Effect of the Tip Shape at Entrance of the Impeller Vane of the Centrifugal Pump on Cavitation

Abstract

An experimental study on the effect of the tip shape at entrance of the impeller vane of the centrifugal pump on cavitation was conducted by the writer with a vertical type centrifugal pump. The experiments were carried out on three different types of tip shape. In each case, the head-capacity curve, the static pressure distribution on the surfaces of the vanes near the entrance tips and the modes of cavitation occurrence were measured. Results of the experiments are as follows : (1) At the shockless entry, there are more chances of cavitation for the round tip vane than for the other type vanes. For the sharp tip vane no cavitation occurs in the experiments. (2) Except at the shockless entry, in spite of the discrepancy of the vane tip shapes, incipient cavitation occurs in each vane at the same relative velocity and suction head. And those facts mentioned above are considered to be natural from the pressure distributions on the vane surfaces.