Understanding Axial Flow Pumps and Liquid Entry

An axial flow pump is a type of pump where the fluid flows parallel to the shaft axis. This is different from other pump types like centrifugal pumps where the fluid flows outwards radially.

In an axial flow pump, the impeller blades push the liquid in a direction that is mostly parallel to the pump's rotating shaft. Think of it like a propeller pushing water. The main flow direction is straight along the axis.

Let's look at how liquid moves in different parts of the pump:

• Entry: The liquid approaches the impeller in a path that is aligned with the axis of rotation.
• Impeller: The impeller blades exert force on the liquid, increasing its pressure and velocity, primarily in the axial direction.
• Exit: The liquid leaves the impeller and the pump discharge typically still moving primarily in the axial direction relative to the pump's axis.

Comparing this to the options:

• Radially inwards or outwards flow is characteristic of radial or mixed-flow pumps, not axial flow pumps.
• Tangential entry through the sides is also not typical for the primary flow path of an axial pump; tangential components might exist due to rotation, but the main entry direction is axial.
• Entering and leaving the impeller axially perfectly describes the fundamental operation of an axial flow pump. The liquid path is predominantly parallel to the impeller shaft's axis as it goes through the impeller.

Therefore, in an axial flow pump, the liquid enters and leaves the impeller in an axial direction.