Study on Setting Elevation of Double-Suction Centrifugal Pump Based on Cavitation Characteristics

Abstract

Setting elevation is an important factor affecting the safe operation of pumps, and the empirical calculation method in engineering cannot fully reflect the cavitation characteristics. In this paper, numerical simulation of cavitation in double-suction centrifugal pump with clearances is carried out. The cavitation characteristics under different flow rates was analyzed based on the setting elevation from the empirical method. It was found that there was cavitation inception under both large flow rate and small flow rate. The cavitation characteristics of the pump with different net positive suction head available (NPSHa) is analyzed. It is found that there is no obvious change in the pump characteristics from cavitation inception to critical cavitation, but after the point of the critical cavitation is reached, a large number of cavities plug the blade passage, and the efficiency decreases rapidly. The results show that in engineer although critical net positive suction head (NPSHc) is considered and the safety margin is increased, it is difficult to ensure that there is no cavitation inception happened in the pump. The cavitation characteristics analyzed by numerical simulation in this paper can provide guidance for the selection of suitable setting elevation.