F.B. Hsiao, R.-N. Shyu

The internal acoustic excitation technique is successfully applied to improve the aerodynamic performance of a NACA 63a-018 cross section airfoil at high angle of attack (AOA). Tests are separately conducted in two suction, open-circuited wind tunnels for measurements and flow visualization at an operating Reynolds number 3.1 x 10^5 and 2.7 x 10^4 respectively. The experimental results indicate that for the low post-stalled airfoil performance at AOA = 18 to 24 degs, the leading-edge flow separation is delayed by excitation of a frequency near the shear layer instability frequency, ft. However, if AOA is increased beyond 24 degs, flow separation from the leading edge of the airfoil is unavoidable. In this case, the most effective frequency for improving the airfoil performance matches the vortex shedding frequency, fs, in the wake. Under effective excitation, the vortex flow takes place prematurely on the upper surface of the airfoil, resulting in both a higher lift and a higher drag due to decreasing base pressure over the upper surface of the airfoil.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 9 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.63-71; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1992