The specific speed of slurry pump has an important use in pump classification, similar design and product serialization.
(1) Pumps are classified by specific speed. The specific speed of centrifugal pump has nothing to do with the nature of liquid delivered, but has a close relationship with the shape of impeller and the characteristic curve of pump. According to the specific speed, the pump can be divided into low specific speed, medium specific speed and high specific speed centrifugal pump, and mixed flow pump and axial flow pump with higher specific speed. See table 1-7. At the same time, table 1-7 also shows the relationship between specific speed and impeller shape and characteristic curve shape. It can be seen that the low specific speed pump mainly refers to the high head and small flow, while the high specific speed pump represents the low head and large flow; the impeller shape of the low specific speed pump is narrow and long, and the impeller of the high specific speed pump is wide and short; the characteristic curve of the low specific speed pump is that the shaft power is small when the flow is zero, and the outlet valve should be closed to start; on the contrary, the shaft power is large when the flow of the high specific speed pump is zero, and it should be started when the outlet valve is open; the low specific speed pump The high efficiency area is wider than that of high specific speed pump, and the efficiency area is narrower; because the impeller of low specific speed pump is narrow, the flow loss in the impeller is larger, and the efficiency is lower, on the contrary, the high specific speed and deep efficiency are relatively high.
(2) Similar design with specific speed。 In the similar design of centrifugal pump, according to the principle of equal specific speed, the model pump can be selected from the existing pumps with good performance, and then the performance parameters and geometric parameters of the model pump can be converted into the performance parameters and structural dimensions of the prototype pump by using the similarity law。 When the value of N calculated by Q, h and N is less than 30, the positive displacement pump is generally used; when the specific speed is more than 30, the centrifugal pump, mixed flow pump or axial flow pump are used。 Slurry pump manufacturer
(3) The centrifugal pump series is designed with specific speed。 In the design of centrifugal pump series, as long as the combination of flow, head and speed is properly selected, the comprehensive parameter n reflecting the performance and structure of the same type pump can be obtained。 It is drawn on the same coordinate map, i。e。 type spectrum, and n。 It is evenly distributed on the type spectrum。 In this way, the number of hydraulic models can be greatly reduced, and a lot of manpower and material resources can be saved for the design and manufacturing department