Masayuki Suganami

Small Two-Stage Centrifugal Blowers

We surveyed small two-stage centrifugal blowers, specifically their static parts and silencers. One of their features was a simple diffuser without a division plate between two centrifugal impellers instead of the normal return channel. Variety chord return vanes that gradually shorten along airflow passes are efficient for our characteristic diffuser channel. Diffuser vanes are efficient for increasing the pressure of a blower only behind the first impeller. If they are behind the second impeller, they cause the pressure of the blower to fall. We designed an original suction-side silencer with channels of two different lengths. The difference in the lengths was aligned to a half wavelength of the main noise, specifically the blade passage frequency noise. With our silencer, sound waves of different phases canceled each other out at the inlet of the blower. As a result, the noise of the blowers was reduced to 18 dB.Copyright