A mode-matching analysis of flexible shells and waveguides with partitioning and muffler conditions

Abstract

This article explores the waveguide phenomenon that possesses trifurcated rigid inlet/outlet and muffler conditions. Additionally, this waveguide is linked to a finite, thin, and flexible shell with the aid of partitioning discs located at the interfaces. The inside of the discs is coated with sound absorbent material, which can be fibrous or perforated, depending on the impedance conditions of the surface. To demonstrate the use of absorbent material at the interfaces, impedance formulation is used. The mode matching procedure is then utilized to find solution, it relies on the orthogonality conditions accompanying the material characteristics of the bounding surface and within the fluid. The study includes modeling the utilization of absorbent material at interfaces, and numerical experiments to analyze the acoustic attenuation. The analysis focuses on a specific configuration with duct region radii and a half length of the chamber at a frequency of 700 Hz. The results demonstrate that the absorption of power and transmission loss versus frequency vary through the fibrous coating and the edge conditions, and changing the clamped ends to pin-jointed ends optimizes the dispersion powers and the loss due to transmission. The study yields useful information to the acoustic dispersion via flexural expansion chamber, highlighting the importance of material properties, edge conditions, and configuration settings in the acoustic attenuation. The mode matching method and numerical experiments presented in this study can be useful for designing acoustic devices with flexible shells, providing a better understanding of the underlying physics and optimizing their performance.