CROSS-REFERENCE TO RELATED APPLICATIONS
N/A
BACKGROUND OF THE INVENTION
The present invention relates to devices having blades that can be spun about a spin axis in response to a flow of fluid (such as air or water) acting upon the blades and/or that can move fluid in response to a source of power spinning the blades about the spin axis.
Of course, the idea of a device having blades spinnable about a spin axis for generating torque that is converted into mechanical work or electrical power in response to fluid flow acting upon the blades has existed for many years. (Note that “blade,” as used herein, is not limited to any particular aerodynamic or hydrodynamic shape and may sometimes be referred to by other names such as plate, panel, board, vane, wing, sail, airfoil or hydrofoil.) Likewise, the idea of applying mechanical or electrical power to such a device to spin the blades for moving fluid relative to an object (which, as used herein includes such movement of the fluid for the purpose of producing a thrust that can be applied to the object) is well known. Among these ideas are designs employed in classical windmills, rotary fans, wind turbines, rotary pumps, air and water craft propellers, and helicopter rotors. Many of these designs include blades with flat or curved surfaces made of material such as cloth, wood, metal, plastic, fiberglass, or graphite. Frequently, in these designs, each of the blades has a longitudinal axis oriented parallel to a radial wherein the radial projects outwardly from the spin axis in a direction perpendicular to the spin axis. The apparatus is typically operated with its spin axis substantially parallel to (which includes it sometimes being slightly offset from) the direction of the undisturbed relative fluid-flow (the direction of the fluid flow as it approaches the device, at a location just before said direction is disturbed by the presence of the device). And, each of the blades generally has a chord wherein the chord is oriented at a chord pitch angle (e.g., for spinnable blades of devices such as turbines and propellers, an angle between the chord and a plane perpendicular to the spin axis). Some blades have a twist (changes in pitch angles at different radial distances from the spin axis, usually a gradual decrease in pitch angle as radial distance increases). References made to the pitch of a blade may generally be understood as referring to the chord pitch angle of a blade that has no twist or to the overall pitch of a blade that has a twist with known values for its various chord pitch angles relative to the overall pitch of the blade.
At least some of the above noted ideas or improvements on them are reflected in previously issued U.S. patents. For example: U.S. Pat. No. 479 issued to Makely on Nov. 23, 1837, discloses a wind wheel that is self-directing with its vanes hinged for allowing them to turn edgewise in the wind; and, with the vanes attached to cords (or chains) wherein one or more weights pull on the cords to draw the surfaces of the vanes in the wind (apparently thereby allowing the pitch of each vane to adjust in response to the force of the wind and the countering pull on the cords). U.S. Pat. No. 2,215 issued to Davis on Aug. 11, 1841, discloses a windmill that has a wind wheel mounted on a tower, with a governor responsive to rotational speed of the wind wheel for turning the tower (thus, the wind wheel) away from direct action of a high wind (thereby partially arresting the wind wheel's rotational speed) and turning the tower back upon sufficient reduction in the rotational speed (as when the wind becomes calmer). U.S. Pat. No. 4,190 issued to Parker on Sep. 11, 1845, discloses a windmill with a wind wheel mounted on a platform and a two-rudder mechanism for regulating the rotational speed of the wheel, wherein one rudder is fixed and the other is connected by a vertical pin (hing) to the platform, the hinged rudder being rotatable (to present more of a feather-edge to the wind) by a wind strong enough to overcome the countering pull from a weight attached to the hinged rudder via a cord, thus allowing the fixed rudder to turn the platform so the front of the wind wheel presents an obtuse angle to the wind.
U.S. Pat. No. 11,324 issued to Erdle on Jul. 18, 1854, discloses a wind wheel with wings that are located between a hub and a rim and are pivotable about their respective longitudinal pivot axes by a mechanism that includes a lever operated piston shaft for regulating the degree of pivot. U.S. Pat. No. 11,629 issued to Halladay on Aug. 29, 1954, discloses a wind wheel with sails mounted on radial spindles that are rotatable via levers by a hydraulic or other form of governor for changing the angle of the sails to present greater or less surface to the wind. U.S. Pat. No. 11,630 issued to Vice on Aug. 29, 1854, discloses a wind wheel with sails comprising cloth surfaces wherein the coverage of the cloth surface is adjustable by turning (via a rod and gear mechanism) a radial leading edge roller. U.S. Pat. No. 192,931 issued to Palmer on Jul. 10, 1877 (reissued as RE 8,235 to Palmer on May 14, 1878), discloses a windmill with fans that are pivotable in and out of the wind on axes oriented at right angles to radial lines, wherein the pivot angle can be changed by force of the wind overcoming a countering force from a spring. U.S. Pat. No. 542,305, issued to Fuller on Jul. 9, 1895, discloses a windmill comprising a wheel with hollow spokes, each spoke having part of a blade carrying rod located and pivotable within the spoke with the rod's pivot axis near an edge of its respective blade, the spokes (thus the pivot axes) extending from a hub and shown inclined (dished) relative to the hub axis, and means for controlling the pivot of the rods and thereby the inclination (pitch) of the blades. U.S. Pat. No. 612,464 issued to Stewart on Oct. 18, 1898, discloses a windmill that includes a sail (blade) bearing wheel, each sail being attached to an angle bracket with the angle bracket hingedly connected via a block to the circumference of the wheel, with the hinge axis perpendicular to a radial and with the blade's longitudinal axis perpendicular to the hinge axis and the blade's chord at an angle to the hinge axis, there being means provided for regulating the pivot of the blades about their respective hinge axes.
