Experimental investigation of geometric shape effect of coupled Helmholtz resonators on aeroacoustics damping performances in presence of low grazing flow

Zhao, Dan; Ji, Chenzhen; Yin, Myawin

doi:10.1016/j.ast.2022.107799

Cited by 14 publications

(8 citation statements)

References 65 publications

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“…In addition, the effect of rectangular resonators and cylindrical resonators on the sound absorption performance of the AAC is considered, and found that the geometric shape of the resonators has almost no change on its absorption performance, which is different from Ref. 20 For the convenience of making PTAA and MAA, the rectangular resonators are chosen.…”

Section: Simulationmentioning

confidence: 99%

Helmholtz resonator-based acoustic metamaterials enabling broadband asymmetric sound absorption and ventilation

Meng

2023

Journal of Low Frequency Noise, Vibration and Active Control

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Acoustic metamaterials with both ventilation and broadband asymmetric absorption have demonstrated great scientific significance and promising applicability. In this work, we design an asymmetric absorbing cell (AAC) consisting of a pair of detuned Helmholtz resonators (HRs) connected by sound channels that allows airflow with a ventilation ratio (ventilation area divided by sound incidence area) of 40%, which can achieve near-perfect sound absorption in the operating frequency range when sound waves are incident from the left port. However, when incident on the right port, the acoustic absorption coefficient does not exceed 40% at most, so asymmetric absorption is achieved. In addition, we form parallel three-cell asymmetric absorber (PTAA) by paralleling three AACs, which have broadband asymmetric absorption compared to AAC. Furthermore, we design multi-asymmetric absorber (MAA), which can achieve broadband asymmetric absorption range from 1000 Hz to 1750 Hz, and also allow air circulation. Moreover, experimental validation is conducted to demonstrate the effectiveness of fabricated MAA by 3D printing technology. Our designs open potential possibilities for developing ventilated functional devices capable of absorbing sound asymmetrically.

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Section: Simulationmentioning

confidence: 99%

Helmholtz resonator-based acoustic metamaterials enabling broadband asymmetric sound absorption and ventilation

Meng

2023

Journal of Low Frequency Noise, Vibration and Active Control

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“…The selected mesh is enough by benchmarking the present predictions with the available experimental data in Refs. [26][27][28]. The frequency step is set to 5 Hz and remains the same in all simulated cases.…”

Section: Model Validationmentioning

confidence: 99%

“…The resonators' damping performance is dramatically deteriorated at a far off-resonant frequency. [26][27][28] To improve the resonators' noise damping performances over a broad frequency range, actively passive control of acoustic damper such as Helmholtz resonators or perforated liners 29,30 could be applied to tune the resonant frequency of the acoustic dampers in real-time. In this way, it enables acoustic damper corresponding to the operating condition changes of the engines.…”

Section: Introductionmentioning

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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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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“…Flight tests, wind tunnel tests, and analytical studies have demonstrated that aeroelastic system with structural nonlinearity may exhibit various complex dynamic behaviors, such as bifurcation, chaos, high-order harmonics, and limit cycle oscillation (LCO). [1][2][3][4] Such nonlinearity can bring great impacts on handling quality, ride quality, and structural fatigue life. [5][6][7][8] Free-play has been recognized as a non-negligible inducement of these problems, because it is the most significant source of structural nonlinearity.…”

Section: Introductionmentioning

confidence: 99%

Aeroelastic investigation on an all-movable horizontal tail with free-play nonlinearity

Ai,

Bai,

Qian

et al. 2023

Journal of Low Frequency Noise, Vibration and Active Control

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Free-play-induced nonlinear dynamic behavior has been one of the most important topics of aeroelastic research in recent decades. In this paper, the describing function (DF) method is developed to investigate the complex dynamic response of a popular all-movable horizontal tail with free-play. Piecewise expressions for the time history and phase portrait of limit cycle oscillation (LCO) are derived by the developed DF method, which is conducive to understand the mechanism of free-play-induced LCO. Another advantage of the developed DF method is the ability to predict the high-order harmonics, which cannot be realized by the classic DF method. A three-dimensional (3D) all-movable horizontal tail model with torsional free-play was designed and manufactured to implement wind tunnel tests via various initial parameters. A good agreement was found between the numerical and experimental results, which can demonstrate the effectiveness of the proposed method. The influence of the initial parameters of the all-movable horizontal tail on the LCO characteristics is analyzed by both numerical calculations and wind tunnel tests. The method and results in this paper can provide a significant reference for the design of all-movable horizontal tail versus the free-play-induced LCO.

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Experimental investigation of geometric shape effect of coupled Helmholtz resonators on aeroacoustics damping performances in presence of low grazing flow

Cited by 14 publications

References 65 publications

Helmholtz resonator-based acoustic metamaterials enabling broadband asymmetric sound absorption and ventilation

Helmholtz resonator-based acoustic metamaterials enabling broadband asymmetric sound absorption and ventilation

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

Aeroelastic investigation on an all-movable horizontal tail with free-play nonlinearity

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