Study of a folded resonator including the effects of higher order modes

Glav, Ragnar; Regaud, Pierre-Luc; Åbom, Mats

doi:10.1016/j.jsv.2003.05.024

Cited by 21 publications

(11 citation statements)

References 4 publications

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“…The configuration in Fig. 8 is typically referred to as a folded resonator [27]. With more pairs of partitions, the tortuous resonator paths further increase the characteristic chamber height, resulting in a lower TL peak at 410 Hz with two folds, and at 320 Hz with three folds.…”

Section: Sub-chamber With Partial Internal Partitionmentioning

confidence: 99%

Sub-chamber optimization for silencer design

Tong

2015

Journal of Sound and Vibration

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Section: Sub-chamber With Partial Internal Partitionmentioning

confidence: 99%

Sub-chamber optimization for silencer design

Tong

2015

Journal of Sound and Vibration

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“…It was found that neglecting the effects of expansion of the sound waves in the folded sections due to wave propagation in radial direction has a significant influence on the acoustic behavior of the resonators. In [121] folded resonators are investigated for the inviscid adiabatic case, which support these findings. The model for a circular air layer in section 4.3.3 can be used to model the expansion effect accurately.…”

Section: Coupled Lrf Modelsupporting

confidence: 63%

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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“…12,13 To examining this effect in water-filled silencer, a perforated pipe with inner diameter d in = 200 mm is inserted in the chamber of straight-through PPS, which forms a new type of silencers called as folded straightthrough PPS as shown in Figure 18. According to the theory of folded quarter wave resonator, 14 the distance from the first row of orifices to the end plate of silencer is chosen reasonably to eliminate the pass-through frequencies. The transmission loss predictions of the silencer without and with flow are presented in Figures 19 and 20, respectively.…”

Section: Partially Plugged Straight-through Ppsmentioning

confidence: 99%

Sound attenuation analysis of water-filled perforated pipe silencers using three-dimensional time-domain computational fluid dynamics approach

Zhou

2016

Advances in Mechanical Engineering

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The three-dimensional time-domain computational fluid dynamics approach is employed to calculate and analyze the sound attenuation behavior of water-filled perforated pipe silencers. Transmission loss predictions from the time-domain computational fluid dynamics approach and the frequency-domain finite element method agree well with each other for the straight-through and cross-flow perforated pipe silencers without flow. Then, the time-domain computational fluid dynamics approach is used to investigate the effects of flow velocity, diameter, and porosity of orifices on the sound attenuation behavior of the silencers. The numerical predictions demonstrate that the flow increases the transmission loss, especially at high frequencies. Based on the above analysis, partially plugged straight-through perforated pipe silencer is proposed to improve the sound attenuation performance by increasing the flow velocity through the orifices. In order to eliminate the pass frequency of the perforated pipe silencers and improve the sound attenuation performance in mid-to high-frequency range, a folded straight-through perforated pipe silencer is designed and its sound attenuation behavior is analyzed numerically using the time-domain computational fluid dynamics approach. KeywordsWater-filled silencer, sound attenuation behavior, time-domain computational fluid dynamics approach, flow effect, perforated pipe Date

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Study of a folded resonator including the effects of higher order modes

Cited by 21 publications

References 4 publications

Sub-chamber optimization for silencer design

Sub-chamber optimization for silencer design

Viscothermal wave propagation

Sound attenuation analysis of water-filled perforated pipe silencers using three-dimensional time-domain computational fluid dynamics approach

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