Stress And Modal Analysis Of Bi-directional Pump Blades

In China, most pumps in low-lying areas along the Yangtze River have the characteristics of low head and large flow, so the axial-flow pump is widely used. Most pump station need bidirectional pumping function. The axial-flow pump which uses two-way symmetric airfoil blade can achieve reverse pumping and take the positive and negative performance into account by reverse the unit directly, thus becoming the preferred for design programs of low-lift reversible pumping station. But in recent years, in the process of operation of water pump, leaves often cracks even blade is ruptured occasionally, which has brought the national economy unnecessary losses.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.In this paper, two-way axial flow pump impeller is used for the study. Based on the RNG k - ε turbulence model, three-dimensional fluid calculation software CFX is used to do the numerical analysis of internal flow field pump for reversible pump and to simulation external characteristic of the pump and the blade surface pressure field under different conditions. On the basis of that, this paper use Static Structural modules Ansys of Workbench platform to achieve solid coupling simulation and calculate stress distribution and total deformation of impeller under different condition of hydraulic pressure. In addition, that module also calculates the intrinsic mode in the air and pre-stressed mode under water pressure and centrifugal force of bidirectional pump impeller.The results show that:the impeller maximum equivalent stress occurs in pressure surface of bidirectional pump blade and the inlet side of the round handle which is used to support the blade. The total deformation displacement of blade occurs at the inlet side of the blade near the rim which increasing with the decreasing of the flow. Under the interaction of centrifugal force and water pressure, the inherent frequency of impeller will decrease, but the rate of which is very small. By analyzing pre-stressed modal of the prototype pump impeller under water pressure and centrifugal force, the paper find that the vibration of the pump impeller type is similar to the model shapes. Frequency multiples of prototype pump is less than a multiple of impeller size change, which indicates that the natural frequency of the impeller is affected by water. Modal analysis by the model can predict the performance parameters of prototype pump impeller pump. Results of the research can provide some reference for the optimized design of two-way pump impeller.