Wavepacket noise source model for microphone array data analysis of hot supersonic jets

Abstract

Phased arrays of microphones have proved themselves to be a powerful tool for aeroacoustic investigations. There are many different algorithms for processing the resulting data, including classical beamforming, its modern derivatives, Linear Programming, and Generalized Inverse Methods. The current work stems from a recognition that, for configurations with extended coherent sources (such as hot supersonic jets), the Generalized Inverse Method may be preferred, but that its accuracy can be improved by improving the underlying source model that it uses. We examine a wavepacket-based source model for analysis of the noise emitted from hot supersonic jets. This approach provides a more physically realistic representation of the jet noise sources than previously used. The model is tested using data obtained from numerical simulations as measured at a “virtual” array of microphones. The resulting generalized inverse method analysis is then used to predict noise at a farfield arc, and this prediction is compared with that from a conventional Ffowcs Williams-Hawkings acoustic analogy prediction. Initial results with the new wavepacket source model are encouraging, with improved directivity predictions and elimination of some spurious noise sources. The results of the ongoing model development will be included in the final paper.