Phased-array advancement for aeroacoustic measurements—A deconvolution approach for the mapping of acoustic sources (DAMAS)

Abstract

Since the 1990s, there has been a significant increase in the use of phased arrays of microphones in studies of noise sources for both wind tunnel models and full-scale aircraft. This is in spite of the fact that array data interpretation has been burdened with considerable uncertainty when using traditional array processing. Results represent noise sources that are convolved with array beamform response functions, which themselves depend on array geometry, size, and frequency. Recently, Langley Research Center developed breakthrough methodology that decouples the array design and processing influence from the noise being measured, using a relatively simple and robust algorithm. The deconvolution approach for the mapping of acoustic sources (DAMAS) method removes beamforming characteristics from output presentations. This presentation shows results from several airframe noise studies and a MIT air brake noise study conducted at Langley’s Quiet Flow Facility (QFF). It is shown that DAMAS can permit an unambiguous and accurate determination of acoustic source positions and strengths that cannot be otherwise attained. The acoustic community is accepting the methodology and applying it to other applications. At Langley, recent enhancements have been made to the original DAMAS code that allow the determination and separation of coherent and incoherent noise source distributions.