The effect of acoustic lining on 'buzz-saw' noise generated by an aero-engine

Abstract

Aero-engines operating with supersonic fan tip speeds generate an acoustic signature containing energy spread over a range of harmonics of the engine shaft rotation frequency. These harmonics are commonly known as the Buzz-saw tones. The pressure signature attached to a supersonic ducted fan will be a sawtooth waveform. In most modern aero-engines the intake duct contains an acoustic lining. The nonlinear propagation of a high-amplitude sawtooth waveform is calculated by a numerical simulation model, termed FDNS, which includes the effect of liner damping on the Buzz-saw tones. In this paper the further development of the FDNS model is described, and preliminary results are presented showing the effect of an acoustic liner on Buzz-saw noise.