Analysis of the Dynamic Characteristics of a Pump Rotor under Supercritical Axial Force

The physics model of the rotor of a boiler-feeding-water pump powered by a gas-turbine used in the supercritical unit in a power plant was established by Pro/E software. The finite element modal analysis of the rotor was carried out by Workbench 12 of software ANSYS. The critical rotational speed of the rotor was computed by using the software with the conditions of no-load, rigid supports、different supporting span and consideration of the influence of the tensile axial force respectively. The results showed that the critical rotational speed of the rotor tremendously increased when the tensile axial force was taken into account in wet-state with critical rotational speed of the rotor. The results indicated that the stiffening effect, caused by the tensile axial force, on the critical rotational speed of the rotor was obvious. Therefore, it is necessary to take tensile axial force into consideration for computing the wet-state critical rotational speed of the rotor when rotating in liquid for multi-stage centrifugal pumps.