An axial-flow pump, or AFP, is a common type of pump that essentially consists of a propeller (an axial impeller) in a pipe. The propeller can be driven directly by a sealed motor in the pipe or by electric motor or petrol/diesel engines mounted to the pipe from the outside or by a right-angle drive shaft that pierces the pipe.

Fluid particles, in course of their flow through the pump, do not change their radial locations since the change in radius at the entry (called 'suction') and the exit (called 'discharge') of the pump is very small. Hence the name "axial" pump.

An axial flow pump has a propeller-type of impeller running in a casing. The pressure in an axial flow pump is developed by the flow of liquid over the blades of impeller. The fluid is pushed in a direction parallel to the shaft of the impeller, that is, fluid particles, in course of their flow through the pump, do not change their radial locations. It allows the fluid to enter the impeller axially and discharge the fluid nearly axially. The propeller of an axial flow pump is driven by a motor.^{[citation needed]}

Work done on the fluid per unit weight = ${\displaystyle U{\frac {(V_{\rm {w2}}-V_{\rm {w1}})}{g}}}$

where ${\displaystyle U=U_{\rm {2}}=U_{\rm {1}}}$ is the blade velocity.

For maximum energy transfer, ${\displaystyle V_{\rm {w1}}=0}$, that is, ${\displaystyle \alpha _{\rm {1}}=90^{\circ }}$

Therefore, from outlet velocity triangle, we have

$${\displaystyle V_{\rm {w2}}=U-V_{\rm {f2}}\cot \beta _{\rm {2}}}$$