【2026 Mechanical Equipment】Centrifugal pumps and axial flow pumps – The difference between \"throwing water\" and \"pushing water\"
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This post was last edited by The one on 2026-7-18 12:59. Centrifugal pump: Uses centrifugal force to \"fling\" water out. Axial flow pump: Like a propeller, it \"pushes\" water forward. One is a swing, the other is a push; their principles are completely different, and their application scenarios vary vastly.
I. Axial flow pump: The “propeller” in pipelines, moving in a straight line. Axial flow pumps belong to the category of vane pumps, and their main characteristic is that the liquid flows in the direction of the pump shaft, without any turning or change in direction.
1. Working principle: The impeller of an axial flow pump is similar to a marine propeller, with blades in the shape of wings. During rotation, the blades generate lift and thrust on the liquid, directly \"pushing\" the fluid forward in an axial direction. No radial ejection, no 90° turns, a straight path the entire way.
2. Core structure (key focus for visualization): Rotor: The main component that performs work, with propeller-style blades that generate axial thrust. Guide vane: Installed behind the impeller, it straightens the rotating water flow, eliminates vortices, and converts kinetic energy into pressure energy. Straight-through flow channel: The inlet and outlet are on a straight line, with the fluid undergoing almost no turning.
3. Features: High flow rate, low head. Small footprint, high efficiency. It is commonly used in circulating water, drainage, and high-flow transportation.
II. Centrifugal pumps: The most common type of \"water-dispelling pump\". Over 90% of the pumps used in factories are centrifugal pumps, and their working principle is well-known: water is drawn in axially and discharged radially, first being accelerated and then pressurized.
1. Working principle: Suction: Liquid is drawn in from the center of the impeller, creating a low pressure at the center. Acceleration: The high-speed rotating impeller uses centrifugal force to throw the liquid toward the edges, achieving maximum velocity. Pressure conversion: High-speed liquid enters a volute shaped like a snail shell; as the flow channel widens gradually, the flow velocity decreases, and kinetic energy is converted into pressure energy, which is used to push the water out. Simply put: the impeller is responsible for acceleration, while the volute is responsible for pressurization.
2. Features: low to medium flow rate, high head. It can handle high pressure and be used to deliver fluid to high locations (distillation towers, reactors, surge tanks). It has the widest range of applications and can be used with various media.
III. Centrifugal Pump vs Axial Flow Pump
The most vivid analogy: Centrifugal pump: it’s like a wringer, throwing the water out. Axial flow pump: Like an electric fan, it pushes air (water) straight forward.
IV. Summary: A straight line for inflow and outflow, resembling a large propeller → axial flow pump, with high flow rate and low head pressure. Seeing a volute with straight-in and straight-out ends → Centrifugal pump, universal type, capable of generating high pressure. Understanding the principles makes selection, operation, and fault diagnosis much simpler!