Engineering seminar on fluid acoustics lecture 4: fluid dynamic noise of turbomachinery systems

摘要

This is fourth of a series of lectures for an engineering seminar on fluid acoustics which focuses on control and utilization of noise generated from unsteady flows. This fourth lecture discusses generation mechanisms and control techniques ofboth tubomachinery noise and self-excited oscillating flow tones. Also discussed are blade passing tones, interference tones between rotor blades and stator blades, as well as between blades and tongue ports, pump pulsation noise, Cavitation noise, pipesystem noise, and self-flow noise of silencers. Cavity and slit-flow tones are discussed as self-excited oscillating flow tones. It is explained that self-excited oscillating flow tones are induced by both a closed loop which forms between turbulenceshedding and sound waves which are generated in a shear flow. It is also explained that acoustic resonance affects the frequency of self-excited osillating.