High efficiency, low axial profile, low noise, axial flow fan

A one-piece high efficiency, low axial profile, low noise, axial flow fan comprising a hub that is rotatable about an axis, a plurality of skewed, airfoil-shaped fan blades distributed circumferentially around said hub and extending both radially and axially away from said hub, each blade having a root joining with said hub, a circular band that is concentric with and spaced radially outwardly from said hub, each blade having a crest joining with said band, and wherein the axially rearward face of said hub, the axially rearward edge of said band and the tails of said blades occupy a common plane that is perpendicular to said axis, and in which each of said blades is constructed substantially in accordance with parameters defined as

• ______________________________________ R C .theta. .epsilon. Y OFFSET SKEW (p.u.) (p.u.) (deg.) (deg) (mm) (adjusted) ______________________________________ 0.43 0.87 42 71.7 0 0.0 0.50 0.80 27 75.6 0 2.5 0.57 0.67 19 75.9 0 3.7 0.64 0.54 18 75.8 0 2.4 0.72 0.47 17 74.9 0 0.9 0.79 0.40 17 73.1 0 -1.2 0.86 0.34 17 72.3 0 -4.4 0.93 0.29 17 72.3 0 -8.0 1.00 0.23 20 72.8 0 -15.4 ______________________________________
• wherein R(p.u.) is radial distance from axis as a function of the fan's radius, C(p.u.) is chord length of the blade's airfoil-shaped cross section at the corresponding radial distance as a fraction of the cross section's radial distance, .theta. is the camber angle of the cross section, .epsilon. is the stagger angle of the cross section, and Y-OFFSET is measured between the trailing edge of the cross section and the back of the hub.