and for what reasons ? please explainTRUE OR FALSE: power delivered by pump decreases in higher speeds ?
Assuming conventional fluid such as water.
Background: Increased flow will result in increased system frictional losses == increased system back pressure. If flow and system back pressure increase the required energy to move the liquid will increase.
If a centrifugal pump (volute/impeller combination) increases in rotational speed the pump curve moves up and to the right with the required horsepower operating curves remaining in the original position on the pump curve. The new operating point will move up on the system curve (also up and to the right). Thus the input power will increase because the flow and/or system back pressure will increase.
If a positive displacement pump increases in speed (whether a rotational PD or an air diaphragm pump with increased strokes), its flow will increase proportionally. The resulting input power will increase for the reason stated above.
Both pump types FALSETRUE OR FALSE: power delivered by pump decreases in higher speeds ?
I presume the pump has a working fluid like air or water. We are not talking vacuum pump. ok.
yes. at higher specific speed the power delivered increases to a maximum, then decreases (this is not a linear function) beyond the maximum, issues like leak rate, cavitation and compressibility start to take over. also at high power levels, the pump material begins to be an issue.
for instance, consider the turbo fuel pump of an Atlass IIe rocket. it must work at cryonic temperatures with a fluid (liquid hyrogen or oxygen) that cavitates easily. the maximum power delivered is that which pumps the fuel, but doesnot cause it to vaporize due to the input of power (energy).
oh, and the bearings cant have grease so the specific speed needs to be compatible with stainless, bronze and some other fairly exotic steels.
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What kind of pump? (many kinds) And what are we pumping?
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