An experimental investigation of a circulation control wing

Abstract

This wind tunnel investigation examined the lift, drag, and pitching moment on a 20% thick, 8.5% camber, partial elliptic cross-section circulation control wing model. The single blowing slot, rectangular wing was tested at an aspect ratio of about four at a chord-based Reynolds number of 500,000. Three trailing edge Coanda surfaces were tested. They had 180, 90, and 45 deg of flow turning. Lift performance for the 180and 90-deg cases was similar and much above that of the 45-deg trailing edge. Equivalent drag for the 90-deg trailing edge was less than that of the typically used 180-deg trailing edge. A large increase in lift for the 180-deg trailing edge occurred at low amounts of blowing coefficient. As the blowing rate was further increased, the increase in lift dropped off. The lift to equivalent drag and lift to drag ratios were maximums at relatively low values of blowing. Increasing the aspect ratio, for the same amount of blowing coefficient, increased the lift coefficient. Nomenclature = wing chord = drag coefficient, D/(q,S) = equivalent drag coefficient = lift coefficient, L/(q_ S) = pitch moment about wing CG = blowing coefficient, m .V. / (qmS) J J = drag = lift = blowing jet mass flow rate = tunnel dynamic pressure = wing planform area = blowing jet velocity = free-stream tunnel velocity