High temperature effects on the insertion loss of absorptive duct silencers

Abstract

Conventional passive rectangular duct silencers, which are in widespread use in commercial and industrial applications, employ a bulk absorptive material such as fibreglass, mineral wool or foam to attenuate noise. The majority of test data and calculation schemes used to predict silencer attenuation consider only the acoustic performance at or near room temperature. While such predictions are useful for silencers used in heating and ventilating duct systems, many industrial applications require an estimate of the acoustical performance of the silencer at high temperatures. The use of absorptive silencers to control noise from gas turbine generators is an example of an application in which the extreme operating temperatures (250 to 700°C) can have a significant effect upon silencer insertion loss performance