Modified Shielding Jet Model for Twin-Jet Shielding Analysis

An analytical model to estimate the shielding of noise emitted from a point noise source has been developed assuming the shielding jet to be a cylinder of constant radius with uniform flow across the cross section. Comparison to experiment indicated that the model overestimates diffraction of sound...

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Bibliographic Details
Published in:Journal of vibration and acoustics 1984-07, Vol.106 (3), p.421-426
Main Authors: Gerhold, C. H, Gilbride, J
Format: Article
Language:English
Online Access:Get full text
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Summary:An analytical model to estimate the shielding of noise emitted from a point noise source has been developed assuming the shielding jet to be a cylinder of constant radius with uniform flow across the cross section. Comparison to experiment indicated that the model overestimates diffraction of sound around the jet in the far downstream region. The shielding jet model is modified to include widening downstream of the nozzle exit. This not only represents a more realistic model of the jet, but is also expected to improve the shielding estimate downstream. The modified jet model incorporates a Mach number dependent widening rate, a corresponding decrease in flow velocity downstream and an equivalent slug flow evaluation to retain the locally parallel flow approximation of the model development. The shielding analysis with modified jet model is compared to measured data for a subsonic isothermal air jet and a simulated hot subsonic jet. Improvement of the shielding estimate is discussed.
ISSN:1048-9002
0739-3717
1528-8927
2161-9611
DOI:10.1115/1.3269212