Influence of the terminal muffler geometry with three chambers and two tailpipes topology on its attenuation characteristics

Aimed at describing the harmonic acoustic waves passage through an exhaust system, the two-tailpipes terminal muffler may be seen as an acoustic element defined by eight quantities (usually arranged in a 2 by 4 matrix). The quantities make up a complex functions depending on the frequency of the wave motion. The engine speed is a variable that can be regarded as another parameter. This contribution presents a procedure how to establish the quantities coming from the suggested mathematical model and using the finite element method. In addition, formulae are derived for calculation of the terminal muffler attenuation based on the indicated characteristics. Finally, the attenuation haracteristics of the terminal muffler are presented and mutually compared for several design options of the mufflers which indeed are different with respect to their geometry but have identical topology of the chambers and tailpipes