Fluid Turbine Rotor Blade

Abstract

A fluid turbine has semi-spherical, hollow blades arrayed about a vertical axis, and a passive wildlife-deterrent system using ultraviolet coloration of the rotor blades. The turbine's blade shape reduces drag on a convex side and increases drag on a concave side. Part of the center of the array of rotor blades is open, allowing flow through the center of the array. The spherical form enhances fluid flow through the center of the array and results in rotational force on a downwind blade, and directs fresh air into bypass flow.

Claims

1. A rotor blade for a vertical axis fluid turbine comprising: a revolute surface with concave side and a convex side, a vertical edge and an edge that lies on the surface of a datum sphere; and a substantially vertical central axis parallel to the vertical edge through the center of said datum sphere; and a space between said vertical central axis and said vertical edge of said revolute surface; and a surface perpendicular to said revolute surface, engaged along said edge that lies on the surface of a datum sphere and coincident with said datum sphere; wherein fluid flowing over said concave side exerts a force about said central axis, and is compressed by said surface perpendicular to said revolute surface as the fluid moves off the surface.

2. The rotor blade of claim 1 wherein the ratio of the volume of space between said vertical central axis and said vertical edge of said revolute surface and the volume surrounded by said revolute surface in combination with said surface perpendicular to said revolute surface is between 1:2 and 1:4.

3. The rotor blade of claim 1 wherein the ratio of the volume of space between said vertical central axis and said vertical edge of said revolute surface and the volume surrounded by said revolute surface in combination with said surface perpendicular to said revolute surface is 1:3.

4. A vertical axis fluid turbine comprising: a rotor assembly having at least two rotor blades; each rotor blade in said rotor assembly having a revolute surface bent to a concave side and a convex side, a vertical edge and an edge that lies on the surface of a datum sphere; and a substantially vertical central axis parallel to the vertical edge of said at least two rotor blades, said central axis extending through the center of said datum sphere; and a space between said vertical central axis and said vertical edge of said revolute surface on each of said at least two rotor blades; and each of said at least two rotor blades having a surface perpendicular to said revolute surface, engaged along said edge that lies on the surface of a datum sphere and coincident with said datum sphere; and each rotor blade in said rotor assembly having a semi spherical vertical cross section; wherein fluid flowing over one of said at least two rotor blades flows through said space between said vertical central axis and said vertical edges and then flows over another of said at least two rotor blades and is compressed by said surfaces perpendicular to said revolute surfaces as the fluid exits the rotor assembly.

5. The vertical axis fluid turbine of claim 4 wherein the ratio of the volume of space surrounded by said vertical central axis and said vertical edge of said revolute surface on said at least two rotor blades, within said datum sphere, and the volume of said datum sphere is between 1:5 and 1:7; wherein said space is sufficient to allow fluid flowing over one of said at least two rotor blades to flow through said space and flow over at least one other of said at least two rotor blades, exerting a force on each of said at least two rotor blades.

6. The vertical axis fluid turbine of claim 4 wherein the ratio of the volume of space between said vertical central axis and said vertical edge of said revolute surface on said at least two rotor blades within said datum sphere, and the volume of said datum sphere is 1:6.

7. A vertical axis fluid turbine comprising: a rotor assembly having at least four rotor blades; each rotor blade in said rotor assembly having a revolute surface bent to a concave side and a convex side, a vertical edge and an edge that lies on the surface of a datum sphere; and a substantially vertical central axis parallel to the vertical edge of each of said at least four rotor blades, said central axis extending through the center of said datum sphere; and a space between said vertical central axis and said vertical edge of said revolute surface on each of said at least four rotor blades; and each of said at least four rotor blades having a surface perpendicular to said revolute surface, engaged along said edge that lies on the surface of a datum sphere, said surface being coincident with said datum sphere; and each rotor blade in said rotor assembly having a semi spherical vertical cross section; wherein fluid flowing over one of said at least four rotor blades flows through said space between said vertical central axis and said vertical edges and then flows over another of said at least four rotor blades, exerting a force on each, and said fluid is compressed by said surfaces perpendicular to said revolute surfaces as the fluid exits the rotor assembly at a higher velocity than the ambient flow.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a front perspective view of an example embodiment;

[0014] FIG. 2 is a top, cross section flow diagram of the embodiment of FIG. 1;

[0015] FIG. 3 is a color diagram of the flow diagram of FIG. 2;

[0016] FIG. 4 is a side, cross section, flow diagram of the embodiment;

[0017] FIG. 5 is a color diagram of the flow diagram of FIG. 4;

[0018] FIG. 6 is an additional color diagram of the flow diagram of FIG. 4;

[0019] FIG. 7 is a front perspective view of a rotor blade of the embodiment;

[0020] FIG. 8 is a rear perspective view of a rotor blade of the embodiment;

[0021] FIG. 9 is a cutaway perspective view of the embodiment.

