Coupled Helmholtz Resonators for Acoustic Attenuation

2000 ◽  
Vol 123 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Steve Griffin ◽  
Steven A. Lane ◽  
Steve Huybrechts
Keyword(s):  
Transmission Loss ◽  
Coupled Resonators ◽  
Acoustic Attenuation ◽  
Similar System ◽  
One Dimensional ◽  
Acoustic Coupling ◽  
Helmholtz Resonators ◽  
Resonator System ◽  
Simplistic Model ◽  
Coupled Resonator

Helmholtz resonators are used in a variety of applications to reduce the transmission of unwanted sound. This work demonstrates that mechanically coupled resonators can be used to design a particular transmission loss response, provide a wider bandwidth of attenuation, and adapt the transmission loss characteristics of a structure to attenuate disturbances of varying frequency. An analytical model is developed for a single, coupled resonator system mounted on a one-dimensional duct. Experiments are conducted on a similar system that uses a thin membrane to couple the resonator volumes. A simplistic model of the membrane is presented to estimate equivalent “piston” properties from measured physical properties. Experiments confirm that the coupled resonator system behaves as predicted by the model simulations, and that the transmission loss can be shaped by adjusting the mass or stiffness of the coupling member. The experimental results also illustrate the structural-acoustic coupling effects between the resonators and the membrane, and indicate that a more inclusive model of the membrane and acoustic dynamics is required in order to accurately predict the resonator transmission loss.

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.

Acoustic performance analysis of Helmholtz resonators with conical necks and its application

2019 ◽  
Vol 67 (3) ◽  
pp. 155-167 ◽  
Author(s):  
Haitao Liu
Keyword(s):  
Finite Element ◽  
Prediction Model ◽  
Transmission Loss ◽  
Low Frequency ◽  
Wide Band ◽  
Acoustic Properties ◽  
Frequency Range ◽  
Acoustic Attenuation ◽  
Acoustic Performance ◽  
Helmholtz Resonators

The acoustic properties of the Helmholtz resonators with conical necks, which have broad acoustic attenuation band performance in the low frequency range, are investigated in this study. In order to investigate its wide-band acoustic attenuation mechanism, three-dimensional finite element models for the Helmholtz resonators with different necks are built respectively. The acoustic performance prediction model based on the one-dimensional analytical approach with acoustic length corrections is built to calculate the transmission loss results more efficiently, and the formula for calculating the resonance frequency is also derived. Then, the prediction model and the formula are verified by finite element method and experiment, which show good agreements. As a result, the prediction model is applied to analyze the sound attenuation properties of the Helmholtz resonators with conical necks, and the results show that the acoustic attenuation bandwidth in the low frequency range is improved by increasing the taper angle of the neck. At last, the approaches for the Helmholtz resonators with conical necks are applied to design an actual middle silencer of a passenger car. The results show that the designed middle silencer performs much better than the original one, which can effectively eliminate the exhaust order noise to meet the standard of exhaust noise control. The test results fully reveal that the Helmholtz resonators with conical necks in the muffler can play a better role in eliminating exhaust order noise, and the approaches proposed in this article can effectively guide the design of Helmholtz resonators with conical necks.

scholarly journals Acoustic Attenuation Performance of Two-Pass Perforated Hybrid Mufflers with Mean Flow

2021 ◽  
Vol 26 (4) ◽  
pp. 306-315
Author(s):  
Yiliang Fan ◽  
Zhenlin Ji
Keyword(s):  
Analytical Approach ◽  
Transmission Loss ◽  
Glass Wool ◽  
Frequency Range ◽  
Mean Flow ◽  
Acoustic Attenuation ◽  
Fiber Glass ◽  
One Dimensional ◽  
The One ◽  
The Right

The one-dimensional (1-D) analytical approach is developed to predict and analyze the acoustic attenuation performance of two-pass perforated hybrid mufflers in the presence of mean flow. The expressions of complex acoustic wavenumber and impedance of long fiber glass wool are presented by using the impedance tube measurement and curve fitting. The 1-D approaches as well as the fitting expressions are validated by comparing the predicted and measured transmission loss of two-pass perforated hybrid mufflers with a different Mach number. Results illustrate that the 1-D predictions agree well with measurements below the plane wave cut-off frequency and deviate in higher frequency range. The influences of geometric parameters including the lengths of extended tubes, perforations on the right bulkhead and the outlet tube, and mean flow on the acoustic attenuation behavior of the hybrid mufflers are examined.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

scholarly journals Single-photon nonreciprocal transport in one-dimensional coupled-resonator waveguides

2017 ◽  
Vol 95 (6) ◽  
Author(s):  
Xun-Wei Xu ◽  
Ai-Xi Chen ◽  
Yong Li ◽  
Yu-xi Liu
Keyword(s):  
Single Photon ◽  
One Dimensional ◽  
Coupled Resonator

Numerical study for increasement of low frequency sound insulation of double-panel structure using sonic crystals with distributed Helmholtz resonators

2019 ◽  
Vol 33 (14) ◽  
pp. 1950138
Author(s):  
Myong-Jin Kim
Keyword(s):  
Free Space ◽  
Transmission Loss ◽  
Numerical Study ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Sound Insulation ◽  
The Finite Element Method ◽  
Helmholtz Resonators ◽  
Sonic Crystal ◽  
Sonic Crystals

Numerical simulations of the sound transmission loss (STL) of a double-panel structure (DPS) with sonic crystal (SC) comprised of distributed local resonators are presented. The Local Resonant Sonic Crystal (LRSC) consists of “C”-shaped Helmholtz resonator columns with different resonant frequencies. The finite element method is used to calculate the STL of such a DPS. First, the STLs of LRSC in free space and the DPS with LRSC are calculated and compared. It is shown that the sound insulations of the local resonators inserted in the double panel are higher than that in free space for the same size of the SCs and the same number of columns. Next, STL of the DPS in which the SC composed of three columns of local resonators having the same outer and inner diameters but different slot widths are calculated, and a reasonable arrangement order is determined. Finally, the soundproofing performances of DPS with distributed LRSC are compared with the case of insertion of general cylindrical SC for SC embedded in glass wool and not. The results show that the sound insulation of the DPS can be significantly improved in the low frequency range while reducing the total mass without increasing the thickness.

scholarly journals 3D Global Weak-Form Mesh-Free Method for Acoustic Attenuation Analysis of Expansion Chambers

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Chun-Hui Fang ◽  
Cheng-Yang Liu ◽  
Zhi Fang
Keyword(s):  
Transmission Loss ◽  
Interpolation Method ◽  
Weak Form ◽  
Computational Accuracy ◽  
Acoustic Attenuation ◽  
Expansion Chamber ◽  
Acoustic Characteristics ◽  
Acoustic Modes ◽  
Mesh Free ◽  
Mesh Free Method

In order to avoid the dependence of mesh method on grids, a 3D global weak-form mesh-free method (MFM) is applied to study the three-dimensional acoustic characteristics of silencers. For the expansion chamber silencers, the 3D acoustic modes are extracted and the transmission loss results are computed by using the 3D global weak-form (MFM), which is based on the radial basis function point interpolation method (RPIM) for calculating the shape functions and Galerkin method for discretizing the system equation. The first 15 order 3D acoustic modes and TL results of a special expansion chamber silencer are presented to validate the computational accuracy of the proposed technique, and the relative errors are controlled within 0.5% by comparing with the 3D finite element method (FEF) calculations. Additionally, the effects of axial modes on the acoustic characteristics are investigated, and the pass through frequencies can be eliminated to enhance the acoustic attenuation performance by locating the side branch outlet on the nodal lines of axial modes.

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