Experimental analysis of biomimetic silencer to reduce exhaust noise in pneumatic devices

Abstract

Pneumatic devices such as pneumatic artificial muscles (PAMs) generate excessive noise during operation, thus inducing safety hazards and becoming a nuisance to nearby communities. In this study, biomimetic silencers consisting of polyurethane foam and slit structures that mimic shark gill slits to reduce the exhaust noise caused by pneumatic devices were developed and experimentally analyzed. Two separate experimental approaches were employed to evaluate and analyze the performance of the developed biomimetic silencer. During these experiments involving the compressor and PAM exhaust noise measurements, the sound pressure signals, noise, and flow rate were obtained for the cases of with and without silencer. The results demonstrated that the slit structure of the developed silencer decreased the relative velocity with the surrounding air, thus resulting in approximately 6 dB improvement in noise reduction performance of the developed silencer compared with that of a general pneumatic silencer. Although the use of porous materials in the silencer causes an exhaust time delay, the delay is insignificant compared with that of a general pneumatic silencer in terms of the exhaust area. Thus, the developed silencer is an effective solution for reducing the exhaust noise in pneumatic devices, particularly in situations where noise reduction is critical.