LIFT ENHANCEMENT ON UNCONVENTIONAL AIRFOILS
Keywords:
Lift enhancement airfoil, aerodynamics .Abstract
Lift augmentation on airfoi ls is a critical task to an aerodynamicist when asked to design new
wings. Flow visualization studies on a corrugated airf oil confi rm that the trapped vortices lead
to a modification of the effective wing shape and an increase in lift. Considerable lift
enhancement is found in the experimental measurements on a wing model incorporated with a
backward-facing step on the upper surface because of a trapped vortex. Furthermore, a
leading-edge rotating cylinder (which behaves like a vortex) effectively extend the lift curve of
an airfoi l without substantially affecting its slope, thus increasing the maximum lift and
delaying stall. While theoretical studies of vortex trapping are limited to airfoils with smooth
surface s, this paper explores the ability of trapping single and multiple vortices on airfo ils
with surface discont inuiti es, such as cavities. corrugations, or a rotating cylinder. Streamlines.
surface pressure distributions and the vortex trajectories are presented in the hope to advance
the knowledge on lift enhancementfor fl ow past unconventional airfoils.
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