Design and fabrication of the subsonic wind tunnel for aeroacoustic measurements

This paper presents the design and analysis of a free jet, blow down subsonic wind tunnel for aeroacoustic measurements. The wind tunnel is made from the artificial fibre which is optimised for achieving subsonic, i.e. 0.3 <= M <= 0.8 steady flow (low turbulence). The flow control techniques such as orifice holes were distributed uniformly over the perforated plates of diameter 302 and 444 mm positioned at 30% and 45% respectively, to reduce the turbulence flow. The aerodynamic performances of the Free Jet Wind Tunnel (FJWT) have been studied at both incompressible (M < 0.3) and compressible (0.3 <= M <= 0.8) conditions of about 75 m/s, 1.3 bar, 2.25 bar and 4.5 bar. From the results, it is evident that the uncertainty in the wind tunnel is low compared with the traditional wind tunnel. Further, the acoustic measurements uncertainty is obviously lesser than other configurations.