Design of multi-chamber cylindrical silencers with microperforated elements

The objective in this study was to develop a compact, multi-chamber silencer incorporating dissipative microperforated elements that could be used to reduce transmitted noise in a flow system. Two expansion mufflers in series were used to create a relatively compact system that attenuated sound effectively over the speech interference range. The microperforated elements were used both to improve the acoustic performance of the silencer and to reduce the system pressure drop with respect to a muffler without a microperforated lining. Both finite element modeling (FEM) simulation and experimental methods were employed in the detailed design of the multi-chamber silencer. In the FEM simulations, the microperforated lining was modeled as a fluid layer having complex properties, and the model was used, for example, to identify the optimal location of the microperforated lining. The predicted results were successfully compared with full-scale experimental results that were obtained by using a four-microphone standing wave tube.