An analysis of the three‐dimensional sound field in a penetrable wedge with a stratified fluid or elastic basement

1993 ◽  
Vol 93 (3) ◽  
pp. 1319-1328 ◽  
Author(s):  
G. B. Deane ◽  
M. J. Buckingham
Keyword(s):  
Three Dimensional ◽  
Sound Field ◽  
Stratified Fluid ◽  
Elastic Basement

Numerical Simulation of Three-Dimensional Trailing Vortex Evolution in Stratified Fluid

AIAA Journal ◽  
10.2514/2.468 ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 981-985 ◽  
Author(s):  
Robert E. Robins ◽  
Donald P. Delisi
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Stratified Fluid

scholarly journals Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3674 ◽  
Author(s):  
Wei Lu ◽  
Yu Lan ◽  
Rongzhen Guo ◽  
Qicheng Zhang ◽  
Shichang Li ◽  
...  
Keyword(s):  
Sound Wave ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Sound Field ◽  
Field Measurements ◽  
Sound Waves ◽  
Underwater Sound ◽  
Three Dimensional Finite Element ◽  
Wave Transducer

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

scholarly journals EFFICIENT ACOUSTIC COMPOSITE PANELS BASED ON GRAPHITE

2021 ◽  
Vol 6 (4) ◽  
pp. 82-90
Author(s):  
E. Fanina
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Sound Field ◽  
Fire Retardant ◽  
Pyramidal Cells ◽  
Sound Insulation ◽  
Composite Panels ◽  
Thin Membrane ◽  
Reverberation Time ◽  
Acoustic Characteristics

A set of experimental studies is carried out to determine the acoustic characteristics of three-dimensional panels of fixed thickness made of carbon-based composite material installed in the opening between the reverberation chambers. Sound insulation indices are determined when they are excited by a diffuse sound field in wide frequency ranges. The reverberation time in model chambers with different partition configurations is calculated. The optimal configuration of the partition with pyramidal cells to reduce the reverberation time in the rooms is determined. The use of graphite in the form of thin membrane applied to various surfaces can significantly reduce the sound pressure levels in the room and increase the sound insulation indices of air noise. In addition to thin membrane, graphite can be used as an additive in composite materials for sound insulation purposes. It is shown that the characteristics of such panels are quite universal. The measured acoustic characteristics of composite panels are compared with similar characteristics of traditional materials. It is determined that the composition belongs to the I group of fire-retardant efficiency and can be recommended for use as a fire-retardant material. The developed acoustic material is an effective absorbing agent that solves problems in architectural acoustics, echo cancellation in construction and architecture. Similar to metamaterials, natural and artificial graphites allow to solve these problems with small volumes and masses using simple and inexpensive technologies.

Three-dimensional sound-field visualization system using head mounted display and stereo camera

2016 ◽  
Vol 140 (4) ◽  
pp. 3195-3196
Author(s):  
Atsuto Inoue ◽  
Yusuke Ikeda ◽  
Kohei Yatabe ◽  
Yasuhiro Oikawa
Keyword(s):  
Three Dimensional ◽  
Sound Field ◽  
Visualization System ◽  
Stereo Camera ◽  
Head Mounted Display

Investigation of turbulence-induced quadrupole source acoustic characteristics of a three-dimensional hydrofoil

2020 ◽  
Vol 34 (14) ◽  
pp. 2050145
Author(s):  
Rennian Li ◽  
Wenna Liang ◽  
Wei Han ◽  
Hui Quan ◽  
Rong Guo ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Three Dimensional ◽  
Sound Field ◽  
Leading Edge ◽  
Pressure Level ◽  
Acoustic Characteristics ◽  
Eddy Simulation ◽  
Unsteady Fluid

In order to investigate the turbulence-induced acoustic characteristics of hydrofoils, the flow and sound field for a model NH-15-18-1 asymmetric hydrofoil were calculated based on the mixed method of large eddy simulation (LES) with Lighthill analogy theory. Unsteady fluid turbulent stress source around the hydrofoil were selected as the inducements of quadrupole sound. The average velocity along the mainstream direction was calculated for different Reynolds numbers [Formula: see text]. Compared to experimental measurements, good agreement was seen over a range of [Formula: see text]. The results showed that the larger the [Formula: see text], the larger the vortex intensity, the shorter the vortex initial shedding position to the leading edge of the hydrofoil, and the higher the vortex shedding frequency [Formula: see text]. The maximum sound pressure level (SPL) of the hydrofoil was located at the trailing edge and wake of the hydrofoil, which coincided with the velocity curl [Formula: see text] distribution of the flow field. The maximum SPL of the sound field was consistent with the location of the vortex shedding. There were quadratic positive correlations between the total sound pressure level (TSPL) and the maximum value of the vortex intensity [Formula: see text] and velocity curl, which verified that shedding and diffusion of vortices are the fundamental cause of the generation of the quadrupole source noise.

Analysis and Control of Internal Flow Induced Noise of Rotor Oil Pump

2014 ◽  
Vol 529 ◽  
pp. 585-588
Author(s):  
Hao Cai ◽  
Jian Li ◽  
Li Ping Yu ◽  
Ya Fei Liu ◽  
Yu He Geng
Keyword(s):  
Sound Pressure ◽  
Field Model ◽  
Three Dimensional ◽  
Sound Field ◽  
Internal Flow ◽  
Flow Noise ◽  
Oil Pump ◽  
Infinite Element Method ◽  
Flow Induced Noise ◽  
And Control

The fluid noise of rotor oil pump is studied in this paper, and the turbulent and flow sound field model of rotor oil pump are built. Based on CFD software, three dimensional unsteady internal flow field numerical simulation of some type rotor oil pump is carried out. And, the velocity and pressure simulation results at different speeds are obtained. Based on acoustic finite element and infinite element method, CFD software and acoustic solver software are used to simulate the flow induced noise of rotor oil pump. And, the sound pressure level values of monitor points in the pump are obtained. This paper puts forward some methods to reduce noise, and the experiment shows these methods can reduce the flow noise effectively.

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