A fan blade comprises an airfoil having an upper surface with region that has a generally elliptical curvature. In some examples, the lower surface has a convex region and a concave region. The curvature of the concave region corresponds with the generally elliptical curvature of the upper surface; while the curvature of the convex region is defined by a substantially constant radius. Some examples also include a trailing edge flap region, which may itself include a first flap portion and a second flap portion. When mounted to a rotating hub member fan, blades with elliptical curvatures may provide air movement at significant efficiencies.
1. A fan blade configured to mount to a rotating fan hub, the fan blade comprising:
(a) a top surface having a portion generally elliptical curvature, wherein at least a portion of the curvature of the top surface is based on a first ellipse;
(b) a bottom surface having a concave region;
(c) a leading edge, wherein the top surface and bottom surface each terminate at the leading edge;
(d) a trailing edge, wherein the top surface and bottom surface each terminate at the trailing edge; and
(e) a trailing edge flap region defined by the top surface and bottom surface and located proximate to the trailing edge, wherein at least a portion of the trailing edge flap region forms the concave region, wherein the angle is at least 20°.
2. The fan blade of claim 1 , wherein the fan blade is substantially hollow.
3. The fan blade of claim 2 , wherein the fan blade has an interior including one or more bosses configured to engage a fan hub mounting member.
4. The fan blade of claim 1 , wherein the fan blade is formed of extruded material.
5. The fan blade of claim 4 , wherein the extruded material comprises aluminum.
6. The fan blade of claim 1 , wherein the first ellipse is generated based at least in part on the following equations:
x=a (COS( t )), and [1]
y=b (SIN( t )), [2]
wherein x and y provide an x-y plot of the first ellipse,
wherein a=length of a primary radius,
wherein b=length of a secondary radius, and
wherein t=angle of rotation of a radius about an origin.
7. The fan blade of claim 1 , wherein a first portion of the concave region has a generally elliptical curvature.
8. The fan blade of claim 7 , wherein the generally elliptical curvature of the concave region is based on the first ellipse.
9. The fan blade of claim 7 , wherein the first portion of the concave region is generally parallel with a corresponding portion of the top surface.
10. The fan blade of claim 1 , wherein the bottom surface further comprises a convex region.
11. The fan blade of claim 10 , wherein the convex region is defined by a substantially constant radius of curvature.
12. The fan blade of claim 11 , wherein the substantially constant radius of curvature is between approximately 2 inches, inclusive, and approximately 20 inches, inclusive.
13. The fan blade of claim 10 , wherein the bottom surface further comprises a transition region providing a transition between the convex region and the concave region.
14. The fan blade of claim 13 , wherein the transition region is defined by a radius of curvature.
15. The fan blade of claim 14 , wherein the radius of curvature is between approximately 0.25 inches, inclusive, and approximately 5.0 inches, inclusive.
16. The fan blade of claim 1 , wherein the trailing edge flap region includes a first flap portion and a second flap portion.
17. The fan blade of claim 16 , wherein the first flap portion is bent inward, toward the leading edge, relative to an adjacent portion of the bottom surface; wherein the second flap portion is bent further inward, further toward the leading edge, relative to the first flap portion.
18. A fan blade configured to mount to a rotating fan hub, the fan blade comprising:
(a) a top surface comprising:
i. a first portion with a curvature defined by a portion of an ellipse that is generated based on the following equations:
x=a (COS( t )), and [1]
y=b (SIN( t )), [2]
wherein x and y provide an x-y plot of the ellipse,
wherein a=length of a primary radius,
wherein b=length of a secondary radius, and
wherein t=angle of rotation of a radius about an origin, and
ii, a second portion having a starting point located distal of the first portion;
(b) a bottom surface having a concave region, a convex region, and a transition region;
(c) a leading edge, wherein the top surface and bottom surface meet at the leading edge; and
(d) a trailing edge, wherein the top surface and bottom surface meet at the trailing edge;
wherein the location of the starting point of the second portion of the top surface is distal of the transition region of the bottom surface.
19. A fan blade configured to mount to a rotating fan hub, the fan blade comprising:
(a) a top surface having a portion generally elliptical curvature, wherein the generally elliptical curvature of the portion of the top surface is based on a first ellipse;
(b) a bottom surface having a concave region and a convex region, with a transition region between the concave region and the convex region, wherein the convex region has a curvature defined by a substantially constant radius;
(c) a leading edge, wherein the top surface and bottom surface each terminate at the leading edge;
(d) a trailing edge, wherein the top surface and bottom surface each terminate at the trailing edge;
(e) a substantially hollow section defined by the convex region and a first portion of the top surface; and
(f) a substantially solid, curved airfoil section defined by the concave region and a second portion of the top surface.