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

In this paper, a vertical long-shaft fire pump XBC18-178-240LC3 was taken as the research object to study the static characteristics of the pump rotor-shaft system under different shaft length connection. To analyse the influence of the length and number of the intermediate shaft section of the pump shaft on the deformation and equivalent stress of the shafting rotor, three shafting rotor models Z4(modified model), Z5(original model) and Z6(modified model) were designed, and then the static characteristics of them were analysed and compared under four operating conditions of 0.65Q d(0.65 times design flow),1.0Q d, 1.2Q d and 1.4Q d by numerical simulation. The results suggested that the changed rules of the three models' deformation and equivalent stress were basically the same. After the rated operating condition, the maximum deformation of the impeller of Z5 model was smaller than that of the Z4 and Z6 models. Under the four operating conditions, the maximum equivalent stress of the impeller of Z5 model was the smallest. This showed that the length and number of the intermediate shaft section affected the deformation and equivalent stress of the shaft rotor. Therefore, Z5 model was selected as the best rotor structure design scheme.

With the development of smart power grid, pumped storage has been developing on a large scale, and the pump-turbine with splitter blades is widely used. A combination of experimental and CFX numerical simulation was carried out to investigate the influence of guide vane openings on the flow characteristics in pump-turbine with splitter blades at different flow rates. The results show that change in the guide vane openings and flow rates have significant impacts on the internal flow characteristics in pump mode. The findings also revealed a poor flow stability in the condition of a small opening at a high flow rate and the condition of large opening at a low flow rate. Under the influence of pressure fluctuation, there exists local high-speed flow at the outlet of the draft tube and mid-span between the runner and the guide vane.