Assessment of the accuracy of microphone array methods for aeroacoustic measurements
R. Merino Martinez (TU Delft - Aircraft Noise and Climate Effects)
S. Luesutthiviboon (TU Delft - Aircraft Noise and Climate Effects)
R. Zamponi (von Karman Institute for Fluid Dynamics)
A. Rubio Carpio (TU Delft - Aircraft Noise and Climate Effects)
D. Ragni (TU Delft - Wind Energy)
P. Sijtsma (PSA3: Pieter Sijtsma Advanced AeroAcoustics, TU Delft - Aircraft Noise and Climate Effects)
M. Snellen (TU Delft - Aircraft Noise and Climate Effects)
C. Schram (von Karman Institute for Fluid Dynamics)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
In this paper, the performance of four acoustic imaging methods: conventional frequency domain beamforming (CFDBF), functional beamforming (FUNBF), enhanced high resolution CLEAN–SC (EHR–CLEAN–SC) and generalized inverse beamforming (GIBF), is investigated in terms of accuracy and variability. Three experimental test cases are considered: 1) a single speaker emitting synthetic broadband noise, 2) two speakers emitting incoherent synthetic broadband noise, and 3) trailing–edge noise generated by a tripped NACA 0018 airfoil. All the measurements were performed in the anechoic wind tunnel of Delft University of Technology. Overall, GIBF and EHR–CLEAN–SC offer the most accurate results when point sources (speakers) are present. They even achieve super–resolution by separating sound sources beyond the Rayleigh resolution limit. Repeating the measurements indicates a standard deviation in the results of less than 1 dB. When analyzing distributed sound sources, such as trailing–edge noise, CFDBF and FUNBF provide the best performance. This indicates that the acoustic imaging method needs to be selected based on the expected sound source configuration.