Abstract
The inducer is very effective to suppress the cavitation in the main impeller. The conventional type attached directly to the main impeller, however, not only has a limit of the suppression, but also must be replaced repeatedly because the inducer is in the cavitating flow in general. To overcome these weak points, this paper prepared the two stage impellers driven by the isolated motor. The front impeller works just like the inducer and the speed is actively optimized in response to the suction head and/or the pump discharge so as not to generate the cavity. The pump performances were predicted and discussed accompanying with the internal flow conditions.
