Measurement of Sound‐Pressure Amplitude in Transparent Solids

1961 ◽  
Vol 33 (11) ◽  
pp. 1673-1673 ◽  
Author(s):  
K. Achyuthan ◽  
M. A. Breazeale
Keyword(s):  
Sound Pressure ◽  
Pressure Amplitude

Spectrum Analysis of Infrasound Signal

2014 ◽  
Vol 644-650 ◽  
pp. 4334-4337
Author(s):  
Bin Wang
Keyword(s):  
Frequency Spectrum ◽  
Frequency Distribution ◽  
Spectrum Analysis ◽  
Sound Pressure ◽  
Power Level ◽  
Amplitude Spectrum ◽  
Frequency Component ◽  
Pressure Amplitude ◽  
Frequency Spectrum Analysis ◽  
Infrasound Signal

In this paper, frequency spectrum of infrasound signal collected was analyzed based on MATLAB. The infrasound power level of change with frequency distribution and the infrasound harmonic of each frequency component of the sound pressure amplitude can be made up judgment visually by frequency spectrum analysis and amplitude spectrum analysis, and thus we can obtain different conditions of infrasound properties scientifically and quantitatively.

scholarly journals Prediction and Reduction of Aerodynamic Noise of the Multiblade Centrifugal Fan

2014 ◽  
Vol 6 ◽  
pp. 712421 ◽  
Author(s):  
Shuiqing Zhou ◽  
Jun Wang
Keyword(s):  
Flow Field ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Hybrid Technique ◽  
Field Calculation ◽  
Pressure Amplitude ◽  
Centrifugal Fan ◽  
Hybrid Techniques

An aerodynamic and aeroacoustic investigation of the multiblade centrifugal fan is proposed in this paper, and a hybrid technique of combining flow field calculation and acoustic analysis is applied to solve the aeroacoustic problem of multiblade centrifugal fan. The unsteady flow field of the multiblade centrifugal fan is predicted by solving the incompressible Reynolds-averaged Navier-Stokes (RANS) equations with conventional computing techniques for fluid dynamics. The principal noise source induced is extracted from the calculation of the flow field by using acoustic principles, and the modeled sources on inner and outer surfaces of the volute are calculated with multiregional boundary element method (BEM). Through qualitative analysis, the sound pressure amplitude distribution of the multiblade centrifugal fan in near field is given and the sound pressure level (SPL) spectrum diagram of monitoring points in far field is obtained. Based on the analysis results, the volute tongue structure is adjusted and then a low-noise design for the centrifugal fan is proposed. The comparison of noise tests shows the noise reduction of improved fan model is more obvious, which is in good agreement with the prediction using the hybrid techniques.

scholarly journals Simulation of Infrasound Pistonphone

2020 ◽  
Vol 32 (5) ◽  
pp. 181-198
Author(s):  
Dmitrii Vital`Evich Golovin
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure ◽  
Control Point ◽  
Tuning Parameter ◽  
Polytropic Index ◽  
Heat Conducting ◽  
Closed Volume ◽  
Pressure Amplitude ◽  
The Stability ◽  
Semi Empirical

There are presented the results of numerical simulation of an applied acoustic problem – modeling of gas processes occurring in the measuring chamber of the infrasound pistonphone 3202 at different frequencies of piston oscillation (0.1 – 1000 Hz) and characterized by extremely small Mach numbers (9.1·10-7÷9.1·10-3). The simulation was performed using quasi-gas-dynamic (QGD) and quasi-hydrodynamic (QHD) equations of a viscous compressible heat-conducting gas with the use of a time-explicit difference scheme, all spatial derivatives was approximated by central differences. It is shown that QGD and QHD models can be used for a simulation of applied acoustics and, in particular, to the simulation of infrasonic pistonphone: the stability limits of the QGD and QHD algorithms in this problem were determined, the dependence of sound pressure on the tuning parameter α is investigated and it is shown that this dependence is quite small. The spectra of sound pressure at the control point calculated by QGD and QHD are given, their dependence on the tuning parameter α is shown, both models equally predict the value of the sound pressure amplitude at the fundamental frequency oscillations. At the end of the article, the sound pressure at the control point at the fundamental frequency oscillations obtained by using QGD and QHD is compared with the values calculated by using semi-empirical formula of sound pressure at closed volume for a case of small oscillations using the polytropic index obtained by Henry Gerber instead of the adiabatic coefficient.

scholarly journals SPH Simulation of Acoustic Waves: Effects of Frequency, Sound Pressure, and Particle Spacing

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Y. O. Zhang ◽  
T. Zhang ◽  
H. Ouyang ◽  
T. Y. Li
Keyword(s):  
Acoustic Waves ◽  
Sound Pressure ◽  
Sound Propagation ◽  
Limited Range ◽  
Sound Frequency ◽  
Numerical Error ◽  
Logarithmic Scale ◽  
Pressure Amplitude ◽  
Sph Method ◽  
Particle Spacing

Acoustic problems consisting of multiphase systems or with deformable boundaries are difficult to describe using mesh-based methods, while the meshfree, Lagrangian smoothed particle hydrodynamics (SPH) method can handle such complicated problems. In this paper, after solving linearized acoustic equations with the standard SPH theory, the feasibility of the SPH method in simulating sound propagation in the time domain is validated. The effects of sound frequency, maximum sound pressure amplitude, and particle spacing on numerical error and time cost are then subsequently discussed based on the sound propagation simulation. The discussion based on a limited range of frequency and sound pressure demonstrates that the rising of sound frequency increases simulation error, and the increase is nonlinear, whereas the rising sound pressure has limited effects on the error. In addition, decreasing the particle spacing reduces the numerical error, while simultaneously increasing the CPU time. The trend of both changes is close to linear on a logarithmic scale.

scholarly journals Sensitive Parameters of Dynamic Excitation on Fuze Airflow-Induced Acoustic Generator

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1033
Author(s):  
Zhipeng Li ◽  
Jinghao Li ◽  
Hejuan Chen
Keyword(s):  
Power Generation ◽  
Vibration Frequency ◽  
Empirical Formula ◽  
Sound Pressure ◽  
Influence Factor ◽  
Structural Parameters ◽  
Resonant Cavity ◽  
Pressure Amplitude ◽  
Combination Scheme ◽  
Sensitive Parameters

This paper aims at the power generation requirements of the fuze airflow-induced acoustic generator, analyzes the influence of structural parameters on the fluid power sound source, which is related to the power generation performance and use performance of the generator. In this paper, the orthogonal experiment method is used to study the sensitive parameters that control fluid dynamic sound sources. The results show that the annulus, the confronting distance, and cavity length can all have an impact on the sound pressure amplitude, and the sound pressure amplitude is most sensitive to the change of the confronting distance. However, the length of the resonant cavity has the most significant effect on the sound pressure frequency. The size of the annulus has a weak effect on the sound pressure frequency, and the confronting distance has almost no effect on the sound pressure frequency. The optimal combination scheme with the highest output power is selected according to the sensitive parameters. In addition, the empirical formula for the vibration frequency of the airflow-induced acoustic generator in the short resonant cavity was revised, and the influence of the annular gap on the vibration frequency was added, and the influence factor α = 0.3 was determined. The corrected frequency empirical formula has the smallest error between the theoretical value and the experimental value, and can be used as an effective method for estimating the vibration frequency. This provides a reference for the engineering design of the fuze airflow-induced acoustic generator, which has high military value and application prospects.

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