U.S. Pat. No. 774,168 issued to Formander on Nov. 8, 1904, discloses a windmill having a pair of concentrically shafted wheels, each wheel having a hub and its own set of blades, the blades on the respective hubs being set in opposite directions, so that wind passing through will drive them in opposite directions. U.S. Pat. No. 1,516,472 issued to Beaty on Nov. 18, 1924, discloses a windmill with a wheel having a hub from which extends a plurality of forwardly inclined masts and rearwardly inclined spokes, wherein triangular sails in diagonal position between mast and spoke have one edge secured along the mast and the top of the rear edge attached to a sail controlling rope for tightening up and releasing the sail (by operation of a pully-and-spring mechanism) in response to wind pressure. U.S. Pat. No. 2,054,383 issued to Ludewig on Sep. 15, 1936, discloses a wind power apparatus having an axle, a hub, and blades, each blade shown attached to a bent rod by which the blade is obliquely hinged to the hub (the rod having a hinged end on one side of the bend, the hinged end being collinear with the hinge axis, with the hinge axis shown in, but not limited to being in, a plane that is perpendicular to a radius of the hub, and having a blade bearing end on the other side of the bend, the blade being attached to the blade bearing end which is shown, but not limited to being, parallel to the blade's longitudinal axis, the blade thus able to swing into and out of a plane that is radial to the axle (each blade being shown as swinging from forward of the plane), and the bend forming an angle other than a right angle, e.g., 30 degrees so that said swinging of the blade changes its pitch angle due to the oblique relation of the blade to the hub. And, U.S. Pat. No. 2,360,792 issued to Putnam on Oct. 17, 1944, discloses a wind turbine having a shaft, about which the turbine rotates, and blades pivotally connected to the shaft, with means for controlling the angular positions of the blades about their own longitudinal axes (to vary the pitch of the blades), and means for permitting the blades to independently cone (independently pivot, within a plane that includes the axis of the shaft, to an angular position wherein the blade's longitudinal axis is at a positive—down-wind- or negative—up-wind-angle (that is, an angle other than 90 degrees relative to the shaft axis).
It is believed that the present invention offers advantages of simplicity and economy over previous ideas for spinnable fluid-dynamic bladed devices.
SUMMARY OF INVENTION
The invention relates to a bladed device that can in some embodiments be used as a turbine, wherein the device is acted upon by a relative flow of fluid for spinning the blades about a spin axis (e.g., where the blades are connected to a shaft for converting the relative flow of fluid into useful electrical or mechanical power); and can, in the same or other embodiments, be used as a propeller, wherein the blades are spun about a spin axis by an external power source to produce or change the relative flow of fluid—e.g., where a source of electrical or mechanical power is coupled to a shaft for spinning the blades about the spin axis and converting the power into thrust. (As used herein, the relative flow of the fluid—sometimes shortened to fluid flow—is the relative movement between the fluid and the device so, for example, it does not matter whether the fluid is moving past the device or the device is moving through the fluid, or both.)
The device comprises at least one blade pair, such as a first blade and a second blade. Each blade has its respective leading edge, trailing edge, root, and tip. Each root being proximal and each tip being distal relative to the spin axis. And, as used herein, the leading edge is the edge of the blade that precedes and the trailing edge is the edge of the blade that follows while the blade is spinning in its normal operation. (In a simple embodiment, the leading and trailing edges are parallel, but they may be non-parallel in other embodiments.) Wherein, preferably, the blades are connected, or connectable, proximate their respective roots to a common shaft, preferably via a hub, wherein preferably the common shaft spins with the blades about the spin axis (although, optionally, the connection may permit the blades to spin about the spin axis independent of any spin by the shaft). The spin axis is normal to a hub plane, the hub plane being a selected reference plane that may or, optionally, may not pass through the hub.
The first blade is canted about a first-blade canting axis by a first-blade canting angle and the second blade is canted about a second-blade canting axis by a second-blade canting angle. Either or both of the first and second blades may be further canted relative to the hub plane by, for example, canting a portion of the hub (to which the blade is connected) about a hub canting axis. Preferably, one of the first and second blades is canted rearward and the other canted forward of the hub plane; although, optionally, both blades may be canted forward or rearward of the hub plane. The magnitude of the first-blade canting angle may be the same as or different from that of the second-blade canting angle. (As used herein, “magnitude” is directionally neutral, such that the magnitude of an angle of a particular number of degrees measured in one rotational direction has the same magnitude as another angle of the same number of degrees measured in the opposite rotational direction; so, for example, plus 20 degrees has the same magnitude as minus 20 degrees.) The angles by which the first and second blades are canted may be fixed (allowing of course for variations that may result from the normal effects of the fluid and other forces acting on the blade and/or hub in the course of the device's operation, which may temporarily bend or otherwise deform the blade and/or hub as compared to its at-rest no-fluid-flow configuration); or, may be adjustable by, for example, the blade and/or hub being rotatable about its particular canting axis (e.g., by being bendable or hinged—preferably with some mechanism, such as stiffness of the material or an attached ratchet, gear, latch, brake, or spring, acting on the blade and/or hub for securing or limiting the canting angle).
Each of the first-blade and second-blade canting axes is oriented at respectively a first-blade canting axis angle and a second-blade canting axis angle, each of which is other than 90 degrees relative to respectively a first radial and a second radial (the first radial being a reference radial associated with the first blade and the second radial being a reference radial associated with the second blade), with each of the first and second radials extending perpendicularly away from the spin axis and being separated from one another by a radial separation angle such as between 30 and 150 degrees. (The canting axis angle for either or both blades may be varied from what it is in one configuration of the device to a different angle for another configuration of the device.) And, preferably, particularly in a 4-bladed device, the first-blade and second-blade canting axis angles and the radial-separation angle may be selected for the first-blade and second-blade canting axes to be collinear with or parallel to one another.
The first blade has a first chord contained within a first chord plane and the second blade has a second chord contained within a second chord plane. The first and second chord planes are reference planes wherein the first chord plane is normal to the first radial and passes through the first blade at a first selected radial distance from the spin axis, and the second chord plane is normal to the second radial and passes through the second blade at a second selected radial distance (which may be equal to the first selected radial distance) from the spin axis. Each of the first and second chords is a straight line running from its respective blade's trailing edge to its respective blade's leading edge. The first chord is oriented at a first-chord pitch angle and the second chord is oriented at a second-chord pitch angle (which may be the same as the first-chord pitch angle), each chord pitch angle being measured relative to the hub plane. Preferably, the first and second chord planes are respectively oriented for the first radial, or a radial parallel to it, to bisect the planform of the first blade at the first chord plane and for the second radial, or a radial parallel to it, to bisect the planform of the second blade at the second chord plane. (As used herein, a blade's planform is the blade's apparent contour in a front view (looking toward the front of the device along the direction of the spin axis) if the blade were uncanted—uncanted being the orientation of the blade if the canting angle(s) that cause or contribute to the blade being canted, as discussed and/or shown herein, were changed to zero degrees. Thus, since the blades are described and shown herein canted, their appearance in the accompanying front-view figures is slightly distorted from their planforms.)
