Overview of the Acoustic Improvement Program for the 9- by 15-Foot Low Speed Wind Tunnel
This report gives an overview of a recent improvement project to reduce the background noise in the NASA Glenn Research Center 9-by 15-Foot Low Speed Wind Tunnel. Noise surveys of the original tunnel configuration indicated that flow surface noise in the test section and noise propagating from other tunnel regions were the primary background noise contributors. Several novel features were incorporated in the design of the upgraded tunnel, including a low noise flow surface and serpentine baffles for noise reduction, along with acoustically treated turning vanes and a new diffuser. Three companion papers present implementation details including the acoustic design and the aerodynamic quality/design CFD. The upgrades reduced background noise in the test section by about 10dBA over a wide range of flow speeds and frequencies. It is hoped this will be a useful summary to aid future users of the facility and wind tunnel engineers everywhere.