Regarding an interesting centrifugal pump problem
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For a typical centrifugal pump, after it is started and the outlet valve is not opened, the pressure inside the volute increases. When this pressure becomes much higher than the inlet pressure, could the inlet of the centrifugal pump turn into an outlet? Seek discussion
This will not happen. Firstly, the centrifugal pump has internal leakage; when the pressure becomes too high, some of the liquid returns to the impeller’s inlet and circulates, reducing the amount of liquid that the pump can draw in from the pipe outlet.
If the outlet isn’t opened, after a while the inlet will stop flowing in
Does that mean the pressure inside the centrifugal pump volute will not be higher than the outlet pressure?
So when the pressure in the volute increases and becomes higher than the inlet pressure, will the fluid inside the volute flow into the outlet pipe?
It will not exceed the outlet pressure during normal operation. The pressure in the volute increases after the outlet valve is closed.
I made a typing mistake, sorry. Can the pressure inside the volute be higher than the pump inlet pressure?
It seems to be understood in this way: the pump’s inlet and outlet are two separate locations. When it is said that the pressure inside the pump increases, it refers to the high pressure at the outlet, that is, near the edge of the impeller. The pressure at the pump’s inlet, That is, where the impeller begins, remains the inlet pressure. Haha, not very professional
Centrifugal pumps are able to draw in liquid because a certain degree of vacuum exists at the inlet of the impeller during rotation.
For now, let’s not discuss whether the pressure in the volute inside the pump could be higher than that at the pump inlet flange
When the pump is started with the outlet closed, the vacuum created by the impeller’s suction will certainly disappear, and moreover the pressure inside the volute will gradually increase. When this pressure exceeds the pressure at the pump’s inlet flange, will the liquid flow back?