Aeroacoustic characteristics of slat finlets

An experimental study was performed on a 30P30N three-element high-lift airfoil fitted with different types of slat finlets and its noise reduction capabilities were assessed. To develop a better understanding of the noise reduction mechanism, simultaneous measurements of the unsteady surface pressure were taken at various locations at the vicinity of the slat cove and at far-field locations. While there was a small reduction in far-field noise for the fundamental peak, the use of slat finlets showed a substantial reduction in surface pressure fluctuations. The reduction of vortex shedding energy by the slat finlets also resulted in the reduction of nonpropagating hydrodynamic field between the slat and the main-element substantially reducing the near-field pressure spectra. Fourier and wavelet-based analysis along with high-order spectral analysis were provided for further confirmation of the observations and hypothesis. Finally, the wavelet coefficient findings showed spectral peaks as well as amplitudes modulated in time in the baseline case; however, these peaks were substantially reduced for the finlet configuration with larger spacing.