I have a question regarding impeller cutting
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Regarding the law of impeller cutting, I have seen that the cutting equations vary depending on the specific speed. Specifically: when the amount of cutting by the impeller is small, the cutting laws are as follows: (1) For pumps with medium to low specific speeds: Q1/Q2 = (D1/D2)², H1/H2 = (D1/D2)², N1/N2 = (D1/D2)⁴. (2) For pumps with high specific speeds: Q1/Q2 = D1/D2, H1/H2 = (D1/D2)², N1/N2 = (D1/D2)³. The question is: what specific speed range corresponds to medium to low speeds, and what range corresponds to high speeds? What is the reason behind this? Please, an expert, help answer this.
Centrifugal pumps: low specific speed: 10-80, medium specific speed: 80-150, high specific speed: 150-300. Mixed-flow pumps: specific speed: 300-800. Axial flow pumps: specific speed: 500-1500