Static analysis on rotor of vertical long-shaft fire pump used for offshore platforms

In order to investigate the static characteristics of the vertical long-shaft fire pump（ VLSFP）rotor,the type XBC18-178-240 LC3 VLSFP was chosen as the study object. First of all,a threedimensional mathematical model of fluid flow in the VLSFP and a physical model for the rotor system of the VLSFP were generated by Creo according to design parameters and the flow fields of the VLSFP with three-stages were simulated numerically by CFX under six conditions of 0.20 Q_d,0.65 Q_d,1.00 Q_d,1.20 Q_d,1.40 Q_dand 1.50 Q_d. Then,the physical model was imported into ANSYS Workbench and constraints were added to it according to the actual running environment. Finally,the numerical simulation results of flow field were imported into the physical model of the structure to realize the unidirectional fluid-structure interaction and then the static characteristics on the rotor system of the VLSFP with the prestress were analyzed. It is demonstrated that the fluid pressure inside the impeller increases as the stage of the impeller increases and decreases as the flow rate increases; the maximum of the total deformation is located at the edge of the rear cover of the third-stage impeller and the maximums of the equivalent stress and equivalent strain are located at the intersection of the edge of the rear cover and the blade outlet in the third-stage impeller,which decrease with the increase of the flow rate; the maximum of equivalent stress of the rotor is 118. 23 MPa under four conditions of 0. 20 Q_d,0.65 Q_d,1. 00 Q_dand 1.50 Q_d,which is smaller than its allowable stress（ 250 MPa） and meets strength requirement; the pump’s working speed of 1 485 r/min is less than its first-order critical speed of 0.85 times,which meets the dynamic design requirement.