Numerical study on tone noise source and noise radiation characteristics of single stage axial flow fan

A numerical simulation on internal unsteady viscosity flow field of single stage axial flow fan was performed using three-dimensional incompressible unsteady Reynolds (UR) average Navier-Stokes equations and RNG k-ε turbulence equations, so as to locate the primary noise source and the reason caused according to flow field analysis results of the rotor/stator interactions, and to study the tone noise radiation characteristics of the fan with FW-H equations based on Lighthill analogy theory coupled with UR analysis results. Results show that the primary source of rotor/stator interaction noise comes from pressure fluctuations at leading edge of the stator, which is caused by periodical interaction on stator leading edge resulted from the upstream rotor wake, tip clearance vortex and a contra-rotating vortex induced by the rotor wake. The tone noise of fan is mainly generated by rotor/stator interaction, in which the BPF component is predominant; the noise is mainly radiated from the duct outlet.