On the design of silent trailing-edges

Abstract

Trailing-edge noise data from an experimental study on a flat-plate and on a twodimensional NACA 0012-like airfoil are presented. Within extensive measurements in the Aeroacoustic Wind Tunnel Braunschweig various flow-permeable (comb-type) edge modifications were tested with respect to their noise reduction capability. Among numerous design parameters a narrow slit width was identified as major requirement for a low-noise trailing-edge design whereas flexibility of the comb material was found to be not imperative for such edge noise reduction means. Because both boundary-layer tripping and trailing-edge thickness show significant influence on trailing-edge noise, a detailed description of these effects i s provided to enable an accurate interpretation of corresponding noise test data. © 2007 Springer-Verlag Berlin Heidelberg.