CN111852941A

CN111852941A - Blade for ceiling fan

Info

Publication number: CN111852941A
Application number: CN202010334031.6A
Authority: CN
Inventors: 博比·尼尔·诺伍德; 查尔斯·威廉·博特金
Original assignee: Hunter Fan Co
Current assignee: Hunter Fan Co
Priority date: 2019-04-26
Filing date: 2020-04-24
Publication date: 2020-10-30
Anticipated expiration: 2040-04-24
Also published as: CN111852941B; CN111852940A

Abstract

The present disclosure relates to blades for ceiling fans. A ceiling fan or similar air moving device may include a motor for rotating one or more blades to drive a volume of air around a space. The blade may include a body having an outer surface with a flat top surface and a flat bottom surface and side edges. A curved transition may extend between one of the flat top surface and the flat bottom surface and the side edge. The curved transition may comprise an elliptical curve.

Description

Blade for ceiling fan

Technical Field

The present disclosure relates to a blade for a ceiling fan.

Background

Ceiling fans are machines that are typically suspended from a structure for moving a volume of air around an area. The ceiling fan includes a motor having a rotor and a stator, and suspended from and electrically coupled to the structure. A set of blades is mounted to the rotor such that the blades are rotatably driven by the rotor and the blades can be disposed in an angled orientation to move a volume of air around the area. As energy costs become more important, there is a need to improve the efficiency with which ceiling fans operate.

Disclosure of Invention

In one aspect, the present disclosure is directed to a blade for a ceiling fan having a fan motor for rotating the blade. The blade includes a body having an outer surface extending in a span-wise direction between a root and a tip and extending in a chord-wise direction between a first side edge and a second side edge. The outer surface has a top surface and a bottom surface, and a curved transition on the top surface has a bend extending to the first side edge or the second side edge, the curved transition having a chordwise length greater than any transition on the bottom surface.

In another aspect, the present disclosure is directed to a blade for a ceiling fan, the blade having a chordwise direction. The blade includes a flat upper surface and a flat lower surface opposite the flat upper surface. A side edge having a width spaces the planar upper surface from the planar lower surface. The first curved transition transitions between the first side edge and the flat upper surface, and the first curved transition has a chordwise width that is greater than any transition between the flat lower surface and the side edge.

Drawings

In the drawings:

FIG. 1 is a schematic view of a structure with a ceiling fan suspended therefrom and including a set of blades.

FIG. 2 is a top view of one of the set of vanes of FIG. 1 having a curved surface transitioning to the vane edge.

FIG. 3 is a cross-sectional view of the blade of FIG. 2 showing curved transitions to the blade edge on the top and bottom surfaces.

FIG. 4 is an enlarged cross-sectional view of one edge of the blade of FIG. 3, showing the elliptically curved surface of the blade.

FIG. 5A is a cross-sectional view of another exemplary blade illustrating a chamfered surface taken through section VA-VA of FIG. 5B.

FIG. 5B is a top down view of the blade of FIG. 5A including chamfered surfaces extending along the leading edge, trailing edge, and tip of the blade.

Detailed Description

The present disclosure relates to a ceiling fan and ceiling fan blade that may be used, for example, in residential or commercial applications. These applications may be indoor, outdoor or both. Although the present description is primarily directed to residential ceiling fans, it may also be applied to any environment in which a ceiling fan is utilized or for cooling an area using air movement.

As used herein, the term "group" or "set" of elements may be any number of elements, including only one. All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, rear, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, rearward, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Joinder references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a series of elements and relative movement between elements unless otherwise indicated. Likewise, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. The exemplary drawings are for illustrative purposes only and the dimensions, locations, order, and relative sizes reflected in the accompanying drawings may vary.

Referring now to FIG. 1, a ceiling fan 10 is suspended from a structure 12. In a non-limiting example, the ceiling fan 10 may include one or more ceiling fan components, including a suspension 14, a cover 16, a downrod 18, a motor adapter 20, a motor housing 22 at least partially enclosing a motor 24 having a rotor 26 and a stator 28, a light kit 30, and a set of blade irons 32. In other non-limiting examples, the ceiling fan 10 may include one or more controllers, wireless receivers, ball racks, pendant balls, light glasses, light cages, spindles, tip trims, switch housings, blade forks, blade tips or blade covers, or other ceiling fan components. A set of blades 34 may extend radially from the ceiling fan 10 and these blades may be rotatable to drive a volume of fluid (such as air). The blades 34 may be operatively coupled to the electric machine 24 at the rotor 26, such as via the blade irons 32. The blades 34 may include a set of blades 34 having any number of blades, including having only one blade.

