Simulation and Analysis of Noise Reductions in a Variable-Volume Resonant Muffler
Date Issued
2010
Date
2010
Author(s)
Lin, Shi-Chun
Abstract
A variable-volume resonant muffler was made by Liu in 2005.The relationship between the size of resonant chamber and the resonant frequency can be obtained by his study.The purpose of this research is to use two indices：transmission loss and noise reduction to find out the performance of this type of muffler.The work can be divided into two parts.The first part is to use the plan wave theory to get a
transmission loss equation of the variable-volume resonant muffler.A software called Matlab is used.If the length of the resonant chamber can be changed,different transmission losses can be obtained.The second part is to use two microphones to measure a variable-volume resonant muffler and the noise reduction can then be obtained.A simple straight-through muffler will be tested at first in order to prove whether the procedure of measurement is correct.After that,the experiments on a variable-volume resonant muffler will be done.In theory,we can find that the wave tendancy of transmission loss moves toward to lower frequency region when the length of the resonant chamber becomes longer.This conclusion is corresponding to Liu’s result.The result of noise reduction experiment doesn’t match this phenomenon,however. It may result from some experimental errors.
Subjects
muffler
plane wave theory
transmission loss
noise reduction
Type
thesis
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