Acoustic Data Processing and Transient Signal Analysis for the Hybrid Wing Body 14- by 22-Foot Subsonic Wind Tunnel Test

Christopher J. Bahr, Thomas F. Brooks, William M. Humphreys, Taylor B. Spalt, Daniel J. Stead
2014 20th AIAA/CEAS Aeroacoustics Conference   unpublished
An advanced vehicle concept, the HWB N2A-EXTE aircraft design, was tested in NASA Langley's 14-by 22-Foot Subsonic Wind Tunnel to study its acoustic characteristics for various propulsion system installation and airframe configurations. A significant upgrade to existing data processing systems was implemented, with a focus on portability and a reduction in turnaround time. These requirements were met by updating codes originally written for a cluster environment and transferring them to a local
more » ... ing them to a local workstation while enabling GPU computing. Post-test, additional processing of the time series was required to remove transient hydrodynamic gusts from some of the microphone time series. A novel automated procedure was developed to analyze and reject contaminated blocks of data, under the assumption that the desired acoustic signal of interest was a band-limited stationary random process, and of lower variance than the hydrodynamic contamination. The procedure is shown to successfully identify and remove contaminated blocks of data and retain the desired acoustic signal. Additional corrections to the data, mainly background subtraction, shear layer refraction calculations, atmospheric attenuation and microphone directivity corrections, were all necessary for initial analysis and noise assessments. These were implemented for the post-processing of spectral data, and are shown to behave as expected.
doi:10.2514/6.2014-2345 fatcat:vxvhntwth5fz3lusm2guhwprku