Localization of the Acoustic Sources of the A340 with a Large Phased Microphone Array during Flight Tests”, AIAA Paper 2002-2506

Flyover measurements with a phased array of microphones extending over an area of 16 m by 16 m are reported. The 161 microphone array was made possible by combining hardware from ONERA and DLR. In this investigation of the airframe noise of an Airbus A340, the yover altitudes were between 90 m and 165 m. The data reduction methods for moving objects of DLR and ONERA are compared. Some source maps are shown and discussed. It is demonstrated that nested arrays must be used for a study over a wide frequency range, and that comparisons of the noise maps between dierent arrays provide valuable information about the noise sources. The ONERA method is shown to be a powerful data reduction method based on a small number of microphones while the DLR method results in alias-free maps at the expense of a much larger number of microphones