Multiple wavepacket source decomposition methods applied to an F404 engine noise source

Characterizing jet noise sources is an important part of noise reduction efforts. Many equivalent source models (ESMs) derived from inverse methods lack a compelling physical interpretation. Connecting the source model to flow properties is an important part of understanding noise radiation methods. Wavepackets are coherent, spatiotemporal structures observed in jet turbulence. Mathematical expressions describing wavepackets have been used in modal decompositions of the turbulent flow. Similar structures appear in frequency domain ESMs and these methods have been applied to create physically meaningful, reduced-order models. This paper applies a multiple wavepacket decomposition method developed by Harker [B. M. Harker, BYU Ph. D Dissertation (2017)] to acoustic data collected near a T- 7A-installed F404 engine. Individual wavepackets are used to create total-field reconstructions and comparisons are made to the dual-lobe behavior observed in full-scale jets. Finally, sound power characteristics of each wavepacket are used to effectuate a sound power decomposition of the noise source. [Work supported by ONR Grant No. N00014-21-1-2069.]