ACOUSTIC ATTENUATION IN DISSIPATIVE SPLITTER SILENCERS CONTAINING MEAN FLUID-FLOW

A theoretical model is presented, describing sound propagation in infinite two-dimensional planar silencers incorporating an arbitrary number of bulk-reacting, anisotropic, sound-absorbing splitters, with uniform mean flow in the gas flow passages; a corresponding computational scheme is also outlined. Experimental data are given, and it is shown that the model yields satisfactory predictions when numerical and measured results are compared. The characteristics of some of the acoustic modes in typical silencers are examined, with some emphasis on the properties of the least attenuated (i.e., most persistent) mode. Some surprising results are obtained, and it is found that modes that do not exist in a single “module” of a repetitive splitter arrangement can be least attenuated over a certain frequency range. © 1993 Academic Press Limited.