Eventos Anais de eventos
MECSOL 2022
8th International Symposium on Solid Mechanics
Variation of porosity in a periodic micro-perforated chamber mufflers using spectral transfer matrix method
Submission Author:
wanderson vinicius de oliveira monteiro , SP
Co-Authors:
wanderson vinicius de oliveira monteiro, CASSIO BRUNO FLORENCIO GOMES, Adriano Goto, Edilson Dantas Nóbrega, Jose Maria Campos dos Santos
Presenter: Jose Maria Campos dos Santos
doi://10.26678/ABCM.MECSOL2022.MSL22-0155
Abstract
Micro-perforated chamber mufflers cause a reduction in the sound level of a system due to high acoustic resistance, and low mass reactance caused for its micro-perforations, making it an effective sound absorber. When arranged periodically it becomes more efficient. Transmission loss is related to the loss of sound waves transmission inside the silencer, and in a periodic acoustic device. For certain frequency bands, it can produce Bragg effect and local resonance, which generates bandgaps (stop band) where the waves can not propagate. These bands can be identified by calculating the dispersion curves, which can be obtained applying the Floquet-Bloch theorem. Here it is obtained using the Spectral Transfer Matrix method applied to a micro-perforated chamber muffler. This work analyzes the variation of porosity in a three-cell periodic micro-perforated chamber muffler. The sound pressure level and the transmission loss are also calculated and presented. It is observed that the transmission loss is not proportional to the amount of micro holes, showing the requirement to study porosity in the muffler's design. The diameter ratio directly influences the transmission loss, where the best value is obtained for a 0.8 mm micro hole diameter.
Keywords
Micro-perforated chamber silencer, Transmission Loss, Transfer Matrix Method, Floquet-Bloch Theorem, wave propagation
