The working principle of axial flow fan

When the impeller rotates, the gas enters the impeller from the inlet axially, and is pushed by the blade on the impeller to increase the energy of the gas, and then flows into the guide blade.  The guide vane turns the deflected airflow into axial flow, and at the same time leads the gas into the diffusing tube to further convert the kinetic energy of the gas into pressure energy, and finally leads it into the working pipeline.  

Axial fan blades work in a similar way to the wings of an airplane.  The latter, however, puts lift up on the wings and supports the weight of the aircraft, while the axial fan holds the air in place and moves it around.  

The cross section of an axial fan is usually a wing section.  The blade may be fixed in position or rotated about its longitudinal axis.  The Angle of the blade to the airflow or the blade spacing may be unadjustable or adjustable.  Changing blade angles or spacing is one of the main advantages of axial fan.  Small blade spacing Angle produces lower flow rate, while increasing spacing produces higher flow rate.  

Advanced axial fans can vary the blade spacing as the fan is running (much like a helicopter rotor), changing the flow rate accordingly.  This is called a vane adjustable (VP) axial fan.