The low frequency sound from multipole sources in axisymmetric shear flows. Part 2

1976 ◽  
Vol 75 (1) ◽  
pp. 17-28 ◽  
Author(s):  
M. E. Goldstein
Keyword(s):  
Shear Flows ◽  
Acoustic Radiation ◽  
Previous Analysis ◽  
Low Frequency ◽  
Frequency Sound ◽  
Doppler Factor ◽  
Axisymmetric Shear ◽  
Multipole Sources

A previous analysis of the acoustic radiation from multipole sources is extended to include additional components of the dipole and quadrupole sources. It is found that, unlike the components of the sources considered in the previous paper, the exponent of the Doppler factor now depends on the location of the sources within the jet.

The low frequency sound from multipole sources in axisymmetric shear flows, with applications to jet noise

1975 ◽  
Vol 70 (3) ◽  
pp. 595-604 ◽  
Author(s):  
M. E. Goldstein
Keyword(s):  
Closed Form Solution ◽  
Low Frequency ◽  
Form Solution ◽  
Point Sources ◽  
Mean Flow ◽  
Doppler Factor ◽  
The Mean ◽  
Axisymmetric Shear ◽  
Arbitrary Velocity ◽  
Multipole Sources

We have obtained a closed-form solution for the sound radiation from multipole sources imbedded in an infinite cylindrical jet with an arbitrary velocity profile. It is valid in the limit where the wavelength is large compared with the jet radius. Simple formulae for the acoustic pressure field due to convected point sources are also obtained. The results show (in a simple way) how the mean flow affects the radiation pattern from the sources. For convected lateral quadrupoles it causes the exponentnof the Doppler factor (1 -Mcosθ)−nmultiplying the far-field pressure signal to be increased from the value of 3 used by Lighthill to 5.

scholarly journals Study on broadband low-frequency sound insulation of multi-channel resonator acoustic metamaterials

AIP Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 045321
Author(s):  
Chi Xu ◽  
Hui Guo ◽  
Yinghang Chen ◽  
Xiaori Dong ◽  
Hongling Ye ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Acoustic Metamaterials ◽  
Frequency Sound

Lightweight Low‐Frequency Sound‐Absorbing Composites of Graphene Network Reinforced by Honeycomb Structure

2021 ◽  
pp. 2100183
Author(s):  
Fan Xu ◽  
Siying Zhang ◽  
Guigen Wang ◽  
Daqiang Zhao ◽  
Junwei Feng ◽  
...  
Keyword(s):  
Low Frequency ◽  
Honeycomb Structure ◽  
Frequency Sound

Effects of low‐frequency sound (ATOC) on marine mammals: An experimental approach

1995 ◽  
Vol 97 (5) ◽  
pp. 3352-3352
Author(s):  
Daniel P. Costa ◽  
Dawn Goley ◽  
Danielle Waples ◽  
Don Croll ◽  
Burney Le Boeuf ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Experimental Approach ◽  
Low Frequency ◽  
Frequency Sound
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