An experimental comparison of beamforming, time-reversal and near-field acoustic holography for aeroacoustic source localization

Abstract

Aeroacoustic source localization is an important experimental tool that uses an array of microphones to locate and quantify aeroacoustic sources. Obtaining such information is the first step towards reducing noise emissions. One emerging method of aeroacoustic source localization is aeroacoustic time-reversal. With a unique blend of numerical simula- tion and experimental data, aeroacoustic time-reversal has the potential to provide superior source resolution and characterization performance over other microphone array processing techniques. This paper presents an experimental comparison of three different aeroacoustic source localization methods: aeroacoustic time-reversal, beamforming and near-field acous- tic holography. The source resolution performance of all three source localization methods is investigated via a wind tunnel experimental study using two line arrays of microphones for the test case of a circular cylinder in low Mach number flow. The experimental results show that all three source localization methods are able to satisfactorily locate the cylinder noise source at the aeolian tone frequency to within λ/6. In addition, information about the directivity characteristics of the noise source are obtained with aeroacoustic time-reversal and beamforming.