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An improved multimodal method for sound propagation in nonuniform lined ducts

Abstract : An efficient method is proposed for modeling time harmonic acoustic propagation in a nonuniform lined duct without flow. The lining impedance is axially segmented uniform, but varies circumferentially. The sound pressure is expanded in term of rigid duct modes and an additional function that carries the information about the impedance boundary. The rigid duct modes and the additional function are known a priori so that calculations of the true liner modes, which are difficult, are avoided. By matching the pressure and axial velocity at the interface between different uniform segments, scattering matrices are obtained for each individual segment; these are then combined to construct a global scattering matrix for multiple segments. The present method is an improvement of the multimodal propagation method, developed in a previous paper [Bi et al., J. Sound Vib. 289, 1091–1111 (2006)]. The radial rate of convergence is improved from O(n−2), where n is the radial mode indices, to O(n−4). It is numerically shown that using the present method, acoustic propagation in the nonuniform lined intake of an aeroengine can be calculated by a personal computer for dimensionless frequency K up to 80, approaching the third blade passing frequency of turbofan noise.
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Contributeur : Denis Lafarge Connectez-vous pour contacter le contributeur
Soumis le : mercredi 25 mars 2020 - 11:50:48
Dernière modification le : vendredi 18 décembre 2020 - 12:47:20




Wenping Bi, Vincent Pagneux, Denis Lafarge, Yves Aurégan. An improved multimodal method for sound propagation in nonuniform lined ducts. Journal of the Acoustical Society of America, 2007, 122 (1), pp.280-290. ⟨10.1121/1.2736785⟩. ⟨hal-02518511⟩



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