The structure 12 may be a ceiling from which the ceiling fan 10 is suspended, for example. It should be understood that the structure 12 is shown schematically by way of example only and may include any suitable building, structure, household, commercial, or other environment suitable or desirable for moving air with a ceiling fan. The structure 12 may also include a power source 36, and the power source may be electrically coupled to the ceiling fan 10 to provide power to the ceiling fan 10 and the motor 24 thereon. It is also contemplated that the power source may come from somewhere outside of the structure 12, such as a battery or generator in non-limiting examples.

The controller 38 may be electrically coupled to the power source 36 to control operation of the ceiling fan 10 via the power source 36. Alternatively, the controller 38 may be wirelessly or communicatively coupled to the ceiling fan 10 and configured to remotely control the operation of the ceiling fan 10 without a dedicated connection. Non-limiting examples of controls for the ceiling fan 10 may include fan speed, fan direction, or light operation. Further, a separate wireless controller 40, either alone or in addition to the wired controller 38, may be communicatively coupled to a controller or wireless receiver located in the ceiling fan 10 to control the operation of the ceiling fan 10. It is also contemplated that in an alternative example, the ceiling fan is operated solely by the wireless controller 40 and is not operatively coupled to the wired controller 38.

Referring to FIG. 2, one blade 34 is separated from the remainder of the ceiling fan 10 of FIG. 1 for purposes of illustration. Three fastener holes 50 are provided in the blade 34 for fastening the blade to the motor 24 for rotating the blade 34 about the ceiling fan 10, preferably via the blade iron 32. Any number of fastener holes or indeed any method or mechanism of blade attachment is within the scope of the present disclosure. The vane 34 includes an outer surface 52 that includes a top surface 54. The top surface 54 terminates at a side edge 56. The top surface 54 may include a flat 58 and a top curved transition 60 that transitions from the flat 58 to the side edge 56. Alternatively, the top surface need not be flat, but may include alternative geometries that extend to the curved transition 60. In one example, the curved transition 60 may be about 1 inch from the top surface 58 to the side edge 56, while any width is contemplated. In another example, the curved transition 60 may extend between 5-40% of the chordwise width of the blade between the opposing side edges 56, although it is contemplated that the distance is less than 5% or greater than 40%.

The blade 34 also includes a tip 62 and a root 64, with the root 64 adjacent the fastener hole 50 and the tip 62 opposite the root 64. For example, the curved corners 66 transition between the apex 62 and the side edges 56, while it should be appreciated that the curved corners 66 are optional or may include other shapes, such as sharp corners. A chordwise direction may be defined between the opposing side edges 56, and a spanwise direction may be defined between the tip 62 and the root 64. The blade 34 may widen extending in a spanwise direction from a root to a tip, and the widening is defined in a chordwise direction, however any top-down shape is contemplated for the blade, such as having an outwardly extending chordwise width defined in the spanwise direction. Non-limiting examples of blade shapes may include square, rectangular, curved, angled, or rounded.

Further, the blade 34 may include a first edge 68 and a second edge 70 as the side edges 56, which may be arranged as a leading edge and a trailing edge, respectively, although the particular arrangement may vary depending on the direction of rotation of the blade. Accordingly, a chordwise direction may be defined between first edge 68 and second edge 70 to define a blade chord. As can be observed, the blade chord is shown to increase from root 64 toward tip 62.

Further, the curved transition 60 may extend along all of the first edge 68, the second edge 70, the tip 62, and/or the root 64. As shown, the curved transition 60 extends along the first edge 68, the second edge 70, and the tip 62, and is curved at the corner 66 where the side edges 68, 70 contact the tip 62.

Referring to FIG. 3 (taken through section III-III of FIG. 2), the blade 34 further includes a bottom surface 80, which may have no flat or planar portions, and a bottom curved transition 82 that transitions from the bottom surface 80 to the side edge 56. Side edge 56 includes a width 84 to define a distance separating curved transition 60 at top surface 54 from curved transition 82 of bottom surface 80. In one other example, the width 84 may be zero such that the curved transition 60 immediately transitions from the top surface 54 to the curved transition 82 of the bottom surface 80. The blade 34 may be symmetrical about the centerline 86, however it is contemplated that the blade 34 may be asymmetrical, bendable, or may include other shapes and should not be limited to the symmetrical shape shown.

