The impeller inlet of the centrifugal pump has a pre-rotation speed
Thread Content
The impeller inlet of a centrifugal pump has a pre-rotation speed, which results in a decrease in both head and flow rate. How should this be understood? Where does the energy loss go?
I reviewed a large amount of information, and it says that both head and flow rate have decreased
Actually, the original poster did not understand what head means. Head refers to the increase in energy per unit mass of liquid after it passes through the pump; it is an increase in energy. The pre-rotation that occurs at the beginning does not contribute to this increase in energy, and moreover, it reduces the actual work done by the impeller, which results in a decrease in head. As for why the flow rate decreases, I’m not quite sure; I hope someone experienced can explain this!
According to what you said, in the two cases the energy increase is different, but is the absolute velocity at the impeller outlet still the same?
In other words, for process pumps of the same model (i.e., those in which the energy of the fluid at the inlet to the impeller is equal), fluid without pre-rotation speed will gain more energy from the pump; then, in what way does this increase in energy manifest itself at the outlet?
The absolute exit velocity of the impeller should be related only to the shape of the impeller (i.e., specific speed), the size of the impeller, and the speed of the pump.
It’s still a conceptual issue: it’s not that the case without pre-rotation yields more energy, but rather that it can obtain more energy from the pump impeller; the total energy achieved in both cases is the same. This is my understanding, from the happy Pat Pat Bear.
More energy can be obtained from the impeller without pre-rotation speed; then in what way is the additional energy obtained compared to when pre-rotation speed is used? You say that the energy at the outlet is the same – you mean it’s possible, but it’s not necessarily true that more energy can be obtained without pre-rotation speed. If that’s the case, what’s the point?
Last reply. Well, let’s assume that the speed at which the robot or butcher retracts its hook is constant. No matter in which direction you are moving when it catches you, by the time you get to its side your speed will be the same as the speed at which its hook retracts, OK?:lol
That’s quite vivid. It’s a shame I haven’t played games in a long time