Pressure Loss Characterisation of Perforated Ducts

Perforated ducts are present in most designs of exhaust mufflers, due to their convenient sound attenuation properties. While suitable tools are available for the estimation of this attenuation, accounting for the influence on attenuation of the perforated ducts for different arrangements, a similar tool but related to the back-pressure generated by mufflers containing perforated ducts is not available. In this paper, the basis for such a tool are set by defining a suitable characterisation of perforated pipes that may allow for the consideration of the influence of a particular perforated duct on the back pressure generated by a given muffler. The results obtained have been validated in a particularly simple case, and the results confirm the feasibility of the proposed methodology, while suggesting possible future improvements.