Accession Number : AD0700024

Title :   THE ACOUSTICAL SOURCE IN A TWO-DIMENSIONAL JET,

Corporate Author : BOEING SCIENTIFIC RESEARCH LABS SEATTLE WASH

Personal Author(s) : Graham,E. W. ; Graham,B. B.

Report Date : SEP 1969

Pagination or Media Count : 26

Abstract : An acoustical point source moving with the local fluid in a two-dimensional jet of infinite length is studied. In particular, the effect of linear velocity profile shear layers separating the uniform jet from the external fluid is studied. Comparison of shear layer jets with jets bounded by velocity discontinuities can show significant differences in far field mean-square pressures. Possible causes of these differences are discussed. It is noted that, for the supersonic jet, far field (but not near field) effects are confined to a downstream Mach cone. Pressures on the Mach cone are calculated to be zero for the velocity discontinuity jet (and surmised to be zero for the shear layer jet) in contrast to the infinite pressure calculated for a moving source when there is no jet. It is noted that as the velocity discontinuity jet approaches zero thickness the potential of an acoustical source traveling with the jet fluid approaches that of a modified moving source different from the conventional moving source ordinarily referred to in the literature. Some speculations regarding 'real' jets (i.e., jets of finite length) are included. (Author)

Descriptors :   (*SOUND, SOURCES), (*JETS, *TWO DIMENSIONAL FLOW), SHEAR STRESSES, PRESSURE, VELOCITY

Subject Categories : Acoustics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE