A New Approach to the Reduction of Pump Cavitation: The Hubless Inducer

Abstract

This paper describes a new and promising inducer which has no hub but a shroud. The design makes it possible to employ drastic vane sweepback. The shroud eliminates the vane clearance cavitation observed in the conventional screw inducer. Test data, cavitation photographs, and an analysis are presented. Maximum suction specific speed reached was 55,000 with 153 F water. Suction specific speed increases with speed and temperature up to a point. A special form of Reynolds number correlates the speed and temperature effect. The possible interrelation of boundary-layer transition and cavitation is discussed. Best suction specific speeds occur at positive incidence angles. The concept of incidence head is introduced and a theoretical equation is given.