title: Interior near-field acoustical holography in flight.
abstract: In this paper boundary element methods (BEM) are mated with near-field acoustical holography (NAH) in order to determine the normal velocity over a large area of a fuselage of a turboprop airplane from a measurement of the pressure (hologram) on a concentric surface in the interior of the aircraft. This work represents the first time NAH has been applied in situ, in-flight. The normal fuselage velocity was successfully reconstructed at the blade passage frequency (BPF) of the propeller and its first two harmonics. This reconstructed velocity reveals structure-borne and airborne sound-transmission paths from the engine to the interior space.
authors.affiliation: Naval Research Laboratory, Washington, DC 20375, USA. williams@genah.nrl.navy.mil
authors.forename: E G
authors.initials: EG
authors.lastname: Williams
authors.forename: B H
authors.initials: BH
authors.lastname: Houston
authors.forename: P C
authors.initials: PC
authors.lastname: Herdic
authors.forename: S T
authors.initials: ST
authors.lastname: Raveendra
authors.forename: B
authors.initials: B
authors.lastname: Gardner
mesh_terms: D000054:Acceleration; D000162:Acoustics; D000401:Aircraft; D006696:Holography; D006801:Humans; D013026:Space Flight