Energy Conversion in a Centrifugal Pump

The fluid entering a centrifugal pump is instantly directed to the low pressure region at the center or eye of the impeller. Since the impeller and blading rotate, they transfer momentum to the incoming fluid. The transfer of momentum to the moving fluid raises the fluid's velocity. Since the fluid's velocity rises, its kinetic energy also rises. Fluid of higher kinetic energy is forced out of the impeller region and enters the volute.

The volute is an area of continuously rising cross-sectional area designed to convert the kinetic energy of the fluid into fluid pressure. The method of this energy conversion is similar as that for subsonic flow via the diverging area of a nozzle. The mathematical analysis of flow via the volute is depending on the general energy equation, continuity equation, and the equation associating the internal properties of a system. The key parameters persuading the energy conversion are the expanding cross-sectional area of the volute, the higher system rear pressure at the discharge of the volute, and the non-compressible, subsonic flow of the fluid. As an outcome of the interdependence of these parameters, the fluid flow in the volute, identical to the subsonic flow in a diverging nozzle, experiences a velocity reduce and a pressure rise.