A preliminary investigation of near-field acoustical holography in characterizing noise from military jet aircraft

Since its introduction, near-field acoustical holography (NAH) has been successfully used in characterizing the vibration of and radiation from a wide class of structural noise sources. In the past several years, some have begun to apply NAH to the characterization of aeroacoustic noise sources. To date, however, research has involved only axial fans and model-scale subsonic jets. In order to meet the growing need for a better description of the source region of high-thrust military jets, we have been investigating the application of NAH to these types of sources. In this paper, we present some of the technical and practical challenges that need to be considered, including instrumentation bandwidth and dynamic range, the large spatial extent and partially correlated nature of the jet noise sources, and acoustical nonlinear effects in near-field propagation. a Email address: [email protected] b Email address: [email protected] c Email address: [email protected] d Email address: [email protected]