A flat-plate wing standing on a wall covered with a thick boundary layer.

Abstract

Pressure distribution on a flat-plate wing surface along the chord is measured in many spanwise positions from the root of the wing, which is immersed in the wall boundary layer, to the wing section far from the wall. The flow near the root of the wing is visualized by the smoke wire method. Two kinds of secondary flow are observed at the junction between the wall and the wing: one is produced by the interaction between the wall boundary layer and the wing; and the other is induced by a static pressure difference between the wall and the suction surface of the wing. With an increasing angle of attack, flow on the suction side of the wing separates from the wing surface. But the two kinds of secondary flow suppress the separation of the flow near the root of the wing. This causes wing characteristics to improve.