On the prediction of "Buzz-saw" noise in aero-engine inlet ducts

"Buzz-saw" noise radiated from an aero-engine inlet duct occurs when the re lative speed of the inlet flow impinging on the fan blades is supersonic. T he pressure field attached to a supersonic ducted fan, in a direction norma l to the shock fronts, closely resembles a sawtooth waveform. The non-linea r propagation of a high-amplitude sawtooth waveform spiralling around a duc t is calculated by two numerical simulation models. The models and their va lidation are discussed critically. Results are presented comparing the nume rical simulations with experimental data. Overall there is good agreement c omparing the results of the simulations with the experimental data, and in particular, the "Buzz-saw" noise in a hard-wailed aero-engine inlet duct is successfully predicted. (C) 2001 Academic Press.