Propagation of high frequency jet noise using geometric acousticsSpherical directivity of noise radiated from a convecting quadrupole source embedded in an arbitrary spreading jet is obtained by ray-tracing methods of geometrical acoustics. The six propagation equations are solved in their general form in a rectangular coordinate system. The noise directivity in the far field is calculated by applying an iteration scheme that finds the required radiation angles at the source resulting in propagation through a given observer point. Factors influencing the zone of silence are investigated. The caustics of geometrical acoustics and the exact locations where it forms is demonstrated by studying the variation in ray tube area obtained from transport equation. For a ring source convecting along the center-axis of an axisymmetric jet, the polar directivity of the radiated noise is obtained by an integration with respect to azimuthal directivity of compact quadrupole sources distributed on the ring. The Doppler factor is shown to vary slightly from point to point on the ring. Finally the scaling of the directivity pattern with power -3 of Doppler factor is investigated and compared with experimental data.
Document ID
19930039244
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Khavaran, A. (Sverdrup Technology, Inc. Brook Park, OH, United States)
Krejsa, E. A. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1993
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 93-0147
Meeting Information
Meeting: AIAA, Aerospace Sciences Meeting and Exhibit