Parametric design and optimization of a low-head axial-flow pump based on variable-circulation control

Low-head axial-flow pumps underpin critical infrastructure for inter-basin water diversion and flood mitigation; however, their energy-efficient operation is often constrained by suboptimal hydraulic performance. To address this, we propose a novel blade design strategy that replaces the conventional constant-circulation assumption with a variable circulation distribution parameterized by cubic Bézier curves. By integrating baseline blade parameters (Crsa, Sr, and Tr) with circulation control parameters (m0, m1, m2, and m3) via orthogonal design, we systematically reshape the impeller outlet velocity triangle to optimize internal flow. The resulting nonuniform-circulation models achieve hydraulic efficiency improvements of 0.89% and 0.95%, respectively, relative to the initial design. Furthermore, numerical analysis reveals that these efficiency gains stem from superior flow field characteristics, including optimized pressure gradients, reduced vorticity, and rectified streamline distributions. These results demonstrate that the proposed circulation-modification strategy offers a robust approach for transcending the performance limits of traditional axial-flow pump designs.