WIND-TUNNEL INVESTIGATION OF BOUNDARY-LAYER CONTROL BY BLOWINGnON AN NACA 655-424 AIRFOIL TO EFFECT DRAG REDUCTION

摘要

An investigation has been made to determine the effectiveness of boundary layer control by blowing in reducing the drag of a two-dimensional airfoil with NACA 655-^24 sections with the blowing slot located at O.65 chord. The airfoil was equipped with a 0.35-chord blowing flap. Momentum coefficients ranged from 0 to 0.0233 for the basic airfoil (flap undeflected) and from 0 to 0.0501 with flap deflected. The flap was deflected from 0° to 30°. The Reynolds number for the investigation was 2.96 X 10°.nResults of the investigation showed that at low lift and momentum coefficients the drag is slightly reduced by blowing and at higher lift coefficients it is greatly reduced by blowing. A blowing momentum coefficient of 0.0107 caused the maximum lift-drag ratio to increase from approximately 20 to 35.nThese drag reductions are of the same order of magnitude as those for a suction slot at the same location. The increase in maximum section lift coefficients for the basic wing was as great or greater than that for the wing with a suction slot at the same chordwise station. A maximum section lift coefficient of 4.0 was obtained with a flap deflection of 30° and a momentum coefficient of 0.05.