The hydrodynamic performance of multi-hydrofoil formations in plain river networks based on fish schooling dynamics

To address the challenge of insufficient hydrodynamic performance in plain river networks, this paper proposes a multi-hydrofoil formation pumping method inspired by fish schooling, building on prior research into the water-pushing performance of a single hydrofoil. Using the finite volume method and overlapping mesh technology, this study conducted a numerical analysis of the hydrodynamic performance for three hydrofoil formations: parallel, positive-triangle, and negative-triangle. The results show that under different spacing configurations, the vortices exhibit significant reorganization phenomena during the development process of the wake flow field, leading to substantial differences in hydrodynamic performance. The optimal spatial parameters for each formation are as follows: parallel hydrofoil formation: D/c=1.4 (D represents the lateral spacing, and c represents the chord length); positive-triangle hydrofoil formation: D/c=1.8 and G/c=0.4 (G represents the longitudinal spacing); and negative-triangle hydrofoil formation: D/c=1.0 and G/c=0.8. Across different oscillation frequencies, each sub-hydrofoil in the multi-hydrofoil system required an increase in input power by 3%–32% compared to a single-hydrofoil system. However, the average flow rate was enhanced by 100%–152% and the average pressure difference increased significantly by 301%–525%. With pump efficiency calculated using the formula: (average flow rate × average pressure difference)/input power, the multi-hydrofoil system achieved a significant efficiency improvement of 144%–327%. The characteristic curves of different hydrofoil formations resemble those of traditional axial flow pumps, exhibiting a head decrease with increasing flow rate and a pumping efficiency trend of initial rise followed by decline as flow rate increases. This similarity suggests potential applications of multi-hydrofoil formations in pump design for plain river networks.