The UTwente aeroacoustic wind tunnel upgrade

This paper describes the UTwente Aeroacoustic Wind Tunnel including its recent anechoic chamber renovation and commissioning. This testing facilitywas originally built in the 1970’s as a closed circuit/closed test section aerodynamic wind tunnel and converted into an aeroacoustic open jet/closed circuit facility in 2001. In 2018 this aeroacoustic wind tunnel has been further upgraded with a special focus on reducing the anechoic chamber cut-off frequency. In the current configuration, the UTwente Aeroacoustic Wind Tunnel is an open test-section facility equipped with a 132 kW electric motor able to produce flow up to 60 m/s with turbulence intensity below 0.08%. The 0.7 x 0.9 m² rectangular jet with Reynolds number of 324.000 based on the criteria of 0:1 √S. This test facility can be used with airfoil models with chord of up to 0.30 m, reaching a chord-based Reynolds number of up to 1.2 million. The anechoic chamber measures 6 x 6 x 4 m³ equipped with a combination of wedges and flat absorbers leading to a cut-off frequency of 160 Hz and is commissioned accordingly to the ISO 3745 norm.