Study On The Blade Optimization And Inner Flow Characteristics Of An Axial Flow Pump

The axial flow pumps is a kind of turbomachinery with the characteristics of large flow and low head. Occupying a very important position in the national economy, they are widely used in agriculture irrigation, municipal water supply, flood control drainage as well as many engineering fields. With the rapid development of the national economy, the requirement of the high specific axial flow pumps’ hydraulic performance will be higher and higher.In this study, a high specific speed axial flow pump model was investigated by the numerical simulation and experimental methods to analyze the internal flow characteristics, especially explore the characteristics under the stall condition. The optimization platform based on the software Isight was established to optimize the blades of the high specific speed axial flow pumps. The main work and creative achievements are:(1) The inner flow of the axial flow pump was numerically simulated. With the test and the numerical simulation, a hump characterics was obtrained in(0.66~0.62)QBEP. The characteristic were analyzed by Boundary vorticity flux(BVF) and the static pressure distribution in the blade surface and the streamline of the impeller section and so on.The area of the blades in the high specific speed axial flow pump where there are negative work were discussed, providing guidance for further optimization work.(2) Based on the software Isight, Catia、ICEM and CFX was integrated together in the Isight by writing the software interface, realizing background auto starting by writing each software script, respectively. A intelligent optimization platform was built which concluded the parametric modeling module and meshing module and numerical simulation module as well as the optimized algorithm module.(3) The 2D sections of the blades in the high specific speed axial flow pump was parametrically analyzed and geometrically constrained fully by using software Catia. Showing variables in the form of knowledge table provided by Catia, achieving the parametric modeling of the high specific axial flow pump.(4) With the hydraulic efficiency as the object function, and the head as the constraint condition, combined with the detailed internal flow, the multi-island genetic algorithm was applied to optimize and calculate the inlet and outlet angles and the maximum thickness of the 2D sections, based on the set-up intelligent optimization platform. The results show: the hydraulic efficiency was increased to 82.4% and 83.4%,respectively. Moreover, the inner flow in the optimized blades was studied by comparing the BVF and the streamline on the blade surface with those without optimization, which shows that the BVF and the vortex was improved as well as the reverse flow, to further discuss the influence of geometrical parameter on the objective function, providing some reference on the design and optimization of the axial pump.(5)Based on the results we obtained above, it can be concluded that:The hydraulic optimization method in this study based on the Isight platform has the advantages of using less time in iterative modeling and controlling the blade shape by applying fewer geometrical variables a, realizing the global optimization based on multi-island genetic algorithm. Meanwhile, the method used in this study was proved to be an effective tool for the optimization of the blades in the axial flow pumps, and the results or summarization obtained in this paper can provide some certain reference for the hydraulic machinery blades.