Further, it should be appreciated that the blades 34 may be mounted with an angle of attack (angle of attack). The angle of attack may be defined based on the angular position of the blades 34 such that the bottom and

top surfaces

80, 54 are arranged at an angle relative to horizontal, or relative to a surface from which the ceiling fan is suspended or suspended. The angle of attack allows the vanes 34 to drive a certain volume of air and push the air in an upward or downward direction based on the direction and angle of movement of the vanes 34. Without an angle of attack, the air movement produced by the blades 34 is minimal.

Referring now to FIG. 4, an enlarged cross-sectional view of the first edge 68 of the blade 34 better illustrates the curvature of the

curved transitions

60, 82. The

curved transitions

60, 82 may provide a transition between the top and

bottom surfaces

54, 80 to the side edges 56 that are arranged perpendicular to the top and

bottom surfaces

54, 80. One or both of the

curved transitions

60, 82 may be specifically shaped to have an elliptical arc, thereby defining at least a portion of an elliptical profile for the

curved transitions

60, 82. More specifically, one or more curved transitions may be expressed by equation (1) written in standard form:

where x represents the x-axis 90 and y represents the y-axis 88 in a cartesian coordinate system. The x-axis 90 may be defined in a chordwise direction, while the y-axis 88 may be defined in a direction extending from the top surface 54 to the bottom surface 80. Furthermore, a represents the respective length of the ellipse in the x-axis, and b represents the respective length of the ellipse in the y-axis. It should also be appreciated that the ellipse may be a circle when a ═ b, since for a circle the diameter is equal, it does not define a major or minor axis. Furthermore, all other ellipses where a is not equal to b may be non-circular, defining a major axis as the largest diameter and a minor axis as the smallest diameter, respectively. Thus, it is contemplated that the

curved transitions

60, 82 may define an elliptical, non-circular elliptical, parabolic, or hyperbolic shape.

In fig. 4, the curved transition 60 from the top surface 54 to the side edge 56 may be represented, for example, by the following equation (2):

wherein a is 6 and b is 1. Further, the curved transition 82 from the side edge 56 to the bottom surface 80 may be a 90 degree circular ellipse, represented, for example, by the following equation (3):

wherein a is 2 and b is 2. It should be appreciated that although the curved transition 82 at the bottom surface 80 is shown as an ellipse having equal major and minor axes and forming a circle, it may alternatively be an ellipse having unequal major and minor axes. Further, the particular equation representing the

curved transition

60, 82 may be any suitable elliptical arc, and should not be limited to the particular arcs defined by equations (2) and (3) above.

In examples where one of the

curved transitions

60, 82 is parabolic, the equation representing at least a portion of the curvature of the

curved transition

60, 82 may be represented by the following standard form:

(x-h)²＝4p(y-k) (4)

here, the focus (focus) may be defined as (h, k + p), and the directrix may be defined as y ═ k-p. x may represent an x-axis 90 and y may represent a y-axis 88.

In an example where one of the other

curved transitions

60, 82 is hyperbolic, the equation representing at least a portion of the curvature of the

curved transition

60, 82 may be represented by the following standard form:

Or

Where equation (5) is based on a horizontal through axis (transverse axis) and equation (6) is based on a vertical through axis, which ultimately depends on the local coordinate system defining the

curved transitions

60, 82 of the blade 34. (h, k) may be used to define the center of the hyperbola, while x may represent the x-axis 90 and y may represent the y-axis 88.

The curved transition 60 at the top surface 54 may have a chordwise extent from the side edges 56 that is greater than the chordwise extent of any curved transition 82 at the bottom surface 80, as may be observed when shown by dashed

lines

88, 90 in fig. 4. This greater chordwise extent may be defined, for example, by the greater major axis of the elliptical curvature of the curved transition 60 at the top surface 54. Further, it should be appreciated that although the blade is shown as having two

curved transitions

60, 82, it is contemplated that the blade 34 includes only one curved transition 60, with the second curved transition 82 being replaced with, for example, a corner or edge, such as along the dashed line at either

curved transition

60, 82. In other words, the transition 82 at the bottom surface may be a sharp corner with little radius.

