62-channel, 2-DOF continuous-scan acoustic measurement system.
Wind tunnel background noise can be a significant confounding factor in the characterization of aeroacoustic noise sources. To improve the quality of data and better understand acoustic source mechanisms, beamforming arrays are used to recover acoustic source maps and perform spatial filtering to reject background noise. Array performance (main lobe width, maximum side level, etc.) is commonly improved by adding more sensors at considerable expense. By continuously moving a set of microphones and phase-referencing them to a set of stationary microphones, a high-resolution synthetic array is created and greatly improves beamforming performance, approaching the theoretical limit for a continuous-aperture (infinite-sensor) array. This continuous-scan acoustic array, developed in collaboration with ATA Engineering, Inc. and NASA Langley Research Center, is a unique testing capability at the Texas A&M 3’ x 4’ Low-Speed Subsonic Wind Tunnel. As a practical consequence of using continuous-scan acoustic systems, software for rapid processing of many (100+) datasets has been developed using efficient partial field methods. The ASPEN (Acoustic Simulation and Processing Environment) software package was developed and represents a three order-of-magnitude reduction in signal processing time.
Acoustic source map of a thin wire in 35 m/s flow at 3.65 kHz.
Related Publications:
- K. F. Lieb, S. Kinney, P. N. Shah, D. Hensley, and D. J. Hartl, “Improved computational efficiency of continuous-scan beamforming with partial field decomposition,” AIAA SCITECH 2024 Forum, DOI: 10.2514/6.2024-2108.
- K. F. Lieb, S. Kinney, P. N. Shah, D. Hensley, L. Schweizer, and D. J. Hartl, “Development of an economical 2-DOF continuous-scan acoustic beamforming array,” AIAA AVIATION 2023 Forum, DOI: 10.2514/6.2023-3815.
Graduate Student: Kevin Lieb