A Dissertation
Entitled
Aerodynamic Control of Slender Bodies from Low to High Angles of Attack through Flow Manipulation
by
Javier Lopera
Submitted as partial fulfillment of the requirements for the Doctor of Philosophy in Engineering
Advisor: Dr. T. Terry Ng
College of Graduate Studies
The University of Toledo May 2007
The University of Toledo
College of Engineering
I HEREBY RECOMMEND THAT THE DISSERTATION PREPARED UNDER MY
SUPERVISION BY Javier Lopera
ENTITLED Aerodynamic Control of Slender Bodies from Low to
High Angles of Attack through Flow Manipulation
BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR
THE DEGREE OF DOCTOR OF PHILOSOPHY IN ENGINEERING
Dissertation Advisor: Dr. T. Terry Ng
Recommendation concurred by
Dr. K. Cyril Masiulaniec Committee
Dr. Ray Hixon On
Final Examination Dr. Sorin Cioc
Dr. G. Glenn Lipscomb
Dean, College of Engineering
Copyright © 2007
This document is copyrighted material. Under copyright law, no parts of this document
may be reproduced without the expressed permission of the author.
An Abstract of
Aerodynamic Control of Slender Bodies from Low to High Angles of Attack through Flow Manipulation
Javier Lopera
Submitted as partial fulfillment of the requirements for The Doctor of Philosophy in Engineering
The University of Toledo May 2007
This dissertation presents experimental investigations of several novel active flow control methodologies that have been implemented for aerodynamic control and maneuvering of slender bodies at low and high angles of attack through flow manipulation.
For low angles of attack, a U.S. Army Smart Cargo projectile was examined. For high angles of attack a U.S. Air Force countermeasure concept projectile termed DEX
(Destructive Expendable) was examined.
Low angle of attack control was attempted using two novel separation control techniques: reconfigurable porosity and miniature deployable spoilers. Results show that significant aerodynamic forces are generated by implementing reconfigurable porosity
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and can be effectively used to steer and maneuver air vehicles. Porous patterns with a
“saw-tooth” configuration seem to be the most effective in generating consistent control forces over a wide range of angles of attack. Miniature deployable spoilers successfully demonstrated their ability in producing both positive and negative pitch and yaw controls by modulating the spoiler height and length when used on the boattail and Aero Control
Fins (ACFs) of a projectile.
The effect of aftbody strake parameters such as shape, locations (axial and azimuthal), deployment height, and number of strakes implemented was examined on a short blunt-nose projectile. Large yaw control authority was attained for α > 40 deg. The largest yaw control authority was produced by a rectangular-shaped strake.
A robust closed-loop feedback controller was successfully tested using dynamic wind tunnel experiments to control the coning motion of a projectile. The controller showed good control authority and was capable of attaining and maintaining the commanded roll angle with a tolerance of ± 10 deg.
A study was conducted to gain some insights into the fluid mechanics of short blunt-nose bodies of revolution at high angles of attack. Off- and on-surface flow visualization records are collected to study the effects of two blunt noses: a hemispherical nose and an elliptical nose with 33% ellipticity. It was found that the elliptical-nose results in flow behaviors typical of a blunt-nose, while the hemispheric-nose results in behaviors that are akin to a pointed-nose. An explanation for the contrasting behaviors is provided.
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Dedication
To my mother and brothers, thank you for your love, support and encouragement
during these years. I have you alw