A MULTIDIMENSIONAL ANALYTICAL STUDY OF SOUND ATTENUATION IN CATALYTIC CONVERTERS

摘要

In this work, a multidimensional analytical model is presented for the sound attenuation assessment of axisymmetric catalytic converters. Bessel functions are considered for the circular ducts, while spherical Hankel and Legendre functions are used for the expansion/contraction tapered ducts. Two alternative modelling techniques are implemented and compared for the monolith: (1) An equivalent bulk reacting absorbent material, in which the wave propagation is determined by the effective complex and frequency dependent density and speed of sound; (2) A coupling approach between both sides of the ceramic monolith in which a plane wave transfer matrix is considered, therefore retaining only one-dimensional propagation within the capillary ducts. Benchmarking of the developed analytical techniques with finite element calculations shows good agreement. The influence of several parameters on the sound attenuation of the catalyst is investigated.