Author:
TAM CHRISTOPHER K. W.,AURIAULT LAURENT
Abstract
It is well-known that sound generated by localized sources embedded
in a jet undergoes
refraction as the acoustic waves propagate through the jet mean flow. For
isothermal or hot jets, the effect of refraction causes the deflection
of the radiated
sound waves away from the jet flow direction. This gives rise to a cone
of silence
around the jet axis where there is a significant reduction in the radiated
sound intensity.
In this work, the mean flow refraction problem is investigated through
the
use of the reciprocity principle. Instead of the direct source Green's
function, the
adjoint Green's function with the source and observation points interchanged
is used
to quantify the effect of mean flow on sound radiation. One advantage of
the adjoint
Green's function is that the Green's functions
for all the source locations in the jet
radiating to a given direction in the far field can be obtained in a single
calculation.
This provides great savings in computational effort. Another advantage
of the adjoint
Green's function is that there is no singularity in the jet flow so
that the problem can
be solved numerically with axial as well as radial mean flow gradients
included in a
fairly straightforward manner. Extensive numerical computations have been
carried
out for realistic jet flow profiles with and without exercising the locally
parallel flow
approximation. It is concluded that the locally parallel flow approximation
is valid as
long as the direction of radiation is outside the cone of silence.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
153 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献