Optimal Design of a Helmholtz Resonator With a Flexible End Plate

2012 ◽  
Author(s):  
Mohammad H. Kurdi ◽  
G. Scott Duncan ◽  
Shahin S. Nudehi
Keyword(s):  
Transmission Loss ◽  
Mathematical Formulation ◽  
Helmholtz Resonator ◽  
Design Parameters ◽  
Flexible Plate ◽  
Frequency Range ◽  
End Plate ◽  
Pareto Curve ◽  
Optimization Formulation ◽  
Design Solutions

A multi-objective optimization formulation to design a Helmholtz resonator with a flexible end plate is studied. The optimization formulation generates a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem is formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate is completed based on the design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume are defined as optimization objectives. Finally, the Pareto curve of optimum design solutions is calculated using a gradient-based approach via the ε-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, one optimal Helmholtz resonator is manufactured and experimentally confirmed.

Optimal Design of a Helmholtz Resonator With a Flexible End Plate

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Mohammad H. Kurdi ◽  
G. Scott Duncan ◽  
Shahin S. Nudehi
Keyword(s):  
Transmission Loss ◽  
Helmholtz Resonator ◽  
Design Parameters ◽  
Flexible Plate ◽  
Frequency Range ◽  
End Plate ◽  
Pareto Curve ◽  
Resonator Design ◽  
Optimization Formulation ◽  
Design Solutions

This paper describes a design process that produces a small volume Helmholtz resonator capable of achieving high transmission loss across a desired frequency range. A multiobjective optimization formulation was used to design a Helmholtz resonator with a flexible end plate. The optimization formulation generated a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem was formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate was completed based on the resonator design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume were defined as optimization objectives. Finally, the Pareto curve of optimum design solutions was calculated using a gradient-based approach via the ɛ-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, two optimal Helmholtz resonators were manufactured and experimentally confirmed.

scholarly journals Tailoring Plate Thickness of a Helmholtz Resonator for Improved Sound Attenuation

2016 ◽  
Author(s):  
Mohammad Kurdi ◽  
Shahin Nudehi ◽  
Gregory Scott Duncan
Keyword(s):  
Transmission Loss ◽  
Plate Thickness ◽  
Helmholtz Resonator ◽  
Element Model ◽  
Flexible Plate ◽  
End Plate ◽  
Receptance Coupling ◽  
Coupling Techniques ◽  
Gradient Based ◽  
Optimization Search

A Helmholtz resonator with flexible plate attenuates noise in exhaust ducts, and the transmission loss function quantifies the amount of filtered noise at a desired frequency. In this work the transmission loss is maximized (optimized) by allowing the resonator end plate thickness to vary for two cases: 1) a non-optimized baseline resonator, and 2) a resonator with a uniform flexible endplate that was previously optimized for transmission loss and resonator size. To accomplish this, receptance coupling techniques were used to couple a finite element model of a varying thickness resonator end plate to a mass-spring-damper model of the vibrating air mass in the resonator. Sequential quadratic programming was employed to complete a gradient based optimization search. By allowing the end plate thickness to vary, the transmission loss of the non-optimized baseline resonator was improved significantly, 28 percent. However, the transmission loss of the previously optimized resonator for transmission loss and resonator size showed minimal improvement.

Acoustic Property Prediction of an Automobile Air Filter with Acoustical BEM

2011 ◽  
Vol 295-297 ◽  
pp. 2155-2160
Author(s):  
Hai Qing Xu ◽  
Hong Zhou ◽  
Chang Jin
Keyword(s):  
Commercial Vehicle ◽  
Transmission Loss ◽  
Acoustic Property ◽  
Helmholtz Resonator ◽  
Frequency Range ◽  
Air Filter ◽  
Property Prediction ◽  
Peak Value

In this paper, we use Acoustical BEM to predict the muffling effect of an air filter improvement with Helmholtz resonator of a domestic commercial vehicle. The result shows that the method works at some frequency range, which means there is a peak value of transmission loss close to the wanted frequency. And the position of the Helmholtz resonator is optimized.

