Ahuja Distinguished Lecture Series - Speaker: Dr. Earl H. Dowell

THEORETICAL AND EXPERIMENTAL MODELS FOR THE DYNAMIC INTERACTIONS OF A FLOW FIELD AND A FLEXIBLE STRUCTURE: CORRELATION IS THE KEY

Speaker:  Dr. Earl H. Dowell, William Holland Hall Professor, Pratt School of Engineering, Duke University

Abstract:  This talk is concerned with the dynamic interaction of flow fields and structural deformation including the effect of thermal fields for very high speed flows. Thus the topics of interest are inherently multidisciplinary. The most dramatic consequence of such a dynamic interaction is the possibility that the fluid, structural and thermal system will be unstable. This can lead to the catastrophic failure of the structure in some circumstances and in other cases to nonlinear limit cycle oscillations. Other physical phenomena of interest include the response of the fluid structural system to random inputs from atmospheric turbulence ("gusts"), jet engine noise and boundary layer pressure fluctuations. And indeed the flow field by itself may become globally unstable due to shock wave boundary layer interaction (variously called buffet, abrupt wing stall or non-synchronous vibration) which then may excite structural motion. Historically the applications to aerospace vehicles have driven much of the research and development of technology including the internal flows in jet and rocket engines as well as the external flow over airframes. However other fields of engineering are concerned with phenomena of a similar fundamental character including civil engineers addressing wind forces on long span bridges and tall buildings, mechanical engineers concerned with fluid structural interaction arising in nuclear reactors, naval engineers designing hydrofoils and submarines and bioengineers studying blood flows in arteries and microorganisms moving in fluids.

Drawing on the work of our research team at Duke in collaboration with colleagues from several universities and government laboratories, a range of experimental/theoretical models will be considered from low speed flows typical of those available in university wind tunnels to high speed flows that have been studied in Air Force and NASA wind tunnels. Several examples of model designs, wind tunnel tests and experimental/theoretical correlations studies will be presented. The experiments provide a basis for assessing the theoretical models and the theoretical models provide a useful, though inevitably imperfect guide to designing and conducting experiments.

Bio:  Dr. Dowell is an elected member of the National Academy of Engineering, an Honorary Fellow of the American Institute of Aeronautics and Astronautics (AIAA) and a Fellow of the American Academy of Mechanics and the American Society of Mechanical Engineers. He has also served as Vice President for Publications and member of the Executive Committee of the Board of Directors of the AIAA; as a member of the United States Air Force Scientific Advisory Board; the Air Force Studies Board, the Aerospace Science and Engineering Board and the Board on Army Science and Technology of the National Academies; the AGARD (NATO) advisory panel for aerospace engineering, as President of the American Academy of Mechanics, as Chair of the US National Committee on Theoretical and Applied Mechanics and as Chairman of the National Council of Deans of Engineering. From the AIAA he has received the Structure, Structural Dynamics and Materials Award, the Von Karman Lectureship the Crichlow Trust Prize and the Reed Aeronautics Award; from the ASME he has received the Spirit of St. Louis Medal, the Den Hartog Award and Lyapunov Medal; and he has also received the Guggenheim
Medal which is awarded jointly by the AIAA, ASME, AHS and SAE.

He has served on the boards of visitors of several universities and is a consultant to government, industry and universities in science and technology policy and engineering education as well as on the topics of his research.
Dr. Dowell research ranges over the topics of aeroelasticity, non-steady aerodynamics, nonlinear dynamics and structures. In addition to being author of over three hundred research articles, Dr. Dowell is the author or co-author of four books, "Aeroelasticity of Plates and Shells", "A Modern Course in Aeroelasticity", "Studies in Nonlinear Aeroelasticity" and “Dynamics of Very High Dimensional Systems”. His teaching spans the disciplines of acoustics, aerodynamics, dynamics and structures.

Dr. Dowell received his B.S. degree from the University of Illinois and his S.M. and Sc.D. degrees from the Massachusetts Institute of Technology. Before coming to Duke as Dean of the School of Engineering, serving from 1983-1999, he taught at M.I.T. and Princeton. He has also worked with the Boeing Company.

Please click the link below to join the webinar:
https://osu.zoom.us/j/94179037941?pwd=TE5tWUpYZ0dMQjJZWS80bTFQYW16Zz09

Webinar ID: 941 7903 7941
Password: 497158