It should be appreciated that one or more

curved transitions

60, 82 between the top and

bottom surfaces

54, 80 and the side edges 56 may provide increased efficiency to the blade 34. Since both the first edge 68 and the second edge 70 may include

curved transitions

60, 82, an increase in efficiency may be perceived in either rotational direction of the blade 34. Moreover, the elliptical geometry for one or more

curved transitions

60, 82 may provide improved efficiency to blade 34, particularly transition 60 located on top surface 54, as compared to a blade without a curved transition.

It should also be appreciated that other geometries for the curved transition 60 are contemplated, such as geometries having root or logarithmic functions. For example, the curved transition 60 may be represented by a root function of degree n:

or

y＝x^1/n(8)

Where x represents a value about the x-axis, and f (x) and y represent values about the y-axis, and n represents any real number. Likewise, the nth-power root function may be a square root function or a cubic root function, or any variation thereof. Further, the curved transition 60 may be represented by a logarithmic equation as:

y＝log_b(x) (9)

where b is the logarithmic base, x represents the value about the x-axis, and y represents the value about the y-axis.

Further, it should also be understood that different combinations of curved transitions 60 may be used for a single blade. For example, a first curved transition 60 may be used for the leading edge and a different curved transition may be used for the trailing edge. In another example, a first curved transition 60 may be used for the curved transition at the top surface 54 and a different second curved transition 82 may be used at the bottom surface 80. In yet another example, the curved transition 60 may vary along the leading edge, trailing edge, upper surface, lower surface, or otherwise vary in the spanwise direction between the root and tip. Thus, it should be appreciated that an infinite number of different curved transitions may be utilized with the ceiling fan blades, which may provide further increased efficiency, as well as being utilized in either rotational direction.

Referring now to fig. 5A and 5B, a cross-sectional profile and a top view, respectively, of another blade 110 are shown. The blade 110 includes a root 108 and a tip 106, and for example, the blade may have a top-down shape substantially similar to that shown in the top-down view of FIG. 2, although other variations in the top-down shape are contemplated. The blade 110 may include leading and trailing

edges

112, 114 and top and

bottom surfaces

116, 118. Each of the leading edge 112 and the trailing edge 114 may include a rounded corner or transition 120 between the top surface 116 and the bottom surface 118.

The blade 110 may include at least one chamfered edge 122 that transitions between the top surface 116 and one of the leading edge 112 and the trailing edge 114. As shown, a chamfered edge 122 is provided at both the leading edge 112 and the trailing edge 114. In one example, the chamfered edge 122 may extend continuously around the blade 110 along the leading edge 112, the tip, and the trailing edge 114, although it is contemplated that any one or more portions of the root, the tip, the leading edge 112, and the trailing edge 114 include the chamfered edge 122. The chamfered edge 122 may contact the leading edge 112 or the trailing edge 114 at the rounded transition 120. Similarly, a rounded corner or transition 124 may be provided at the junction between the top surface 116 and the chamfered edge 122.

In one example, the chamfered edge 122 may be between 5% and 40% of the chordwise width of the blade, which extends between the leading edge 112 and the trailing edge 114 and is measured. The chamfered edge 122 may be disposed at an angle 130 of less than 180 degrees but greater than 90 degrees relative to the top surface 116. In one example, the angle 130 may be between 175 and 155 degrees. Further, the chamfered edge 122 may be disposed at an angle 132 relative to the leading edge 112 or the trailing edge 114. Angle 132 may be greater than 90 degrees. In one example, the angle may be between 95 degrees and 115 degrees. In one other alternative example, the chamfered edge 122 may be radiused, such as concave or convex.

Further, the height of the chamfered edge 122 may be such that the thickness of the leading edge 112 or the trailing edge 114 meets control requirements. Thus, the thickness between the top surface 116 and the bottom surface 118 will necessarily be thicker compared to the thickness of the leading edge 112 or the trailing edge 114 having the chamfered edge 122. Further, the rounded transition 120 may be the minimum rounded edge that requires control to contact the leading edge 112 or the trailing edge 114. In one example, the leading edge 112 or the trailing edge 114 may be flat, perpendicular to the top surface 116 and the bottom surface 118, with rounded transitions connecting the leading edge 112 and the trailing edge 114 to the top surface 116 and the bottom surface 118. Alternatively, it is contemplated that the leading edge 112 and the trailing edge 114 are fully rounded.

