Impeller

Impeller from a three-stage air compressor

An impeller, or impellor,[1] is a driven 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, propellers 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.

  1. ^ "impeller, n.". OED Online. March 2013. Oxford University Press. 20 March 2013 [1].