Problems in the design of axial flow pump blades

Lift design of axial flow pump blade is a semi-empirical semi-theoretical design method, there are many problems, mainly because: 1 no single wing characteristics of information, axial flow pump impeller blade is a group of cascades, only by empirical correction The error is too big. 2 The characteristics of a single wing are measured in a wind tunnel test. There is a big difference between air flow and water flow. 3 aerodynamic airfoil, in order to meet the changes in the flow of imported parts of the smooth and fat, not suitable for use in axial flow pump blades above. 4 calculated by lift method exit angle of attack, the hub side is large, the more on the edge margin of the smaller, increasing the distortion of the blade, affecting the efficiency of the pump.