Acoustic Attenuation Performance Analysis of Three-pass Perforated Tube Muffler with End-resonator

Muffler characterization with implementation of the finite element method and experimental techniques

“…Ji et al incorporated mass flow rate at an elevated temperature in his muffler model built in GT-Power (12). As a temperature gradient was applied to the model, there was not only a frequency shift in the transmission loss but amplitude variations as well.…”

“…The amplitude variations seemed to be unpredictable with respect to frequency although the overall amplitude level was fairly consistent. Ji et al conducted a parametric study on the effects of varying the air flow rate through the muffler (12). The results showed a fairly substantial increase in TL (around 10 to 15dB at a flow of 60m/s) across the entire frequency band, predominantly at higher frequencies.…”

“…In order to describe where in the frequency spectrum the resonance is located, it is necessary to describe what type of extended tube resonator is being used. There are two different types of extended tube resonators as can be seen in wave grazes past the perforations it feels a resistance which converts the acoustical energy into heat (12). The driving parameter in the performance of the perforated section is the equivalent impedance, .…”

“…Many parametric studies have been performed on the effects of perforation properties (3,12,14,22). All the results have revealed that by decreasing the porosity the TL is increased at all frequencies slightly.…”

“…On the other hand, FEM is a three-dimensional mesh which needs to be created for the entire exhaust system cavity. Because of this, the FEM mesh will contain well over an order of magnitude more nodes and elements than its counterpart, the BEM (12). If the same computational solver is used for each method then the BEM can serve as a major computational advantage.…”