Slat noise reduction by means of adaptive leading edge devices

Abstract

Slat noise is regarded as the major noise source of state of the art high lift systems and contributes to the overall aircraft noise signature in particular during the approach phase [1]. Consequently any attempt to reduce high lift system generated noise should first of all target slat noise reduction. Having furthermore in mind that the slat at the same time is a very important means to achieve the necessary high lift performance any approach to reduce slat noise should address the conservation of the aerodynamic performance as well. In the course of this work two different adaptive systems to reduce slat noise will be presented, namely an “adaptive slat” and the “smart droop nose”. The concept of the adaptive slat was investigated in a joint approach between the DLR internal project SLED (Silent Leading Edge Devices) and the EU co-financed project OPENAIR. In the mainframe of the EU co-financed project SADE [2] and again within SLED studies on the smart droop nose were driven. Both approaches have in common that the conventional slat is replaced by an actuated system. The basic difference is in fact that the adaptive slat addresses a slat gap variation in order to reduce or control slat noise while on the other hand the smart droop nose concept represents a 2-element high lift system without slat aiming at the reduction of the aerodynamic penalty that occurs due to omitting the slat. […]