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.

Application of Hartmann Acoustic Generator in Source of Underwater Pyrotechnic Combustion

2013 ◽  
Vol 787 ◽  
pp. 638-643
Author(s):  
Jie Li ◽  
Hua Guan ◽  
Dong Ming Song ◽  
Qi Wang ◽  
Jun Du ◽  
...  
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Structural Parameters ◽  
Resonant Cavity ◽  
Experimental Studies ◽  
Combustion Products ◽  
Pressure Level ◽  
Radiation Characteristics ◽  
Acoustic Frequency

In order to investigate acoustic radiation characteristics of underwater pyrotechnic combustion, Hartmann acoustic generator was applied and its main structural parameters effecting acoustic radiation characteristics were studied by using underwater acoustic measurement system. Experimental studies have shown that, when Hartmann acoustic generator was applied, the sound pressure level of underwater pyrotechnic combustion increased significantly because of the strengthening of turbulence degree. The distance between the nozzle and the resonant cavity is an important factor of affecting acoustic radiation characteristics of Hartmann acoustic generator. When the resonant cavity was placed in the unstable pressure area, it could stimulate strong sound waves. On account of the resistance of the water, the combustion products speed of reaching resonant cavity drooped and the collision strength between the feedback combustion products and the newly generated products reduced. So when the distance was larger, the SPL(sound pressure level) was smaller. The SPL of underwater pyrotechnic combustion increased and the acoustic frequency moved to the low frequency with the depth of resonant cavity increased, which is consistent with the acoustic characteristics of Hartmann acoustic generator applied in air.

scholarly journals Influence of the Power Generation Capacity of the Structural Parameters of a Piezoelectric Bimorph

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaochao Tian ◽  
Jinzhi Zhu ◽  
Zhicong Wang ◽  
Hu Wang ◽  
Yuze Sun ◽  
...  
Keyword(s):  
Power Generation ◽  
Integrated Circuits ◽  
Energy Supply ◽  
Output Voltage ◽  
Structural Parameters ◽  
Electronic Devices ◽  
Generation Effect ◽  
Modulus Ratio ◽  
Piezoelectric Vibrator ◽  
Generation Capacity

With the popularization of integrated circuits, MEMS, and portable electronic devices, chemical batteries have many disadvantages as the main energy supply method, such as large size, high quality, and limited energy supply life, requiring regular replacement, resulting in waste of materials, environmental pollution, and other issues. From the above reasons, energy harvesting technology plays an important role in improving the efficiency and life of electronic equipment. In order to explore the influence of the bimorph piezoelectric vibrator’s structural parameters on the power generation capacity, this paper establishes a cantilever beam rectangular bimorph piezoelectric vibrator power generation model, derives the mathematical expression of the bimorph piezoelectric vibrator power generation, and determines the parameter factors that affect the power generation effect. Using MATLAB simulation analysis to obtain the influence relationship curve of system output voltage and structural parameters, the experiment tests the influence law of output voltage and thickness ratio, width-to-length ratio, and Young’s modulus ratio; the test results are consistent with the theoretical analysis, verifying the theory and the correctness of the analysis. The results show that when the thickness ratio is 0.58 and the width-to-length ratio is 1, the power generation effect of the piezoelectric vibrator is the best to reach 14.5V; the power generation capacity of the transducer is inversely proportional to Young’s modulus ratio. This research provides a new idea for the popularization of integrated circuits, MEMS, and portable electronic devices.

Vacuum Forming Refrigerator Inner Liner Structural Optimization

2011 ◽  
Vol 291-294 ◽  
pp. 1069-1073
Author(s):  
Wen Bin Su ◽  
Xiang Bing Sun ◽  
Tao Li ◽  
Bao Jian Liu
Keyword(s):  
Numerical Simulation ◽  
Structural Optimization ◽  
Structural Parameters ◽  
Forming Process ◽  
Significance Level ◽  
Orthogonal Experiments ◽  
Combination Scheme ◽  
Vacuum Forming ◽  
Validation Experiment

Thickness thinning is the principal quality problem in the vacuum forming process of the refrigerator inner liner. In this paper, the structural parameters of refrigerator inner liner were analyzed based on orthogonal experiments and numerical simulation. Optimized structural parameters combination scheme and the significance level of structural parameters to thickness were obtained by analyzing the results of orthogonal experiments. Validation experiment results shown that the quality of refrigerator inner liner based on the optimized structural parameters combination scheme improved effectively.

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 Influence of Convex and Concave Curvatures in a Coastal Dike Line on Wave Run-up

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1333 ◽  
Author(s):  
Suba Periyal Subramaniam ◽  
Babette Scheres ◽  
Malte Schilling ◽  
Sven Liebisch ◽  
Nils B. Kerpen ◽  
...  
Keyword(s):  
Influence Factor ◽  
Structural Parameters ◽  
Opening Angle ◽  
Physical Model Test ◽  
Model Studies ◽  
Planning And Design ◽  
Precise Analysis ◽  
Run Up ◽  
Mesh Less

Due to climatic change and the increased usage of coastal areas, there is an increasing risk of dike failures along the coasts worldwide. Wave run-up plays a key role in the planning and design of a coastal structure. Coastal engineers use empirical equations for the determination of wave run-up. These formulae generally include the influence of various hydraulic, geometrical and structural parameters, but neglect the effect of the curvature of coastal dikes on wave run-up and overtopping. The scope of this research is to find the effects of the dike curvature on wave run-up for regular wave attack by employing numerical model studies for various dike-opening angles and comparing it with physical model test results. A numerical simulation is carried out using DualSPHysics, a mesh-less model and OpenFOAM, a mesh-based model. A new influence factor is introduced to determine the influence of curvature along a dike line. For convexly curved dikes (αd = 210° to 270°) under perpendicular wave attack, a higher wave run-up was observed for larger opening angles at the center of curvature whereas for concavely curved dikes (αd = 90° to 150°) under perpendicular wave attack, wave run-up increases at the center of curvature as the opening angle decreases. This research aims to contribute a more precise analysis and understanding the influence of the curvature in a dike line and thus ensuring a higher level of protection in the future development of coastal structures.

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 Field Investigation of Blasting-Induced Vibration in Concrete Linings during Expansion of Old Highway Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ya-Qiong Wang ◽  
Lin-Jin Gong ◽  
Nan-Nan An ◽  
Xing-Bin Peng ◽  
Wei Wang ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Particle Velocity ◽  
Vibration Frequency ◽  
Empirical Formula ◽  
Field Investigation ◽  
Primary Method ◽  
Design Standards ◽  
Highway Tunnel ◽  
The Relationship ◽  
Blasting Method

Numerous mountain highway tunnels in China do not satisfy the current traffic design standards and therefore need to be rebuilt or expanded. The drilling-blasting method is the primary method employed in China for expanding mountain highway tunnels, and it is crucial to monitor the vibrations caused by blasting. This study conducted a field investigation of the vibrations caused by blasting during the expansion of Yujiaya tunnel, which was built in 1999. The blasting-induced vibrations in the new and old concrete linings were monitored and analyzed during the expansion. The measured values of the peak particle velocity (PPV) varied within the range of 0.097–8.246 cm/s. The attenuation law of the PPV was determined via a regression analysis using Sadovsky’s empirical formula. The relationship between the main vibration frequency and the distance from the blasting source was expressed as a power function. Finally, the safety distances of the concrete linings subject to blasting vibrations were analyzed and discussed.

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
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