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.