Slurry Pumps Instability Investigation Using High Fidelity CFD Simulation

Abstract Slurry pumps are widely used in a variety of applications in the mining, dredging, and aggregate industries. Ensuring stable operation is a major task during pump operation. In the current study, two slurry pumps are compared which differ only in the design of their casing hydraulics, both using the same exact impeller. The test results showed that a severe instability was formed in the head curve when the smaller casing was used which persisted over a large portion of the curve and resulted in a much lower operating efficiency. changing to the larger casing eliminated the instability and restored the expected pump efficiency. In order to investigate the root cause by examining the underlying flow patterns, a high fidelity, transient, full machine model, including impeller side gap, was developed and applied in a flow range from about 110% to 30% of the pump best efficiency flowrate or QBEP. The CFD simulation results were in good agreement with the measured performances, detecting the instability at the same flow rate for the smaller casing, and no instability when the larger casing is used. Surprisingly, considerable difference between the models appears within the impeller passages, even though its hydraulic design did not change. These differences are characterized, some theories offered regarding the underlying physical effects, and design guidelines proposed for avoiding the undesirable instability in future designs.