Characterization of engine jet noise in flight conditions using advanced acoustic imaging methods

International audienceThis paper presents some applications of advanced acoustic imaging techniques to flight test data. Engine jet is one of the main sources contributing to cabin noise in cruise flight conditions. The use of fuselage microphone arrays offers the possibility to extract information about the noise source mechanisms responsible for the jet noise, in terms of localization, quantification and directivity. Previous studies present beamforming space-frequency maps allowing the localization of main sources of noise along the jet axis as a function of the frequency. Beamforming is a robust acoustic imaging method, well adapted to the measurement conditions of fuselage microphones (low SNR), however it suffers from several drawbacks (space resolution, source correlations) that limits the analysis possibilities. In the present work, some advanced acoustic imaging echniques are implemented in order to overcome limitations inherent to beamforming. Deconvolution and identification methods are used to draw 1D and 2D source maps, offering the possibility to go deeper in the source characterization and to draw some physical interpretations about jet noise source mechanisms