This paper shows the details of comparison of noise attenuation level by convergent and divergent cylindrical duct with space constraints by using Transmission loss parameter. Reactive muffler is noise reduction element on exhaust system. Two basic term is used for noise attenuation first is transmission loss (TL) and other is insertion loss (IL). The main aim of this paper is to use of TMM, FE...

The development of high-performance mufflers associated to a compact volume it is of great importance in industrial field in order to obtain duct noise reduction in an economically and efficiently way. The Helmholtz resonator (HR), a classical reactive muffler, is considered in this work. The main purpose of this paper is to optimize numerically the sound transmission loss (TL) of the HR, since...

In this work, a finite element approach is presented for modelling sound propagation in perforated dissipative mufflers with non-homogeneous properties. The spatial variations of the acoustic properties can arise, for example, from uneven filling processes during manufacture and degradation associated with the flow of soot particles within the absorbent material. First, the finite element metho...

This paper reviews recent developments in the application of the boundary element method (BEM) to muffler and silencer analysis. Initial results of modeling built-in catalyst converters are also presented. A so-called “direct mixed-body boundary element method” has been developed for muffler and silencer analysis since 1996. The idea of the method is to integrate all kinds of different boundary...

In recent years, when consumers buy home appliances and cars, energy efficiency has been considered to be significant. Therefore, studies on how to increase the energy efficiency are being accelerated. A representative study is to raise the energy efficiency of the compressor which is a core part of the refrigerator using acoustic theory in suction part. However, the acoustic source characteris...

Automotive exhaust systems give a major contribution to the sound quality of a vehicle and must be properly designed in order to produce acceptable acoustic performances. Obviously, noise attenuation is strictly related to the internal gas-dynamic field that, on the other hand, needs to be optimised also in terms of pressure losses. In this work, the noise attenuation characteristics of a perfo...