An axial flow fan includes a hub rotatable about a central axis. The hub includes a front face and a cylindrical portion. A plurality of apertures is provided in the front face of the hub, each aperture at least partially defined by a first surface oriented non-parallel with the front face. A plurality of ribs is provided, each rib aligned with one of the plurality of apertures such that a free edge of the rib at least partially overlaps the respective one of the plurality of apertures. The fan further includes a plurality of lips, each lip coupled to the front face of the hub and aligned with one of the plurality of apertures that is not aligned with one of the plurality of ribs, each lip having a second surface, adjacent the first surface of a respective aperture, that at least partially overlaps the respective aperture.