Proper orthogonal Decomposition analysis of noise generation mechanisms in the slat cove

Abstract

Airframe became a relevant source of noise in commercial aircrafts because of the introduction of high by-pass ratio turbofans. The slat is one of the most important airframe noise source, since it represents a source distributed along the wing span. The flow mechanism responsible for noise generation is not completely understood yet. Time-accurate Lattice-Boltzmann simulations were carried out in order to deliver flow data for the calculations of coherent structures in the slat cove by means of the Proper Orthogonal Decomposition (POD) technique. The first two POD-modes are dominated by mixing-layer like structures. Power Spectral Density of the amplitude of these leading POD-functions present the highest level at frequencies that are dominant in the spectrum of far-field acoustic fluctuations.