scholarly journals Numerical investigation on low-frequency noise damping performances of Helmholtz resonators with an extended neck in presence of a grazing flow

2021 ◽  
pp. 146134842110205
Author(s):  
Weiwei Wu ◽  
Yiheng Guan
Keyword(s):  
Resonant Frequency ◽  
Stokes Equations ◽  
Transmission Loss ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Frequency Noise ◽  
Frequency Range ◽  
Helmholtz Resonators ◽  
Numerical Predictions ◽  
Grazing Flow

In this work, modified designs of Helmholtz resonators with extended deflected neck are proposed, numerically evaluated and optimized aiming to achieve a better transmission loss performance over a broader frequency range. For this, 10 Helmholtz resonators with different extended neck configurations (e.g. the angle between extended neck and the y-axis) in the presence of a grazing flow are assessed. Comparison is then made between the proposed resonators and the conventional one, i.e. in the absence of an extended neck (i.e. Design A). For this, a two-dimensional linearized Navier Stokes equations-based model of a duct with the modified Helmholtz resonator implemented was developed in frequency domain. The model was first validated by comparing its numerical predictions with the experimental results available in the literature and the theoretical results. The model was then applied to evaluate the noise damping performance of the Helmholtz resonator with (1) an extended neck on the upstream side (Design B); (2) on the downstream side (Design C), (3) both upstream and downstream sides (Design D), (4) the angle between the extended neck and the y-axis, i.e. (a) 0°, (b) 30°, and (c) 45°, (d) 48.321°. In addition, the effects of the grazing flow Mach number (Ma) were evaluated. It was found that the transmission loss peaks of the Helmholtz resonator with the extended neck was maximized at Ma = 0.03 than at the other Mach numbers. Conventional resonator, i.e. Design A was observed to be associated with a lower transmission loss performance at a lower resonant frequency than those as observed on Designs B–D. Moreover, the optimum design of the proposed resonators with the extended neck is shown to be able to shift the resonant frequency by approximately 90 Hz, and maximum transmission loss could be increased by 28–30 dB. In addition, the resonators with extended necks are found to be associated with two or three transmission loss peaks, indicating that these designs have a broader effective frequency range. Finally, the neck deflection angles of 30° and 45° are shown to be involved with better transmission loss peaks than that with a deflection angle of 0°. In summary, the present study sheds light on maximizing the resonator’s noise damping performances by applying and optimizing an extended neck.

scholarly journals Tailoring Plate Thickness of a Helmholtz Resonator for Improved Sound Attenuation

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Mohammad Kurdi ◽  
Shahin Nudehi ◽  
Gregory Scott Duncan
Keyword(s):  
Transmission Loss ◽  
Plate Thickness ◽  
Helmholtz Resonator ◽  
Element Model ◽  
End Plate ◽  
Receptance Coupling ◽  
Coupling Techniques ◽  
Minimal Improvement ◽  
Gradient Based ◽  
Optimization Search

In this work, the transmission loss of a Helmholtz resonator is maximized (optimized) by allowing the resonator end plate thickness to vary for two cases: (1) a nonoptimized baseline resonator and (2) a resonator with a uniform flexible endplate that was previously optimized for transmission loss and resonator size. To accomplish this, receptance coupling techniques were used to couple a finite element model of a varying thickness resonator end plate to a mass-spring-damper model of the vibrating air mass in the resonator. Sequential quadratic programming was employed to complete a gradient-based optimization search. By allowing the end plate thickness to vary, the transmission loss of the nonoptimized baseline resonator was improved significantly, 28%. However, the transmission loss of the previously optimized resonator for transmission loss and resonator size showed minimal improvement.

