Near‐field and far‐field sound radiation from a line‐driven fluid‐loaded infinite flat plate having periodic and non‐periodic attached rib stiffeners

1993 ◽  
Vol 93 (4) ◽  
pp. 2244-2244
Author(s):  
Benjamin A. Cray
Keyword(s):  
Flat Plate ◽  
Near Field ◽  
Sound Radiation ◽  
Far Field ◽  
Field Sound

On-axis and far-field sound radiation from resilient flat and dome-shaped radiators

2009 ◽  
Vol 125 (3) ◽  
pp. 1444-1455 ◽  
Author(s):  
Ronald M. Aarts ◽  
Augustus J. E. M. Janssen
Keyword(s):  
Sound Radiation ◽  
Far Field ◽  
Field Sound

scholarly journals Near-field sound radiation of fan tones from an installed turbofan aero-engine

2015 ◽  
Vol 138 (3) ◽  
pp. 1313-1324 ◽  
Author(s):  
Alan McAlpine ◽  
James Gaffney ◽  
Michael J. Kingan
Keyword(s):  
Near Field ◽  
Sound Radiation ◽  
Aero Engine ◽  
Near Field Sound ◽  
Field Sound

Estimation of Plate Vibration and Its Far Field Sound by Means of Near Field Sound Measurement

1986 ◽  
Vol 29 (252) ◽  
pp. 1874-1880 ◽  
Author(s):  
Kiyohiko UMEZAWA ◽  
Haruo HOUJOH ◽  
Tadashi KITANO
Keyword(s):  
Near Field ◽  
Plate Vibration ◽  
Far Field ◽  
Sound Measurement ◽  
Near Field Sound ◽  
Field Sound

Acoustic communication

2018 ◽  
Author(s):  
Heiner Römer
Keyword(s):  
Acoustic Communication ◽  
Background Noise ◽  
Near Field ◽  
Background Information ◽  
Natural Environments ◽  
Far Field ◽  
Sensory Receptors ◽  
Substrate Vibration ◽  
Field Sound ◽  
Mechanical Disturbances

This chapter, takes a broad look at insect acoustic communication, by including near-field and far-field sound, as well as substrate vibration, as signals. These mechanical disturbances differ greatly in their physical properties—they propagate in their natural environments over distances that can span from a few millimetres up to several hundred metres. Therefore, background information is provided to understand how the insect sound-emitting systems for the different signals work and in which behavioral contexts they are used. Evidence is also provided to describe the substantial changes signals undergo on their way to receivers, the effects of background noise on communication and how unintended receivers may represent costs in this system. Finally, a short overview of the structure and evolution of the tremendous diversity of sensory receptors is presented.

Coherence decay and its impact on sound radiation by wavepackets

2014 ◽  
Vol 748 ◽  
pp. 399-415 ◽  
Author(s):  
André V. G. Cavalieri ◽  
Anurag Agarwal
Keyword(s):  
Coherence Function ◽  
Sound Radiation ◽  
Turbulent Jets ◽  
Sufficient Condition ◽  
Far Field ◽  
Mean Flow ◽  
Spectral Densities ◽  
Flow Fluctuations ◽  
Order Of Magnitude ◽  
Field Sound

AbstractWavepackets obtained by a linear stability analysis of the turbulent mean flow were shown in recent works to agree closely with some relevant statistics of turbulent jets, such as power spectral densities and averaged phases of flow fluctuations. However, when such wavepacket models were used to calculate the far-field sound, satisfactory agreement was only obtained for flows that were supersonic relative to the ambient speed of sound; attempts with subsonic flows led to errors of more than an order of magnitude. We investigate here the reasons for such discrepancies by developing the integral solution of the Helmholtz equation in terms of the cross-spectral densities of turbulent quantities. It is shown that agreement of a statistical source, such as would be obtained by the above-mentioned wavepacket models, in averaged amplitudes and phases in the near field is not a sufficient condition for exact agreement of the far-field sound. The sufficient condition is that, in addition to the amplitudes and phases, the statistical source should also match the coherence function of the flow fluctuations. This is exemplified in a model problem, where we show that the effect of coherence decay on sound radiation is more prominent for subsonic convection velocities, and its neglect leads to discrepancies of more than an order of magnitude in the far-field sound. For supersonic flows errors are reduced for the peak noise direction, but for other angles the coherence decay is also seen to have a significant effect. Coherence decay in the model source is seen to lead to similar decays in the coherence of two points in the far acoustic field, these decays being significantly faster for higher Mach numbers. The limitations of linear wavepacket models are illustrated with another simplified problem, showing that superposition of time-periodic solutions can lead to a correlation decay between two points. However, the coherence between any pair of points in such models remains unity, and cannot thus represent the behaviour observed in turbulent flows.

A Potential-Theoretic Method for Far-Field Sound Radiation Calculations

2000 ◽  
Vol 164 (1) ◽  
pp. 143-164 ◽  
Author(s):  
S.I. Hariharan ◽  
J.R. Scott ◽  
K.L. Kreider
Keyword(s):  
Sound Radiation ◽  
Far Field ◽  
Theoretic Method ◽  
Field Sound

scholarly journals Near-field Wavepackets and the Far-field Sound of a Subsonic Jet

2013 ◽  
Author(s):  
David E. Breakey ◽  
Peter Jordan ◽  
Andre Cavalieri ◽  
Olivier Léon
Keyword(s):  
Near Field ◽  
Far Field ◽  
Field Sound ◽  
Subsonic Jet
Sign in / Sign up

Export Citation Format

Share Document