Abstract
In order to reduce the noise of centrifugal blowers, the authors investigated the pressure fluctuation inside vaned diffusers using unsteady pressure measurement and compressible flow simulation. The number of revolution at which the pressure fluctuation in diffuser is highest matches the number of revolution of resonance obtained from the tracking analysis results of noise and is influenced by the acoustic resonance in diffuser. The pressure fluctuation in diffuser at resonant revolution has a node at the downstream of the overlapped region. The pressure fluctuation node at the inlet of the overlapped region, as well as the amplitude of the pressure fluctuation, varies with the number of revolution.
