Application of MEMS Microphone Array Technology to Airframe Noise Measurements

NASA Langley Research Center, Hampton, Virginia, 23681Current generation microphone directional array instrumentation is capable ofextracting accurate noise source location and directivity data on a variety of aircraftcomponents, resulting in significant gains in test productivity. However, with this gain inproductivity has come the desire to install larger and more complex arrays in a variety ofground test facilities, creating new challenges for the designers of array systems. Toovercome these challenges, a research study was initiated to identify and develop hardwareand fabrication technologies which could be used to construct an array system exhibitingacceptable measurement performance but at much lower cost and with much simplerinstallation requirements. This paper describes an effort to fabricate a 128-sensor arrayusing commercially available Micro-Electro-Mechanical System (MEMS) microphones. TheMEMS array was used to acquire noise data for an isolated 26%-scale high-fidelityBoeing 777 landing gear in the Virginia Polytechnic Institute and State University StabilityTunnel across a range of Mach numbers. The overall performance of the array wasexcellent, and major noise sources were successfully identified from the measurements.