September 9, 2024-Earl Dowell, Duke University
September 9, 2024
4:00 p.m.
Room: Torgersen Hall 2150
Speaker: Earl Dowell, Duke University
Faculty Host: Dr. Justin Jaworski
"Hypersonic Fluid Structure Interaction"
Abstract: Fluid Structure Interaction can lead to dynamic instabilities due to coupling between the fluid forces on a deforming elastic structure and the change in these forces due to the structural deformation. This feedback between aerodynamic forces and elastic structures is the subject of aeroelasticity which is often studied using linear dynamical models for the aerodynamic flow and the structural deformation. In high speed flows and especially hypersonic flows there are several essential nonlinearities that add complexity to the classical linear models. In this talk we will consider a range of aerodynamics models ranging from potential flow theory to Euler to Navier-Stokes (RANS) and two prototypical structural configurations. A thin elastic plate fixed (clamped) on all edges (representative of skin panels on a fuselage or wing) has a strong structural nonlinearity due to inplane tension induced by out of plane bending that dominates the nonlinear response with deflections on the order of the plate thickness. Buckling may occur as a consequence of thermal stresses or limit cycle oscillations due to an aeroelastic instability and both can occur in the same experiment or flight. On the other hand an elastic structure clamped on only one edge (e.g. a control surface) may have much larger deformations on the order of the span or chord of the structure and thus multiple structural and flow nonlinearities may be present. Representative computations and correlations with experiments will be discussed and the talk with will conclude with an assessment of the state of the art and opportunities for future advances.
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, Lyapunov Medal and the Caughey 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 and teaching ranges over the topics of acoustics, aerodynamics, aeroelasticity, dynamics and structures. In addition to being author of over four 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”.
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.