DESCRIPTION

[0022] In FIG. 1 rotor blades 110 are arrayed about a central axis 121. Each rotor blade's inner longitudinally oriented surface is concave 113 and each longitudinally oriented outer surface is convex 111. The concave inner surface 111 experiences increased drag in a fluid stream while the convex side 113 experiences relatively less drag. Latitudinally, each rotor blade has an upper surface 112 and a lower surface 114 which are both substantially perpendicular to the concave/convex surfaces 113/111. The upper surface 112 and lower surface 114 are coincident with a spherical datum surface.

[0023] The rotor blades 110 are connected to a shaft 117 that turns a generator 115. A housing 119 is located proximal to the rotor blades 110 and houses electronic controls. The apparatus is mounted on a base 123. The overall shape of the blades when assembled is that of a sphere. In an example embodiment, rotor blades are constructed of a fiber-reinforced polymer combined with a dye that appears fluorescent to birds and as monochromatic to humans.

[0024] The illustration in FIG. 2 is a top, cross-section view depicting flow through the turbine 100. The example embodiment shows four rotor blades 110, each having a concave side 113 and a convex side 111. One blade is at θ=0°, one at θ=90°, one at θ=180°, and another at θ=270°, One skilled in the art understands that the convex side 111 exhibits less drag when facing the fluid stream than a concave side 113. The rotor blade at θ=180°, while the concave side 113 exhibits greater drag when facing the fluid stream, causing rotation of the blades. In this view the apparatus is rotating in a clockwise rotation.

[0025] FIGS. 2 and 3 show a fluid stream meeting the turbine as an impediment, causing some of the stream 132 to flow past the turbine. This is referred to as bypass flow 132. The primary means of energy extraction occurs when fluid flows into the concave side of a blade 113, at position forming the resultant force vector 140. Some fluid streams flowing into the concave side of the blades at positions θ=270°, and θ=0°, are depicted by lines 136. Another portion of the fluid stream flows into the concave side of a blade at position θ=270 is shown as fluid stream 138. In one example, a portion of the fluid stream 136 and another portion of the fluid stream 138 encounters the concave side of a rotor blade at θ=270°, initially interacting with the concave side of the blade at θ=270°, creating the resultant force vector 144. The fluid then flows through the center of the turbine to the concave side of a rotor blade at position θ=90°, creating the resultant force vector 142. Some of the fluid 138 passes through the open center 139 of the turbine and creates a resultant force vector 142. Other portions of the fluid stream 134 flow through the center and out an upstream blade at θ=180°, creating force vector 146 before exiting the turbine to mix with bypass flow 132.

[0026] FIG. 4 is a flow diagram depicting a fluid stream moving through a vertical cross-section of the rotor blades. The spherical form of the rotor assembly guides the portion of the stream 136 through the open center of the rotor assembly. The portion of the fluid stream 136 is compressed as it passes through the turbine. Specifically, as it passes through the rotor assembly, some of the flow 136 becomes compressed, increasing in velocity. This compressed, higher-velocity fluid stream is depicted in dashed-line area 137. The higher velocity flow 137 then mixes with the relatively slower bypass flow 132 in the region of the turbine wake.

[0027] FIG. 5 shows a computer fluid-dynamics image of some of the wake flow 137 traveling at a relatively higher velocity than the surrounding wake flow 141. This is further supported by the image in FIG. 6.

[0028] FIG. 7 is a front perspective view of an example rotor blade 110 of the embodiment. The rotor blade 110 has a concave surface 113, a top surface 112 and a bottom surface 114. A space 116 is open in the center portion of the rotor blade 110. The top surface 112 and bottom surface 114 are coplanar. All four surfaces form a semi-spherical datum surface revolving around central axis 118.

[0029] FIG. 8 is a rear perspective view of an example rotor blade 110 of the embodiment. The rotor blade 110 has a convex surface 111, a top surface 112 and a bottom surface 114. A space 116 is open in the center portion of the rotor blade 110. A ratio between the area occupied by the open space 116 and the area occupied by the blade; made up of top surface 112, bottom surface 114 and convex/concave surface 111/113 (FIG. 8) is between 1:2 and 1:4 and in one embodiment is approximately 1:3. The top surface 112 and bottom surface 114 are coplanar. All four surfaces form a semi-spherical datum surface revolving around central axis 118.

[0030] FIG. 9 is a cutaway, perspective view showing the open center 116 and an example fluid stream line 136 creating force vectors 144 and 142 as it passes through the turbine. One skilled in the art understands how the flow diagram of FIG. 2 applies to the perspective view of FIG. 9. In some embodiments the ratio of open space in the center of the turbine to the area occupied by the rotor blades is between 1:5 and 1:7 and in one embodiment is approximately 1:6.

[0031] While example embodiments have been described herein, it is expressly noted that these embodiments should not be construed as limiting, but rather that additions and modifications to what is expressly described herein also are included within the scope of the invention. Moreover, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations are not made express herein, without departing from the spirit and scope of the invention.