Engineering Noise Control

Bies, David A.; Hansen, Colin H.

doi:10.4324/9780203163900

Cited by 165 publications

(207 citation statements)

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“…1 method and boundary element method to calculate the normal and random 23 incidence transmission losses through finite double panels with porous linings, 24 respectively.…”

Section: Introductionmentioning

confidence: 99%

Sound transmission through triple-panel structures lined with poroelastic materials

Liu

2015

Journal of Sound and Vibration

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“…1 method and boundary element method to calculate the normal and random 23 incidence transmission losses through finite double panels with porous linings, 24 respectively.…”

Section: Introductionmentioning

confidence: 99%

Sound transmission through triple-panel structures lined with poroelastic materials

Liu

2015

Journal of Sound and Vibration

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“…Obtaining length corrections for a coupling between (multiple) arbitrary waveguides is not trivial and deriving suitable analytical expressions is only feasible in special cases. Expressions for length corrections are available for a limited number of waveguide geometries for the inviscid adiabatic case [70]. In chapter 6 it is demonstrated that these length corrections give satisfying results in the viscothermal case as well.…”

Section: (B)(c)(d) Lrf Modelsmentioning

confidence: 99%

“…The LRF models for the resonator are coupled to the LRF model for the duct carrying a mean flow and the active and passive fan model described in 7.1.3. The lengths of the resonator sections that are connected to the main tube are adjusted with the length correction for a slit in a baffle [70]. The resulting LRF model for the 3-resonator setup is given in figure 7.14.…”

Section: Coupled Lrf Modelmentioning

confidence: 99%

“…Consequently, the LRF assumptions are violated locally and the accuracy of the velocity and pressure amplitudes predicted at the entrances of a two-port network can decrease considerably. corrections or end corrections are available, that compensate for the local behavior [28,29,70,72]. The corrections are aimed at compensating for the effects of higher order acoustic modes which are not captured by the two-port model.…”

Section: Length Correctionsmentioning

confidence: 99%

“…Based on the pressure at p 1 and p 2 , equations (7.11) and (7.12) can be used to determine the absorption coefficient. Note that the lengths of the resonator were adjusted with the length correction for a circular tube centrally located in another circular tube [70]. …”

Section: Two-port Lrf Modelmentioning

confidence: 99%

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Viscothermal wave propagation

Nijhof¹

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SummaryIn engineering practice, the simplest, most efficient model that yields the desired level of accuracy is usually the model of choice. This is particulary true if an optimization process is involved, in which case the choice of the underlying models is often a trade-off between efficiency and accuracy. It is therefore important to know not only how efficient a model is, but also how accurate.In this work, the accuracy, efficiency and range of applicability of various (approximate) models for viscothermal wave propagation are investigated in a general setting. Models for viscothermal wave propagation describe the wave behavior of fluids including viscous and thermal effects. Cases where viscothermal effects are significant generally involve small fluid domains, low frequencies, or fluid systems near resonance. Examples of practical applications of these models are, for instance, describing the behavior of in-ear hearing aids, MEMS devices, microphones, inkjet printheads and muffler systems involving acoustic resonators.Amongst the various models for viscothermal wave propagation that are considered, a prominent role is taken by the family of approximate models known as Low Reduced Frequency (or LRF) models. These are the most efficient approximate models available and they have been used extensively to model a wide variety of problems involving viscothermal wave propagation. Nevertheless, LRF models are only available for a limited number of geometries and can become inaccurate under certain conditions. A second family of models that is considered consists of exact solutions to the equations describing viscothermal wave propagation. These models, which are less efficient than the LRF models, provide reference solutions which can be used to determine the accuracy of the LRF models. A drawback of the exact models is that they are only available for a small number of geometries. Therefore a third family of models is considered, which is based on a newly developed Finite Element (or FE) approximation of the equations for viscothermal wave propagation. The main attraction of these FE models is that they can be used to model arbitrary geometries and boundary conditions. A drawback is that obtaining a solution requires much more computing power than needed for the LRF or exact models. The vi numerical stability and convergence properties of the developed FE methods are investigated to ensure that they can yield reference solutions of a desired accuracy for cases where an exact solution is not available.Using these three families of models, a number of parameter studies are carried out that yield detailed information on accuracy of the highly efficient LRF models for a range of geometries and boundary conditions. The gathered data provides a means of estimating the accuracy of simple coupled LRF models a priori.Besides the investigation into the accuracy of LRF models, two engineering applications where viscothermal wave propagation takes a prominent role are described. The first application involves the passive si...

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Insulation, Acoustic

Hirtle¹,

Parssinen²

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Acoustic insulation refers to materials and constructions that reduce the passage of sound into or out of a medium such as air, water, or a solid structure. This article is concerned with airborne and structureborne sound and provides an overview of a wide variety of materials and constructions used for acoustic insulation purposes. Included are discussions of sound‐absorbing treatments for reducing the reflection of impinging sounds; sound‐blocking materials and constructions for reducing the transmission of sound from one location to another; vibration isolation devices for reducing the transmission of vibration from vibrating sources into supporting structures (potential sound‐radiators); and vibration damping treatments used to reduce vibrations within and sound radiation from materials and structures. Test methods, measurement units, rating procedures, and specific uses of materials, devices, and constructions for acoustic insulation purposes also are discussed.

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Engineering Noise Control

Cited by 165 publications

References 0 publications

Sound transmission through triple-panel structures lined with poroelastic materials

Sound transmission through triple-panel structures lined with poroelastic materials

Viscothermal wave propagation

Insulation, Acoustic

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