Study on Exit Flow of a Centrifugal Pump Impeller in Cavitating Condition.

Abstract

In order to clarify the deterioration mechanism of the pump head due to cavitation, the exit flow of a centrifugal pump impeller with cavitation was studied experimentally. The velocity and total pressure near the exit of the impeller passages were measured by Laser Doppler Velocimetry(LDV) and a total pressure tube both under the cavitating and non-cavitating conditions. From the measured velocities, the slip factor was calculated for different values of the cavitation coefficient and flow rate. It was found that the exit flow pattern was considerably deformed by the existence of the cavities inside the impeller passages and that the increase of slip factor as well as the increase of the hydraulic loss were generated when the cavitation coefficient is decreased.