How does an axial flow pump primarily increase head?

An axial flow pump primarily increases head through the lifting action of the blades on the propeller. In this type of pump, fluid enters parallel to the pump shaft and is accelerated by the rotating blades. These blades create lift due to their angle and design, which imparts kinetic energy to the fluid, thereby increasing its velocity as it moves through the pump. This kinetic energy is then converted into pressure, resulting in an increase in head.

The design of the blades is crucial; as they spin, they create a pressure differential that moves the fluid through the pump while elevating its potential energy, leading to an increase in head. This mechanism is fundamentally different from how other types of pumps operate, where changes in velocity and pressure occur in different components, such as volutes or casings. Therefore, the lifting action of the propeller blades is the primary mechanism by which axial flow pumps increase head.