Study on Passaging Flow and Aerodynamics Noise in Multi-Blade Fan

Abstract

The internal flow and noise-generating mechanism in a muliti-blade fan were investigated by using a computational fluid dynamics analysis. Additionally, particle image velocimetry was used to interrogate the passing flow between the blades in order to validate the computational flow fields. The results of computational fluid dynamics show that a large static pressure fluctuation was taken place near the leading edge on suction side of z/b=0.5. It was confirmed that this region was a boundary which was constituted between the main flow near the hub and vortical flow near the shroud and the flow near this boundary was very unstable. Furthermore, a sound pressure level between 400～700Hz was high in this region. The near-field downstream of the leading edge at suction side showed a high correlation each other. So, it is concluded that this region was seemed to be a strong noise source. Comparing the flow pattern and the static pressure fluctuation, it was found that a pulsating inflow into the blades induced the aerodynamics noise.