Noise characteristics and internal flow under cavitating conditions in a centrifugal pump with a holed blade fan type inducer

Noise characteristics in industrial centrifugal pumps is an important design item because they affect the comfort of the working space where the pumps are installed. Various studies have been conducted on the shape of the blades as a noise source, but the most effective design method is not clear. This study focuses on a centrifugal pump with a low solidity fan type inducer with holed blades. The pump was operated under various cavitating conditions, and the noise was measured. In addition, a high-speed camera was used to capture images of the internal flow during the occurrence of cavitation. These were related and analyzed for effects in noise characteristics due to the presence of holes. In particular, the presence of holes resulted in a reduction in noise increase under conditions prior to the clearly head reduction caused by cavitation. It was determined from the results of the internal flow capture that this was due to the suppression of cavitation near the trailing edge of the blades by the flow passing through the holes from the pressure side to the suction side. It is concluded that the holed blade structure is a solution to control noise.