Acoustic source characterization of shock-associated noise in an installed, full-scale F404 engine

Abstract

Shock-associated noise in supersonic jets is an important factor in acoustic radiation, particularly in the upstream direction. A previous paper [L. T. Mathews et al., J. Acoust. Soc. Am. 154, A325 (2023)] discussed a preliminary source characterization of shock-associated noise in a full-scale, installed tactical jet engine. Acoustical holography was used to reconstruct the acoustic behavior near the jet and high-amplitude features were produced that were consistent with shock-associated noise sources. This paper presents a more detailed characterization of shock-related noise in the jet using higher-fidelity methods, such as subarray processing and bandwidth extension. The spatial and spectral characteristics of the shock cell noise sources are discussed. A virtual reference decomposition method is used to examine the source and radiative characteristics of each detected shock noise source. The results are compared with shock noise characteristics in the literature. [Work supported by ONR Grant No. N00014-21-1-2069.]