The propagation and attenuation of sound in lined ducts containing uniform or “plug” flow

The acoustic spectrum of axial flow machines

Sound Generation in Centrifugal Compressors

Multiple tone generation by transonic compressors

The objective of this paper is to expose the computational aeroacoustics (CAA) community to the current unresolved issues in modeling and predicting fan noise The paper includes a description of the sources of fan noise and a discussion of the current status of the fan noise prediction methods and their shortcomings The discussion is focused on the issues and includes sufficient details to help outline the scope of the fan noise problem and define the level of fidelity required for meaningful CAA simulations

Fan Noise: A Challenge to CAA

Over the subsonic speed range, the pressure field attached to a ducted rotor decays rapidly with distance away from the rotor. This exponential decay, coupled with the low radiation efficiency of a subsonically rotating pressure pattern, is generally sufficient to bring the radiated sound power well below that produced by interaction of the rotor with disturbances in the flow. This is particularly true for multibladed rotors as used in aircraft-engine fans and compressors, and accounts for the importance of rotor-stator interaction as a source of noise at subsonic tip speeds.

M. J. Fisher

Papers

Shock-Wave Radiation from a Supersonic Ducted Rotor