How does a centrifugal pump move liquid with an impeller?

A centrifugal pump moves liquid by imparting velocity to the fluid through a rotating impeller, which is a wheel equipped with vanes.12

The process functions as follows:
* Intake: Fluid enters the pump near the center (axis) of the high-speed rotating impeller.12
* Acceleration: The impeller’s vanes throw the fluid radially outward toward the surrounding pump casing. This action creates a partial vacuum at the center, which continuously draws more fluid into the system.12
* Pressure Conversion: As the fluid is forced against the casing, it enters an outlet that widens in a spiral fashion (in a volute pump). This design reduces the fluid's velocity and converts that kinetic energy into pressure head, resulting in a continuous flow of high-pressure liquid.12

In some designs, such as a diffuser pump, the fluid passes through a ring of fixed vanes after leaving the impeller to provide a more controlled conversion of velocity into pressure.2