The magnitude of the first chord pitch angle is determined at least in part by the amount by which the first-blade canting axis angle deviates from 90 degrees and by the magnitude of the first-blade canting angle; and, the magnitude of the second-chord pitch angle is determined at least in part by the amount by which the second-blade canting axis angle deviates from 90 degrees and by the magnitude of the second-blade canting angle. Thus, for a given first-blade canting axis angle, a change in the first-blade canting angle would result in a change in the first-chord pitch angle; and, for a given second-blade canting axis angle, a change in the second-blade canting angle would result in a change in the second-chord pitch angle. And, likewise, for a given first-blade canting angle, a change in the first-blade canting axis angle would result in a change in the first-chord pitch angle; and, for a given second-blade canting angle, a change in the second-blade canting axis angle would result in a change in the second-chord pitch angle. In other words, the first-chord pitch angle is coupled to the first-blade canting angle and first-blade canting axis angle, and the second-chord pitch angle is coupled to the second-blade canting angle and second-blade canting axis angle.
Note that the connection between the shaft and either of said blades may be direct or indirect (such as via a hub or other linking mechanism). Where there is a hub or other linking mechanism (also referred to herein simply as a hub), the connection between the hub and either or both of the blades (hub-blade connection) may be fixed (e.g., where the hub and blade are of the same piece of material, or separate pieces attached together such as by being welded, bolted, or adhered together) and (as mentioned above) may permit adjustment of the blade's canting angle; and, said hub-blade connection may be between different pieces of material or between different portions of a single piece of material (e.g., where a hub and blade are different portions of a single piece of material and the connection between them is a bend in the material made about a canting axis). (Thus, a single continuous piece of material having two blade portions, each blade portion extending outwardly from the spin axis in a different direction, may constitute a blade pair, even if the piece of material appears to be a single blade, which might be the case if the radial separation angle between the blade portions is or approximates 180 degrees and the blade portions are canted as the result of a gentle bend in the material.) Preferably, the connection between the blades and the shaft is effective for spinning the shaft about the spin axis in response to the blades being acted upon by a fluid flow (e.g, for converting the energy from the fluid flow into useful power) or for the blades in a fluid medium to be rotated about the spin axis in response to application of an external source of rotational power to the shaft (e.g., for propelling the fluid and/or moving an object through the fluid). Alternatively, however, the shaft may be fixed relative to the spin axis with the blades remaining spinnable about the spin axis—such as where the blade assembly is coupled to another device by means other than by turning the shaft (e.g., by turning an induction or friction device, gear, or pulley) or where the purpose of the spinnable blade assembly is simply amusement or decoration (e.g., a pinwheel).
The present invention is intended to include all aspects, embodiments, and uses of it that are consistent with the disclosures herein, without limitation to the specific aspects and embodiments described or shown herein. Thus, the foregoing summary is not intended to limit any of the claims, which are based on the overall disclosure herein and limited only by the claims themselves and their equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more clearly understood by reference to this specification in view of the accompanying drawings, in which:
FIG. 1 is a perspective view of an embodiment of the present invention, shown in a 4-blade configuration with a simple two-layer hub.
FIG. 2 is a front view of the embodiment in FIG. 1.
FIG. 2A is a cross-sectional view of a first blade on the embodiment in FIG. 1, as seen through sectional cut I-I; FIG. 2B is a cross-sectional view of a second blade on the embodiment in FIG. 1, as seen through sectional cut II-II; and, FIGS. 2C and 2D are cross-sectional views of the blade in FIG. 2B as it would appear through sectional cut II-II if its airfoil shape were changed to one or the other of two alternative airfoil shapes.
FIG. 3 is a left side view of the embodiment in FIG. 1.
FIG. 4 is a front view of the embodiment in FIG. 1, rotated 45 degrees about the spin axis from the orientation shown in FIG. 2.
FIG. 5 is a left side view of the embodiment in FIG. 1, with its orientation about the spin axis being the same as shown in FIG. 4.
FIG. 6 is a front view of a second embodiment of the present invention, shown in a 4-blade configuration with a one-layer hub.
FIG. 7 is a left side view of the embodiment in FIG. 6.
FIG. 8 is a perspective view of a third embodiment of the present invention, shown in an 8-blade configuration.
FIG. 9 is a front view of the embodiment in FIG. 8.
FIG. 9A is a cross-sectional view of a first blade on the embodiment in FIG. 8, as seen through sectional cut III-III; and, FIG. 9B is a cross-sectional view of a second blade on the embodiment in FIG. 8, as seen through sectional cut Iv-Iv.
FIG. 10 is a left side view of the embodiment in FIG. 8.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, FIGS. 1-5 illustrate an embodiment of the present invention in the form of a simplified two-layer 4-blade device 1 in the presence of a relative fluid flow 2 (flow not indicated in FIG. 2 or 4 but indicated by an arrow in FIG. 1 and by two arrows in FIGS. 3 and 5). As shown in FIG. 1, a first blade 3 and second blade 4 form a first blade pair 5 and a third blade 6 and fourth blade 7 form a second blade pair 8. The first blade 3 is shown with a first-blade leading edge 9, a first-blade trailing edge 10, a first-blade root 11, and a first-blade tip 12. The second blade 4 is shown with a second-blade leading edge 13, a second-blade trailing edge 14, a second-blade root 15, and a second-blade tip 16. The third blade 6 is shown with a third-blade leading edge 17, a third-blade trailing edge 18, a third-blade root 19, and a third-blade tip 20. And, the fourth blade 7 is shown with a fourth-blade leading edge 21, a fourth-blade trailing edge 22, a fourth-blade root 23, and a fourth-blade tip 24.
