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Updated: Aug 27, 2025

Design and Optimization Strategies of a High-Performance Vented Box
Published on: June 9, 2023
A mathematical formulation for the optimal impedance of a curved axial microperforated panel in a duct bend
1Institute of Vibration Shock and Noise, School of Mechanical Engineering, Shanghai Jiao Tong University, China cheng.yang@sjtu.edu.cn.
Abstract:
Previous work [J. Acoust. Soc. Am. 145, 501-511 (2019)] showed that a micro-perforated panel (MPP) placed in a duct bend will couple to the separated air channels to constitute a resonant system. This coupling effect results in the vibration of air mass inside micropores and provides damping to the duct. However, only limited attenuation was obtained. To enhance the damping effect, a mathematical formulation for the optimal impedance of the MPP (or a thin structure that has continuous normal velocity and pressure jump boundary conditions) is derived based on the concept of Cremer impedance which is mathematically equivalent to finding the exceptional point of a non-Hermitian system. Validation of the proposed model is made by examining the mode merging phenomenon at the exceptional point. The optimal damping is also compared with a straight duct having one of its wall lined.
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