A combined experimental and numerical study on aerodynamic load reduction for a swept wing by using jets

Abstract

This paper presents a combined experimental and numerical investigation on aerodynamic load reduction through steady blowing on the suction surface of a swept wing. In the experiment, a swept wing with an array of jet exit holes near the wing tip was studied in a low-speed wind tunnel. Numerical studies based on solving the Reynolds-averaged Navier-Stokes equations provide further insight into aerodynamic load and bending moment reduction and the associated flow physics caused by the surface jets with various jet parameters, including blowing direction, blowing strength and jet velocity distribution. It is found that the upstream blowing causes a much larger reduction in both lift and bending moment than that caused by the normal blowing. Both the experiment and numerical simulations confirm that the aerodynamic load reduction increases as the jet momentum increases. It is also found that the linear jet velocity distribution, with the lowest blowing velocity at the outer end (y/b=0.98) of jets region and the highest blowing velocity at the inner end (y/b=0.755), achieves the maximum aerodynamic load reduction among the six different distributions studied. In addition, three key flow mechanisms associated with aerodynamic load reduction are identified, including the pressure rise on the suction surface caused by the flow separation, the wingspan shortening effect caused by the large drop in lift in the tip region of a three-dimensional swept wing as well as the jet reaction force.