Also, for the embodiment in FIGS. 1-5, a two-layer hub 25 is shown having a rear hub layer 26 (hidden but location indicated in FIG. 3) and a forward hub layer 27. (The two-layer hub 25 is represented by its two separate hub layers 26,27 in FIGS. 2-5.) In FIGS. 1-5, the first blade 3 is connected along the first-blade root 11 to one edge of the rear hub layer 26 and the third blade 6 is connected along the third-blade root 19 (hidden in FIG. 3) to the opposite edge of the rear hub layer 26, and the second blade 4 is connected along the second-blade root 15 to one edge of the forward hub layer 27 and the fourth blade 7 is connected along the fourth-blade root 23 to the opposite edge of the forward hub layer 27. In FIGS. 1-5, a shaft 28 (hidden in FIG. 2) penetrates the two-layer hub 25 and is shown capped by a nose cone 29, the shaft 28 extending rearward of the rear hub layer 26 as shown in FIGS. 1 and 3-5, with the nose cone 29 shown in FIGS. 1-3 and 5 as having a diameter greater than that of the shaft 28 and protruding forward of the forward hub layer 27. As seen in FIGS. 1, 3 and 5, the shaft 28 center-line is collinear with a spin axis 30, the blades 3,4,6,7 being rotatable (spinnable) about the spin axis 30 with the two-layer hub 25 spinning with the blades. The shaft 28 (and typically its nose cone 29) may be connected to the two-layer hub 25 and the blades 3,4,6,7 (such as by being fixed or geared to the two-layer hub 25) for the shaft 28 to spin in response to the spinning of the blades 3,4,6,7 (or vice verse); or, may be connected in a manner (such as by providing sufficient tolerance between the shaft 28 and the two-layer hub 25) for the shaft 28 to remain stationary while the two-layer hub 25 spins.
In FIGS. 1-5, each of the blades 3,4,6,7 is canted relative to a reference hub plane 31. (Although the hub plane 31 is not shown in FIGS. 1, 2 and 4, it is a reference plane oriented normal to the spin axis 30 with its location indicated in FIGS. 3 and 5 as being at the interface between the rear hub layer 26 and the forward hub layer 27. (The hub plane alternatively may be located at a different position along the spin axis, such as mid-thickness of the hub layer with which it is associated.) In regard to the first blade pair 5, the first blade 3 is shown canted about a first-blade canting axis 32 at a first-blade canting angle 33 rearward of the hub plane 31 and the second blade 4 is shown canted about a second-blade canting axis 34 at a second-blade canting angle 35 forward of the hub plane 31. And, in regard to the second blade pair 8, the third blade 6 is canted about a third-blade canting axis 36 at a third-blade canting angle 37 rearward of the hub plane 31 and the fourth blade 7 is canted about a fourth-blade canting axis 38 at a fourth-blade canting angle 39 forward of the hub plane 31. Also, for the embodiment shown in FIGS. 1-5, all of the blade canting axes 32,34,36,38 are reference lines contained within the hub plane 31, the first-blade canting axis 32 being collinear with the second-blade canting axis 34 and the third-blade canting axis 36 being collinear with the fourth-blade canting axis 38; and, all of the blade canting angles 33,35,37,39 have the same magnitude (although the forward and rearward blade canting angles are in opposite directions). (The blade canting axes are not indicated in FIGS. 1 and 3, but are indicated in FIGS. 2, 4 and 5. The blade canting angles are not indicated in FIGS. 1, 2 and 4, but are indicated in FIG. 5 where the view is looking in the direction of the blade canting axes and thus reflects the true magnitude of the blade canting angles, and in FIG. 3 for the second and fourth blades 4,7 where the view is offset from the direction of the blade canting axes and thus reflects distorted magnitudes for the second-blade and fourth-blade canting angles 35,39, the distorted second-blade and fourth-blade canting angles being identified as 35′,39′ respectively. And, although FIG. 5 shows the magnitudes of the blade canting angles as equal to one another, other embodiments may have the magnitude of each blade canting angle different from the magnitude(s) of one, some, or all of the other blade canting angles.)
For the embodiment in FIGS. 1-5, the blade canting axes 32,34,36,38 are reference lines within the hub plane 31 (although, in another embodiment, one or more of the blade canting axes could be in one or more planes parallel to the hub plane). And, preferably (as indicated in FIGS. 2, 4 and 5) each blade canting axis is collinear with or parallel to its respective associated blade root. (In FIG. 5, each blade canting axis 32,34,36,38 is represented simply as a point since the view in that figure is in the same direction as the blade canting axes. And, although the blade canting axes are not indicated in FIGS. 1 and 3, their locations and directions are discernible by reference to the parts shown in those figures in view of the description provided herein.) For the embodiment in FIGS. 1-5, each of the blades is shown having the same form, each with its leading edge being a straight line parallel to its straight-line trailing edge and, outboard of its wing root, with its airfoil shape and chord being constant. (In other embodiments, the directions and locations of the blade canting axes need not be the same as those shown herein and may differ from one blade to another; and, the blades need not have the same form as shown in FIGS. 1-5 nor need they have the same form as one another.)
FIG. 2 shows the location of an exemplary reference chord plane for each blade, a first chord plane 40 passing through the first blade 3, a second chord plane 41 passing through the second blade 4, a third chord plane 42 passing through the third blade 6, and a fourth chord plane 43 passing through the fourth blade 7. (In FIG. 3 the locations of the second and fourth chord planes 41,43 are shown, but not the locations of the first and third chord planes 40,42 since they are perpendicular to that viewing direction and thus not discernible.) Each of the chord planes 40,41,42,43 is normal to a reference radial associated with that chord plane, the radial extending perpendicularly from the spin axis 30. FIG. 2 indicates a first radial 44 normal to the first chord plane 40, a second radial 45 normal to the second chord plane 41, a third radial 46 normal to the third chord plane 42, and a fourth radial 47 normal to the fourth chord plane 43.
Although all of the chord planes 40,41,42,43 indicated in FIGS. 2 and 3 are shown at the same radial distance from the spin axis 30, other radial distances may be selected for locating the chord planes for each, some, or all of the blades. And, in FIGS. 2 and 4 each of the radials 44,45,46,47 is shown crossing its respective blade root 11,15,19,23 midway and continuing outward at a slight angle from the centerline of its respective blade as seen in those figures due to the blade being canted (although, if the blades 3,4,6,7 were shown uncanted in those figures, each of the radials would appear collinear with the centerline of its respective one the blades). Other embodiments may have one or more blades with a swept and/or curved planform, with a root that does not span the full breadth of the blade and/or is not collinear with or parallel to its canting axis, and/or with other geometric characteristics that result in different relationships between the blade's radial and its root and/or planform. However, each radial shown herein is oriented for it to bisect the planform of its associated blade at the blade's chord plane. (Since the blades shown in all of the front-view figures—FIGS. 2, 4, 6 and 9—are canted, their appearance in those figures is slightly distorted from their planforms. As noted in the Summary section above, the planform of a blade is the blade's apparent contour in a front view of the device—looking along the spin axis—such as in FIGS. 2, 4, 6 and 9, if the blade were uncanted—i.e., if the canting angle(s) that cause or contribute to the blade being canted, as discussed and/or shown herein, were changed to zero degrees.)
