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Chair's Distinguished Seminar Series

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The Chair’s Distinguished Seminar Series brings scholars of national and international reputation who have made an impact in the field of aerospace engineering and beyond. This seminar series will cover a diversity of topics of current interest to those in academia, industry and the general public. It is our hope that these monthly seminars will encourage an exchange of ideas and bring aerospace engineering and science to the forefront. Please join us for our upcoming seminars.

 

Dr. Israel J. Wygnanski, U of Arizona & Tel Aviv Univerity  | Thursday, June 2, 2016

  • Professor U. of Arizona & Professor Emeritus Tel Aviv University

  • AIAA Dryden Lecturer

  • NASA Associate Administrator of Aeronautics Award

  • NASA Group Achievement Award For full scale test proving the flight feasibility of Active Flow Control

  • Meir Hanin International Memorial Prize, Technion—Israel Institute of Technology, Israel

4:30pm to 5:20pm
Guggenheim Hall 220
UW Campus, Seattle WA

RSVP to attend for free: http://goo.gl/forms/XswGSHokAT
Watch the video: A video of the presentation will be posted a week after the talk.
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The Fluidic Fence as an Enabler for Improving the Aerodynamic Performance of Wings Without Destabilizing the Airplane Using Them.

Abstract: 

There is trend in airplane design to blend the fuselage with the wing thus improving the airplane’s efficiency when compared with the conventional tube and wing configuration. Uninhabited Combat Air Vehicles (UCAVs) follow the same trend. A typical wing has a λ planform consisting of an inner trapezoidal portion and an outer swept-back part. The leading edge radius, camber and wing thickness may change along the span as well as the local incidence (twist). The flow over such wings is very complex, particularly at intermediate angles of incidence where a leading edge vortex is formed, becomes unstable and detaches itself from the surface while being swept back in the direction of streaming. This affects mostly the pitching moment that may result in the loss of stability. Wing-tip stall is a very undesirable phenomenon that makes ailerons ineffective and it may result in an abrupt wing drop. To avoid it, some military aircraft have cranked wings that reduce the sweep-back at the tip and some even have a wing that swings forward at low speed flight. Many older civilian and military airplanes used fences to compensate for the adverse effects of the large sweep. They reduced the spanwise flow component in their vicinity changing somewhat the load distribution on swept back wings. However they spanned most of the local chord and their height exceeded the boundary layer thickness, consequently they increased the drag during cruise.

The idea of the “fluidic fence” germinated during tests aimed to increase the effectiveness of a rudder on a twin engine commercial aircraft by using active flow control (AFC). Physically, the concept consists of sparsely spaced, small sweeping or steady jet actuators that reduce or eliminate the spanwise flow over the rudder by creating a jet curtain., In one case the rudder effectiveness was increased by 9% when a single small jet was used. The big advantage of fluidic fences is that they are more effective than solid ones, they can be applied only when needed and they can be moved to different locations at various stages of the flight envelope. The fluidic fence was tested on three configurations: a constant chord swept-back wing, a purely tapered trapezoidal wing and a λ wing designed by DLR as a challenge for overcoming stability problems on typical tailless aircraft configurations (SACCON). It transpired that the concept works best when the flow is still attached but its spanwise velocity component dominates its direction. Flow visualization and pressure sensitive paint (PSP) helped to understand the complex interaction among the many parameters affecting the flow over a wing that is aided by Active Flow Control (AFC). Two AFC strategies emerged: one that reduces spanwise flow and the other that delays its separation from the wing’s surface.

 

Speaker Bio:

Dr. Israel J. Wygnanski
Professor U. of Arizona & Professor Emeritus Tel Aviv University
 

Education

  • Ph.D. Mechanical Engineering, McGill University, Montreal, Canada, 1964
  • M.E. Aerodynamics, McGill University, 1962
  • B.E. Mechanical SciencesHonors Option, McGill University, 1961

Honors and Awards

  • 2017 AIAA Dryden Lecturer
  • 2015 NASA Associate Administrator of Aeronautics Award
  • 2014 NASA Group Achievement Award For full scale test proving the flight feasibility of Active Flow Control
  • 2014 Meir Hanin International Memorial Prize, Technion—Israel Institute of Technology, Israel
  • 2014 Certificate of Anniversary for 25 years of active membership in NAE
  • 2010 28 th Annual Gallery of Fluid Motion Award for “Global Modes in a Swirling Jet Undergoing Vortex
  • Breakdown,” 63 rd APS Division of Fluid Dynamics Meeting, Long Beach, CA, November 2010
  • 2003 Recognition by Industry, Full-scale Demonstration of a Micro Adaptive Flow System on the XV-15
  • tiltrotor, Bell Helicopter Textron facilities, July 2003
  • 2001 AIAA Fluids Dynamics Award,
  • 1995 Senior Fulbright Fellow,
  • 1996 Fellow, AIAA
  • 1995 L.S.G. Kovasznay Lecturer
  • 1990 Fellow, Institute of Advanced StudyBerlin
  • 1989 Member, U.S. National Academy of Engineering
  • 1983 Fellow, Division of Fluid Dynamics, American Physical Society
  • 1982 Lazarus Chair of Aerodynamics, Tel Aviv University
  • 1973 Landau Prize for Research on Transition (Israel)
  • 1963 Graduate Fellow, McGill University
  • 1962-64 Fellowship, National Research Council of Canada
  • 1962 AIAA Prize for Technical Paper
  • 1961 Institute of Aerospace Science Prize for Technical Paper
  • 1961 Canadian Aeronautical Institute Medal for a Technical Paper
  • 1961 British Association Medal for Great Distinction in Engineering,

    200+ Scholarly publications

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