News & Events

Chair's Distinguished Seminar Series

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.


William E. Boeing Department of Aeronautics & Astronautics
Distinguished Seminar Series:

Winter 2018 Series
Mondays, 4-5pm
Johnson Hall 075
UW Campus, Seattle WA

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We welcome our Distinguished Guests:

 

BEVERLY MCKEON

01.22.18 | BEVERLY MCKEON - Bio and Abstract | Flyer
Systems analysis of wall turbulence: Characterizing natural and synthetic self-sustaining processes
Theodore von Karman Professor of Aeronautics
California Institute of Technology

The financial and environmental cost of turbulence is staggering: manage to quell turbulence in the thin boundary layers on the surface of a commercial airliner and you could almost halve the total aerodynamic drag, dramatically cutting fuel burn, emissions and cost of operation. Yet systems-level tools to model scale interactions or control turbulence remain relatively underdeveloped. The resolvent analysis for turbulent flow proposed by McKeon & Sharma (J. Fluid Mech, 2010) provides a simple, but rigorous, approach by which to deconstruct the full turbulence field into a linear combination of (interacting) modes. After a brief review of some key results that can be obtained by analysis of the linear resolvent operator concerning the statistical and structural make-up of wall turbulence, I will describe some of our recent progress towards determining how to reconstruct self-sustaining turbulent systems, both natural and synthetic. Implications for both the classical picture of wall turbulence and control of turbulent flows will be discussed.

 

Eric Paterson

02.5.18 | ERIC PATERSON - Flyer
At the Intersection of Aerospace and Ocean Engineering: Structure and Persistence of Ship Wakes and the Role of Langmuir-Type Circulations
Department Head, Kevin T. Crofton Department of Aerospace and Ocean Engineering
Virginia Tech

Since the early days of manned space flight, it has been known that ship wakes persist for long duration, and can be observed from air and space. However, for the past 50 years, a first-principles explanation has eluded fluid dynamicists. In this talk, it will be shown that surface ships operating in ocean waves generate transverse surface currents which persist long after the initial ship--induced currents have decayed. These surface currents are due to the formation of large-scale Langmuir-type circulations and are suggested to be the mechanism for the concentration of surface-active materials into streaks or bands, which are regularly seen in synthetic aperture radar imagery of the ocean surface. These circulations are generated by the Craik-Leibovich vortex force, which arises due to the interaction of ship--induced current with ambient surface waves, and persist due to their large-scale nearly-inviscid nature. Numerical simulations of the wake behind a surface ship in calm, head, and following seas are presented and show good agreement with radar imagery from at--sea experiments. It is demonstrated that surface currents do not persist in the absence of surface waves, but can persist for tens of kilometers through the formation of Langmuir-type circulations. Since the circulations are driven by the cross product of the Stokes drift and the wake vorticity, the structure of the persistent wake is not a function of the propeller count or rotational direction, but is instead due to the relative heading of the ship with respect to the ambient surface-wave vector.

Eric Loth

02.12.18 | ERIC LOTH - Flyer
Will a Segmented Ultralight Morphing Rotor Allow the World’s Largest Wind Turbine?
Chair, Mechanical and Aerospace Engineering
University of Virginia

To reduce the levelized cost of energy, wind turbines have become larger and larger with rated powers approaching 10 MW per turbine. However, the conventional upwind design is faced with several barriers for sizes much greater for extreme-scales (10 MW). This includes issues associated with increased gravity loads, increased flexibility, and inertial response. Herein, a novel concept is proposed which employs a downwind rotor with blades whose elements are relatively stiff (no intentional flexibility) but with hub-joints that can be unlocked to allow for moment-free downwind load alignment. Aligning the combination of gravitational, centrifugal, and thrust forces along the blade path reduces downwind cantilever loads, resulting in primarily tensile loading for a load-aligned coning angle. The concept is called Segmented Ultralight Moprhing Rotor (SUMR). To quantify potential mass savings, a downwind load-aligning rotor two-bladed was investigated with a near-hub hinge to allow morphing as a function of wind speed. For a 13 MW reference turbine, the morphing rotor had a significantly reduced mass as compared to a conventional design. The morphing schedule results in a downwind coning angle that varied linearly between cut-in and rated conditions. Aeroelastic analysis and unsteady simulations (e.g. at gust and off-design conditions) indicate this concept is feasible and may allow the world’s largest wind turbine. However, there are challenges regarding tower shadow, blade segmentation, morphing mechanics and manufacturing. But there are also potential benefits via compressed air energy storage if an extreme-scale concept is achieved.

  • Dr. Mason Peck (Cornell) | 10/09/17
  • Dr. Matthew Johnson-Roberson (U. Michigan) | 10/16/17
  • Dr. Paul McConnaughey (NASA Marshall Space Flight Center) | 10/30/17
  • Dr. Panagiotis Tsiotras (Georgia Tech) | 11/20/17
  • Philip M. Condit (The Boeing Company) | 12/04/17
  • Carlos E.S. Cesnik (U Mich) | 5/22/17 - Flyer
  • Christopher S. Lynch (UCLA) | 5/15/17 - Flyer
  • Gretar Tryggvason (Notre Dame) | 5/8/17 - Flyer
  • Geoffrey Spedding (USC) | 5/1/17 - Flyer
  • Angela Schoellig (U. Toronto) | 4/24/17 - Flyer
  • Marco Ceze (Amazon Prime Air) | 4/17/17 - Flyer
  • Thomas Jarboe (U. Washington) | 4/10/17 - Flyer
  • Krishnan Mahesh (U. Minnesota) | 4/3/17 - Flyer
  • Aaron Ames (Caltech) | 3/27/17 - Flyer
  • Satya Atluri (Texas Tech) | 3/6/17 - Flyer
  • Norman Wereley (U. Maryland) 2/27/17 - Flyer 
  • Lars Blackmore (SpaceX) | 2/13/17 - Flyer
  • Richard Wirz (UCLA) | 02/06/17 - Flyer 
  • Philippe H. Geubelle (U Illinois at Urbana-Champaign) | 01/30/17 - Flyer
  • Daniel Inman (U-Mich) | 01/23/17 - Flyer
  • Morteza Gharib (Caltech) | 12/05/16  -  abstract not available
  • Rodney Bowersox (TAMU) | 11/28/16 - Flyer | Video
  • Noel Clemens (University of Texas) | 11/14/16 - Flyer | Video
  • Zdenek P. Bazant (Northwestern) | 11/07/16 - Flyer | Video
  • Tom I-P Shih (Purdue) | 10/24/16 - Flyer | Video
  • Charbel Farhat (Stanford) |  10/10/16 - Flyer | Video