FIGS. 2 and 4 show the first-blade canting axis 32 oriented at a first-blade canting axis angle 48 relative to the first radial 44 and the second-blade canting axis 34 oriented at a second-blade canting axis angle 49 relative to the second radial 45; and, shows the first and second radials 44,45 oriented at a first-pair radial separation angle 52 relative to one another. And, FIGS. 2 and 4 show the third-blade canting axis 36 oriented at a third-blade canting axis angle 50 relative to the third radial 46 and the fourth-blade canting axis 38 oriented at a fourth-blade canting axis angle 51 relative to the fourth radial 47; and, show the third and fourth radials 46,47 oriented at a second-pair radial separation angle 53 relative to one another. In FIGS. 2 and 4, each blade canting axis angle 48,49,50,51 is shown as being other than 90 degrees. FIGS. 2 and 4 show the first-blade and second-blade canting axis angles 48,49 at respectively 45 and 135 degrees, and show the third-blade and fourth-blade canting axis angles 50,51 also at respectively 45 and 135 degrees. In other embodiments, the blade canting axis angles of each or both of the blades in a blade pair may differ from 90 degrees by amounts other than 45 degrees (preferably by amounts between 10 and 80 degrees).
FIGS. 2 and 4 also show the first-pair radial separation angle 52 and second-pair radial separation angle 53 as equal to one another at 90 degrees. In other embodiments each, some or all of the pair radial separation angles may differ from 90 degrees and may be different from one another. (Presumably, the pair radial separation angle selected would be between 30 and 150 degrees, although in an embodiment where there is only one pair of blades—in which case, both blades may optionally be canted forward or rearward rather than one forward and one rearward—the pair radial separation angle may be 180 degrees. Examples of this would be if the embodiment shown in FIGS. 1-5 had only one blade pair and that pair consisted of either the first and third blades 3,6 or the second and fourth blades 4,7; or, consisted of either the first blade pair 5 or the second blade pair 8 but with the orientation of one of the blades in the pair turned about the spin axis 30 so that, as applicable, the first-pair radial separation angle 52 or second pair radial-separation angle 53 were changed, e.g., to 180 degrees.)
Also shown in FIG. 2 are cross-sectional cuts I-I and II-II which are coplaner with respectively the first chord plane 40 and the second chord plane 41, revealing in respectively FIG. 2A and FIG. 2B a basic (parallelogram) first airfoil shape 54 and first chord 55 (as representative not only of the airfoil shape and chord for the first blade 3 at the first chord plane 40 but also for the third blade 6 as it would appear looking away from the spin axis through a cross-sectional cut—not shown—that is coplaner with the third chord plane 42) and a second airfoil shape 154 and second chord 155 (as representative not only of the airfoil shape and chord for the second blade 4 at the second chord plane 41 but also for the fourth blade 7 as it would appear looking away from the spin axis through another cross-sectional cut—not shown—that is coplaner with the forth chord plane 43). (Airfoil shape of a blade at a chord plane being the contour of the blade within the chord plane, which airfoil shape may in some embodiments vary as the selected radial distance for the chord plane is changed. And, “airfoil shape” is not intended to be limited only to blades designed for operation in air but applies also to blades designed for operation in any other type of fluid medium.) The first airfoil shape 54 is shown in FIG. 2A with its first chord 55 oriented at a first-chord pitch angle 56 and the second airfoil shape 154 is shown in FIG. 2B oriented at a second-chord pitch angle 156. (A chord's pitch angle being the chord's angle, within a blade's chord plane, relative to the hub plane.) As shown in FIGS. 2A and 2B, each of the first and second chords 55,155 is a straight line shown in those figures as having its endpoints at the center of the trailing edge surface and the center of the leading edge surface of its respective airfoil shape 54,154. These end points were selected for convenience in regard to the first and second airfoil shapes since those shapes deviate only slightly from the rectangular shape they would have if the blades were uncanted. The deviation in the first airfoil shape being due to the blade being canted rearward and the deviation in the second airfoil shape being due to the blade being canted forward. Although, each airfoil shape's deviation from the uncanted “neutral” airfoil shape is nearly imperceptible as a result of the modest amount by which each of the blades is canted, as best shown in FIGS. 1, 3 and 5 (and in FIGS. 7, 8 and 10 discussed below), the deviation would tend to increase with an increase in the amount by which the blade is canted. (One may optionally select different chord endpoints for the first and second airfoil shapes 54,154, such as the vertex of one corner of the airfoil shape shown in FIG. 2A or 2B and the vertex of the diagonally opposite corner—which of course would change the magnitude of the chord and the magnitude of the chord pitch angle. However, once selected, the criteria for determining a chord's trailing edge point and leading edge point should be followed consistently.) As seen in FIGS. 2A and 2B, the first and second chords have the same length and magnitude as each other and the magnitude of the first pitch angle is the same as that of the second pitch angle, although these pitch angles have opposite rotational directions. (In other embodiments, the chord lengths and the pitch angle magnitudes for one blade of a blade pair may differ from those of the other blade of the blade pair.) Also, in other embodiments, the blades may have one or more other airfoil shapes. For example, FIG. 2C shows, for a first alternative second blade 4A, a symmetrical curved airfoil shape 157 and FIG. 2D shows, for a second alternative second blade 4B, a non-symmetrical curved airfoil shape 158, the symmetrical curved airfoil shape 157 and the non-symmetrical curved airfoil shape 158 each being shown with the same second chord 155 and second-chord pitch angle 156 as is shown for the second airfoil shape 154, although they may optionally have any other chord(s) and/or chord pitch angle(s) desired. Thus, the embodiment in FIGS. 1-5 is shown in FIG. 1 rotating about the spin axis 30 in a clockwise spin direction 59 (as viewed from the front) in response to the fluid flow 2.
