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AEM Seminar: Active Control of High-Speed Turbulent Free Shear Flows Using Excitation of Instabilities: O (1) Gain for O Input

Professor Mo Samimy Gas Dynamics & Turbulence Laboratory, Aerospace Research Center, The Ohio State University, Columbus

2:30 PM on 2018-11-09


Abstract:

Shear layers are present in nearly all flows of interest in applications and if the Reynolds number is sufficiently high, the shear layer is turbulent. A significant portion of such flows involves free shear layers (FSL), which are developed away from solid surfaces. FSL are building blocks of many flows of interest in applications, including jets, cavity flows, and separated flows. Their instability has been known for over a century and a half and extensive studies for the past several decades have shown that FSL are unstable to small amplitude perturbations over a wide range of frequencies, that they are dominated by coherent large-scale structures (LSS), even at high Reynolds numbers, and that the dynamics of these structures dominate important processes, such as entrainment, mixing, momentum transport, and noise generation. These findings have motivated extensive research activities to actively control the development of LSS using excitation of instabilities, but the early experimental research had focused primarily on the control of low-speed, low Reynolds number FSL, due to the lack of existence of suitable actuators, which are an essential part of any active flow control. This extensive body of the literature will be briefly reviewed in this lecture. Then the development of thermal-based high-amplitude and wide-bandwidth plasma actuators in recent years will be briefly discussed. Finally some sample active flow control results from a few different flows will be presented to illustrate the similarity of instabilities, flow structures, and control mechanisms over a wide range of flow speeds and Reynolds numbers.

Bio:

Professor Samimy is the John B. Nordholt Professor of Mechanical and Aerospace Engineering and the founding director emeritus of the Aerospace Research Center at The Ohio State University. His interests are in flow physics and control and in aeroacoustics. He has made significant contributions towards the understanding of the physics and control of high-speed and high Reynolds number turbulent shear flows and jet aeroacoustics. He has published over 300 technical papers, including over 110 journal articles, on these topics. He has educated a large number of engineers and scientists who are currently in academic positions, national laboratories, and industry. He has served on various national committees and editorial boards and has lectured extensively in the U.S. and abroad. He is a fellow of AIAA, ASME, APS, and AAAS. He has received several teaching, mentoring, and research awards from OSU, including the Ohio State University’s Distinguished Scholar Award. The University Distinguished Scholar Award, one of the highest awards within the university, recognizes and honors six faculty members per year, from all the fields and from over two thousand faculty, who have demonstrated scholarly activity, research, or other creative works which represent exceptional achievements in their fields.


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