Critical speed analysis of the shafting rotor of the vertical long shaft fire pump under the different positions of the impellers

Abstract For multi-stage pumps, the change of impeller stage spacing will have a greater impact on dynamic characteristics shafting rotor. The paper took XBC18-178-240LC3 vertical long shaft fire pump as research object, using ANSYS Workbench software to study relationship between critical speed rotor and different positions impellers. First, 9 rotors (based Z4,Z5 Z6 models) under impellers were established; then law in first 12 modes was studied. results showed that great With increase distance stages, low-order (6th order within) Z4 model decreases. However, (5th Z5 decreases with high-order doesn’t satisfy this law. Considering static actual engineering applications, selected Z5-stage 800mm best case, providing theoretical support for subsequent design optimization.