Abstract
This paper summarizes a case study example on the methodology used for phased array microphone measurements in a realistic acoustic environment. A ducted fan rotor is measured in an environment, where structure born noise and aerodynamically generated noise cannot be separated using conventional single microphone acoustic analysis. The conditions of the measurement are similar to an industrial acoustic measurement scenario, where no acoustics treatment can be implemented for aiding in the source localization. The acoustics propagation paths are complex and combined with the high level of wind noise which the microphones exposed to, the interpretation of the results is difficult. The paper presents the processing and analyses of the many microphone worth of data of the phased array microphone system. The wind noise dominated cross spectral matrix is analyzed and source positions are obtained with beamforming procedures for both stationary and rotating sources.
Highlights
In recent years, acoustic analysis has become an important aspect of machine design and of the evaluation of existing facilities, workshops or crowded community areas affected by noise
This paper summarizes a case study example on the methodology used for phased array microphone measurements in a realistic acoustic environment
The conditions of the measurement are similar to an industrial acoustic measurement scenario, where no acoustics treatment can be implemented for aiding in the source localization
Summary
Acoustic analysis has become an important aspect of machine design and of the evaluation of existing facilities, workshops or crowded community areas affected by noise. Beamforming techniques provide a unique means for i) the identification of dominant noise sources, ii) making a distinction between rotor-originated noise and other noise components [5] These features help to extend the possibilities of the presently used measuring instrumentation for use in the acoustic diagnostics of machines. Because of the coexistence of many sources, acoustic measurements with a single microphone do not allow the precise characterization of the directivity and source strength of the sources, and at far-field locations the dominant acoustic sources cannot be identified In these cases the phased array microphone system could have an important diagnostic use. In reference [6] tonal noise components of a turbofan engine were investigated and it was found that installation effects of the inflow control device alter
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