Gas Turbine Silencers

The silencing of gas turbine installations is primarily a problem of attenuating the noise from the atmospheric inlet and the exhaust openings except where installations are made in residential or rural areas in which case the sound from the gas turbine enclosure, auxiliaries, and driven equipment must also be included as part of the silencing program. The subject matter of this paper is limited to the inlet and exhaust openings. The amounts of attenuation that can be obtained from natural factors such as divergence, directivity, air attenuation, and duct configuration are given and graphically shown. The sound absorbing qualities of baffles for the absorption of sound in the eight octave bands is described. At elevated temperatures, the performance of baffles at any octave band must be adjusted to the wavelength at the elevated temperature. Airflow characteristics are designed to be compatible with turbine operating efficiencies. Accepted fabrication practice is described and mechanical performance standards recommended. Properly designed silencers incorporate structurally adequate and durable casings, balanced sound attenuation, and pressure drops that will not adversely affect turbine performance.