Low Specific Speed Centrifugal Composite Impeller Internal Flow Field Numerical Calculation,

Low specific speed pump has the features of low-flow rate and high head, which is widely used in the field of agriculture, industry and life. Nevertheless, the low specific speed pump has the disadvantages of low efficiency, easy to be overloaded and has deficient head of the curve. Different methods are used to conquer the problem mentioned above. In this paper, the project of short impeller is researched and developed to improve the performance of the centrifugal pump. The contents mentioned in this paper are as following:1.On the basis of analyzing the loss of the centrifugal pump, the theory foundation of the short impeller is proposed two means, that is to say, one is the mathematic principle and the other one is the physical basis. The mathematic one gives the conclusion that setting splitting vanes is the best way to overcome the, conflict between increasing head and decreasing loss, meanwhile the physical theory shows that the splitting vanes can improve the velocity distribution in the impeller and therefore satisfied pump characteristics can be obtained. Furthermore, the formulae to be used to calculate the number of the impeller and its geometry are conducted.2. The flow field of the centrifugal pump at conditions of different rotation speed and different flow rate is simulated by the methods of the slipper theory. And the method of the slipper theory is the main work of this paper. This kind of computation can display the flow field easily and which is easy to be analysis. The result computed by this method has a good agreement with that of the experiential data.3. Using PRO/ENGINEER software design impellers, using CFD software (Fluent) carry through numerical simulation. Using turbulence model and discrete format calculate the flow field of the centrifugal pump at conditions of short-blade of different length and different offset position. Because turbulence model think about hydro-viscosity, result is more accurate. The result computed by this method has a good agreement with that of the experiential data and that by the methods of the slipper theory.