Control of Flow Separation Using Adaptive Airfoils
Abstract
A novel way of controlling compressible flow separation,
using a dynamically deforming leading edge
airfoil whose nose curvature can be changed by 400%
to keep the flow attached at post-stall angles of attack
is reported. The strong fluid acceleration around the
airfoil nose and the resulting steep adverse pressure
gradient were reduced by progressively rounding the
airfoil leading edge. Steady flow studies at M — 0.3
showed that the flow separating at about 14 degrees
angle of attack over a NAG A 0012 airfoil could be
kept attached up to about 18 degrees by increasing
the nose radius. Also, a fully separated flow at high
angles could be made to reattach by rounding the
leading edge. Interestingly, the flow over an airfoil
having a nearly semicircular nose was separated even
at low angles. The research showed that a "window"
of angles of attack and airfoil profiles exists in which
it appears possible to keep the flow attached through
a maneuver. The shape change also modified the multiple
shocks that form over the NAG A 0012 airfoil at
M = 0.45. Significant effects of shape change were
observed on the vorticity flux in the flow.
Description
AIAA Paper 97-0655, Reno, NV, Jan.1997.
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