Centrifugal Pump Action Explained

A centrifugal pump operates by converting rotational kinetic energy, typically from a motor, into increased fluid pressure. An impeller rotates rapidly, drawing fluid into the pump casing and flinging it outwards. This outward movement increases the fluid's velocity (kinetic energy).

The pump casing, often a volute shape, is designed to slow down the fluid flow. As the velocity decreases, the kinetic energy is converted into pressure energy, according to Bernoulli's principle.

Pump vs. Turbine Analogy

This process is the inverse of a reaction turbine. In a reaction turbine, high-pressure fluid enters the runner, and the pressure energy is converted into kinetic energy and then mechanical shaft power as the fluid expands and flows through the turbine blades.

Therefore, the action of a centrifugal pump is analogous to that of a reversed reaction turbine, where the energy input is mechanical (shaft power) and the energy output is fluid pressure energy.

• Centrifugal Pump: Mechanical Energy -> Kinetic Energy -> Pressure Energy
• Reaction Turbine: Pressure Energy -> Kinetic Energy -> Mechanical Energy

The hydraulic ram operates on a different principle (using water hammer effect) and an impulse turbine relies on a change in momentum due to a high-velocity jet, making them incorrect comparisons.