The axial flow fan is still widely used in the present life, that is, the air flow in the same direction as the shaft of the wind blade, such as the electric fan, and the fan of the air conditioner is the fan running in the axial flow mode. The reason is called "axial flow type" because the gas flows parallel to the fan shaft. Axial flow fan is usually used in high flow requirements and low pressure requirements. Axial fan fixed position and make air move. Axial fan is mainly composed of fan impeller and housing, simple structure but very high data requirements. Generally used in metallurgy, chemical industry, light industry, food, medical equipment, mechanical equipment and civil buildings and other places ventilation or strengthen heat dissipation. If the casing is removed, it can also be used as a free fan, or it can be installed in series at intervals in a longer exhaust pipe to increase the wind pressure in the pipe.