Parametrization of blade leading and trailing edge positions and its influence on mixed-flow pump performance

Based on the three-dimensional design platform, this article conducted parametrization of blade leading and trailing edge positions, and analyzed the influence of different position parameters on mixed-flow pump hydraulic performance and internal flow with model test and numerical simulation. The results showed that the hydraulic efficiency η of a mixed-flow pump increased slightly when the position parameter θh of the blade leading edge on the hub increased, and η increased significantly when the position parameter θt of the blade leading and trailing edge positions on the shroud increased. However, with θt increasing, the growth rate of η decreased. Numerical simulation has shown that by selecting a proper value of θt, the impeller energy conversion capacity can be effectively improved, and the distributions of static pressure and total energy can be more uniform in the flow passage. Meanwhile, with θt increasing, blade angle on the blade trailing edge decreased. Correspondingly, the absolute velocity in the outlet zone decreased, and the hydraulic loss in the outlet zone also decreased, which is beneficial to improving hydraulic efficiency of the mixed-flow pump. Within the value range of 7–9°, with different combinations of position parameter θt1 of the blade leading edge on the shroud and position parameter θt2 of the blade trailing edge on the shroud, the mixed-flow pump hydraulic efficiency η and blade wrap angle ϕ show a linear positive correlation, suggesting that an increase in ϕ could significantly improve impeller energy conversion capacity. Compared to θt1, θt2 has a more significant influence on ϕ and η. Thus, the value of θt2 should be carefully attended to during design process.