Abstract
This paper analyses the influence of microphone cavity geometry on beamforming measurements with a turbulent boundary layer present on the microphone array. A 16- microphone array was tested in the anechoic open-jet wind tunnel of the Delft University of Technology. The array was placed on a flat plate mounted flush with the exit nozzle of the wind tunnel. Microphones were installed in three different cavity geometries along with a flush mounted microphone array which was used as a baseline for comparison. The geometries include a chamfered-cylindrical hard-plastic cavity, a chamfered-cylindrical cavity made of melamine foam, and a chamfered-cylindrical cavity with star-shaped protrusions, also made of melamine. The recessed cavities were covered with a 0.026 mm gauge steelwire cloth. A speaker emitting white noise outside of the flow was employed as a sound source. Different flow velocities at the same sound power level for the speaker (and hence different signal-to-noise ratios) were studied. The results obtained with the three cavity geometries are compared with the flush-mounted case in terms of the quality of the acoustic source maps (location and strength of the sound source). The signal-to-noise ratio of the beamforming measurements increased by as much as 30 dB by placing microphones within a conical cavity with melamine foam walls when compared to the flush mounted case.
Original language | English |
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Number of pages | 18 |
Publication status | Published - 2020 |
Event | 8th Berlin Beamforming Conferece - Berlin, Germany Duration: 2 Mar 2020 → 3 Mar 2020 Conference number: 8 http://www.bebec.eu |
Conference
Conference | 8th Berlin Beamforming Conferece |
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Abbreviated title | BeBeC 2020 |
Country | Germany |
City | Berlin |
Period | 2/03/20 → 3/03/20 |
Internet address |