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Professor Ann R. Karagozian
UCLA
Active Control of Transverse Jet
Instabilities
Abstract
This talk will describe an experimental and computational study on the
actively controlled gas jet injected transversely into crossflow, also known
as the transverse jet. The transverse jet has widespread technological
applications, ranging from dilution and fuel jet injection in gas turbine
engines to thrust vector control systems for high speed aerospace vehicles.
In our experimental studies, the jet actuation system consists of a
loudspeaker placed within a plenum upstream of the jet nozzle. The dynamics
of this actuator are characterized and modeled in the study, allowing a
dynamic compensator or feedforward controller to be developed which permits
the jet to be forced in a more precisely prescribed manner. Ongoing studies
on feedback control of jet excitation, in addition to the feedforward
control, allow for further improvement of the jet's temporal waveform. Use
of the controllers allows for straightforward comparisons among different
conditions for jet excitation. Clear identification can be made of specific
excitation frequencies and characteristic temporal pulse widths which
optimize transverse jet penetration and spread through the formation of
distinct, deeply-penetrating vortex structures. Corresponding numerical
simulations of the flowfield will also be described, wherein detailed
examinations of the nature of vorticity generation are possible in addition
to comparisons of simulation results with the experimental observations.
Biosketch
Ann R. Karagozian has been a Professor in the Department of Mechanical
and Aerospace Engineering at UCLA since 1982. Her research interests lie in
the fluid mechanics of combustion systems, with current emphasis on
numerical simulation and experimental interrogation of acoustically driven
reacting flows and high speed combustion systems. Recent research activities
have applications to improved efficiency and emissions reduction for
aircraft engines, fuel-air mixing enhancement for high speed aircraft,
behavior and simulation of pulse detonation engines, microgravity combustion
processes, and environmental waste destruction systems. Professor Karagozian
is a member of the Air Force Scientific Advisory Board and recently chaired
a panel for the Air Force examining Sensor Technologies for Deeply Buried
Facilities. She was also recently elected a Fellow of the American Institute
of Aeronautics and Astronautics. She received her B.S. in Engineering, summa
cum laude, from UCLA in 1978 and her M.S. and Ph.D. in Mechanical
Engineering from the California Institute of Technology in 1979 and 1982,
respectively.
DATE: June 2, 2004
TIME: 10:10—11:00 a.m.
PLACE: Bourns Hall A265
Refreshments are provided |
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