Numerical and Experimental Investigation on the Radial Force Characteristic of a Large Double Suction Centrifugal Pump in a Real Pumping Station

Abstract

The pump operation stability is one of the most important indicators for large discharge pumping stations. Impeller seal rings wear is a key problematic issue. A large double suction centrifugal pump in a real water supply pumping station is numerically and experimentally investigated, of which the seal rings are seriously wore on a fixed location. The pump shaft throws in two orthorhombic directions are measured at flow rates ranging from 0 to 110% of nominal flow rate, as well as the startup and shut down periods. And careful analysis of radial forces under various steady and unsteady conditions is carried out combining with the experimental results. The results show that the value of the shaft displacement obviously increases as the flow rate decreases, especially on the operating conditions with the flow rates below 87% of the design flow rate for the drive end side. The absolute value of the shaft displacement is 0.37mm, which is more than 3 times as large as that at nominal operating condition. There exit a lasting time of large shaft displacements during pump startup and shutdown periods, and the largest value of shaft displacement at the drive end side happens during the pump startup process, which can be increase to 0.95mm. There exists relative large radial force, and the direction of which is exactly the same with the pump shaft displacement at the flow rate from 0.73Qn to 0.32Qn, and also meet the wear locations of the impeller seal rings.