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Radiation of Sound from a Coaxial Duct Formed by a Semi-Infinite Rigid Outer Cylinder and Infinite Inner Cylinder Having Different Linings

Öztürk Hülya, Tiryakioglu Burhan

Archives of Acoustics

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2020

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Vol. 45, No. 4

655--662

EN

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.

2

Comparison of numerically determined noise of a 290 kW induction motor using FEM and measured acoustic radiation

Nahlaoui M. Al, Steins H., Kulig S., Exnowski S.

Archives of Electrical Engineering

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2013

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Vol. 62, nr 2

195--207

EN

In this paper a comparison of numerically determined and measured electromagnetically exited noise of an induction motor is presented. The calculations are accomplished using FEM for an example motor, which is a 290 kW inverter-fed asynchronous machine. The approach starts with the electromagnetic and mechanical consideration. The focus is set on acoustic considerations, which contain the 3D-FE-model and measurement setup in the sound chamber.

3

Comparison of numerically determined noise of a 290 kW induction motor using fem and measured acoustic radiation

Al Nahlaoui M., Steins H., Kulig S., Exnowski S.

Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały

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2012

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Vol. 66, nr 32, t. 1

333-338

EN

Abstract - In this paper a comparison of numerically determined and measured electromagnetically exited noise of an induction motor is presented. The calculations are accomplished using FEM for an example motor, which is a 290 kW inverter-fed asynchronous machine. The approach starts with the electromagnetic and mechanical consideration. The focus is set on acoustic considerations, which contain the 3D-FE-model and measurement setup in the sound chamber. The determination of the induction and force waves is presented using parts of the results. In the case of the mechanical modeling the three dimensional FE-model is shown.

4

Acoustic intensity vector generated by vibrating set of small areas with random amplitudes

Kozień M. S.

Journal of Theoretical and Applied Mechanics

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2009

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Vol. 47 nr 2

411-420

EN

The paper presents a generalisation of the hybrid method of estimation of sound radiated by vibrating surfaces, formulated previously for the deterministic case of random vibrations. The analysis is made for random amplitudes of vibrations in a narrow frequency band. The results show complexity of the analysis in comparison with the deterministic case. Therefore, the method does not seem to be efficient, like the deterministic one, in engineering applications.

PL

W artykule omówiono rozszerzenie metody hybrydowej oszacowania dźwięku promieniowanego przez drgające powierzchnie, sformułowanej pierwotnie dla przypadku drgań deterministycznych, na przypadek drgań losowych. Rozważono przypadek drgań z losowo zmienną amplitudą w wąskim paśmie częstotliwości. Rezultaty analiz pokazują złożoność uzyskanych formuł w stosunku do zagadnień deterministycznych. Dlatego też wydaje się, że metoda ta w prezentowanym podejściu nie jest tak użyteczna w zastosowaniach inżynierskich, jak to ma miejsce w sformułowaniu deterministycznym.