A Flow Visualization Study of LEX Generated Vortices on a Scale Model of a F/A-18 Fighter Aircraft at High Angles of Attack

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90Jun_Cavazos_Redacted.pdf (5.68 MB)
Authors
Cavazos, Odilon V., Jr.
Subjects
High angle of attack aerodynamics
effect of pitch rate and yaw
vortex development and bursting
flow visualization by dye injection
water tunnel studies
F/A-18 fighter aircraft
Advisors
Hebbar, S. K.
Platzer, M.F.
Date of Issue
1990-06
Date
June 1990
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
A water tunnel flow visualization investigation was performed into the high angle of attach aerodynamics of a 2% scale model of the F/A-18 fighter aircraft. The main focus of this study was the effect of pitch rate on the development and bursting of vortices generated from the leading edge extensions in the high angle of attack range with and without yaw. Results of this investigation indicate that that the vortex bursting point (relative to the static case) moves rearward with increasing pitch-up motion and forward with increasing pitch-down motion. For the same pitch rate, vortex bursting was found to occur earlier for the pitch-down motion than for the pitch-up motion, implying aerodynamic hysteresis effects. Yawing the model generated significant vortex asymmetries due to the delayed vortex breakdown on the leeward side for yaw angles of less than 10' . The presence of these asymmetric vortices led to undesirable side forces and yawing moments.
Type
Thesis
Description
URI
https://hdl.handle.net/10945/44341
Series/Report No
Department
Department of Aeronautics and Astronautics
Organization
Naval Postgraduate School (U.S.)
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NPS Report Number
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Distribution Statement
Approved for public release; distribution is unlimited.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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