of Unsteadiness in Modelling Premixed Turbulent Flames at High Damkohler Numbers: Our phenomenological understanding the interactions between unsteady flows and burning rates is not as well developed as for steady flames. Most practical flames are turbulent, so they are rife with unsteadiness. The objective of this study is to ensure that these unsteady effects are properly accounted for in modelling the burning rate of premixed flames. Of particular interest is the way that flames respond to flow features that have time scales of the same order as the flame chemistry. As those time scales approach each other the response of the flame's heat release are profoundly affected in terms of phase lag and amplitude. Depending on the equivalence ratio of the reactants this may occur at frequencies as low as 100 Hz. Consequently, non-direct numeric simulations (i.e., large eddy simulations and G-equation models) miss the time (and hence location) and amplitude of heat release. The approach we are taking is to develop flame transfer functions based on simple direct numeric simulations and make models available to those studying complex turbulent flows.******Taken collectively, this research will contribute to more a responsible and environmentally sustainable use of hydrocarbon fuels.**