Abstract: An axial flow fan has a casing having an air flow passage therein which terminates at one end in an air inlet port and at the other end in an air outlet port. A hub carrying fan blades is rotatably disposed within the casing and rotationally driven by a motor contained interiorly of the hub. A set of stays support the motor and hub on the casing. Projections are provided on the casing and/or hub in the region of the outlet port to effectively divide air swirls which tend to form at the outlet port into smaller size swirls thereby reducing energy losses and improving efficiency.