An axial fan is a compressor that increases the pressure of the air flowing through it. The blades of an axial fan force the air to rotate parallel to the shaft, which rotates around the shaft. In other words, flow is axial and axial, linear, so their names. The design priority of the axial-flow fan is around the design of the propeller, generating a pressure difference to maintain the suction through the fan. The main components to be studied in propeller design include the number of blades and the design of each blade. Their applications include aircraft propellers, helicopters, hovercraft, ships and hydrofoils. They are also used in wind tunnels and cooling towers. If the propeller is propulsion, then efficiency is the only parameter of interest, and other parameters such as power demand and flow rate are considered meaningless. When the propeller is used as a fan, the parameters of interest include power, flow rate, pressure rise and efficiency.
Compared with duct fans, axial fans consist of fewer blades, i.e. 2 to 6. Axial flow fans operate at high specific speed, i.e. high flow rate and low head, so adding more blades will limit the high flow rate required for their operation. Due to the small number of blades, they are unable to apply their geometry to the flow, making the rotor geometry and the inlet and outlet velocity triangles meaningless. In addition, the blades are manufactured to be very long with varying blade sections along the radius.https://www.ck-stone.com/