Title page for ETD etd-32498-21232


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 PhD
Department Engineering Mechanics
Advisory Committee
Advisor Name Title
Telionis, Demetri P. Committee Chair
Hajj, Muhammad R. Committee Member
Kriz, Ronald D. Committee Member
Mook, Dean T. Committee Member
Simpson, Roger L. Committee Member
Keywords
  • Vortex Breakdown
  • High Angle of Attack Control
  • Delta Wing Aerodynamics
Date of Defense 1998-04-20
Availability unrestricted
Abstract
The quality of the flow over a 75 degree-sweep delta wing

was 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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