Assessment of slat and flap side-edge noise reduction potential from far field noise measurements

Abstract

Within Task 1.6.3.2 new high lift devices were noise tested in DNW-LLF's open test section at a 1/10.6 scaled A340 model, aiming at an optimization of selected devices and the quantification of their respective noise potentials. From the test results the model slat-tracks were identified as the major sources of aerodynamic noise. Ad-hoc fairings, when added to the tracks, provided some noise reduction. However, in contrast to the expected results, still no significant noise reduction could be demonstrated through "low noise" modifications of the slat trailing-edges. Some noise reduction was observed for porous treatments of the slat-horn and the flap side-edges as well as through seals applied to the slat-pylon junction gaps. As a consequence a description of the slat and flap side-edge noise source characteristics with respect to flight conditions could be performed as planned.