Effect of Twist Angle Regulation via Flexible Variable-Twist Blades on External Characteristics of Axial-Flow Pumps

In the field of marine resource development, conventional axial-flow adjustable-blade pumps rely on the monolithic rotation of rigid blades for operational condition regulation, a mechanism constrained by simplistic angular adjustments that inadequately adapt to the dynamic and complex marine operational environment. To address this limitation, this study proposes a novel angle-adjustment scheme utilizing flexible variable-twist blades, where operational condition regulation is achieved through active blade twisting, enabling refined and adaptive angle modulation. Four typical blade profiles were selected for the variable-twist blades at distinct angular positions (−1°, +1°, −2°, and +2°), corresponding to the four conventional angle-adjustment positions of axial-flow adjustable-blade pumps. Numerical simulations were conducted to investigate the hydraulic performance impacts of the proposed flexible variable-twist blades compared to traditional rigid blades under identical angular configurations. The results demonstrate that under high-flow conditions (1.2 Q), the torsion-based angle-adjustment strategy exhibits superior efficiency across all four angular positions: −1° configuration: 11.1% efficiency improvement; +1° configuration: comparable efficiency; −2° configuration: 78% efficiency improvement; and +2° configuration: 3.2% efficiency improvement. Moreover, at equivalent angular settings, the variable-twist blades significantly enhance hydraulic performance and expand the high-efficiency operating range of the pump compared to conventional rigid blades. The implementation of flexible variable-twist blade technology not only advances the performance of axial-flow pumps in marine engineering applications but also provides a new approach for high-efficiency research on axial-flow pumps.