Acoustic and aerodynamic design and characterization of a small-scale aeroacoustic wind tunnel

The aeroacoustic wind tunnel at Brandenburg University of Technology at Cottbus is a newly commissioned research facility for the experimental study of sound generation from bodies immersed in a fluid flow. The paper discusses the design criteria for the open jet wind tunnel that provides a maximum wind speed of 72 m/s at continuous operation and may be operated with nozzles of different dimension between 35 cm diameter (circular nozzle) and 12 cm by 14.7 cm (rectangular nozzle). Experiments may be performed either in a reverberant or in an anechoic environment. Both the aerodynamic and the acoustic design of the wind tunnel components are discussed in detail. Background noise measurements in the completed facility revealed very low levels comparable to other wind tunnels. The results of aerodynamic wind tunnel calibration confirmed a uniform flow quality in the jet and a very low axial turbulence intensity which is less than 0.2% for the 35 cm nozzle and less than 0.1% for the other nozzles. A final benchmark is provided by results of successful trailing edge noise measurements on an SD7003 airfoil that are presented and compared to results from the literature.