Stress And Modal Analysis Of Axial-flow Pump Blades

As the development of civil economy, especially for the start of south-to-north water transfer project of China, a series of large-scale pump station should be founded. Axial-flow pump which charactered by large flow and low head was widely used in east-route of south-to-north water transfer project. However, in recent years,crack even fracture accidents were observed frequently on blades in operating condition of pump station, and the losing is huge and unnecessary.The aftermath of these accedents is more severe in large-scale pump station.The fracture on blades was mostly caused by fatigue failure effected by exciting force or resonance damage in operating condition of pump station. Therefore, for the improvement of pump design and safety of pump operation , it is very important to compute accurately the dynamic parameters of blade of impeller with the Finite Element Method at the design stage. The modal analysis is used to determine the vibration behavior of components which is an important parameter for dynamic structure design includes natural frequency and mode shape.The vibration behaviors of impeller of pump is studied in this paper. It gives the mathematical model and introduces the prestressing cyclic symmetric structure modal analysis method. The model of impeller were builded in PRO/E and meshed in ANSYS. The water pressure is loaded on blade by APDL. The stress of blade affected by water pressure is computed, and the result shows that the concentrated force takes place on the root of blade. The natural frequency of blade of modal impeller in air and affected by centrifugal force are computed separately. It is found that the centrifugal force increase the natural frequencies of blade, but the vaule is so small that it could be ignored. The natural frequency of blade are measued and The data are compared with the results obtained from a numerical solution with ANSYS and the result shows that it is dependable. As the modal analysis of model and prototype blade, it is shown that the relationship between natural frequency and blade frequency of model blade are similar with prototype, which means it could be predict the working condition of prototype blade by modal analysis of the model blade. The research results are significative for improving the reliability of pump design and operation...