The blade 110 including the chamfered edge 122 provides improved blade efficiency and aerodynamic performance. Such as blades 110, may require less energy to move air per unit volume, thereby increasing the overall efficiency of the fan. Further, for the fan blade, the flat bottom surface provides a traditional design aesthetic to cater to the consumer. Thus, efficiency may be improved without sacrificing the visual appeal of the ceiling fan or the blades themselves.

The blades and sections thereof described herein provide for an increase in the total flow volume of the ceiling fan, resulting in increased efficiency, while maintaining the aesthetic appearance desired by consumers with an undecorated bottom surface of the ceiling fan. More specifically, the

curved transitions

60, 82 provide an increased downward force on the air, which increases the overall volume of airflow, while the flat upper and lower surfaces of the blade match the conventional fan blade form, providing a pleasing or attractive user aesthetic.

The various features, aspects, and advantages of the disclosure may be implemented in any arrangement of aspects including, but not limited to, the technical solutions defined in the following enumerated aspects:

1. A blade for a ceiling fan having a fan motor for rotating the blade, the blade comprising a body having an outer surface extending in a span-wise direction between a root and a tip and in a chord-wise direction between a first side edge and a second side edge, the outer surface having a top surface and a bottom surface, and at least one curved transition on the top surface having a curve extending to at least one of the first side edge and the second side edge, the at least one curved transition having a chord-wise length greater than any transition on the bottom surface.

2. The blade according to any of the preceding aspects, wherein the at least one curved transition is a first transition extending to the first side edge, and the blade further comprises a second transition between the first side edge and the flat lower portion.

3. The blade of any of the preceding aspects, wherein each of the first and second transitions comprises an elliptical bend, wherein a major axis of the elliptical bend for the first transition is greater than a major axis of the elliptical bend for the second transition.

4. The blade of any of the preceding aspects, wherein the bend defines a non-circular profile.

5. The blade according to any of the preceding aspects, wherein the at least one curved transition comprises a first transition at the junction of the first side edge with the flat upper portion and comprises a second transition at the junction of the second side edge with the flat upper surface, and the blade comprises a third transition at the junction of the first side edge with the flat lower surface and comprises a fourth transition at the junction of the second side edge with the flat lower surface.

6. The blade of any of the preceding aspects, wherein the curvature is one of an ellipse, a hyperbola, a parabola, an nth root curve, a logarithmic curve, and combinations thereof.

7. The blade of any of the preceding aspects, wherein the bend is elliptical and has a major axis extending in a chordwise direction.

8. The blade of any of the preceding aspects, wherein the bend is elliptical and has a minor axis parallel to one of the first and second side edges.

9. The blade of any of the preceding aspects, wherein the at least one curved transition defines about 1 inch wide in the chordwise direction.

10. The blade of any of the preceding aspects, wherein the at least one curved transition extends between 5% and 40% of the chordwise width between the first side edge and the second side edge.

11. The blade of any of the preceding aspects, wherein at least one transition extends along the first and second side edges to the tip and along the entire tip.

12. The blade of any preceding aspect, wherein the transition extends along the entire first side edge.

13. A blade for a ceiling fan, the blade having a chordwise direction and comprising: a flat upper surface; a flat lower surface opposite the flat upper surface; a side edge having a width that spaces the planar upper surface from the planar lower surface; and a first curved transition transitioning between the side edge and the flat upper surface, the first curved transition having a chordwise width greater than any transition between the flat lower surface and the side edge.

14. The blade of any of the preceding aspects, wherein the first curved transition has a curvature that is one of elliptical, hyperbolic, parabolic, nth root curve, logarithmic curve, and combinations thereof.

15. The blade of any of the preceding aspects, wherein the first curved transition comprises an elliptical curve.

16. The blade of any of the preceding aspects, wherein the elliptical curvature does not define a circular profile.

17. The blade of any preceding aspect, further comprising a second curved transition between the side edge and the flat lower surface.

18. The blade of any of the preceding aspects, wherein the second curved transition has a curvature that is one of elliptical, hyperbolic, parabolic, nth root curve, logarithmic curve, and combinations thereof.

