Cavitation performance of multistage slurry pump in deep-sea mining

Abstract

Liquid–gas and liquid–solid phase relationships are established in this study using the theories of cavitation nucleation and solid–liquid two-phase flow, respectively. The relationship between gas and solid phases is then derived, and the effect of solid phase parameter characteristics on the cavitation characteristics of the slurry-conveying slurry in the pump is analyzed. The influence law of particle concentration and speed on the airing performance of two-stage slurry pumps is studied on the basis of computational fluid mechanics. Results show that the cavitation phenomenon reduces the overall pressure of the flow field of deep-sea mining slurry pump. The lowest pressure area is the area of airing development at the entrance of the first-stage impeller blade. The cavitation of the mineral pulp pump becomes evident, and air bubbles rapidly spread over the outlet as the solid phrase particle grows in size. Moreover, solid phase concentration heightens the cavitation of the slurry pump. The cavitation in the pump gradually intensifies as the speed of the slurry pump increases, and a large area of air bubbles sharply forms and disturbs the flow field of the pump when the speed reaches 2000 r/min. In addition, the vortex increases, and the jet phenomenon becomes serious. A comprehensive analysis of the cavitation characteristics of the slurry pump is obtained at the following speed, solid phase volume concentration, and solid phase particle size: n = 1450 r/min, C = 5.3% and d = 20 mm, respectively.