Geometric shapes effect of in-duct perforated orifices on aeroacoustics damping performances at low Helmholtz and Strouhal number

Zhao, Dan; Ji, Chenzhen; Wang, Bing

doi:10.1121/1.5096642

Cited by 19 publications

(8 citation statements)

References 57 publications

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“…Within the measured frequency range, the frequency response of the experimental equipment is less than ±0.2 dB, and the sensitivity of the built-in microphone is 30 mV/Pa. In conclusion, the experimental measurements and findings in this work are applicable to other porosities and other shaped orifices/liners as reported in (Zhao et al ., 2019b).…”

Section: Discussionsupporting

confidence: 77%

“…There is alternative model approach such as Lattice Boltzmann method (Ji and Zhao, 2014a, b), which can also be used for the present work. Experimental studies are conducted to measure the aeroacoustics damping performances of in-duct perforated plates in a cold-flow pipe with a variable Mach number in (Zhao et al ., 2019b). It is shown that the orifice shape has little influence on power absorption and reflection coefficient at a lower Helmholtz number.…”

Section: Discussionmentioning

confidence: 99%

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Sound absorption performance of composite structures from a kind of lightweight ceramic foam with perforated plate

Liu,

Song,

Sun

2023

MMMS

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PurposeThe purpose of this paper is mainly to know: (1) the sound absorption coefficient of porous composite structures constituted by a new kind of lightweight ceramic foam and perforated plate; (2) the availability of an equivalent porous material model, recently proposed by the present author, to these composite structures in sound absorption.Design/methodology/approachA kind of lightweight ceramic foam with bulk density of 0.38–0.56 g·cm-3 was produced by means of molding, drying and sintering. The effect of stainless steel perforated plate on sound absorption performance of the ceramic foam was investigated by means of JTZB absorption tester.FindingsThe results indicate that the sound absorption performance could be obviously changed by adding the stainless steel perforated plate in front of the porous samples and the air gap in back of the porous samples. Adding the perforated plate to the porous sample with a relatively large pore size, the sound absorption performance could be evidently improved for the composite structure. When the air gap is added to the composite structure, the first absorption peak shifts to the lower frequency, and the sound absorption coefficient could increase in the low frequency range.Originality/valueBased on the equivalent porous material model and the “perforated plate with air gap” model, the sound absorption performance of the composite structures can be simulated conveniently to a great extent by using Johnson-Champoux-Allard model.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Sound absorption performance of composite structures from a kind of lightweight ceramic foam with perforated plate

Liu,

Song,

Sun

2023

MMMS

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“…According to Zhao, 42 it was found that the geometry of the perforation has a non-negligible effect on the acoustic performance of perforated plates in the flow state. This paper will extend to the effect of perforation angle on the acoustic impedance of perforations under the action of swept flow.…”

Section: Effect Of Perforation Angle On Transmission Lossmentioning

confidence: 99%

Acoustic impedance extraction method and acoustic characteristics analysis of perforated plates under grazing flow

Wen,

Wu,

et al. 2023

Journal of Low Frequency Noise, Vibration and Active Control

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As an important component of inlet and exhaust mufflers, the acoustic characteristics of perforated components are inevitably affected by the flow of air. Therefore, obtaining the acoustic impedance of the perforated element under airflow conditions is a prerequisite for accurate calculation of the muffler’s muffling performance. In this work, the frequency domain linear Navier–Stokes (L-NS) method is used to extract the acoustic impedance of perforated plates under grazing flow. The predicted perforated acoustic impedance is consistent with the calculation results of published acoustic impedance expression, and the impedance boundary condition is defined to calculate the transmission loss (TL) of the perforated muffler, which agrees well with the experimental results and verifies the accuracy of the method. The effect of perforation angles on the transmission loss of mufflers in different Mach numbers ( Ma) and aperture plate thickness ratio ( dh/ tp) is analyzed by the frequency domain L-NS method. The results show that when 1≤ dh/ tp<2 and Ma≤2, the effect of perforation angles on the muffler performance is obvious, and the angle tilted upstream shifts the resonant frequency to a lower frequency while its corresponding peak value is also increased. As an engineering application, it has certain significance for the prediction of muffler muffling performance and the regulation of the muffling frequency band.

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“…[5][6][7]12 The governing equations are coupled nonlinear Navier-Stokes equations. The vorticity-involved damping physics of Helmholtz resonators are visualized by these simulations 12,13,15 or flow visualizations or laserinvolved experimental measurements. 16 Such time-domain simulations and experimental measurements may be economically costly, and numerically time-costly.…”

Section: Introductionmentioning

confidence: 99%

Numerical optimizing noise damping performances of Helmholtz resonators with a rigid baffle implemented at neck in presence of a grazing flow

Guan

2022

Journal of Low Frequency Noise, Vibration and Active Control

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As an applicable noise attenuator, Helmholtz resonator is mainly used to dampen acoustic noise at low- and medium-frequency ranges. It is typically implemented in combustion-engines and gas turbines to dampen thermoacoustic instabilities. However, it has a narrow effective frequency range and does not work effectively at off-design conditions. In this work, we consider a modified structured Helmholtz resonator (HR) at its neck by applying a rigid baffle in order to maximize its’ noise damping effect and to broaden its frequency bands. The resonator is attached to a cylindrical duct/pipe in presence of a mean flow (grazing flow), aiming to simulate the practical engines flow configuration. For this, a two-dimensional frequency domain numerical model is developed by using COMSOL V5.3. The numerical simulations are carried out by solving the linearized Navier–Stokes equation in frequency domain with low computational cost and time. In order to obtain an optimum design in terms of the maximum noise damping performances, 10 new different configurations/designs are proposed. The effects of 1) the single baffle attached to the upstream or downstream sidewall of the neck ends, that is, Design A, B, C, and D or double baffles, that is, Design E, F, G, and H), 2) the baffle implementation location, 3) the length of the rigid baffle, and 4) the grazing flow low Mach number are evaluated and compared. It is found that Design C is associated with improved TL by 50% and decreased resonant frequency by 20% comparing with the conventional HR. The present preliminary study shows that Design C is the better design. Further experimental and optimization researches are needed to sheds light on the optimum design of a Helmholtz resonator with neck structure being modified, as there is a low Mach number grazing flow.

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Geometric shapes effect of in-duct perforated orifices on aeroacoustics damping performances at low Helmholtz and Strouhal number

Cited by 19 publications

References 57 publications

Sound absorption performance of composite structures from a kind of lightweight ceramic foam with perforated plate

Sound absorption performance of composite structures from a kind of lightweight ceramic foam with perforated plate

Acoustic impedance extraction method and acoustic characteristics analysis of perforated plates under grazing flow

Numerical optimizing noise damping performances of Helmholtz resonators with a rigid baffle implemented at neck in presence of a grazing flow

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