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Axial fan is a kind of ventilation equipment which conveys gas through axial flow, and its core impeller is composed of hub and twisted blades. When working, the motor drives the impeller to rotate, and the blades push the gas to flow along the axial direction (parallel to the direction of the rotating axis), and the gas flows directly from the inlet end to the outlet end of the fan, and the flow direction is basically unchanged, which is similar to the principle of propeller propulsion.