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Analytical study of sound radiation from semi-infinite elliptic ducts with uniform subsonic flow

Published online by Cambridge University Press:  15 September 2025

Ruichen Wang Open the ORCID record for Ruichen Wang [Opens in a new window]  and
Xun Huang Open the ORCID record for Xun Huang [Opens in a new window]
Ruichen Wang
Affiliation:
State Key Laboratory of Turbulence and Complex Systems, Department of Aeronautics and Astronautics, School of Mechanics and Engineering Science, Peking University, Beijing 100871, PR China
Xun Huang*
Affiliation:
State Key Laboratory of Turbulence and Complex Systems, Department of Aeronautics and Astronautics, School of Mechanics and Engineering Science, Peking University, Beijing 100871, PR China
*
Corresponding author: Xun Huang, huangxun@pku.edu.cn
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Abstract

This paper presents an analytical method for modelling the acoustic field radiation from a semi-infinite elliptic duct in the presence of uniform subsonic flow. In contemporary aircraft design, elliptic ducts play crucial roles as inlets for advanced blended wing body configurations owing to their capacity to maximise the pre-compression effect of the fuselage and enhance the stealth performance of aircraft. The method uses Mathieu functions to describe the incident and scattered sound in the elliptic cylindrical coordinates. An analytical Wiener–Hopf technique is developed in this work to derive near- and far-field solutions. Numerical simulations based on a finite element method are conducted to validate the accuracy of the analytical method, revealing a strong correspondence with analytical predictions. A parametric study is conducted to explore the influence of the elliptic cross-section shape on noise directivity. Moreover, we investigate reflections within the duct via an extended derivation of the analytical model. The proposed method can be used to examine the acoustic characteristics of elliptic ducts with inflow mean flows, which holds relevance for noise control and optimisation of turbofan engine inlets and blended wing body applications.

JFM classification

Waves/Free-surface Flows: Wave scattering Acoustics: Aeroacoustics

Information

Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 1019 , 25 September 2025 , A9
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Copyright
© The Author(s), 2025. Published by Cambridge University Press

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