Aperture extension for near-field acoustical holography of jet noise

2013 ◽  
Author(s):  
Alan T. Wall ◽  
Kent L. Gee ◽  
David W. Krueger ◽  
Tracianne B. Neilsen ◽  
Scott D. Sommerfeldt ◽  
...  
Keyword(s):  
Near Field ◽  
Jet Noise ◽  
Acoustical Holography

Military jet noise source imaging using multisource statistically optimized near-field acoustical holography

2016 ◽  
Vol 139 (4) ◽  
pp. 1938-1950 ◽  
Author(s):  
Alan T. Wall ◽  
Kent L. Gee ◽  
Tracianne B. Neilsen ◽  
Richard L. McKinley ◽  
Michael M. James
Keyword(s):  
Noise Source ◽  
Near Field ◽  
Jet Noise ◽  
Source Imaging ◽  
Acoustical Holography

Modified statistically optimized near-field acoustical holography for jet noise characterization

2013 ◽  
Vol 133 (5) ◽  
pp. 3296-3296
Author(s):  
Alan T. Wall ◽  
Kent L. Gee ◽  
Tracianne B. Neilsen
Keyword(s):  
Near Field ◽  
Jet Noise ◽  
Noise Characterization ◽  
Acoustical Holography

Aperture extension for near-field acoustical holography applied to jet noise

2011 ◽  
Vol 130 (4) ◽  
pp. 2344-2344
Author(s):  
Alan T. Wall ◽  
Kent L. Gee ◽  
David W. Krueger ◽  
Tracianne B. Neilsen ◽  
Michael M. James
Keyword(s):  
Near Field ◽  
Jet Noise ◽  
Acoustical Holography

Full-spectrum near-field acoustical holography for fighter jet noise imaging

2018 ◽  
Vol 144 (3) ◽  
pp. 1671-1671
Author(s):  
Alan T. Wall ◽  
Kent L. Gee ◽  
Kevin M. Leete ◽  
Mylan R. Cook ◽  
Michael M. James
Keyword(s):  
Near Field ◽  
Jet Noise ◽  
Full Spectrum ◽  
Acoustical Holography

A proposed wavy shield for suppression of supersonic jet noise utilizing reflections

2021 ◽  
Vol 20 (1-2) ◽  
pp. 4-34
Author(s):  
Reda R Mankbadi ◽  
Saman Salehian
Keyword(s):  
Large Scale ◽  
Flat Surface ◽  
Near Field ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Dominant Frequency ◽  
Wavy Surface ◽  
Initial Region ◽  
Reflected Waves ◽  
Free Jet

In this work we propose replacing the conventional flat-surface airframe that shields the engine by a wavy surface. The basic principle is to design a wavy pattern to reflect the incoming near-field flow and acoustic perturbations into waves of a particular dominant frequency. The reflected waves will then excite the corresponding frequency of the large-scale structure in the initial region of the jet’s shear layer. By designing the frequency of the reflected waves to be the harmonic of the fundamental frequency that corresponds to the radiated peak noise, the two frequency-modes interact nonlinearly. With the appropriate phase difference, the harmonic dampens the fundamental as it extracts energy from it to amplify. The outcome is a reduction in the peak noise. To evaluate this concept, we conducted Detached Eddy Simulations for a rectangular supersonic jet with and without the wavy shield and verified our numerical results with experimental data for a free jet, as well as, for a jet with an adjacent flat surface. Results show that the proposed wavy surface reduces the jet noise as compared to that of the corresponding flat surface by as much as 4 dB.

USE OF RIGID REFLECTORS FOR THE VIRTUAL INCREASE OF FIELD DATA IN THE NEAR-FIELD ACOUSTICAL HOLOGRAPHY

2007 ◽  
Vol 15 (01) ◽  
pp. 49-61 ◽  
Author(s):  
SUNG-IL KIM ◽  
JEONG-GUON IH ◽  
JI-HOON JEONG
Keyword(s):  
Boundary Element Method ◽  
Transfer Matrix ◽  
Field Data ◽  
Near Field ◽  
Measurement Data ◽  
Source Reconstruction ◽  
Matrix Equations ◽  
Inverse Boundary ◽  
Additional Information ◽  
Acoustical Holography

This paper suggests the use of rigid reflectors to provide additional information for source reconstruction in near-field acoustical holography based on the inverse boundary element method. The additional field pressure and transfer matrix equations introduced provide a virtual increase in the measurement data without increasing the number of sensors or altering their arrangement, which could cost more than using reflectors. In order to validate this method, we successfully reconstruct a vibrating ellipse.

Application of cylindrical near-field acoustical holography to the visualization of aeroacoustic sources

2003 ◽  
Vol 114 (2) ◽  
pp. 842-858 ◽  
Author(s):  
Moohyung Lee ◽  
J. Stuart Bolton ◽  
Luc Mongeau
Keyword(s):  
Near Field ◽  
Acoustical Holography

Near‐field acoustical holography in cylindrical spaces

1993 ◽  
Vol 94 (6) ◽  
pp. 3519-3519
Author(s):  
Charles J. Konzelman
Keyword(s):  
Near Field ◽  
Acoustical Holography
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