Active Control of Leading Edge Flow Separation for a Swept High-Lift Airfoil

Kurzfassung

This paper presents an active flow control swept wing experiment. The wind tunnel measurements were conducted with a two-element airfoil in high-lift configuration at Reynolds numbers of 1.9M and 2.5M and a corresponding Mach number of 0.14 and 0.18. Previous 2D wind tunnel experiments revealed a significant benefit of the AFC system. Based on this results an investigation with a swept wing (Λ=30°) was carried out to determinate the influence of a 3D boundary layer to the AFC system. The investigation was performed in the low speed wind tunnel DNW-NWB1 at Braunschweig, Germany. The AFC system was located close to the attachment line on the pressure side and consists of co-rotation vortex generator jets to suppress the leading edge stall at the airfoil. The jets can be run either in “static” mode or as dynamically pulsed jets. The AFC system used solenoid fast switch vales with can run with reasonable high frequencies up to F+=12. The measurements allow to determinate the effects of frequency and momentum coefficient on the swept wing. The results show that the AFC system can increase the maximum lift. It seems to be that the actuation frequency and momentum coefficient have a significant influence to the performance of the system. For all cases dynamic blowing is noticeably more effective than constant blowing.