Three-dimensional underwater sound pressure sensitivity in oceanic environments

2019 ◽  
Vol 145 (3) ◽  
pp. 1887-1887
Author(s):  
Ying-Tsong Lin
Keyword(s):  
Sound Pressure ◽  
Three Dimensional ◽  
Pressure Sensitivity ◽  
Underwater Sound ◽  
Oceanic Environments

scholarly journals Measurement of Underwater Acoustic Energy Radiated by Single Raindrops

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2687
Author(s):  
Shu Liu ◽  
Qi Li ◽  
Dajing Shang ◽  
Rui Tang ◽  
Qingming Zhang
Keyword(s):  
Ambient Noise ◽  
Sound Pressure ◽  
Tap Water ◽  
Acoustic Energy ◽  
Underwater Sound ◽  
Underwater Noise ◽  
Energy Characteristics ◽  
Sound Energy ◽  
Dipole Radiation ◽  
Series Of Experiments

Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise. Therefore, it is necessary to study the associated underwater noise when drops strike the water surface. Previous research focused primarily on the sound pressure and frequency spectrum of underwater noise from single raindrops, but the study on its sound energy is insufficient. The purpose of this paper is to propose a method for predicting the acoustic energy generated by raindrops of any diameter. Here, a formula was derived to calculate the underwater sound energy radiated by single raindrops based on a dipole radiation pattern. A series of experiments were conducted to measure the underwater sound energy in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The analysis of the acoustic energy characteristics and conversion efficiency from kinetic to acoustic energy helped develop the model to predict the average underwater sound energy radiated by single raindrops. Using this model, the total underwater sound energy of all raindrops during a rainfall event can be predicted based on the drop size distribution.

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.

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.

scholarly journals A laboratory study for occupational safety and health on the structure of airborne ultrasound fields

Acta Acustica ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 12
Author(s):  
Robert Schöneweiß ◽  
Christoph Kling ◽  
Christian Koch
Keyword(s):  
Laboratory Study ◽  
Occupational Safety ◽  
Sound Pressure ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Measurement Procedure ◽  
Measuring System ◽  
Public And Private ◽  
Sound Pressure Levels ◽  
Airborne Ultrasound

While exposure to airborne ultrasound is increasing in occupational contexts and in public and private spaces, existing demand for reliable and traceable determination of exposure to sound with frequencies above 16 kHz cannot currently be satisfied due to a lack of adequate measurement devices and procedures adapted to the specifics of airborne ultrasound. So that this study may serve as a first step for the development of a novel measurement procedure, its aim is to create a comprehensive database of the structures of airborne ultrasound fields present in occupational contexts. Based on this, the limitations of measurement procedures commonly used in the audible frequency range are clarified and the structural characteristics of airborne ultrasound fields investigated. This paper presents a laboratory study of the structure of the airborne ultrasound field of an ultrasonic welding machine, which can be considered a representative occupational source of airborne ultrasound. For this study, the technical and procedural requirements of a measuring system are derived and used to set up and calibrate a measuring system for three-dimensional, high spatial resolution scans of sound pressure levels in the laboratory. The measurement results reveal complex, extensive and very fine-structured interference patterns, some of which have sound pressure levels of up to 138 dB (re 20 μPa).

Underwater sound pressure and particle motion (acceleration, velocity, and displacement) from recreational swimmers, divers, surfers, and kayakers

2018 ◽  
Vol 143 (3) ◽  
pp. 1712-1712
Author(s):  
Christine Erbe ◽  
Miles Parsons ◽  
Alec J. Duncan ◽  
Klaus Lucke ◽  
Alexander Gavrilov ◽  
...  
Keyword(s):  
Particle Motion ◽  
Sound Pressure ◽  
Underwater Sound
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