Transmission Loss Analysis of Simple Expansion Tube with Micro-perforated Cylindrical Panel

Abstract

This study presents a development of simple expansion tube attach with micro-perforated cylindrical panel (MPCP) to improve the acoustic performance. A simulation based boundary element method (BEM) was carried out using PLM Simcenter 3D. The model was constructed in three dimensional in CAD NX Nastran 12 application and then meshing into small elements. The acoustic properties and boundary condition were defined for the simulation purpose. The model was then fabricated by 3D printer material and verified with the transmission loss measurement utilized the two-load method. In comparison, the transmission loss of simple expansion tube with and without MPCP show a good agreement of BEM analysis and experimental result. The addition of the MPCP inside the expansion tube improved the transmission loss by 2-10 dB in wider frequency band compared to the simple expansion tube. Finally, the air cavity depth of the expansion tube is varied to study it effect. Its showed that, the larger air cavity depth caused the transmission loss peak shift to a lower frequency range.