Muffler structure improvement based on acoustic finite element analysis

Abstract

Aiming to obtain the acoustic attenuation performance of exhaust muffler of diesel engine and the influence of main structural parameters on its acoustic attenuation characteristics, the finite element analysis method and acoustic theory were adopted to numerically investigate the acoustic attenuation performance under the boundary condition of acoustic adiabatic propagation and muffler wall. It suggested that the noise cancellation effect of muffler was poor at the middle and low frequency in range of 0-3000 Hz, and the transfer loss of muffler was basically 0 dB pass frequency at 1100 Hz. According to previous single-factor study experience, the structural factors, such as the expansion ratio, insertion length of outlet perforated pipe, the distance between the diaphragm and the front part of muffler, have influences on the acoustic performance of muffler at low frequency. Thus, they were taken as the starting point to study the influence of multiple interaction factors on the muffling performance by using orthogonal design method combined with the finite element analysis method. The influence degree of different structure parameters on the acoustic performance of muffler and the optimized structure parameters were obtained. Through the analysis on the acoustic characteristic of the optimized muffler, it indicated that the transmission loss of the improved muffler had significant increase in other frequency range except the range of 650-800 Hz and 2500-2700 Hz, especially at frequency of 1100 Hz compared with the original muffler. In the range of 0-3000 Hz, the mean of transmission loss of the improved muffler was about 9.8 dB larger than that of original muffler, which indicated that better noise cancellation effect was achieved. The improved muffler also provided a certain reference for the structural improvement of similar muffler.

Local Structural Optimization Method Based on Orthogonal Analysis for a Resistant Muffler

“…Orthogonal design is the most widely used method in experimental design and has been applied for more than 70 years. Orthogonal design has been applied to muffler design over the last ten years [9]. Many studies on muffler optimization design have been performed.…”

“…The orthogonal test has been used to analyze muffler units, such as perforated pipes [9]- [11], and the acoustic performance of mufflers [12], [13] have been optimized with good results. However, those works only optimize the design of a certain muffler unit [14], [15], or only consider acoustics performances without considering aerodynamic performances.…”

Recent Developments in Using a Modified Transfer Matrix Method for an Automotive Exhaust Muffler Design Based on Computation Fluid Dynamics in 3D

“…He also studied the TL measurement techniques, such as the Chung-Blaser, two-source, and two-load methods, similar to Kumar's [7]. Fu et al studied unique muffler structures to improve TL in the frequency range 0-3 kHz [14]. Using the finite element analysis (FEA), Fu et al obtained an increase in TL over the frequency range 0-3 kHz, except for the low-frequency ranges 650-800 Hz and 2500-2700 Hz; this aspect represents a limitation of using FEA in muffler acoustic performances.…”

Compression performance and low-frequency damping characteristics of pyramidal lattice cylinder skeleton structure

“…Traditional expansion chamber silencers have widespread use in pipeline systems. However, to eliminate low-frequency noise, these silencers require lengthy expansion chambers, and they are prone to periodic transmission losses [3] . Therefore, reasonable suppression of structural vibration can prolong the service life of machinery and increase the safety and comfort of structure.…”