Noise reduction capabilities of slat cusp serration were experimentally assessed and demonstrated for a 30P30N three-element high-lift airfoil fitted with two different types of serrated slat cusps. Aerodynamic characteristics were evaluated with the aid of surface pressure distribution, and insignificant differences were found among all the tested configurations. The unsteady flow characteristics of the slat serrations were examined using near- A nd far-field measurements to gain a deeper understanding of the noise generation mechanism. Although increased surface pressure fluctuations were demonstrated by the slat serrations, a substantial reduction in the far-field noise was observed. The increase in the near-field energy levels was attributed to the non-propagating hydrodynamic energy field within the slat cove and the main element, whereas the far-field noise reduction was attributed to the elimination of vortex shedding by the slat serration. Further reaffirmation of the observations and hypothesis was provided with higher-order spectral analysis and wavelet analysis.
