Effects of Matching between the Inducer and the Impeller of a Centrifugal Pump on Its Cavitation Performance

Abstract

The inducer is often used to prevent cavitation in a centrifugal pump. However, it may lead to deterioration of the cavitation performance of the pump when poorly matched with the impeller. Numerical simulations are employed to study the effects of the matching, specifically, the axial space and the circumferential deflection between the inducer and the impeller, on the cavitation performance. The results show that the inducer destroys the rotational symmetry of the velocity distribution at the inlet of the impeller, resulting in the influence of cavitation on the part of the channels in advance, which explains why the inducer cannot improve the cavitation performance even though it improves the inlet energy of the impeller. On the basis of not changing the geometric shape of the inducer and the impeller, the suction-specific speed is increased by nearly 300 by only adjusting the axial space and by nearly 100 by only adjusting the circumferential deflection. The cavitation performance is better with a larger axial space. There is an optimal value of the circumferential deflection at which the pump works at the best cavitation performance. The effect of the axial space on the overall cavitation performance is more significant than that of the circumferential deflection. The results provide a useful reference for the design and installation of a centrifugal pump inducer.