Why does the efficiency of a centrifugal pump decrease once its flow rate is increased to a certain level?
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For example, if all my outlet valves are opened, there is basically no loss at this point – will the efficiency of the water pump still decrease?
To give an example. . . Bike riding. ，。 . The speed can go up to a maximum of 50 kilometers per hour. . . You can’t go any faster no matter how hard you try. . . . Push harder. There’s no way to go any faster
Every pump has a performance curve. Generally, the pump achieves its highest efficiency at around its rated displacement or at flow rates that are slightly higher. Different pumps have their own performance curves.
The performance curve of each pump is peak-shaped; a high flow rate does not necessarily correspond to the point of highest efficiency!
Formula for apparent power: N=QHr/367
Changing the opening degree of the outlet valve essentially alters the pipeline characteristic curve. As the valve is opened, the local resistance in the pump’s outlet pipeline decreases; accordingly, the outlet pressure drops while the flow rate increases. If the opening is too large, it can lead to what is commonly referred to as insufficient flow – that is, the outlet pressure is not high enough, and the material cannot be forced out. In actual production, the pump outlet valve is generally not required to be fully open.