Date of Award

Spring 1998

Document Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical & Aerospace Engineering


Aerospace Engineering

Committee Director

Colin P. Britcher

Committee Member

Ponnampalam Balakumar

Committee Member

Oktay Baysal

Committee Member

John Lin

Committee Member

Natalia Alexandrov


A study is reported on geometry optimization techniques for high-lift airfoils. A modern three-element airfoil model with a remotely actuated flap was designed, tested, and used in wind tunnel experiments to investigate optimum flap positioning based on lift. All the results presented were obtained in the Old Dominion University low-speed wind tunnel. Detailed results for lift coefficient versus flap vertical and horizontal position are presented for two airfoil angles-of-attack: 8 and 14 degrees. Three automated optimization simulations, the method of steepest ascent and two variants of the sequential simplex method, were demonstrated using experimental data. An on-line optimizer was demonstrated with the wind tunnel model which automatically seeks the optimum lift as a function of flap position. Hysteresis in lift as a function of flap position was discovered when tests were conducted with continuous flow conditions. It was shown that optimum lift coefficients determined using continuous flow conditions exist over an extended range of flap positions when compared to those determined using traditional intermittent conditions.


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