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Calculation of a Multi-Port Scattering Matrix for the Acoustic Power Flow Using Finite Element Method

Abstract : Ă Duct acoustic network modeling is commonly carried out using the transfer matrix formalism which is limited to the low frequency range as only the plane wave mode is allowed to propagate in the ducts connecting the different elements of the network. The aim of this work is to extend the formalism to higher frequencies by taking into account the multi-mode acoustic propagation. The first step is to compute, via finite element discretisation (FEM), the multi-port scattering matrix of each element. The second step is to rely on simplifying assumptions which are often used for the study of medium-to-high frequency broadband noise. These are: (i) all propagating modes are uncorrelated and (ii) each mode carries the same quantity of acoustic energy. This allows to derive of a multi-port scattering matrix for the acoustic power flow. The method is applied to typical elements such as T-junctions, bends, expansion chambers, lined ducts and contractions. In all cases, the power-flow model is compared to the FEM solution in terms of Transmission Losses. It is concluded that this simplified model is a reliable tool for the analysis of complex networks encountered in HVAC systems. Further work is ongoing by the authors to apply this technique to the simulation of realistic HVAC systems installed in helicopters and this should include the computation of sound generation via appropriate aero-acoustic simulations and the modeling of the acoustic radiation in the cabin.
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https://hal.archives-ouvertes.fr/hal-03221404
Contributor : Claude Inserra <>
Submitted on : Thursday, May 20, 2021 - 10:23:11 AM
Last modification on : Thursday, May 20, 2021 - 10:30:05 AM

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Cyril Calmettes, Emmanuel Perrey-Debain, Emmanuel Lefrançois, Julien Caillet. Calculation of a Multi-Port Scattering Matrix for the Acoustic Power Flow Using Finite Element Method. Forum Acusticum, Dec 2020, Lyon, France. pp.383-385, ⟨10.48465/fa.2020.0576⟩. ⟨hal-03221404⟩

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