Study on sound pressure level and acoustic damping ratio of one dimensional sound field partitioned by perforated plate with geometric similarity

AbstractRecently strong sound wave was proposed to enhance precipitation. The theoretical basis of this proposal has not been effectively studied either experimentally or theoretically. Based on the microscopic parameters of atmospheric cloud physics, this paper solved the complex nonlinear differential equation to show the movement characteristics of cloud droplets under the action of sound waves. The motion process of individual cloud droplet in a cloud layer in the acoustic field is discussed as well as the relative motion between two cloud droplets. The effects of different particle sizes and sound field characteristics on particle motion and collision are studied to analyze the dynamic effects of thunder-level sound waves on cloud droplets. The amplitude of velocity variation has positive correlation with Sound Pressure Level (SPL) and negative correlation with the frequency of the surrounding sound field. Under the action of low-frequency sound waves with sufficient intensity, individual cloud droplets could be forced to oscillate significantly. The droplet smaller than 40μm can be easily driven by sound waves of 50 Hz and 123.4 dB. The calculation of the collision process of two droplets reveals that the disorder of motion for polydisperse droplets is intensified, resulting in the broadening of the collision time range and spatial range. When the acoustic frequency is less than 100Hz (@ 123.4dB) or the Sound Pressure Level (SPL) is greater than 117.4dB (@ 50Hz), the sound wave can affect the collision of cloud droplets significantly. This study provides theoretical perspective of acoustic effect to the microphysics of atmospheric clouds.

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The effect of receiving room sound field on the impact ball sound pressure level

The Journal of the Acoustical Society of America ◽

10.1121/1.4708426 ◽

2012 ◽

Vol 131 (4) ◽

pp. 3321-3321

Author(s):

Jeong Jeong Ho

Keyword(s):

Sound Pressure Level ◽

Sound Pressure ◽

Sound Field ◽

Pressure Level ◽

The Impact

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

Modern Physics Letters B ◽

10.1142/s0217984920501456 ◽

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.

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Evaluation and Improvement of the Sound Quality of a Diesel Engine Based on Tests and Simulations

Energies ◽

10.3390/en13040777 ◽

2020 ◽

Vol 13 (4) ◽

pp. 777 ◽

Cited By ~ 1

Author(s):

Zhengwei Yang ◽

Huihua Feng ◽

Bingjie Ma ◽

Ammar Abdualrahim Alnor Khalifa

Keyword(s):

Diesel Engine ◽

Sound Pressure Level ◽

Sound Pressure ◽

Subjective Evaluation ◽

Sound Field ◽

Sound Quality ◽

Pressure Level ◽

Sound Power ◽

Improvement Strategy ◽

Radiated Sound

Traditional acoustic evaluation of a diesel engine generally uses the A-weighted sound pressure level (AWSPL) and radiated sound power to assess the noise of an engine prototype present in an experiment. However, this cannot accurately and comprehensively reflect the auditory senses of human subjects during the simulation stage. To overcome such shortage, the Moore–Glasberg loudness and sharpness approach is applied to evaluate and improve the sound quality (SQ) of a 16 V-type marine diesel engine, and synthesizing noise audio files. Through finite element (FE) simulations, the modes of the engine’s block and the average vibrational velocity of the entire engine surface were calculated and compared with the test results. By further applying an automatically matched layer (AML) approach, the engine-radiated sound pressure level (SPL) and sound power contributions of all engine parts were obtained. By analyzing the Moore–Glasberg loudness and sharpness characteristics of three critical sound field points, an improvement strategy of the oil sump was then proposed. After improvement, both the loudness and sharpness decreased significantly. To verify the objective SQ evaluation results, ten noise audio clips of the diesel engine were then synthesized and tested. The subjective evaluation results were in accordance with the simulated analysis. Therefore, the proposed approach to analyze and improve the SQ of a diesel engine is reliable and effective.

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