Experimental study on comparison on noise characteristics of noise reduction leading-edge slats

Aircraft high-lift devices are important components to ensure the safety of take-off and landing, and it is also the main contributor to airframe noise in the process of take-off and landing, especially the leading-edge slat. The problem of leading-edge slat noise recently has been receiving much attention. In an effort to reduce noise, two kinds of noise reduction leading-edge slat that reduce gap by rotating with the fixed axis and rigid deformation, respectively, are introduced in this paper. Experiment on comparison on noise characteristic of two-dimensional landing configuration model at an angle of attack range from 3°to 6°in D5 aero-acoustic wind tunnel at Beihang University is carried out. Experimental results show that, at the beginning of the process of gap reduction, the model noise increases at a small angle of attack (below 4°). Among that, leading-edge slat with deformation has less noise increase. This is found to be closely related to the selection of primary mode of self-excited oscillation within leading-edge slat cove. Besides, the noise reduction effect of these two is obvious when the gap is completely closed.