Study on the influence of volute structure on the performance of seawater-pumped storage hydropower plant unit

The vertical centrifugal pump is a commonly utilized unit in seawater-pumped storage hydropower plants. The volute, a crucial part of the pump, directly influences the hydraulic characteristics, stability, and efficiency. The effect of single- and double-voluted configurations on a vertical centrifugal pump is studied using the SAS (Scale Adaptive Simulation) turbulence model in this study. The validity of the computation procedure is confirmed when compared to the test results. An investigation into the pressure pulsation and the radial force is carried out. The findings indicate that different volute types do not have appreciable effects on pump efficiency or head, and the variance is less than 2 %. However, the volute design greatly affects the pressure pulsation of the casing. At three typical working conditions (0.6Q, 1.0Q and 1.1Q), the main frequency amplitude at the first tongue of the double volute is reduced by 70 %, 38 % and 40 % compared with the corresponding single volute. At the outlet of the double volute, it is 31 %, 18 %, and 22 % lower when compared to a typical single volute. The type of volute used in the pump influences the pressure distribution as well as the pressure pulsation characteristics. As the double volute adopts the diaphragm structure, its radial impeller force is smaller. When comparing single and double volute pumps, the latter has a smaller radial impeller force. Therefore, it is advised to utilize a vertical centrifugal pump with a double-volute structure. This paper provides valuable insights for selecting units for seawater-pumped storage hydropower plants.