Finite element computation of attenuation in bar-silencers and comparison with measured data

A finite element formulation for sound attenuation in ''bar-silencers'', consisting of rectangular prisms of sound-absorbing material placed in a rectangular lattice arrangement within a rigid-walled duct, is described. The presence of a uniform mean gas flow in the ''airway'' of the silencer is taken into account, as is anisotropy of the absorbent. Comparisons are made between experimental insertion less data and numerical predictions, and generally reasonable agreement is noted. Comparison is also made between the acoustic performance of bar-silencers and the equivalent splitter silencers, and it is shown that bar-silencers tend to have superior attenuation characteristics at low frequencies. The present results are discussed in the context of previously published work on bar-silencers. (C) 1996 Academic Press Limited