Nonlinear Behavior of Helmholtz Resonator With a Compliant Wall for Low-Frequency, Broadband Noise Control

Pishvar, Maya; Harne, Ryan L.

doi:10.1115/1.4052870

Cited by 5 publications

(4 citation statements)

References 34 publications

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“…where, A þ and A À indicate the same wave propagating in different directions, [84][85][86][87][88] and k þ and k À represents the wave numbers in terms of Mach number, given as:…”

Section: Discussionmentioning

confidence: 99%

“…Overview of the noise damping mechanism and resonant frequency of Helmholtz resonators Review of noise damping mechanism of conventional Helmholtz resonators. The acoustic damping mechanism [86][87][88] of Helmholtz resonators consists of the conversion of acoustical energy into vortical energy. They are also known as linear and nonlinear damping mechanism.…”

Section: Overview Of Helmholtz Resonators and Characterizing Resonato...mentioning

confidence: 99%

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Case studies on aeroacoustics damping performances of Coupled Helmholtz Resonators over low frequency ranges

Zhang

Win

2022

Journal of Low Frequency Noise, Vibration and Active Control

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Helmholtz resonators are widely applied in industries to reduce the transmission of unwanted noise and passively attenuate tonal noise in pipes/ducts. For example, internal combustion engines take advantage of Helmholtz resonators by combining air box, subwoofers and perforated pipes/plates to reduce engine noise emission nowadays. However, the main drawback of the conventional Helmholtz resonators includes a very narrow bandwidth. To broaden the effective noise damping frequency range of Helmholtz resonators, a number of different improved designs are reported and tested recently in the literature such as applying an array of separated resonators or implementing mechanical-coupled Helmholtz resonators. In this work, we conduct a brief review on the aeroacoustics damping performance of coupled Helmholtz resonators over low frequency range. The noise damping performances could be characterized and quantified in terms of transmission loss and sound absorption coefficient. Both definitions are discussed. Comparison is then made between the separately working resonators and the mechanical-coupled ones. This is achieved by replacing the sharable flexible sidewall with a rigid sidewall. The effect of the mean grazing flow is also discussed and examined on the noise damping performances. An experimental case study of the present authors is included. Additionally, to improve the noise damping performance further, an overview of the resonators neck with different noise damping materials inserted is conducted. Finally, 3D numerical approaches in simulating the aeroacoustics damping performances of coupled Helmholtz resonators are reviewed. This case study and brief overview provides a guidance on improving the design of coupled Helmholtz resonators and an array of Helmholtz resonators.

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“…where, A þ and A À indicate the same wave propagating in different directions, [84][85][86][87][88] and k þ and k À represents the wave numbers in terms of Mach number, given as:…”

Section: Discussionmentioning

confidence: 99%

Section: Overview Of Helmholtz Resonators and Characterizing Resonato...mentioning

confidence: 99%

Case studies on aeroacoustics damping performances of Coupled Helmholtz Resonators over low frequency ranges

Zhang

Win

2022

Journal of Low Frequency Noise, Vibration and Active Control

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“…By adding the value of Z s determined by the Delany-Bazely model to equation (9), the amount of energy absorbed by the liner at a particular frequency can easily be calculated. The next step is to calculate the incident sound energy.…”

Section: Principles Of Sound Absorptive Materialsmentioning

confidence: 99%

“…One of the familiar examples is exhaust mufflers, which are engineered to function as an effective acoustic control system by suppressing emitted engine noise [1]. In all kinds of sound and noise sources of vehicles, in addition to manipulating topology parameters [2,3], using acoustic metamaterials [4,5], porous or absorbent materials [6,7], Helmholtz resonance [8,9], and perforated structures [10,11] are commonly used nowadays. An inlet duct of the turbocharger compressor is one of the primary sources of vehicle noise propagation [12].…”

Section: Introductionmentioning

confidence: 99%

Porous liner coated inlet duct: a novel approach to attenuate automotive turbocharger inlet flow-induced sound propagation

et al. 2023

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This paper proposes utilizing a thin porous material coating liner on the inlet duct of the turbocharger compressor in order to absorb the incident excitation and hence, broadband reduction of the flow-induced sound wave propagation. To this end, first, a sound-absorbing inlet duct model is designed based on efficient structural parameters. Then, three different types of absorptive materials are used as coating liners to analyze the impact of varying material properties on the acoustic absorption performance of the system. Meanwhile, a sensitivity analysis is carried out to evaluate the influence of coating layer thickness on the system’s flow-induced sound insulation performance. The research involves applying a finite element approach to conducting acoustic pressure and poroacoustics studies over the desired frequency range of human hearing (1-20 kHz). In this regard, sound transmission loss (TL) and sound pressure level (SPL) are investigated for the models with and without liners. The results indicate that sound-absorbing materials can be employed to significantly diminish flow-induced sound levels in the turbocharger inlet duct. According to the results, absorptive liners would considerably increase the maximum TL and lessen the sharp drop in TL that appeared in the model without liners at around 4321Hz. In addition, the average TL has increased due to the replacement of valleys with peaks. The sensitivity analyses demonstrated that denser absorptive materials and larger liner thicknesses are associated with higher TL levels and better sound attenuation response. By adding 15 mm of rock wool liner to the designed inlet duct, the average TL and root mean square of TL were increased up to 98 and 32 dB, respectively. The proposed design procedure of this study unlocks a fundamental approach that can be practically applied to many promising fields, such as aerospace and automotive engineering.

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Design of Metamaterial for Broadband Sound Absorption Through Double Resonances

Ma,

Wang,

Fan

et al. 2024

Journal of Vibration and Acoustics

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Broadband acoustic absorber via a structure with sub-wavelength thickness is of great and continuing interest in research and engineering communities. To broaden the absorption band of acoustic absorbers, common methods often involve using septum to create a double-layer structure or replacing cavity walls with flexible materials. However, such approaches require strict restrictions of thickness and structure design for the absorbers. This work presents a metamaterial design method that uses an external frame to construct double resonant metamaterials, effectively improving broadband sound absorption performance. Specifically, this method can be decoupled from the design of original cavity-type absorber structure and external frame. The absorption performance is significantly improved by adding an external frame to wrap around a cavity-type acoustic absorber structure with air. Furthermore, utilizing the coaction of cascade coupling and external frame, the average absorption ratio of the metamaterial in high frequency domain (above 2000 Hz) can be improved by 6 times. Since this structural design broadens the absorption band without changing structural parameters of the original absorber, it has potentials to be applied in various engineering fields.

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Nonlinear Behavior of Helmholtz Resonator With a Compliant Wall for Low-Frequency, Broadband Noise Control

Cited by 5 publications

References 34 publications

Case studies on aeroacoustics damping performances of Coupled Helmholtz Resonators over low frequency ranges

Case studies on aeroacoustics damping performances of Coupled Helmholtz Resonators over low frequency ranges

Porous liner coated inlet duct: a novel approach to attenuate automotive turbocharger inlet flow-induced sound propagation

Design of Metamaterial for Broadband Sound Absorption Through Double Resonances

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