Noise Control on Flap Side Edge

Efficient aircraft noise reduction is a major factor for the continuing growth of civil aviation. Within the last decades large effort has been spent to successfully reduce the engine noise contribution. During landing approach, however, airframe noise is of comparable importance as the engine noise. Therefore, further noise reduction studies consider also the major airframe sources, i.e. landing gears and high lift devices. High lift device sources are usually differentiated in to the slat sources and the flap side edge source, latter being the main focus of the present paper. Studies have been performed within the last years on the mechanisms and the modeling of high lift device noise sources, providing a number of numerical, semi-analytical modeling approaches for the local flow unsteadiness, which is the drive of the farfield acoustics. Also remarkable reductions of flap side edge noise at the source have been demonstrated by designs such as e.g. flap fences or porous side edges in model scales. The present work shall provide a novel low noise flap side edge tested in a parametric wind tunnel study.