Acoustical analysis of multiple cavities connected by necks in series with a consideration of evanescent waves

Lee, J.W.; Lee, J.M.; Kim, S.H.

doi:10.1016/s0022-460x(03)00508-x

Cited by 12 publications

(3 citation statements)

References 21 publications

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“…(4) depend on how α 1 and α 2 are estimated. Although there is a lot of literature dealing with open-end corrections, it is difficult to determine the correction lengths in the current case because the wavelength at the resonance of the cavity in this study is not long enough compared with the cavity length (5) .…”

Section: End Correctionmentioning

confidence: 96%

Sound-Attenuation Effect of a Partially Shut Rectangular Chamber at the End of an Inner Cylinder, Modeling a Ceiling-Mounted Ventilator

Sadamoto

Shirahama

Ando

2009

JEE

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Some ceiling-mounted ventilators have a sound-attenuating function due to the resonant effect that takes place within a chamber that consists of a rectangular outer cover and a cylindrical fan unit. In order to control the resonant properties in a reactive manner and maximize the sound-attenuation effect of this resonant system, the chamber is separated by a partial shutting plate, called a "separator," located at the end of an inner cylinder-modeling a fan unit-into two spaces that are expected to approximate a Helmholtz resonator with two degrees of freedom. Variations in resonant properties are shown, experimentally obtained by modulating the dimension of the separator. In this model, the second resonance frequency can be widely changed depending on the clearance between the two spaces, without attenuation of the resonant effect. This is meaningful because the second resonance frequency can be shifted into a frequency range that corresponds to the main component of the radiated sound from an actual ventilator. In addition, it is indicated that the resonance frequencies can be approximated by a simple analytical approximation. Furthermore, detailed considerations of sound fields of relatively delicate models concerned are provided using numerical calculation (BEM) and the effectiveness of the chamber is summarized.

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Section: End Correctionmentioning

confidence: 96%

Sound-Attenuation Effect of a Partially Shut Rectangular Chamber at the End of an Inner Cylinder, Modeling a Ceiling-Mounted Ventilator

Sadamoto

Shirahama

Ando

2009

JEE

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“…2. Their approximate values were obtained as described in a previous paper (3) , which details a suitable method for estimating the end correction lengths of the opening between domains I and II (6), (7) .…”

Section: Average Sound Pressure In Each Domain Of the Chambermentioning

confidence: 99%

Attenuation of Radiated Sound from a Duct End Attached to a Resonant Chamber Having Two Degrees of Freedom and Modeling a Ceiling-Mounted Ventilator

Sadamoto

Shirahama

Ando

2011

JEE

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The quietness of a ceiling-mounted ventilator consisting of a rectangular outer cover and a cylindrical fan unit is investigated. In order to confirm the sound-attenuation effect using a space between the cover and the fan unit, several properties of a chamber having a simplified symmetrical shape, which models an actual ventilator, have been investigated. In a previous study, in which the chamber was located in an infinite duct, the chamber was separated into two domains by a partially shutting plate to control the chamber performance. In the present study, this chamber is attached to one end of a duct and the properties of the sound radiated from the duct end into free space are investigated experimentally and numerically using the boundary element method. The effect of the chamber is similar when located at a duct end and in an infinite duct. In a certain low-frequency range, however, the chamber has an adverse effect in the duct-end case. Fortunately, this is not serious for an actual ventilator because the corresponding frequency range is not dominant for the sound radiated from an actual ventilator. Although the sound pressure in the chamber is quite different between the two chamber locations, the sound pressure ratio of the two domains is the same. Although the chamber performance depends on the chamber location, the physical aspect of the chamber as a resonator can be said to be independent of its location. When the opening connecting the two domains is moderately narrow, the chamber behaves approximately as a Helmholtz resonator having two degrees of freedom.

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“…The coupling effects of the trunk on the acoustic modes using discontinuities have also been reported in the literature. By developing an analytical model, Lee et al 10 claimed that such discontinuities generated evanescent waves in addition to standing waves, resulting in a change in the computed acoustic modes. Ahn et al 11 modelled those holes as an equivalent spring–damper system.…”

Section: Introductionmentioning

confidence: 99%

The effect of the folding rear-seat aperture in the acoustic response of a sedan car

Oktav

Anlaş

Yılmaz

2016

Proceedings of the Institution of Mechanical Engineers, Part D:

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The coupled vibro-acoustic response of a sedan is analysed, and the effect of the folding rear-seat aperture is studied. First, a simplified model of an acoustic cavity that consists of two adjacent boxes connected by an aperture is modelled. An analytical solution is proposed to calculate the acoustic eigenfrequencies of the simplified model. Then, the uncoupled acoustic eigenfrequencies of the actual cavity (where the trunk cavity and the cabin cavity are connected through an aperture) are computed. It is shown that the planar acoustic eigenfrequencies of the sedan can be calculated approximately using the analytical solution proposed. To clarify the effect of the folding rear-seat aperture further, the coupled vibro-acoustic response of the sedan is analysed using different case studies. It is observed that the booming noise is highly correlated with the calculated uncoupled planar acoustic eigenfrequencies.

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Acoustical analysis of multiple cavities connected by necks in series with a consideration of evanescent waves

Cited by 12 publications

References 21 publications

Sound-Attenuation Effect of a Partially Shut Rectangular Chamber at the End of an Inner Cylinder, Modeling a Ceiling-Mounted Ventilator

Sound-Attenuation Effect of a Partially Shut Rectangular Chamber at the End of an Inner Cylinder, Modeling a Ceiling-Mounted Ventilator

Attenuation of Radiated Sound from a Duct End Attached to a Resonant Chamber Having Two Degrees of Freedom and Modeling a Ceiling-Mounted Ventilator

The effect of the folding rear-seat aperture in the acoustic response of a sedan car

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