Attenuation of Acoustic Energy Across a Turbine Stage With Subsonic Relative Flow

The attenuation of sound energy propagating through a turbine is analyzed using an actuator disk theory. The analysis is restricted to low frequency disturbances and subsonic relative flow. Mach number changes and flow turning across a stage element are taken into account. Results indicate that the attenuation of acoustic energy across a typical turbine stage is at least 10 dB.