E.J. Kerschen

The control of wake-airfoil interaction noise by trailing-edge flap motion is investigated. Time-domain predictions are developed for the unsteady interaction of a single wake with an airfoil. The analysis considers the case of low Mach numbers and O(l) aerodynamic reduced frequencies. The acoustic wavelength is then long compared to the airfoil chord and singular perturbation techniques can be utilized to simplify the problem. Results are presented for the unsteady lift and sound field produced by the wake-airfoil interaction, and for the trailing-edge flap motion required to cancel this sound field. The asymptotic limit of wake widths narrow compared to the airfoil chord is also examined. Two time scales arise in this limit a short time scale for the wake to pass the airfoil leading edge, and a longer time scale for the resulting unsteady aerodynamic response. Asymptotic formulas are derived for the unsteady lift, sound field, and cancelling flap motion. The narrow wake limit leads to a particularly simple result for the peak of the sound field, which occurs on the short time scale and has the same temporal dependence as the wake upwash which impinges on the leading edge.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 12 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.238-249; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1992