Affiliations: Department of Aeronautics and Astronautics, The
University of Tokyo, Hongo, Tokyo 113-8656, Japan.
Abstract: Wind tunnel tests are carried out using a 70 · delta wing
model with leading-edge vortex flaps. The structure of the leading-edge
separation vortex over the leading-edge vortex flap is measured by use of a 5
holes pitot probe, surface pressure measurement technique and oil flow
visualization technique. Separation vortices formed on a plain delta wing, on a
vortex flap and inboard the vortex flap hinge line are clearly visualized.
Results indicate that the flow around the vortex flaps is classified into
several different cross flow patterns. The streamwise flap deflection angle is
defined to discuss the vortex flap performance. The optimum lift to drag ratio
is attained when the amount of the wing angle of attack is not far different
from that of the streamwise flap deflection angle, as long as the vortex flap
is deflected modestly.