Generation of a single cylindrical duct mode using a mode synthesiser

Snakowska, Anna; Gorazd, Łukasz; Jurkiewicz, J.; Kolber, Karolina

doi:10.1016/j.apacoust.2016.07.007

Cited by 9 publications

(5 citation statements)

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“…3a) requires precise determination of the relative amplitudes and phases of individual point sources, which are sensitive to any inaccuracies, and the experimental er- ror increases with the difference between the excitation frequency and the cut-off frequency of the generated mode. More details can be found in (Snakowska et al, 2016). The single-mode generation method based on Green's function is particularly sensitive to the correct positioning of the point source in the grid node of the source matrix (cf.…”

Section: Experimental Determination Of the S Matrix By Means Of Gener...mentioning

confidence: 99%

“…3a). The eccentricity of the measuring grid (microphone positioning), as well as of point sources, was found to be another possible source of error (Snakowska et al, 2016). The parameters of the muffler are as follows: inlet/outlet pipe of radius a = 103.2 mm, for which cut-on frequency of the first higher order mode (1,1) is 976 Hz (ka = 1.84).…”

Section: Experimental Determination Of the S Matrix By Means Of Gener...mentioning

confidence: 99%

“…The gain of generating "pure" single mode stems from the fact that in such case calculation of the S-matrix does not require, as will be presented in the paper, calculation of the inverse matrix of experimental data. In practice, mode selected to be generated is always accompanied by other modes (Snakowska et al, 2016), however of much lower amplitudes and so exited fields are substantially different and the matrix of experimental data is well determined. It is important as in general the S-matrix determination represents an inverse problem.…”

Section: Introductionmentioning

confidence: 99%

“…4. Selection of the excitation frequency.The complex amplitudes of individual point sources of the source matrix allowing to generate a single mode were determined on the basis of the duct-Green's function(Snakowska et al, 2016)…”

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confidence: 99%

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Archives of Acoustics

Gorazd

2021

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The aim of the paper is to experimentally determine the scattering matrix S of an example reflective muffler of cylindrical geometry for Helmholtz number exceeding the plane wave propagation.Determining the scattering matrix of an acoustic systems is a new and increasingly used approach in the assessment of reduction of noise propagating inside duct-like elements of heating, ventilation and air conditioning systems (HVAC). The scattering matrix of an acoustic system provides all necessary information on the propagation of wave through it. In case of the analysed reflective silencer, considered as a two-port system, the noise reduction was determined by calculating the transmission loss parameter (TL) based on the scattering matrix (S). Measurements were carried out in two planes of the cross-section of pipes connected to the muffler.The paper presents results of the scattering matrix evaluation for the wave composed of the plane wave (mode (0,0)) and the first radial mode (0,1), each of which was generated separately using the self-designed and constructed single-mode generator. The gain of proceeding measurements for single modes stems from the fact that theoretically, calculation of the S-matrix does not require, as will be presented in the paper, calculation of the measurement data inverse matrix. Moreover, if single mode sound fields are well determined, it ensures error minimization. The presented measurement results refer to an example of a duct like system with a reflective muffler for which the scattering matrix S was determined. The acoustic phenomena inside such a system can be scaled by the parameter ka.

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Section: Experimental Determination Of the S Matrix By Means Of Gener...mentioning

confidence: 99%

Section: Experimental Determination Of the S Matrix By Means Of Gener...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gorazd

2021

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“…the integral can be evaluated through the saddle-point technique (Snakowska, Idczak, 2006), we obtain…”

Section: Far Fieldmentioning

confidence: 99%

Archives of Acoustics

Öztürk

Tiryakioglu

2020

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In the present work, the radiation of sound waves from a coaxial duct is considered. This coaxial duct has an inner wall which is infinite and has piecewise acoustically absorbent material, while the outer wall is semi-infinite and rigid. The analytical solution of the problem is found by means of the Wiener-Hopf technique. Applying the Fourier transformation to the boundary value problem, the explicit expression for the scattered field is obtained. In the end, some numerical results are displayed for different parameters and compared to rigid case.

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Achieving cylindrical duct modes generation in spinning mode synthesizer via a least-square identification of the global calibration factor

Huang

Pan

et al. 2022

Applied Acoustics

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Generation of a single cylindrical duct mode using a mode synthesiser

Cited by 9 publications

References 23 publications

Archives of Acoustics

Archives of Acoustics

Archives of Acoustics

Achieving cylindrical duct modes generation in spinning mode synthesizer via a least-square identification of the global calibration factor

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