Modeling and Experimental Investigation of a Helmholtz Resonator With a Flexible Plate

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Shahin S. Nudehi ◽  
G. Scott Duncan ◽  
Umar Farooq
Keyword(s):  
Experimental Investigation ◽  
Transmission Loss ◽  
Helmholtz Resonator ◽  
Single Frequency ◽  
Flexible Plate ◽  
Resonant Frequencies ◽  
Response Characteristics ◽  
Receptance Coupling ◽  
Frequency Response Characteristics ◽  
Plate Assembly

A Helmholtz resonator with a uniform, flexible end plate is studied in this work. This work shows that the flexible plate modifies the frequency response characteristics of the resonator, providing multiple distinct resonant frequencies instead of a single resonant frequency. Therefore, acoustical transmission loss will increase at each of the multiple resonant frequencies of the resonator and plate assembly versus at a single frequency for the unmodified Helmholtz resonator. By using receptance coupling as the modeling approach, the receptance of the Helmholtz resonator and flexible plate assembly is predicted by coupling receptance models of an unmodified Helmholtz resonator and a clamped plate. Finally, the predicted receptance of the Helmholtz resonator and flexible plate assembly is compared against experimental results.

Acoustic meta-silencer: Toward enabling ultrawide-band air-permeable noise barrier

2021 ◽  
pp. 107754632110011
Author(s):  
Mohammad Javad Khodaei ◽  
Amin Mehrvarz ◽  
Reza Ghaffarivardavagh ◽  
Nader Jalili
Keyword(s):  
Heat Transfer ◽  
Design Methodology ◽  
Heat Transfer Performance ◽  
Transmission Loss ◽  
Design Parameters ◽  
Transfer Performance ◽  
Noise Mitigation ◽  
Acoustic Cavity ◽  
Road Map ◽  
Noise Barrier

In this article, we have first presented a metasurface design methodology by coupling the acoustic cavity to the coiled channel. The geometrical design parameters in this structure are subsequently studied both analytically and numerically to identify a road map for silencer design. Next, upon tuning the design parameters, we have introduced an air-permeable noise barrier capable of sound silencing in the ultrawide band of the frequency. It is has been shown that the presented metasurface can achieve +10 dB sound transmission loss from 170 Hz to 1330 Hz (≈3 octaves). Furthermore, we have numerically studied the ventilation and heat transfer performance of the designed metasurface. Enabling noise mitigation by leveraging the proposed metasurface opens up new possibilities ranging from residential and office noise reduction to enabling ultralow noise fan, propellers, and machinery.

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Design and simulation of Helmholtz resonator assembly used to attenuate tire acoustic cavity resonance noise

2021 ◽  
Vol 263 (6) ◽  
pp. 942-953
Author(s):  
Wei Zhao ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Tian He
Keyword(s):  
Natural Frequencies ◽  
Helmholtz Resonator ◽  
Operating Conditions ◽  
Cavity Resonance ◽  
Frequency Range ◽  
Sound Fields ◽  
Acoustic Cavity ◽  
The Poor ◽  
Alloy Wheel ◽  
Reduction Effect

Tire acoustic cavity resonance noise (TACRN) is a typical annoying lower-frequency interior noise of a passenger car. The widely used attenuating method of attaching the porous sound absorption material in tire cavity can reduce TACRN effectively, but causes the increase of tire-wheel assembly weight and cost, also the poor durability. Additionally, the Helmholtz resonator (HR) is also used in the wheel of some cars although having only narrow effective band. The existing investigation shows that the frequency of TACRN varies with the car speed and load and also has the split characteristics. The change of TACRN frequency causes a certain difficulty to suppress TACRN effectively. Aiming at this problem, in this paper, TACRN frequency range of a specific tire cavity under different operating conditions is first calculated and analyzed. Then, for a specific aluminum alloy wheel, a HR assembly including several HRs is designed to make the natural frequencies of HR assembly cover the TACRN frequencies. Finally, the reduction effect of TACRN is simulated and evaluated by comparing the sound fields in tire cavity with/without HR assembly under same volume velocity sound source. This work is helpful for attenuating TACRN effectively under the changing operating conditions.

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