Analysis of Acoustic Characteristics for Expansion-chamber Muffler Using Finite Element Method

The finite element method is used to analyze the acoustic characteristics of an expansion-chamber muffler with its inlet and outlet pipes being co-axial.Its transmission loss(TL) is calculated.The result is compared with that of the one-dimensional solutions based on planar wave theory.The limitation of one-dimensional planar wave theory is discussed.The acoustic characteristics of eccentric outlet muffler,double-outlet muffler and double-cavity muffler are analyzed.The result indicates that the position and the number of outlet can affect the acoustic characteristic of a muffler for higher and medium frequencies;while the double-cavity muffler has high noise-elimination efficiency for lower and medium frequencies.