Study on fish damage mechanism of the large flow rate centrifugal pump in hydraulic engineering pump station

Large high-head centrifugal pumps have the characteristics of large flow rate, high head, and high specific speed, making them important engineering equipment in large-scale water transfer projects. However, these pumps inevitably cause the death of a large number of fish during operation, which has adverse effects on the ecological environment. Therefore, studying the damage of large high-head centrifugal pump stations on fish is of great significance. This article establishes a new mathematical model for blade strike and predicts the strike probability and mortality rate of fish passing through the inlet of the centrifugal pump impeller. The prediction results show that under various flow conditions, the strike mortality rate for 50 mm fish passing through the model pump exceeds 82.5%, indicating that the model pump will cause significant damage to the pumped fish. This article further investigates the damage to fish caused by unstable flow inside the impeller and diffuser in low-pressure, high-shear, and high-pressure gradient regions. The research results show that fish suffer less low-pressure damage and more high-pressure gradient damage while passing through the model pump.