Laser Velocimetry Measurements of Oscillating Airfoil Dynamic Stall Flow Field
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Authors
Chandrasekhara, M.S.
S.Ahmed
Subjects
LV measurement
dynamic stall
unsteady random data alquistion
dynamic stall
unsteady random data alquistion
Advisors
Date of Issue
1991
Date
Publisher
Language
Abstract
Ensemble averaged two components velocity measurements over an airfoil experiencing
oscillatory dynamic stall under compressibility conditions were obtained. The
measurements show the formation of a separation bubble over the airfoil that persists
till angles of attack close to when the dynamic stall vortex forms and convects. The
fluid attains mean velocities as large as 1.6 times the free stream velocity (U(infinity))
with instantaneous values of 1.80 U(infinity). The airfoil motion induces these large velocities
in regions that are far removed from its surface. Also, depending upon the behavior
of the separation bubble, the wall jet profiles near the leading edge region could
become wake like over the airfoil in a cycle at different phase angles. Vorticity
contours indicate that the levels around the leading edge continuously increase till
the vortex begins to convect. Some of the measurements difficulties, especially,
particle behavior are discussed as well.
Type
Description
AIAA Paper 91-1799, Jun. 1991, Honolulu, HI.
Series/Report No
Department
Organization
Identifiers
NPS Report Number
Sponsors
U.S. Army Research Office, ARO MIPR 114-91, ARO 27894.6-EG
Funder
U.S. Army Research Office, ARO MIPR 114-91, ARO 27894.6-EG
Format
Citation
M.S. Chandrasekhara and S. Ahmed, "Laser Velocimetry Measurements of Oscillating Airfoil Dynamic Stall Flow Field", AIAA Paper 91-1799, Jun. 1991, Honolulu, HI.