Eventos Anais de eventos
COBEM 2019
25th International Congress of Mechanical Engineering
Analysis of the geometric parameters of acoustic filters of the expansion chamber type
Submission Author:
Maria dos Reis Santos Borges , DF , Brazil
Co-Authors:
Maria dos Reis Santos Borges, Maria Alzira de Araújo Nunes
Presenter: Maria dos Reis Santos Borges
doi://10.26678/ABCM.COBEM2019.COB2019-0624
Abstract
Reactive acoustic filters are elements that use geometry as a tool for reflection of incident acoustic energy. These include those of the expansion chamber type, which consists of one or more chambers acting as resonators, where part of the incident sound energy returns directly to the source. Such elements are widely used in automotive, industrial and air conditioning systems. In this paper, the acoustic performance of three simple expansion chambers: with circular, square and rectangular cross section, was analyzed by the Transmission Loss (TL) curve. The analysis was performed in two steps: analytical and numerical. Firstly, through the analytical formulations, which are based on the one-dimensional plane waves theory, the TLs were calculated for the three different geometric forms, obtaining results only up to the highest cut-off frequency among the three models. To visualize the influence of such geometries at high frequencies, we used the Finite Element Method, since analytically the TL curve does not express the influence that different acoustic filter forms can exert. Comparison between the results showed that changing the cross-sectional area of this type of element can modify the TL of the acoustic filter at high frequencies.
Keywords
expansion chamber, acoustic filters, Transmission Loss, geometric parameters, Finite Element Method
