Arrayed Microphone Measurement in Low Speed Wind Tunnel

Phased array microphone system has been developed in JAXA's 2m x 2m low-speed wind tunnel. The wind tunnel is a conventional facility for aerodynamic testing with closed test section, not designed for aeroacoustic measurement which doesn't have anechoic room and low noise treatment. Therefore, one of the purpose of this testing is the availability of aeroacoustic wind tunnel in a noisy-closed wind tunnel to realize simultaneous measurement of aerodynamic and aeroacoustic data in future. Basic performances of the microphone system in the tunnel were checked using the known acoustic sound from speaker and aerodynamic noise by a small delta-shaped blade, and it was confirmed that the sound source could be observed and the location was identified. NACA0012 wing model was tested and the trailing edge noises from the wing model were observed clearly with the microphone array system and the noise depended on angle of attack and wind speed, which showed correlation with oil flow and hot film results.