Hybrid noise control in a duct using a periodic dual Helmholtz resonator array

Cai, Chenzhi; Mak, Cheuk Ming

doi:10.1016/j.apacoust.2018.01.015

Cited by 35 publications

(11 citation statements)

References 19 publications

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“…This configuration employs the Bragg reflection. 7,11 It is obvious that the optimized silencers provide much more uniform transmission loss in the given frequency range. Moreover, the Bragg silencer, due to large inter-tube distances, has the total length of L Bragg ¼ (N -1)d ¼ 286 cm, whereas for the optimized silencers Figure 8 shows the minimum transmission loss TL min of l i , d i , and l i , d optimized silencers as a function of the number of side-branch tubes N, and the frequency range Df.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…5 Transmission properties of periodic ducted HRs with added parallel HRs were theoretically and numerically studied in Cai et al, 6 hybrid noise control using dual periodic HRs was also presented. 7 Coulon et al 8 studied the role of the distances between differently tuned HRs in an array, they used an optimization approach to improve the overall wide-band transmission properties.…”

Section: Introductionmentioning

confidence: 99%

“…It is also assumed that the waveguide downstream the silencer is infinite (or anechoic), so that there is no wave impinging from the right side. Within this work, as it has been adopted in the previous works, [3][4][5][6][7][8][9][10][11] the fluid is considered non-dissipative (all forms of acoustic energy dissipation are neglected), and stationary. Even if in almost all practical applications the fluid would be moving, the assumption of stationary fluid does not represent too much simplification, as Tang and Li 12 have reported that slow in-duct airflow does not affect the transmission loss of single or double sidebranch arrangements very much.…”

Section: Introductionmentioning

confidence: 99%

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Optimized reactive silencers with narrow side-branch tubes

Červenka

Bednařı́k

2018

The Journal of the Acoustical Society of America

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This paper presents a theoretical study of the sound propagation in a waveguide loaded by an array of flush-mounted narrow side-branch tubes, forming a simple low-frequency reactive silencer. The individual tube-lengths and the distances between the adjacent tubes are optimized in order to maximize the minimum transmission loss over a given frequency range. The transmission properties of the silencer are calculated using the transfer matrix method, heuristic evolutionary approach is employed for the determination of the optimal parameters. The numerical results are validated against the finite element method simulation. A comprehensive parametric study is performed to demonstrate the optimized silencer performance as a function of the number of side-branch tubes, and the frequency range. It is shown that for the given frequency range, the minimum transmission loss of the optimized silencer increases linearly with the number of the side-branch tubes.

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Section: Numerical Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimized reactive silencers with narrow side-branch tubes

Červenka

Bednařı́k

2018

The Journal of the Acoustical Society of America

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“…However, increasing the length of the 2 nd resonator neck leads to the resonant frequencies being decreased. Similar configuration of coupled Helmholtz resonators is proposed by Cai and Mak [20]. A broader bandwidth is achieved.…”

Section: Introductionmentioning

confidence: 72%

Aeroacoustic Attenuation Performance of a Helmholtz Resonator with a Rigid Baffle Implemented in the Presence of a Grazing Flow

Guan

Zhao

Ren

2020

International Journal of Aerospace Engineering

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To broaden its’ effective frequency range and to improve its transmission loss performance, a modified design of a Helmholtz resonator is proposed and evaluated by implementing a rigid baffle in its cavity. Comparison is then made between the proposed design and the conventional one by considering a rectangular duct with the resonator implemented in the presence of a mean grazing flow. For this, a linearized 2D Navier-Stokes model in frequency domain is developed. After validated by benchmarking with the available experimental data and our experimental measurements, the model is used to evaluate the effects of (1) the width Lp of the rigid baffle, (2) its implementation location/height Hg, (3) its implementation configurations (i.e., attached to the left sidewall or right sidewall), (4) the grazing mean flow Mu (Mach number), and (5) the neck shape on a noise damping effect. It is shown that as the rigid baffle is attached in the 2 different configurations, the resonant frequencies and the maximum transmission losses cannot be predicted by using the classical theoretical formulation ω2=c2S/VLeff, especially as the grazing Mach number Mu is greater than 0.07, i.e., Mu>0.07. In addition, there is an optimum grazing flow Mach number corresponding to the maximum transmission loss peak, as the width Lp is less than half of the cavity width Dr, i.e., Lp/Dr≤0.5. As the rigid plate width is increased to Lp/Dr=0.75, one additional transmission loss peak at approximately 400 Hz is produced. The generation of the 12 dB transmission loss peak at 400 Hz is shown to attribute to the sound and structure interaction. Finally, varying the neck shape from the conventional one to an arc one leads to the dominant resonant frequency being increased by approximately 20% and so the secondary transmission loss peak by 2-5 dB. The present work proposes and systematically studies an improved design of a Helmholtz resonator with an additional transmission loss peak at a high frequency, besides the dominant peak at a low frequency.

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“…The acoustic excitation of the sound source uses velocity boundary conditions. The real and imaginary parts of the sound pressure at the reference point 1 and point 2 can be obtained by the acoustic-vibration coupling calculation, and the sound absorption coefficient of the HR can be obtained [17]. The experimental results of the HR sound absorption coefficient and the simulation results are shown in Fig.…”

Section: Simulation 41 the Simulation Of Hrmentioning

confidence: 99%

Experiment-simulation Study on Noise Reduction of Cylinder Shell with Horn Helmholtz Resonator

Yan

et al. 2020

Teh. vjesn.

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This paper focuses on the noise reduction of the cylindrical structure at low frequency (130 Hz-180 Hz). The low-frequency noise response spectrum in the cylindrical cavity is obtained by using the Helmholtz resonator (HR) to reduce the noise peak amplitude. The acoustic simulation software Virtual.Lab is used to establish the finite element model of the cylindrical shell with HR, and to obtain the low-frequency acoustic response in the cylindrical cavity. The simulation model is validated by the experimental results. Then, the influence of installation position, the number of installed resonators and the resonators with different resonance frequencies in the cylindrical cavity are discussed. The results indicate that both the noise reduction band and peak amplitude are increased by installing the HR's on the cylinder shell. The noise reduction of the cylinder shell with HR installed on the upper position is larger than other situations. As the number of resonators increased, the frequency range of the noise reduction in the cylindrical cavity gradually increases, and the noise reduction of the cylinder cavity increases first and then decreases.

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Hybrid noise control in a duct using a periodic dual Helmholtz resonator array

Cited by 35 publications

References 19 publications

Optimized reactive silencers with narrow side-branch tubes

Optimized reactive silencers with narrow side-branch tubes

Aeroacoustic Attenuation Performance of a Helmholtz Resonator with a Rigid Baffle Implemented in the Presence of a Grazing Flow

Experiment-simulation Study on Noise Reduction of Cylinder Shell with Horn Helmholtz Resonator

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