A circulatory device comprising a large
diameter fan having reinforced fan blades with a tapered airfoil shape is disclosed. The fan blades may be formed using an
extrusion method of fabrication, wherein each
fan blade may comprise a reinforced
trailing edge with a downwardly extending
flange. The benefit of forming each
fan blade with a reinforced
trailing edge of the present invention results in improved structural characteristics such that the
trailing edge of each
fan blade may be fabricated longer so as to improve aerodynamic performance. Also, the reinforced trailing edge resists tearing that may occur during
extrusion by adding the bent flanged region to at least one distal end of the trailing edge. For example, the bent portion of the trailing edge tends to rigidly orient the extruded material in a stabilized position more readily during formation. Also, the bent portion provides added strength by providing supporting forces in two dimensions that relatively parallel and perpendicular to its length so as to neutralize the adverse effects of pressure forces acting on the trailing edge of the fan blade during
extrusion.