Type of Document Dissertation Author Schaeffler, Norman Walter Author's Email Address schaeffler@vt.edu URN etd-32498-21232 Title All The King's Horses: The Delta Wing Leading-Edge Vortex System Undergoing Vortex Breakdown: A Contribution to its Characterization and Control under Dynamic Conditions. Degree Doctor of Philosophy Department Engineering Mechanics Advisory Committee
Advisor Name Title Demetri P. Telionis Committee Chair Dean T. Mook Committee Member Muhammad R. Hajj Committee Member Roger L. Simpson Committee Member Ronald D. Kriz Committee Member Keywords
- High Angle of Attack Control
- Vortex Breakdown
- Delta Wing Aerodynamics
Date of Defense 1998-04-20 Availability unrestricted Abstract The quality of the flow over a 75 degree-sweep delta wingwas documented for steady angles of attack and during
dynamic maneuvers with and without the use of two control
surfaces. The three-dimensional velocity field over a delta
wing at a steady angle of attack of 38 degrees and Reynolds
number of 72,000 was mapped out using laser-Doppler
velocimetry over one side of the wing. The three-dimensional
streamline and vortex line distributions were visualized.
Isosurfaces of vorticity, planar distributions of helicity
and all three vorticity components, and the indicator of
the stability of the core were studied and compared to see
which indicated breakdown first. Visualization of the
streamlines and vortex lines near the core of the vortex
indicate that the core has a strong inviscid character, and
hence Reynolds number independence, upstream of breakdown,
with viscous effects becoming more important downstream of
the breakdown location. The effect of cavity flaps on the
flow over a delta wing was documented for steady angles of
attack in the range 28 degrees to 42 degrees by flow
visualization and surface pressure measurements at a
Reynolds number of 470,000 and 1,000,000, respectfully.
It was found that the cavity flaps postpone the occurrence
of vortex breakdown to higher angles of attack than can be
realized by the basic delta wing. The effect of
continuously deployed cavity flaps during a dynamic
pitch-up maneuver of a delta wing on the surface pressure
distribution were recorded for a reduced frequency of
0.0089 and a Reynolds number of 1,300,000. The effect of
deploying a set of cavity flaps during a dynamic pitch-up
maneuver on the surface pressure distribution was recorded
for a reduced frequency of 0.0089 and a Reynolds number of
1,300,000 and 187,000. The active deployment of the cavity
flaps was shown to have a short-lived beneficial effect on
the surface pressure distribution. The effect on the
surface pressure distribution of the varying the reduced
frequency at constant Reynolds number for a plain delta
wing was documented in the reduced frequency range of
0.0089 to 0.0267. The effect of the active deployment of
an apex flap during a pitch-up maneuver on the surface
pressure distribution at Reynolds numbers of 532,000,
1,000,000, and 1,390,000 were documented with reduced
frequencies of 0.0053 to 0.0114 with flap deployment
locations in the range of 21° to 36°. The apex flap
deployment was found to have a beneficial effect on the
surface pressure distribution during the maneuver and in
the post-stall regime after the maneuver is completed.
Files
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access ApexFlapMotion.mov 1.28 Mb 00:05:54 00:03:02 00:02:39 00:01:19 00:00:06 DyPPiR.mov 594.10 Kb 00:02:45 00:01:24 00:01:14 00:00:37 00:00:03 etd.pdf 41.39 Mb 03:11:37 01:38:32 01:26:13 00:43:06 00:03:40 Motion1-Deploy.mov 2.12 Mb 00:09:49 00:05:03 00:04:25 00:02:12 00:00:11 Motion1.mov 1.10 Mb 00:05:04 00:02:36 00:02:17 00:01:08 00:00:05
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