Active Control of Flow Seperation on a Swept Constant Chord Half Model in a High-Lift Configuration

Abstract

The purpose of this manuscript is to address the impact of active separation control by means of pulsed blowing in a three-dimensional and complex flow environment. Experimental investigations are undertaken in order to enhance the performance of a three-element high-lift configuration by preventing the flow separation on the single-slotted flap. The configuration includes some less investigated aspects as the wing has a constant sweep angle of 30 and a finite wing span. An eort is made to implement an actuator system inside the small flap in order to excite the flow locally with the desired frequency and amplitude. The results show that, despite the strong three-dimensionality due to sweep and finite wing span, periodic excitation is able to delay separation on the flap or to reattach an already separated flow. Lift is improved by 10% to 12% over a wide range of angle of attack and flap settings. The influence on drag by periodic excitation seems to be ambiguous because in some cases the higher induced drag due to the attached flow compensates the drag benefit resulting from the elimination of the recirculation region. However, preliminary tests show that high amplitude forcing in the wing tip area is able to reduce the drag by as much as 10%.