Enhancing Aeroacoustic Wind Tunnel Studies through Massive Channel Upscaling with MEMS Microphones

Abstract

This paper presents a large 6~m x 3~m aperture 7200 MEMS microphone array. The array is designed so that sub-arrays with optimized point spread functions can be used for beamforming and thus, enable the research of source directivity in wind tunnel facilities. The total array consists of modular 800 microphone panels, each consisting of four unique PCB board designs. This modular architecture allows for the time-synchronized measurement of an arbitrary number of panels and thus, aperture size and total number of sensors. The panels can be installed without gap, so that the array's microphone pattern avoids high sidelobes in the point spread function. The array's capabilities are evaluated on an open wind tunnel airframe test at DNW-NWB. Prominent sources are identified and their directivity is evaluated. Additional far-field microphones are employed to validate the beamforming results and directivity analysis.