Back blades are usually assembled on the outside surface of impeller back shroud as a sealing device in centrifugal slurry pumps. The presence of solid particles in slurry leads to an obvious problem about the abrasion of the flow components of pump. Especially, the life of sealing devices, like the back blades, the oil seals and the shaft sleeve, is only a quarter or less of other components. Hence, an important engineering significance lies in the research on the abrasion of back blades.

In this paper, a single-stage horizontal type centrifugal pump was chosen as the main study model. The 3D model of the entire flow field was meshed by hexahedral structured grids. Based on the Particle model, which is an Eulerian multiphase method, the internal two-phase flow in the centrifugal slurry pump was simulated by using ANSYS CFX software. Six optimized design cases with the variation of back blades were analyzed to study the influence of vane profile and blade number of back blades on the abrasion characteristic and sealing performance. The main conclusions obtained are as follows: the volume fraction of solid phase achieved by simulation is in good agreement with the test results; the effect of vane profile on the flow of particles in the passages and the pressure on the seal is small; the usage of less back blade number will lower the flow constraint of blades on the particles and increase the area of axial vortex in each single passage, which means that the impact velocity of particles towards the pressure side grows and the pressure on the seal increases significantly. Based on the simulation mentioned above, two better cases were selected and manufactured for trial. Then, a wear test rig was set up to study the wear pattern of impeller during the operation of pump. Through the comparison of these two impellers after the wear test, it is found that: the back blades with the back forward shape can effectively reduce the abrasion of back blades at the pressure sides near the trailing edge; thickening the trailing edge of back blades to increase the life of back blades is feasible in practical application. The optimization design of back blades was preliminarily achieved which could provide some reference for the optimization design of back blades in centrifugal slurry pumps.

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