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SEMINAR – Numerical Simulation of High Mach Number Viscous Flow
January 26 @ 10:00 am - 11:00 am
To support the design of high-speed air vehicles, a number of scientific challenges must be addressed in the prediction and control of supersonic and hypersonic flow. The present talk focuses on two main themes: large-scale unsteadiness and plasma-based flow control. Some preliminary work on hypersonic transition will also be discussed.
Large-scale separation unsteadiness is a crucial issue in high-speed aircraft design because it promotes structural fatigue loading. To investigate the phenomenon, spectra of wall pressure fluctuations were compared for data obtained from wind tunnel experiments, the HIFiRE-1 flight test, and large-eddy simulations. The results were found to be in generally good agreement, despite differences in Mach number and two orders of magnitude difference in Reynolds number. Relatively good agreement was also obtained between these spectra and the predictions of a theory developed by Plotkin. The results support the idea that separation unsteadiness has common features across a broad range of compressible flows, and that the separation region behaves as a selective amplifier of large-scale disturbances in the incoming flow.
The idea of plasma-based flow control can trace its origin to the beginning of the space age, in particular to a time when designers realized that plasmas would have a significant influence on reentry flows. Interest in the field has grown significantly in recent years. Two aspects of plasma-based flow control will be discussed in the presentation: mitigation of large-scale separation unsteadiness using plasma actuators, and modeling of nanosecond-pulse dielectric barrier discharges. Simulations carried out by the author have established the feasibility of plasma control in the high-speed regime, and the field has reached a stage where we can consider practical implementations on air vehicles.
An internationally recognized authority in the computational, theoretical, and experimental aspects of fluid and plasma dynamics, Jonathan Poggie possesses a unique breadth of experience. For more than 20 years, he served as a research engineer at Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio. His work focused on the prediction and control of flow at extremely high speeds. In addition to his personal research, he provided strategic R&D advice to the organization, helped to prioritize and steer multiple research projects, and mentored junior scientists and engineers. Committed to the training of a new generation of engineers, he moved in fall 2015 to a position as a professor at Purdue University. In this new role, he is pursuing aerospace applications of plasma technology and developing tools to support the design of a new generation of hypersonic aircraft. His recent work has involved large-scale computation under a DoD HPCMP Frontier Project and a DoE INCITE award.