John T. Rettaliata Engineering Center
10 West 32nd Street
Chicago, IL 60616
Armour College of Engineering's Mechanical, Materials, and Aerospace Engineering Department will welcome Dr. Thomas C. Corke, the Clark Chair Professor of Engineering in the Aerospace and Mechanical Engineering Department at the University of Notre Dame, on Friday, April 5th, to present his lecture, Turbulent Boundary Layer Drag Reduction Using Pulsed-DC Plasma Actuation. The seminar is a part of MMAE Distinguished Alumni Seminar Series.
The results of experiments are presented that utilize an active flow control approach designed to inhibit the lift-up and subsequent instability of the low-speed wall streak structure, and as a result, reduce the viscous drag in turbulent boundary layers. The flow control involves a new pulsed-DC plasma actuator array that is designed to produce a uniform spanwise velocity component on the order of uτ to reduce the mean flow distortion caused by the quasi-steady wall streak structure first observed by Kline et al. (1967). Such measures were predicted to produce as much as a 50% drag reduction in turbulent channel flow simulations of Shoppa and Hussain (1998). Direct drag measurements are performed using a floating element on which the plasma array was mounted. These revealed as much as an 78% drag reduction from the flow control. The amount of drag reduction was found to scale with the actuator spanwise inter-electrode spacing, with the largest occurring for a spacing corresponding to approximately 8 wall streak spanwise wavelengths. This scaling remained consistent for the full decade range (0.05 ≤ M∞ ≤ 0.5) of freestream Mach numbers examined. Accounting for the power input to the actuator, maximum net power savings from 225-700% was achieved. The net power reduction is a consequence of the efficiency of the pulsed-DC actuator, and the sensitivity of the wall streaks to the flow control approach. Hotwire measurements documented the changes in the turbulent boundary layer that accompanied the plasma actuator drag reduction. Wall layer “burst" counts based on the VITA detection technique, verified a linear correlation between the reduction in the “burst" frequency and the viscous drag reduction. Finally, Clauser fits to the mean profiles established the drag-reduced boundary layers to be equivalent to canonical equilibrium adverse pressure gradient turbulent boundary layers.
Dr. Thomas C. Corke is the Clark Chair Professor of Engineering in the Aerospace and Mechanical Engineering Department at the University of Notre Dame. Professor Corke is a Fellow of the American Association of Aeronautics and Astronautics (AIAA), a Fellow of American Association of Mechanical Engineers (ASME), and Fellow of the American Physical Society (APS). He was the recipient of the University of Notre Dame's 2007 "President's Research Achievement Award", and the 2009 "R.T. Davis Memorial Lecture Award" from the University of Cincinnati. He has received two NASA Achievement Awards for his research. The first was in 1982 in recognition of his Ph.D. research "for outstanding research contributions in the area of turbulence control and viscous drag reduction." The second came in 1995 "for the development of important insights into basic fluid mechanics phenomena and theoretical analysis tools which have contributed to major advances in flow prediction and control including laminar flow control." In 2010 he received the AIAA Aerodynamics Award which is presented annually in recognition of meritorious achievement in the field of applied aerodynamics. His citation read "For his strong commitment to academic and research achievement, consistent record of superior technical accomplishment and numerous experimental and computational contributions to aerodynamics." In 2014, he received the James A. Burns Award for contributions to the graduate program at the University of Notre Dame. Dr. Corke's research includes hydrodynamic stability and transition to turbulence, fully turbulent flows and flow control. It includes both experimental and computational approaches at a full range of Mach numbers from incompressible to hypersonic. He is considered a leading authority on plasma flow control, and currently holds 40 patents on plasma based flow actuators, sensors, adaptive optics and meta-materials. Dr. Corke is the Founding Director of the Notre Dame Institute for Flow Physics and Control (FlowPAC), and the Director of the Notre Dame Hessert Laboratory for Aerospace Research. FlowPAC involves 22 faculty in the College of Engineering, and presently supports 70 Ph.D. students. The externally funded research involves 13 government agencies and partnerships with 25 companies. He has over 300 publications including two text books on "Design of Aircraft" and "Wind Energy Design".