Kentucky NASA EPSCoR: Subgrid-Scale Models for LES of Compressible Turbulent Combustion

During the early to mid 21st Century it is expected that NASA will establish continued presence on the Moon, and later on Mars. Propulsion systems needed to accomplish such missions, especially exploration of Mars, are expected to be significantly different from those in wide use on Earth simply because of the extreme differences between Earth and Martian environments. Thus, not only will the propulsion systems be novel but in addition it will be difficult, if not impossible, to test all aspects of their operation on Earth. This implies that numerical simulation will be essential, and in turn this means the calculation of turbulent, compressible combusting flow fields will playa critical role in the success of future Moon and Mars missions. In this regard it is becoming apparent that large-eddy simulation (LES) in some form will be the best choice of method during this period, and NASA Glenn researchers have already begun development of the National Combustion Code (NCC) to provide such capabilities. At the same time, the PI of the present proposal has pursued a somewhat different (but related) approach that specifically addresses certain deficiencies of the NCC, in particular (but not limited to) its lack of phy~ic31 models for the small scales at which turbulence and chemical kinetics interact. This work is nearly complete for incompressible flows, and the goal of the research proposed herein is to begin transitioning this new approach to the more difficult case of compressible flows. The successes achieved by the PI in this earlier work, largely supported by NASA/EPSCoR Grants, are documented in the reference list of the current proposal, and in the PI's accompanying CV. (Copies of most papers can be viewed and downloaded from the website www.engr.uky.edu/~acfd) This funding has provided a significant education component, contributing to the studies of a post-doctoral scholar, two different PhO students, a MS student and four undergraduates. The expected outcome of the research being proposed include development of a new class of turbulence models for use in successors to the NCC, education of graduate students and continuation of the working relationship already established between the PI and the Combustion Group at NASA Glenn. Furthermore, the Commonwealth of Kentucky has established a working relationship with researchers at NASA Ames in Mountainview, CA, related to possible Moon and Mars mission efforts. So the work being proposed here could lead to interactions with (and possible funding from) other NASA Research Centers. But in addition, because combustion is our most efficient energy source, it will be of use to apply computer software developed for studies of space propulsion systems to numerous other combustion-related problems, not the least of which might be production of syn-gas (made from coal) and its use as a fuel in power plants. Clearly, this could lead to direct benefits for the Commonwealth of Kentucky.