A Comparison of Microphone Phased Array Methods Applied to the Study of Airframe Noise in Wind Tunnel Testing

International audienceIn this work, various microphone phased array data processing techniques are applied to two existing datasets from aeroacoustic wind tunnel tests. The first of these is from a large closed-wall facility, DLR's Kryo-Kanal Köln (DNW-KKK), and is a measurement of the high-lift noise of a semispan model. The second is from a small-scale open-jet facility, the NASA Langley Quiet Flow Facility (QFF), and is a measurement of a clean airfoil self-noise. The data had been made publicly available in 2015, and were analyzed by several research groups using multiple analysis techniques. This procedure allows the assessment of the variability of individual methods across various organizational implementations, as well as the variability of results produced by different array analysis methods. This paper summarizes the results presented at panel sessions held at AIAA conferences in 2015 and 2016. Results show that with appropriate handling of background noise, all advanced methods can identify dominant acoustic sources for a broad range of frequencies. Lower-level sources may be masked or underpredicted. Integrated levels are more robust and in closer agreement between methods than narrowband maps for individual frequencies. Overall there is no obvious best method, though multiple methods may be used to bound expected behavior. i Research Engineer, Aeroacoustics Branch, Senior Member AIAA, christopher.j.bahr@nasa.gov ii Research Engineer, Adv. Measurements and Data Systems Branch, Associate Fellow AIAA, william.m.humphreys@nasa.go