An axial fan is a type of a compressor that increases the pressure of the air flowing through it. The blades of the axial-flow fans force air to move parallel to the shaft about which the blades rotate. In other words, the flow is axially in and axially out, linearly. All of the designing in an axial fan revolves around the design of the propeller that creates the pressure difference and hence the suction force that retains the flow across the fan.
The main components that need to be studied in the designing of the propeller include the number of blades and the design of each blade. Axial fans operate at high specific speed i.e., high flow rate and low head and hence adding more blades will restrict the high flow rate required for its operation.