KSGC: Construction of 3-D Discrete Dynamical System Models of Turbulent Combustion

Although considerable effort is now being focused on alternative sources of power, e.g., hydrogen fuel cells, for various applications, there remains the basic fact that energy density of hydrocarbon fuels is so high compared with essentially every alternative that it is very difficult to forego use of such fuels in many applications. This, in turn, underscores the need to better understand, and, hopefully, as a consequence be better able to predict, combustion processes in general. Moreover, because turbulent mixing of fuel and oxidizer (often air) is crucial to proper performance of most combustion devices ranging from automobile engines to gas turbine power systems, it is essential that turbulent combustion be better understood , characterized and controlled. Yet, at present neither turbulence nor combustion is very well understood, and much research will be needed before reliable prediction of, e.g., amount of pollutants produced and power generated in any particular combustion process will be possible. At the same time it is very important that we be able to do this, and with the rapid increases in computing power now occurring we are entering an era in which simulations of such processes will begin to provide useful results-if we start now to develop the necessary modeling procedures. In particular, direct numerical simulation of real engineering devices and processes is not expected to be possible any time in the foreseeable future, so modeling will be necessary for a long time to come. But with the anticipated increases in computing power it will be possible to employ more sophisticated, realistic and reliable models. The research being proposed herein is such as to have an immediate impact on turbulent modeling procedures. The PI/mentor has already demonstrated feasibility of a class of methods that are both accurate and efficient; in addition they are capable of incorporating essentially any desired level of combustion model (in the sense of any kinetic mechanism for a given overall reaction) for any desired fuel-oxidizer combination. The work to be carried out by an undergraduate researcher (Mr. John C. Holloway) will constitute some of the final (but nontrivial) steps needed to render this modeling procedure fully operational in computer codes of the general nature of large-eddy simulation. The results will be employed in ongoing work of the PI with colleagues at NASA Glenn Research Center and will have direct application to studies associated with aircraft and rocket engine propulsion systems. But since the approach is actually very general it could be used also in the automotive industry, both for internal combustion gasoline and diesel engines, and even for analyses involving the new fuel cell based power plants.