Actions for Modeling of Turbulence Generated Noise in Jets

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Modeling of Turbulence Generated Noise in Jets

Author
Bridges, James
Published
June 2004.
Physical Description
1 electronic document
Additional Creators
Khavaran, Abbas
Online Version

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Summary
A numerically calculated Green's function is used to predict jet noise spectrum and its far-field directivity. A linearized form of Lilley's equation governs the non-causal Green s function of interest, with the non-linear terms on the right hand side identified as the source. In this paper, contributions from the so-called self- and shear-noise source terms will be discussed. A Reynolds-averaged Navier-Stokes solution yields the required mean flow as well as time- and length scales of a noise-generating turbulent eddy. A non-compact source, with exponential temporal and spatial functions, is used to describe the turbulence velocity correlation tensors. It is shown that while an exact non-causal Green's function accurately predicts the observed shift in the location of the spectrum peak with angle as well as the angularity of sound at moderate Mach numbers, at high subsonic and supersonic acoustic Mach numbers the polar directivity of radiated sound is not entirely captured by this Green's function. Results presented for Mach 0.5 and 0.9 isothermal jets, as well as a Mach 0.8 hot jet conclude that near the peak radiation angle a different source/Green's function convolution integral may be required in order to capture the peak observed directivity of jet noise.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 20040086533.
NASA/TM-2004-213105.
AIAA Paper 2004-2983.
E-14580.
Tenth Aeroacoustics Conference; 10-12 May 2004; Manchester; United Kingdom.
Terms of Use and Reproduction
No Copyright.
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