Numerical and experimental investigation of the effects of different reversible hydrofoils on the performance of a bidirectional axial-flow pump

To improve the energy efficiency during bidirectional pumping operations and enhance urban resilience against the frequent alternation of droughts and floods, this study focused on a bidirectional axial-flow pump with a specific speed of approximately 1400. A comparative analysis of the lift and drag characteristics between a Reversible S-shaped hydrofoil (RSH) and a Reversible Flat-plate hydrofoil (RFH) was conducted, investigating the impact of different reversible hydrofoils on the performance of bidirectional pumps. The results indicate that as the maximum camber ratio increases, the rising trend of the RSH's drag coefficient with increasing lift coefficient becomes more gradual, and its high-efficiency operating range broadens. Specifically, within the lift coefficient range of 0 to 0.42, the drag coefficient of the RSH shows an upward trend, but transitions to a downward trend within the range of 0.42 to 0.8. The RSH is more suitable for bidirectional pump design. The bidirectional pump designed with RSH achieved a significant improvement in maximum efficiency, a wider high-efficiency operating range, and a notable reduction in irreversible losses caused by turbulent dissipation across a broad flow range. Applying the optimized bidirectional impeller to a Bulb Tubular Pump (BTP), the experimental results confirmed that the bidirectional pump designed with RSH possesses superior hydraulic performance. These findings elucidate the influence of reversible hydrofoil selection on the performance of bidirectional pumps and provide a valuable reference for the optimal design of other types of reversible rotating machinery.