The aeroacoustic wind tunnel at the University of Bristol is a unique facility, with a National Wind Tunnel status and heavily used for academic and industrial projects. The facility was designed by Professor Mahdi Azarpeyvand and consists of a very quiet closed-circuit wind tunnel and a large anechoic chamber*. The Wind tunnel is powered by a 75kW centrifugal fan and is equipped with a series of large silencers to reduce the fan noise in the ductwork. The wind tunnel is equipped with a 40kW water cooled chiller, enabling continuous testing at a set temperature, between 15^o to 30^o. The anechoic chamber is approximately 7m x 4.5m x 3.5m and is fully anechoic down to 160Hz. Several contraction nozzles with different aspect- and contraction-ratios, including nozzles with exit cross-sectional areas of 500mm (W) x 775mm (H), 400mm (W) x 600mm (H) and 600mm (W) x 200mm (H), have been made for measurement of aerodynamic and aeroacoustic performance of different aero-components, such as aerofoils, bluff bodies, boundary layer, etc. A free-stream velocity range from 8m/s to 120m/s can be achieved with very low free-stream turbulence intensity of approximately 0.1% at 30m/s.

The working section of the tunnel is extended with a Kevlar-wall test section can for examining static and dynamic aerofoil noise at large angles of attack. In terms of measurement capabilities, the wind tunnel is equipped with three Dantec hotwire CTA system (6 channels), 2D PIV, several pressure scanners, hotfilm CTA system (80 channels), two  source location beamforming arrays (a circular and an elliptic array with 73 and 83 free-field microphones, respectively ), an far-field arc of over 50 GRAS and B&K free-field microphones for far-field noise measurements, and large number of in-house designed and fabricated unsteady pressure transducers (over 120), suitable for surface pressure fluctuation measurements. Four National Instrument DAQ are used in the aeroacoustics facility, enabling simultaneous data collection of up to 160 channels for simultaneous dynamic surface pressure and coupled pressure-velocity measurements.

*Mayer, Yannick D., et al. "Design and performance of an aeroacoustic wind tunnel facility at the University of Bristol." Applied Acoustics 155 (2019): 358-370.