Alternatively, the embodiment in FIGS. 1-5 (and in FIGS. 6 and 7 discussed below) could be made to rotate about the spin axis in a counterclockwise spin direction. Although not shown in FIGS. 1-5 (or FIGS. 6 and 7), counterclockwise spinning may be achieved, for example, by canting the blades in the opposite direction (e.g., wherein the blades shown canted rearward are instead canted forward and the blades shown canted forward are instead canted rearward) or by changing the angular orientation of the blade canting axes (and preferably the blade roots) by 90 degrees about axes that are parallel to the spin axis; and (where the airfoil shape is different at the leading edge than it is at the trailing edge), by reversing the airfoil shape so leading and trailing edges are reversed. In the first of these examples, the second blade 4 shown in FIGS. 1-5 (and FIGS. 6 and 7) would be canted rearward rather than forward—so the second-chord pitch angle 156 shown in FIGS. 2B, 2C, and 2D would change from forward of (which appears above in those figures) the hub plane 31 to rearward of (which would appear below in those figures) the hub plane—and, accordingly, the non-cross hatched portion of the second blade would change from forward of (above) to rearward of (below) the hatched portion. In the second of these examples, the second blade 4 would remain canted forward but the second-chord pitch angle (as well as the leading and trailing edges on blades where they have different airfoil shapes) would be reversed right to left from how they appear in FIGS. 2B, 2C and 2D—resulting in the second-chord pitch angle opening toward the left and the leading edge being on the left side of the airfoil shape. (Also see the discussion below relating to FIGS. 8-10 showing an example of the blades on a counterclockwise rotating 8-blade embodiment of the device.)
By reference to FIGS. 1-5 (and to FIGS. 6-10 discussed below) and the discussion herein relating to those figures, it is apparent that a change in any blade canting angle or in any blade canting axis angle will produce a change in its respective blade's chord pitch angle. This is perhaps best understood by reference to the second blade 4, as a representative example of this concept as it relates to all of the blades. (It being understood that the blade canting axis angle, blade canting angle, chord pitch angle, and/or chord plane referred to in regard to the second blade 4 may be different from the ones associated with one or more of the other blades 3,6,7 (and 103,104,106,107 for the embodiment in FIGS. 8-10) so any application of this example to any other blade must be accompanied by a substitution of the appropriate reference to the name and number for each of the corresponding parts associated with the other blade.) Thus, in regard to the example of the second blade 4 (particularly as shown in FIGS. 2, 2B, 4 and 5, as well as in FIGS. 6, 7, 9, 9B and 10 discussed below), it can be seen that a change in the magnitude of the second-blade canting axis angle 49 (appearing distorted and identified as 49′ in FIG. 9) (which change would of course also occur in the magnitude of the angular deviation of the second-blade canting axis 34 from the second chord plane 41), while maintaining the same second-blade canting angle 35, would produce a change in the second-chord pitch angle 156 (156R in FIG. 9B); or, a change in the magnitude of the second-blade canting angle 35, while maintaining the same second-blade canting axis angle 49, would also produce a change in the second-chord pitch angle 156. Other embodiments may include more or fewer blades by adding or subtracting blade layers, such as by adding or subtracting the 2-blade layer shown in FIGS. 1-5 as the first and third blades 3,6 (together with the rear hub layer 26) and/or the 2-blade layer shown as the second and fourth blades 4,7 (together with the forward hub layer 27).
FIGS. 6 and 7 illustrate an embodiment of the present invention in the form of a simplified one-layer 4-blade device 60 in the presence of a relative fluid flow 2 (flow not indicated in FIG. 6 but indicated by two arrows in FIG. 7). The one-layer 4-blade device 60 is shown in FIGS. 6 and 7 as being substantially similar to the two-layer 4-blade device 1 discussed above except that the rear hub layer 26 and the forward hub layer 27 of the two-layer hub 25 are merged together into a one-layer hub 61 and the location of the reference hub plane 31 is moved along the spin axis 30 from the interface between the rear hub layer 26 and the forward hub layer 27 to mid-thickness of the one-layer hub 61. Accordingly, in FIGS. 6 and 7, the location of each of the blades 3,4,6,7 is shown shifted along the direction of the spin axis from the position it would have had relative to the two-layer hub 25 to its corresponding position relative to the one-layer hub 61. And, in FIG. 6 the blades 3,4,6,7 (together with their respective blade roots 11,15,19,23 and blade canting axes 32,34,36,38) are shown at a greater radial distance from the spin axis than they are in FIGS. 2 and 4, with first-blade canting axis 32 shown collinear with second-blade canting axis 34 and third-blade canting axis 36 shown collinear with fourth-blade canting axis 38. This greater radial distance provides space for the one-layer hub 61 to accommodate the larger nose cone 29 (the size of which is optional) and the full-span blade roots 3,4,6,7 (see discussion below relating to FIGS. 8-10 regarding roots that do not span the full breadth of the blades). With the appropriate adjustments made to the referenced parts and relationships in accordance with the changes noted above, the description in regard to FIGS. 1-5 may be applied also to FIGS. 6-7 (for this purpose, FIG. 6 may be regarded as analogous to FIG. 2 and FIG. 7 as analogous to FIG. 3).
FIGS. 8-10 illustrate an embodiment of the present invention in the form of a one-layer 8-blade device 100 in the presence of a relative fluid flow 2 (flow not indicated in FIG. 9 but indicated by an arrow in FIG. 8 and by two arrows in FIG. 10). In FIGS. 8-10, the 8-blade device 100 is shown as substantially similar to the 4-blade devices 1,60 shown respectively in FIGS. 1-5 and 6-7, except that the 8-blade device is shown with parts configured and oriented for accommodating 8 rather than 4 blades and for a reversed spin direction.
