A method for parameterized design and rapid optimization of axial flow pumps

To design a high-specific-speed axial flow pump with excellent hydraulic performance, this study comprehensively improves the hydraulic performance of the axial flow pump unit using a two-stage iterative orthogonal parameter optimization method while meeting the design requirements. In the design process, by integrating the mixed vortex hypothesis theory, a fourth-order two-segment method and a five-point Bézier curve were used to construct the camber lines of the impeller and guide vane airfoil, respectively. The planar cascade configuration was designed by superimposing the NACA 4-digit series airfoil thickness distribution. The variable projection method was introduced to achieve three-dimensional airfoil parametric modeling, enabling precise control of the circulation distribution by adjusting the projection coefficients. A 9-factor 9-level orthogonal table was used to optimize nine variables, including the cascade density, in the first stage. After four iterations, an initial optimized model was obtained with an efficiency of 85.73%, a head of 4.84 m, and a specific speed of 1028.9. Compared to the initial scheme in the first orthogonal test, which had a hydraulic efficiency of 80.52%, a head of 4.91 m, and a specific speed of 1017.17, the efficiency increased by 5.21%. Based on the first-stage optimization results, a 6-factor 5-level orthogonal table was used for the second-stage optimization of skeletal line control coefficients. After two iterations, the final optimized model was obtained with an efficiency of 86.59%, a head of 4.86 m, and a specific speed of 1025.75, representing an overall efficiency improvement of 6.07% compared to the initial scheme. The study confirms that this multi-parameter collaborative optimization design strategy effectively reduces turbulent entropy generation losses and fully validates the superiority and practicality of this design method and optimization process in improving the performance of axial flow pumps.