On tuning a reactive silencer by varying the position of an internal membrane

Lawrie, Jane B.; Guled, Idil M. M.

doi:10.1121/1.2213571

Cited by 47 publications

(48 citation statements)

References 17 publications

(33 reference statements)

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“…Finally, mode matching is used to accommodate the discontinuity between regions 1 and 2 using the same method as that described in the previous section, see Eq. (34) and (35). To combine Eqs.…”

Section: Hybrid Numerical Methodsmentioning

confidence: 99%

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On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

Kirby

Zlatev

Mudge³

2012

Journal of Sound and Vibration

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Long range ultrasonic testing is now a well established method for examining in-service degradation in pipelines. In order to protect pipelines from the surrounding environment it is common for viscoelastic coatings to be applied to the outer surface. These coatings are, however, known to impact on the ability of long range ultrasonic techniques to locate degradation, or defects, within a coated pipe. The coating dissipates sound energy travelling along the pipe, attenuating both the incident and reflected signals making responses from defects difficult to detect. This article aims to investigate the influence of a viscoelastic coating on the ability of long range ultrasonic testing to detect a defect in an axisymmetric pipe. The article focuses on understanding the behaviour of the fundamental torsional mode and quantifying the effect of bitumen coatings on reflection coefficients generated by axisymmetric defects. Reflection coefficients are measured experimentally for coated and uncoated pipes and compared to theoretical predictions generated using numerical mode matching and a hybrid finite element technique. Good agreement between prediction and measurement is observed for uncoated pipes, and it is shown that the theoretical methods presented here are fast and efficient making them suitable for studying long pipe runs. However, when studying coated pipes agreement between theory and prediction is observed to be poor for predictions based on those bulk acoustic properties currently reported in the literature for bitumen. Good agreement is observed only after conducting a parametric study to identify more appropriate values for the bulk acoustic properties. Furthermore, the reflection coefficients obtained for the fundamental torsional mode in a coated pipe show that significant sound attenuation is present over relatively short lengths of coating, thus quantifying those problems commonly encountered with the use of long range ultrasonic testing on coated pipes in the field.3

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Section: Hybrid Numerical Methodsmentioning

confidence: 99%

“…3. Note, however, that for modal based solutions balancing sound power does not always provide reliable evidence that the model has been implemented correctly (see Lawrie and Guled [35]). Nevertheless the data reported in Fig.…”

Section: Uncoated Pipementioning

confidence: 99%

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

Kirby

Zlatev

Mudge³

2012

Journal of Sound and Vibration

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“…It is worthwhile noting that for three-part problems involving propagation in closed waveguides, a mode-matching approach offers a convenient alternative; see e.g. [41]. This method enables problems that combine both type I and type II features to be reduced to an infinite system of linear algebraic equations that can be numerically solved by truncation.…”

Section: Extensions Variations and Applications Of The Techniquementioning

confidence: 99%

A brief historical perspective of the Wiener–Hopf technique

2007

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It is a little over 75 years since two of the most important mathematicians of the 20th century collaborated on finding the exact solution of a particular equation with semi-infinite convolution type integral operator. The elegance and analytical sophistication of the method, now called the Wiener-Hopf technique, impress all who use it. Its applicability to almost all branches of engineering, mathematical physics and applied mathematics is borne out by the many thousands of papers published on the subject since its conception. The Wiener-Hopf technique remains an extremely important tool for modern scientists, and the areas of application continue to broaden. This special issue of the Journal of Engineering Mathematics is dedicated to the work of Wiener and Hopf, and includes a number of articles which demonstrate the relevance of the technique to a representative range of model problems.

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“…Lawrie and Guled [4] and Huang [5] developed modal approaches to investigate the performance of modified reactive silencers in which a membrane is attached to the internal walls of an expansion chamber.…”

Section: Introductionmentioning

confidence: 99%

Using a Dual-BEM formulation to model the sound pressure wavefield provided by absorbing thin screens attached to the walls of a duct

António

Godinho

Amado-Mendes

et al. 2012

WIT Transactions on Modelling and Simulation

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The modelling of the 2D sound pressure wavefield in the presence of thin absorbing screens attached to the walls of a duct, assumed to be infinitely long, is described in this paper. The simulation uses a frequency-domain Dual-BEM (BEM/TBEM) formulation, which overcomes the thin-body difficulty that arises with the classical BEM formulation. The sound absorption is simulated by imposing impedance boundary conditions, which are applied in conjunction with a Dual-BEM approach. The fundamental solutions used in the formulation allow the solution to be obtained without discretizing the duct's walls. Thus, only the boundary of each absorbing screen attached to the duct's walls is modelled, which makes the proposed formulation efficient even at high excitation frequencies. The hypersingular integrals that result from the implementation of the TBEM are computed analytically. The formulation is used to compare results obtained with absorbing screens with those obtained with rigid screens and with those obtained in a duct without screens. Results in the time domain are obtained by applying an inverse Fourier transform to the frequency results.

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On tuning a reactive silencer by varying the position of an internal membrane

Cited by 47 publications

References 17 publications

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

A brief historical perspective of the Wiener–Hopf technique

Using a Dual-BEM formulation to model the sound pressure wavefield provided by absorbing thin screens attached to the walls of a duct

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