Dissipative silencers used to attenuate noise emanating from air moving devices such as fans are normally of a simple splitter design, with parallel baffles of absorbent material arranged over the width of a duct. However in more specialist applications, such as the exhaust systems of gas turbines, different silencer geometries are often used. One such geometry is a so-called bar silencer, in which rectangular bars, or bricks, of absorbing material are placed in a lattice arrangement over the duct cross section. The acoustic performance of these bar silencers is investigated here using a finite element based numerical mode matching scheme. The insertion loss of the bar silencers is then calculated and compared against traditional splitter designs in order to investigate the relative efficiency of each design the performance of the bar silencer is observed to be very dependent on the material chosen and the flow resistivity of this material (which is linked to the overall bulk density of the material placed in the silencer). This places a strong emphasis on the development of accurate design tools suitable for optimizing silencer performance for a particular application.

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• AAF International

• Silencer

• Article