Measurements in the wake of upper surface blowing

Abstract

Wind tunnel tests were conducted to investigate the flow field characteristics in the wake of a wing exposed to tangential upper surface blowing near the leading edge of the model. This effort stems from the need of understanding the aerodynamics associated with upper surface blowing, being one of the potential techniques used to control the boundary layer and alleviate stall in high angle-of-attack flight regimes. Flow field measurements in the wake were taken at model negative, zero, positive low and high angles of attack. Detailed results of the streamwise development of the mean velocity, turbulence and Reynolds shear stress distributions using hot wire anemometry were reported. The mean velocity results at low angles of attack indicated that the influence of upper surface blowing is significant only beyond the practical range of jet blow rate, where the jet velocity exceeded double the free stream value. At high angles of attack, its effect was invariably significant.