A study on noise and pressure fluctuation in diffuser of compact centrifugal blower

Abstract

Recently, it has become more important to develop vacuum cleaners which achieve both high suction power and low noise along with comfortable sound quality. To reduce the noise of centrifugal blowers, the authors investigated the pressure fluctuation in vaned diffusers using unsteady pressure measurement and compressible flow simulation. From the tracking analysis of the results of noise, it was confirmed that the rotational speed at which the pressure fluctuation in diffuser becomes maximum matches a resonance rotational speed. The pressure fluctuation in the diffuser has a node at the downstream of the overlapped region at any resonance rotational speed. On the other hand, the node position near the inlet of the overlapped region and the amplitude of the pressure fluctuation depend on the resonance rotational speed. Furthermore, it was revealed that stationary wave modes were dominant in the pressure fluctuation and governed the positions of the maximum and minimum pressure fluctuations along the flow direction.