Sound attenuation of air entrainment devices with hybrid acoustic silencer

Abstract

The sound from operating traditional medical ventilators have been found to exceed recommended sound levels. This thesis addresses the sound attenuation by numerically studying the feasibility of an integrated ventilation system that connects a medical Venturi device serially to a slit-type Helmholtz resonator (SHR) embedded with an optional micro-perforated panel (MPP), with the goal of preserving ventilation while attenuating any undesired noise in the audible range. Compared with a base SHR model, the SHR embedded with a 0.9-mm-pored MPP exhibits an improved broadband transmission loss (TL) by 4 dB but without any adverse influence on the ventilation. Through finite element acoustic and flow simulations, the results also exhibit apparent nonlinearity in the integrated ventilation system. Further research should be conducted to experimentally validate the results found and improve on the design by addressing other flow rates and ventilation methods.