The embodiment in FIGS. 8-10 has a one-layer 8-blade hub 101 (not visible in FIG. 10 but its position is indicated in that figure) which is shown with an eight-pointed star shape, and serves as an example of a hub configuration that is capable of accommodating 8 blades. The 8-blade hub 101 also may be seen as a form of hub that could, if desired, be modified (such as by reducing the number of edges—e.g., reducing the number of star points) for application to a device having fewer than eight blades—for example as an alternative to the one-layer hub 61 shown in FIGS. 6 and 7. (Although the hubs shown herein are presented with their surfaces in the form of segmented linear sharp edges and abrupt angles, the edges and angles may alternatively be non-linear and include surfaces that transition smoothly—e.g., from front to edge to back, or even from hub to blade which transition may simply be a bend in the same material.)
The planform of the blades shown in FIGS. 8-10 reflect only a slight difference from the planform shown in FIGS. 1-5, 6 and 7, the difference being optional as further discussed below. Thus, the references to the blades and their related axes and radials used in connection with FIGS. 1-5, 6 and 7 may be carried over and applied to their corresponding counterparts in connection with FIGS. 8-10. As in FIG. 1, FIG. 8 shows first and second blades 3,4 forming a first blade pair 5, and third and fourth blades 6,7 forming a second blade pair 8. However, as seen in FIG. 8, the 8-blade device 100 also has fifth and sixth blades 103,104 forming a third blade pair 105, and seventh and eighth blades 106,107 forming a fourth blade pair 108. A comparison of FIG. 9 with FIGS. 2, 4 and 6 shows angular separation between adjacent blades of the 8-blade device 100 being approximately half that of the 4-blade devices 1,60. Also, as in FIG. 1, FIG. 8 shows first through fourth-blade leading edges 9,13,17,21; first through fourth-blade trailing edges 10,14,18,22; first through fourth-blade roots 11,15,19,23; and first through fourth-blade tips 12,16,20,24. But, in addition, FIG. 8 shows fifth through eighth-blade leading edges 109,113,117,121; fifth through eighth-blade trailing edges 110,114,118,122; fifth through eighth-blade roots 111,115,119,123; and fifth through eighth-blade tips 112,116,120,124. And, FIG. 8 shows the 8-blade hub 101 having a first, second, third, and fourth hub portion 162,163,164,165 to which respectively the second, fourth, sixth, and eighth blade 4,7,104,107 is connected at its respective blade root 15,23,115,123. The blades shown for the embodiment in FIGS. 8-10 are oriented for a counterclockwise spin direction 159 as shown in FIG. 8, rather than for the clockwise spin direction 59 shown in FIG. 1 for the embodiments in FIGS. 1-5, 6 and 7.
In FIGS. 8-10 the blades are shown (as best seen in FIG. 9) with a planform that has an angle in the trailing edge proximate the root, forming a V-shaped trailing edge with a part of the trailing edge (the part shown in FIG. 9 at substantially a right angle to the root) facing toward but not fixed—although, alternatively, it could be fixed—to the 8-blade hub 101. Note that, although not depicted in any of the figures, a blade may instead (or in addition) have an angle in its leading edge, forming a V-shaped leading edge. For example, this would be the case with respect to the second blade 4 as it is shown in FIGS. 8-10 if both the first hub portion 162 and the second blade 4 were uncanted, if the edge of the blade serving as the second-blade root 15 were then disconnected from the 8-blade hub 101 (i.e., from the first hub portion 162) to become a new portion of the second-blade leading edge 13, if the part of the V-shaped second-blade trailing edge 14 that is shown facing toward the leading-edge side of a star of the 8-blade hub were then connected to the leading-edge side of the star forming a new position and orientation for the second-blade root 15, if the second-blade canting axis 34 were repositioned to be collinear with the repositioned second-blade root 15, and if the second blade 4 were then canted forward about the repositioned second-blade canting axis 34. Note that a V-angle in the trailing/leading edge is also an option available for the 4-blade devices shown in FIGS. 1-5, 6 and 7, but is particularly useful for accommodating the connection of a larger number of blades, such as the eight blades shown in FIGS. 8-10, to the hub using a shortened root while maintaining the blade's breadth throughout most of its length. Likewise, the straight trailing edge shown in FIGS. 1-5, 6 and 7 is an option available for the 8-blade device shown in FIGS. 8-10, as for example where a blade breadth is selected such that the trailing edge need not be modified for it to intercept the root. In other words, they are all blades of potential application in regard to embodiments of the invention, so references herein to blades is intended, unless expressly stated otherwise, to be inclusive of straight blades such as shown in FIGS. 1-5, 6 and 7; V-shaped blades such as shown in FIGS. 8-10, and blades having any other planforms including those having a leading and/or trailing edge that includes multiple angles and/or one or more curves.
In FIGS. 8-10 (as in FIGS. 1-5, 6 and 7) the first through fourth blades 3,4,6,7 are connected along their respective first through fourth-blade roots 11,15,19,23 to the edge of the hub (the hub in FIGS. 8-10 being in the form of the one-layer 8-blade hub 101), with the shaft 28 penetrating the hub and capped by the nose cone 29, the shaft extending rearward of the hub, and with the centerline of the shaft 28 being collinear with the spin axis 30. Additionally, however, in FIGS. 8-10 each of the fifth through eighth blades 103,104,106,107 is shown as being a copy of, respectively, the first through fourth blades 3,4,6,7, with each copy rotated 180 degrees about the spin axis 30 and (as best seen in FIGS. 8 and 9) connected to the opposite edge of the 8-blade hub 101 along the blade's respective one of the fifth through eighth-blade roots 111,115,119,123. (The portion of the 8-blade hub to which each of the second, fourth, sixth, and eighth blades 4,7,104,107 is connected being respectively the first, second, third, or fourth hub portion 162,163,164,165.) For the embodiment in FIGS. 8-10, the 8-blade hub 101 and all of the blades 3,4,6,7,103,104,106,107 are spinnable together about the spin axis 30. The shaft 28 (and typically its nose cone 29) may be connected to the 8-blade hub 101—and thus to the eight blades shown in FIGS. 8-10 (just as with the two-layer hub 25 and four blades shown in FIGS. 1-5, or the one-layer hub 61 and four blades shown in FIGS. 6 and 7)—for the shaft to spin in response to the spinning of the blades (or for the blades to spin in response to the spinning of the shaft); or, may be connected in a manner for the shaft 28 to remain stationary while the hub spins.
