Transmission loss estimation of three-dimensional silencers by system graph approach using multi-domain BEM

2009 ◽  
Vol 328 (4-5) ◽  
pp. 575-585 ◽  
Author(s):  
Young-Bum Park ◽  
Hyeon-Don Ju ◽  
Shi-Bok Lee
Keyword(s):  
Transmission Loss ◽  
Three Dimensional ◽  
Loss Estimation ◽  
System Graph

Transmission loss estimation for ephemeral sand rivers in Southern Africa

2021 ◽  
pp. 126487
Author(s):  
Simon A. Mathias ◽  
Sim M. Reaney ◽  
Piet K. Kenabatho
Keyword(s):  
Southern Africa ◽  
Transmission Loss ◽  
Loss Estimation

Seismic Collapse Probability Considering Pounding and Financial Loss Estimation of Base-Isolated Reinforced Concrete Buildings

2018 ◽  
Vol 12 (03) ◽  
pp. 1850008 ◽  
Author(s):  
Satish Bhagat ◽  
Anil C. Wijeyewickrema
Keyword(s):  
Reinforced Concrete ◽  
Three Dimensional ◽  
Loss Estimation ◽  
Financial Loss ◽  
Reinforced Concrete Buildings ◽  
Nonstructural Components ◽  
Concrete Buildings ◽  
Collapse Probability ◽  
Seismic Collapse ◽  
Financial Losses

In this paper, the seismic collapse probability of base-isolated reinforced concrete buildings considering pounding with a moat wall and financial loss estimation is studied. For this purpose, three-dimensional finite element models of a code-compliant 10-story base-isolated shear wall-frame (BI-SWF) building and a 10-story base-isolated moment resisting frame (BI-MRF) building are used. Results indicate that the BI-MRF building has a greater probability of collapse compared to that of the BI-SWF building, the probability of collapse in 50 years for the BI-MRF building is 1.3 times greater than that of the BI-SWF building for both no pounding and pounding cases. The probability of collapse increases when pounding is considered, which results in a smaller value of the collapse margin ratio compared to no pounding case for both the buildings. The financial losses resulting from damage to the BI-MRF and BI-SWF buildings under design earthquake (DE) and risk-targeted maximum considered earthquake (MCER) levels are calculated for the no pounding case, since there was no pounding under DE-level and very few instances of pounding under MCER-level. Calculation of financial losses due to damage to structural and nonstructural components, service equipment and downtime shows that the BI-SWF building results in larger repair costs and downtime cost compared to the BI-MRF building.

A CFD APPROACH TO THE COMPUTATION OF THE ACOUSTIC RESPONSE OF EXHAUST MUFFLERS

2005 ◽  
Vol 13 (02) ◽  
pp. 301-316 ◽  
Author(s):  
A. BROATCH ◽  
X. MARGOT ◽  
A. GIL ◽  
F. D. DENIA
Keyword(s):  
Numerical Solution ◽  
Time Domain ◽  
Cfd Simulation ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Alternative Procedure ◽  
Acoustic Response ◽  
Frequency Domains ◽  
The Time Domain ◽  
Numerical Approaches

The study of the three-dimensional acoustic field inside an exhaust muffler is usually performed through the numerical solution of the linearized equations. In this paper, an alternative procedure is proposed, in which the full equations are solved in the time domain. The procedure is based on the CFD simulation of an impulsive test, so that the transmission loss may be computed and compared with measurements and other numerical approaches. Also, the details of the flow inside the muffler may be studied, both in the time and the frequency domains. The results obtained compare favorably with a conventional FEM calculation, mostly in the ability of the procedure to account for dissipative processes inside the muffler.

scholarly journals Research of Acoustically Improved Helmholtz Resonator

2021 ◽  
Vol 7 (1) ◽  
pp. 270-278
Author(s):  
J. Li ◽  
J. Shan ◽  
Z. Guo ◽  
A. Levtsev
Keyword(s):  
Transmission Loss ◽  
Three Dimensional ◽  
Helmholtz Resonator ◽  
Acoustic Characteristics ◽  
Helmholtz Resonators ◽  
Extension Tube ◽  
Section Shape ◽  
In Series ◽  
Combined Structure ◽  
The One

The three-dimensional acoustic finite element method is used to predict the transmission loss of the Helmholtz resonance muffler. The results are in good agreement with the experimental results, indicating the applicability and accuracy of the numerical method used in this paper. On the one hand, in order to reduce the resonance frequency without changing the shape of the resonator, the connecting tube is extended to the inside of the resonator, and the influence of the extension length and the cross section shape of the extension tube on the acoustic characteristics of the resonator is discussed in detail. On the other hand, in order to broaden the muffled frequency band of the traditional Helmholtz resonators, the resonators are combined in series and parallel, and the influence of the combined structure on the acoustic characteristics is discussed in detail.

Analysis of Acoustic Performance of Compound Muffler by Finite Element Method

2012 ◽  
Vol 529 ◽  
pp. 257-263
Author(s):  
Deng Hui Cai ◽  
Xin Tan Ma
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Transmission Loss ◽  
Complex Structure ◽  
Three Dimensional ◽  
Sound Field ◽  
Acoustic Vibration ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Element Method

Since the theory of one-dimensional plane wave can not accurately predict the internal sound field of the complex structure muffler. The three-dimensional finite element method is adopted to establish the acoustic model of the composite muffler based on the application of composite muffler model. Transmission loss and characteristics of internal sound field of the composite muffler's are calculated through acoustic vibration software Sysnoise. The calculation shows that the muffler under the interference of fluid flow has the higher transmission loss compared with the absence of liquidity function with an additional silencer band. The analysis method and conclusions provide a basis for the design of composite muffler.

ACOUSTIC ATTENUATION CHARACTERISTICS OF STRAIGHT-THROUGH PERFORATED TUBE SILENCERS AND RESONATORS

2008 ◽  
Vol 16 (03) ◽  
pp. 361-379 ◽  
Author(s):  
Z. L. JI
Keyword(s):  
Performance Prediction ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Geometrical Parameters ◽  
Mean Flow ◽  
Acoustic Attenuation ◽  
One Dimensional ◽  
The One ◽  
Attenuation Characteristics ◽  
Perforated Tube

The one-dimensional analytical solutions are derived and three-dimensional substructure boundary element approaches are developed to predict and analyze the acoustic attenuation characteristics of straight-through perforated tube silencers and folded resonators without mean flow, as well as to examine the effect of nonplanar waves in the silencers and resonators on the acoustic attenuation performance. Comparisons of transmission loss predictions with the experimental results for prototype straight-through perforated tube silencers demonstrated that the three-dimensional approach is needed for accurate acoustic attenuation performance prediction at higher frequencies, while the simple one-dimensional theory is sufficient at lower frequencies. The BEM is then used to investigate the effects of geometrical parameters on the acoustic attenuation characteristics of straight-through perforated tube silencers and folded resonators in detail.

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