scholarly journals An experimental investigation of planar nearfield acoustic holography using pressure and particle velocity measurements

2010 ◽  
Vol 59 (2) ◽  
pp. 1108
Author(s):  
Bi Chuan-Xing ◽  
Zhang Yong-Bin ◽  
Xu Liang ◽  
Chen Xin-Zhao
Keyword(s):  
Experimental Investigation ◽  
Particle Velocity ◽  
Velocity Measurements ◽  
Acoustic Holography ◽  
Nearfield Acoustic Holography

scholarly journals Patch near field acoustic holography based on particle velocity measurements

2009 ◽  
Vol 126 (2) ◽  
pp. 721-727 ◽  
Author(s):  
Yong-Bin Zhang ◽  
Finn Jacobsen ◽  
Chuan-Xing Bi ◽  
Xin-Zhao Chen
Keyword(s):  
Particle Velocity ◽  
Near Field ◽  
Velocity Measurements ◽  
Acoustic Holography

Nearfield acoustic holography in a moving medium based on particle velocity input using nonsingular propagator

2021 ◽  
Author(s):  
Bi-Chun Dong ◽  
Run-Mei Zhang ◽  
Bin Yuan ◽  
Chuan-Yang Yu
Keyword(s):  
Particle Velocity ◽  
Flow Direction ◽  
Sound Field ◽  
Singular Problem ◽  
Moving Medium ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Sound Field Reconstruction ◽  
Velocity Input ◽  
Nearfield Acoustic Holography

Abstract Nearfield acoustic holography in a moving medium is a technique which is typically suitable for sound sources identification in a flow. In the process of sound field reconstruction, sound pressure is usually used as the input, but it may contain considerable background noise due to the interactions between microphones and flow moving at a high velocity. To avoid this problem, particle velocity is an alternative input, which can be obtained by using Laser Doppler Velocimetry in a non-intrusive way. However, there is a singular problem in the conventional propagator relating the particle velocity to the pressure, and it could lead to significant errors or even false results. In view of this, in this paper nonsingular propagators are deduced to realize accurate reconstruction in both cases that the hologram is parallel to and perpendicular to the flow direction. The advantages of the proposed method are analyzed, and simulations are conducted to verify the validation. The results show that the method can overcome the singular problem effectively, and the reconstruction errors are at a low level for different flow velocities, frequencies, and signal-to-noise ratios.

Equivalent Source Method-Based Nearfield Acoustic Holography in a Moving Medium

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Chuan-Xing Bi ◽  
Bi-Chun Dong ◽  
Xiao-Zheng Zhang ◽  
Yong-Bin Zhang
Keyword(s):  
Particle Velocity ◽  
Analytical Relationship ◽  
Moving Medium ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Equivalent Source ◽  
Source Method ◽  
Velocity Input ◽  
Equivalent Source Method ◽  
Nearfield Acoustic Holography

To identify sound sources situated in a fluid flow, an equivalent source method (ESM)-based nearfield acoustic holography (NAH) in a moving medium is proposed, and two types of acoustic inputs, pressure and particle velocity, are considered. In particular, an analytical relationship between the particle velocity perpendicular to the flow direction and the equivalent source strength is deduced, which makes it possible to realize the reconstruction with particle velocity input. Compared to the planar NAH in a moving medium, the proposed method is applicable to sound sources with more complicated geometries. Numerical simulations with sound sources distributed over two types of geometries including planar geometry and nonplanar one are conducted to test the performances of the proposed method. The results indicate that the proposed method provides satisfactory reconstructed results whatever with pressure input or with particle velocity input, and it is valid and robust over a wide range of flow velocities and frequencies and under different levels of background noise.

scholarly journals Experimental investigation of the initial regime in fingering electrodeposition: Dispersion relation and velocity measurements

2002 ◽  
Vol 65 (4) ◽  
Author(s):  
Matthias Schröter ◽  
Klaus Kassner ◽  
Ingo Rehberg ◽  
Josep Claret ◽  
Francesc Sagués
Keyword(s):  
Experimental Investigation ◽  
Dispersion Relation ◽  
Velocity Measurements
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