A fan blade comprises an airfoil having a generally elliptical top surface and a generally elliptical bottom surface. The fan blade has a lower radius of curvature toward its leading edge as compared to a higher radius of curvature toward its trailing edge. When mounted to a rotating hub member, elliptical fan blades 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 generally elliptical curvature, wherein the curvature of the top surface is based on a first ellipse;
(b) a bottom surface having a generally elliptical curvature, wherein the curvature of the bottom surface is based on a second ellipse;
(c) a leading edge, wherein the top surface and bottom surface each terminate at the leading edge; and
(d) a trailing edge, wherein the top surface and bottom surface each terminate at the trailing edge.
2. The fan blade of claim 1 , further comprising: a first radius of curvature proximate the leading edge, and a second radius of curvature proximate the trailing edge, wherein the first radius of curvature is lower than the second radius of curvature.
3. The fan blade of claim 1 , wherein the curvature of the second ellipse is dependent on the curvature of the second ellipse.
4. The fan blade of claim 1 , wherein the fan blade is substantially hollow.
5. The fan blade of claim 1 , wherein the fan blade is configured to receive a mounting member of a fan hub.
6. The fan blade of claim 5 , wherein the fan blade is secured to the fan hub by at least one fastener.
7. The fan blade of claim 1 , wherein the fan blade has a chord and a maximum thickness, wherein the maximum thickness is approximately 14.2% of the chord.
8. The fan blade of claim 1 , wherein fan blade has a chord and a maximum camber, wherein the maximum camber is approximately 15.6% of the chord.
9. The fan blade of claim 1 , wherein the fan blade is mounted to a hub at an angle of attack between approximately −1° and approximately 13°, inclusive.
10. The fan blade of claim 1 , wherein the fan blade is formed of extruded aluminum.
11. The fan blade of claim 1 , wherein the fan blade has a length between approximately 4 feet and approximately 14 feet, inclusive.
12. The fan blade of claim 1 , wherein the fan blade has a uniform cross section along the entire length of the fan blade.
13. The fan blade of claim 1 , wherein the fan blade has a hub mounting end, wherein an oblique cut is formed in the leading edge of the fan blade at the hub mounting end.
14. The fan blade of claim 1 , wherein the fan blade is substantially straight along the entire length of the fan blade.
15. 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.
16. The fan blade of claim 15 , wherein the second ellipse is generated based at least in part on the following equations:
x 2 =x (COS(⊖))− y (SIN(⊖)), and [3]
Y 2 =y (COS(⊖))− x (SIN(⊖)), [4]
wherein x 2 and Y 2 provide an x-y plot of the second ellipse,
wherein x and y are the same x and y obtained using equations [1]and [2], and
wherein ⊖=a degree to which the first ellipse is rotated about the origin.
17. The fan blade of claim 16 , wherein ⊖is approximately 0.525 radians.
18. The fan blade of claim 1 , wherein the first ellipse and the second ellipse intersect at four intersection points when the first ellipse and the second ellipse are plotted on a common graph, wherein the generally elliptical curvature of the top surface and the generally elliptical curvature of the bottom surface are based on the curvature of the first ellipse and the second ellipse, respectively, in a region between a pair of the intersection points.
19. A fan blade configured to mount to a rotating fan hub, the fan blade comprising:
(a) a top surface having a generally elliptical curvature, wherein the curvature of the top surface is based on a first ellipse;
(b) a bottom surface having a generally elliptical curvature, wherein the curvature of the bottom surface is based on a second ellipse;
wherein the first ellipse and the second ellipse intersect at four intersection points when the first ellipse and the second ellipse are plotted on a common graph, wherein the generally elliptical curvature of the top surface and the generally elliptical curvature of the bottom surface are based on the curvature of the first ellipse and the second ellipse, respectively, in a region between an adjacent pair of the intersection points.
20. A fan blade configured to mount to a rotating fan hub, the fan blade comprising:
(a) a top surface having a generally elliptical curvature, wherein the curvature of the top surface is based on a first ellipse;
(b) a bottom surface having a generally elliptical curvature, wherein the curvature of the bottom surface is based on a second ellipse;
wherein the formation of the second ellipse is based on the formation of the first ellipse.