19. The blade of any of the preceding aspects, wherein the first curved transition is defined wider than the second curved transition in a chordwise direction between the side edge and an opposite side edge of the blade.

20. The blade of any preceding aspect, wherein the first curved transition extends around a circumference of the blade.

Insofar as not described, different features and configurations of the individual features can be used in combination as desired. The failure of a feature to be shown in all aspects of the disclosure is not meant to be construed as it cannot be shown in all aspects of the disclosure, but is done for the sake of brevity of description. Thus, various features of the different aspects described herein can be mixed and matched as desired to form new features or aspects thereof, whether or not such new features or aspects are explicitly described. This disclosure is intended to cover all combinations or permutations of the features described herein.

This written description uses examples to detail aspects of the disclosure, including the best mode, and to enable any person skilled in the art to practice aspects described herein, including making and using any devices or systems or performing any incorporated methods. The patentable scope of the aspects described herein is defined by the claims, and may include other examples that occur to those skilled in the art. It is intended to be within the scope of the claims if these other examples have structural elements that do not differ from the literal language of the claims, or if these other examples include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A blade for a ceiling fan having a fan motor for rotating the blade, the blade comprising a body having an outer surface extending in a spanwise direction between a root and a tip and in a chordwise direction between a first side edge and a second side edge, the outer surface having a top surface and a bottom surface, and at least one curved transition on the top surface having a curvature extending to at least one of the first side edge and the second side edge, the at least one curved transition having a chordwise length greater than any transition on the bottom surface.

2. The blade of claim 1, wherein the at least one curved transition is a first transition extending to the first side edge, and further comprising a second transition between the first side edge and a flat lower surface.

3. The blade of claim 2, wherein each of the first transition and the second transition comprises an elliptical bend, wherein a major axis of the elliptical bend for the first transition is greater than a major axis of the elliptical bend for the second transition.

4. The blade of claim 1, wherein the bend defines a non-circular profile.

5. The blade according to claim 1, wherein the at least one curved transition comprises a first transition at the junction of the first side edge and a flat upper surface and comprises a second transition at the junction of the second side edge and the flat upper surface, and the blade comprises a third transition at the junction of the first side edge and a flat lower surface and comprises a fourth transition at the junction of the second side edge and the flat lower surface.

6. The blade of claim 1, wherein the curvature is one of elliptical, hyperbolic, parabolic, nth-root curve, logarithmic curve, and combinations thereof.

7. The blade of claim 6, wherein the bend is elliptical and has a major axis extending in the chordwise direction.

8. The blade of claim 6, wherein the bend is elliptical and has a minor axis parallel to one of the first side edge and the second side edge.

9. The blade of claim 1, wherein the at least one curved transition defines about 1 inch wide in the chordwise direction.

10. The blade of claim 1, wherein the at least one curved transition extends between 5% and 40% of a chordwise width between the first side edge and the second side edge.

11. The blade of claim 1, wherein the at least one curved transition extends along the first and second side edges to the tip and along the entire tip.

12. The blade of claim 1, wherein the at least one curved transition extends along the entire first side edge.

13. A blade for a ceiling fan, the blade having a chordwise direction and comprising:

a flat upper surface;

a flat lower surface opposite the flat upper surface;

a side edge having a width that spaces the planar upper surface from the planar lower surface; and

a first curved transition transitioning between the side edge and the flat upper surface, the first curved transition having a chordwise width greater than any transition between the flat lower surface and the side edge.

14. The blade of claim 13, wherein the first curved transition has a curvature that is one of elliptical, hyperbolic, parabolic, nth power curve, logarithmic curve, and combinations thereof.

15. The blade of claim 14, wherein the first curved transition comprises an elliptical curve.

16. The blade of claim 15, wherein the elliptical bend does not define a circular profile.

17. The blade of claim 13, further comprising a second curved transition between the side edge and the flat lower surface.

18. The blade of claim 17, wherein the second curved transition has a curvature that is one of elliptical, hyperbolic, parabolic, nth power curve, logarithmic curve, and combinations thereof.

19. The blade of claim 18, wherein the first curved transition is defined wider than the second curved transition in a chordwise direction between the side edge and an opposite side edge of the blade.

20. The blade of claim 13, wherein the first curved transition extends around a circumference of the blade.