Editing Impeller (section)

{{short description|Rotor used to increase (or decrease in case of turbines) the pressure and flow of a fluid or gas}}
[[File:Impeller 2.jpg|thumb|upright=1.2|Impeller from a three-stage air compressor]]
An '''impeller''', or '''impellor''',<ref>"impeller, n.". OED Online. March 2013. Oxford University Press. 20 March 2013 [http://www.oed.com/view/Entry/92207?redirectedFrom=impeller].</ref> is a driven [[wikt:rotor#English|rotor]] used to increase the pressure and flow of a fluid. It is the opposite of a [[turbine]], which extracts energy from, and reduces the pressure of, a flowing fluid.

Strictly speaking, [[propeller]]s are a sub-class of impellers where the flow both enters and leaves axially, but in many contexts the term "impeller" is reserved for ''non''-propeller rotors where the flow enters axially and leaves radially, especially when creating [[suction]] in a [[pump]] or [[compressor]].