A two-dimensional finite element approach to evaluate the sound transmission loss in perforated silencers

Abstract

In this work, the two-dimensional finite element method approach is presented to evaluate sound transmission loss (TL) of perforated reactive silencers with holes uniformly distributed. In the hole domain, the sound pressure was described using a periodic positive square wave function to simplify the evaluation of sound waves in the azimuthal direction. Eight different models with perforated inner concentric tube are evaluated in terms of their TL. The proposed formulation results were verified using the traditional three-dimensional finite element method (FEM), showing good agreement. An additional verification was also performed using the three-dimensional FEM and the specific acoustic impedance of perforated inner concentric tube to couple the inner concentric duct with an expansion chamber. The periodic formulation and three-dimensional finite element analysis (FEA) used 4-node quadrilateral and 4-node tetrahedral elements, respectively. A final check was carried out with experimental analysis of 8 models and there was good agreement with results of the three numerical methods.