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Midwest Mechanics Seminar Series Flight
experiments on laminar flow control in swept-wing boundary layers (An unlikely
journey of a mechanician) William S. Saric,
Ph.D. Department
of Aerospace Engineering Texas
A&M University Abstract Data are
presented on boundary-layer transition to turbulence in low-disturbance flight
environments. The measurements include infra-red thermography and hotfilm
anemometry to study roughness-related issues of boundary-layer transition on a
swept-wing model that is mounted on the wing of a Cessna O-2 aircraft. A
Navier-Stokes code is used calculate the aircraft flowfield and boundary layer
while Nonlinear Parabolized Stability Equations (NPSE) quantify the stability
measurements and transition locations. The laminarization scheme of
spanwise-periodic distributed roughness elements (DRE) is investigated at chord
Reynolds numbers of 8 million. Measurements were made to determine the
transition locations for clean configurations and for enhanced surface
roughness that simulates an operational surface finish. For clean
configurations, natural laminar flow was achieved over 80% of the surface of a
37° swept-wing model at chord Reynolds numbers of 8.1 million. With a
background surface roughness of 1 mm rms, transition moved forward to 30%
chord. The DRE delayed transition to 60% chord. The work
was supported by: AFOSR, AFRL, and Northrop-Grumman Corporation. Tuesday,
April 22, 2008, 10:30 am
3540
Engineering
Refreshments
served at 10:15 am
Biography William S. Saric is the Stewart
& Stevenson Professor of Aerospace Engineering at Texas A&M University
where he has been since Jan 2005. He received his PhD in Mechanics from the
Illinois Institute of Technology in 1968 and has held appointments at Sandia
Laboratories (Atomic & Fluid Physics, 1963-66, 1968-75), Virginia Tech
(Engineering Science & Mechanics, 1975-84), and Arizona State University (Mechanical
& Aerospace Engineering, 1984-2005). He a member of the National Academy
of Engineering and The Academy of
Medicine, Engineering, and Science of Texas.
He received the AIAA Fluid Dynamics Award in 2003, the SES G.I. Taylor Medal in 1993, the AGARD (NATO) Scientific Achievement Award in 1996, IIT Alumni Recognition Award in 2005, and
the Alumni Research Award from
V.P.I.&S.U in 1984. He is a Fellow of AIAA and APS, and a Life Fellow of ASME. He is presently re-establishing two major
wind tunnels and a flight research laboratory at Texas A&M University. Most
recently, he has conducted computational, experimental, and flight research on
stability, transition, and control of 2-D and 3-D boundary layers. He is also
conducting stability experiments on temporally modulated Taylor-Couette flow. |