Acoustic propagation in rigid ducts with blockage

El‐Raheb, Michael; Wagner, Paul

doi:10.1121/1.388236

Cited by 17 publications

(11 citation statements)

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“…n l c f (6) where n is the integer mode number n = 1; 2; 3…. Additionally, Hamilton et al [9] introduced 1D Webster horn equation to obtain analytical solutions of eignfrequency shift due to the changes of cross-sectional area in a closedclosed acoustic duct.…”

Section: Theoretical Analysis Of Eigenfrequency Shift In Open-closed mentioning

confidence: 99%

“…With the blockages inside the chamber shown in figure 1(b), the perturbed acoustic pressure field inside the duct would modify the eigenmodes and probably shift the eigenfrequency of the resonator. To evaluate the shift of eigenfrequency induced by the blockages in acoustic duct, 1D analysis based on plane wave theory was introduced by El-Raheb et al [6] and Wu et at [7] using piecewise solutions for Helmholtz equations in regions of different cross sections. The non-dimensional geometry quantities are firstly defined: …”

Section: Theoretical Analysis Of Eigenfrequency Shift In Open-closed mentioning

confidence: 99%

“…The eigenfrequencies of quarter-wavelength resonators gradually decrease when the piezoelectric cantilevers are installed inside the resonators. There were a few studies focused on the changes of eigenfrequencies caused by blockages in acoustic ducts [6][7][8][9][10][11]. As results of the volume exclusion and wave scattering, the presence of blockages modifies the wave equation and boundary condition, thus changes the eigenmodes of ducts.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced output power by eigenfrequency shift in acoustic energy harvester

You

2014

SPIE Proceedings

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In our previous studies, multiple piezoelectric cantilever plates were placed inside a quarter-wavelength straight tube resonator to harvest low frequency acoustic energy. To investigate the modification of eigenmodes in the tube resonator due to the presence of piezoelectric plates, the eigenfrequency shift properties by introducing single and multiple rectangular blockages in open-closed ducts are studied by using 1D segmented Helmholtz equations, Webster horn equation, and finite element simulations. The first-mode eigenfrequency of the duct is reduced when the blockage is placed near the open inlet. The decrease of eigenfrequency leads to the enhancement of absorbed acoustic power in the duct. Furthermore, the first half of the tube resonator possesses high pressure gradient resulting in larger driving forces for the vibration motion of piezoelectric plates. Therefore, in our harvesters, it is better to place the piezoelectric plates in the first half of the tube resonator to obtain high output voltage and power.

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Section: Theoretical Analysis Of Eigenfrequency Shift In Open-closed mentioning

confidence: 99%

Section: Theoretical Analysis Of Eigenfrequency Shift In Open-closed mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhanced output power by eigenfrequency shift in acoustic energy harvester

You

2014

SPIE Proceedings

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“…7 Their calculations are valid for both small and large samples with respect to the dimensions of the duct, and frequency shifts for longitudinal and transverse acoustic resonances can be calculated.…”

Section: Introductionmentioning

confidence: 99%

A resonance shift prediction based on the Boltzmann–Ehrenfest principle for cylindrical cavities with a rigid sphere

Santillan

Cutanda-Henríquez

2008

The Journal of the Acoustical Society of America

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An investigation on the resonance frequency shift for a plane-wave mode in a cylindrical cavity produced by a rigid sphere is reported in this paper. This change of the resonance frequency has been previously considered as a cause of oscillational instabilities in single-mode acoustic levitation devices. It is shown that the use of the Boltzmann-Ehrenfest principle of adiabatic invariance allows the derivation of an expression for the resonance frequency shift in a simpler and more direct way than a method based on a Green's function reported in literature. The position of the sphere can be any point along the axis of the cavity. Obtained predictions of the resonance frequency shift with the deduced equation agree quite well with numerical simulations based on the boundary element method. The results are also confirmed by experiments. The equation derived from the Boltzmann-Ehrenfest principle appears to be more general, and for large spheres, it gives a better approximation than the equation previously reported.

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“…[3][4][5][6][7][8][9] Most of these studies are theoretical, dealing with more or less elaborate techniques to predict the frequency resonance shifts for various object shapes and sizes, as well for different boundary conditions. Experimental results are scant, exceptions being the rather complete studies performed by Barmatz et al 5 and Chen et al 9 In this letter, we present an experimental study of longitudinal mode resonant frequency shifts induced by a solid spherical object in a quasi-one-dimensional air-filled acoustic cavity.…”

Section: Introductionmentioning

confidence: 99%

Resonant frequency shifts induced by a large spherical object in an air-filled acoustic cavity

Cordero

Mujica

2007

The Journal of the Acoustical Society of America

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Acoustic resonances are modified when objects are introduced into a chamber. The magnitude of these changes depends on the object position, size, and shape, as well as on its acoustic properties. Here, an experimental study concerning the resonant frequency shifts induced by a solid spherical object in a quasi-one-dimensional air-filled acoustic cavity is reported. It is shown that Leung's theory does not account quantitatively for the observations. A novel and simple approach is proposed, based on the wave equation in a cavity of variable cross section. The results fit more accurately the measured frequency shifts.

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Acoustic propagation in rigid ducts with blockage

Cited by 17 publications

References 0 publications

Enhanced output power by eigenfrequency shift in acoustic energy harvester

Enhanced output power by eigenfrequency shift in acoustic energy harvester

A resonance shift prediction based on the Boltzmann–Ehrenfest principle for cylindrical cavities with a rigid sphere

Resonant frequency shifts induced by a large spherical object in an air-filled acoustic cavity

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