The axial flow fan is widely used, that is, the airflow in the same direction as the shaft of the fan blade, such as an electric fan, and the fan of the air conditioner is an axial flow mode operation fan. It is called "axial flow" because the gas flows parallel to the fan shaft. Axial fans are typically used where flow requirements are high and pressure requirements are low. The axial fan is fixed in position and moves the air. The axial flow fan is mainly composed of a fan impeller and a casing, and has a simple structure but a very high data requirement.