In FIGS. 8-10 (as in FIGS. 1-5, 6 and 7 for the first through fourth blades), each of the first through eighth blades 3,4,6,7,103,104,106,107 is canted relative to a reference hub plane 31. (The hub plane 31 is not shown in FIGS. 8 and 9 but its location is shown in FIG. 10 as being at about mid-thickness of the 8-blade hub 101.) FIG. 9 shows a first-blade, second-blade, third-blade, fourth-blade, fifth-blade, sixth-blade, seventh-blade and eighth-blade canting axis 32,34,36,38,132,134,136,138 and a first, second, third and fourth hub canting axis 166,167,168,169. Regarding the blade pairs 5,8,105,108 shown in FIG. 8 for the embodiment in FIGS. 8-10, one blade of each blade pair (i.e., each blade pair's respective one of the first, third, fifth, and seventh blades 3,6,103,106) is canted rearward (best seen in FIGS. 8 and 10) about the respective one of the first-blade, third-blade, fifth-blade or seventh-blade canting axis 32,36,132,136 (which axes are shown in FIG. 9 but not in FIGS. 8 and 10). And, for the embodiment in FIGS. 8-10, the other blade of each blade pair (i.e., each blade pair's respective one of the second, fourth, sixth, and eighth blades 4,7,104,107) is canted forward (best seen in FIGS. 8 and 10). Note, however, that the forward cant of the second, fourth, sixth, and eighth blades 4,7,104,107 for the embodiment in FIGS. 8-10 is the result of each of those blades being canted rearward relative to its respective hub portion and canted forward by its respective hub portion being canted forward. Thus, each of the second, fourth, sixth, and eighth blades 4,7,104,107 is shown in FIGS. 8 and 10 canted rearward about respectively the second-blade, fourth-blade, sixth-blade and eighth-blade canting axes 34,38,134,138 (which axes are shown in FIG. 9 but not in FIGS. 8 and 10) relative to its respective one of the first, second, third, and fourth hub portions 162,163,164,165 (the third hub portion 164 being hidden in FIG. 10). And, the second, fourth, sixth, and eighth blades are also canted forward—to their respective forward-canted positions (best seen in FIGS. 8 and 10)—by the forward canting of the first through fourth hub portions 162,163,164,165 about respectively the first through fourth hub canting axes 166,167,168,169 (which axes are shown in FIG. 9 but not in FIGS. 8 and 10). (Preferably, as they are for the embodiment in FIGS. 8-10, each of the first, second, third and fourth hub canting axes 166,167,168,169 is perpendicular to its respective one of the second, fourth, sixth and eighth radials 45,47,145,147, and is contained within the hub plane 31 or parallel to the hub plane.)
In FIG. 9, the first-blade, third-blade, fifth-blade and seventh-blade canting axes 32,36,132,136 are considered to be contained within the hub plane 31; but, the second-blade, fourth-blade, sixth-blade and eighth-blade canting axes 34,38,134,138 deviate from the hub plane due to the forward canting of the hub portions about their respective hub canting axes. (However, for the embodiment in FIGS. 8-10, the second-blade, fourth-blade, sixth-blade and eighth-blade canting axes shown in FIG. 9 would be within the same plane plane as are the first-blade, third-blade, fifth-blade and seventh-blade canting axes, if the hub portions were uncanted.) While the magnitude of canting of each blade and each hub portion is optional and may be the same as or different from the amount of canting of some or all of the other blades and/or hub portions, all of the blades 3,4,6,7,103,104,106,107 as shown in FIGS. 8-10 would have the same magnitude of rearward blade canting angle—e.g., 10 degrees—relative to the hub plane 31 if the hub portions were uncanted (or, relative to the blade's respective hub portion where that hub portion is canted at an angle relative to the hub plane—a hub-portion canting angle). And all of the hub portions 162,163,164,165 have the same magnitude of forward hub-portion canting angle (while not explicitly shown in the figures, the hub-portion canting angles are implicit in view of the relationships that are shown in FIGS. 8-10)—e.g., 20 degrees—relative to the hub plane. Thus, as shown in FIGS. 8 and 10, the overall result is that the first, third, fifth, and seventh blades 3,6,103,106 are canted rearward of the hub plane 31 and the second, fourth, sixth, and eighth blades 4,7,104,107 are canted forward of the hub plane 31.
As noted above and shown in FIG. 10, the first and fifth blades 3,103 are each canted rearward about respectively the first-blade canting axis 32 and the fifth-blade canting axis 132 (these axes are shown in FIG. 9 but not in FIG. 10) relative to the hub plane 31 at a rearward canting angle 133. In FIG. 10, the rearward canting angle 133 is shown at its true—i.e., undistorted—magnitude, since the view in FIG. 10 is in the same direction as the first-blade and fifth-blade canting axes 32,132. The third and seventh blades 6,106 are shown in FIG. 10 each canted rearward about respectively the third-blade canting axis 36 and the seventh-blade canting axis 136 (these axes are shown in FIG. 9 but not in FIG. 10) relative to the hub plane 31 at a rearward canting angle shown in FIG. 10 as distorted rearward canting angle 137′. (The distorted rearward canting angle 137′ has the same true magnitude as the rearward canting angle 133 but normally would appear distorted from the point of view presented in FIG. 10 since the view in FIG. 10 is different from the direction of the third-blade and seventh-blade canting axes 36,136—although, for the embodiment shown in FIGS. 8-10, the relative positions and orientations of the first-blade, third-blade, fifth-blade and seventh-blade canting axes 32,36,132,136 and rearward canting angle 133 happen to be just right for the rearward canting angle 133 and the distorted rearward canting angle 137′ to appear substantially the same in FIG. 10).
FIG. 10 also shows the fourth and eighth blades 7,107 each canted at a forward canted angle shown in FIG. 10 as distorted forward canted angle 139′. The distorted forward canted angle 139′ has a true magnitude—not shown—that is the result of: the fourth and eighth blades shown in FIG. 10 each being canted rearward about respectively the fourth-blade canting axis 38 and the eighth-blade canting axis 138 (these axes are shown in FIG. 9 but not in FIG. 10) relative to respectively the second and fourth hub portions 163,165; and, the second and fourth hub portions each being canted forward about respectively the second hub canting axis 167 and the fourth hub canting axis 169 (these axes are shown in FIG. 9 but not in FIG. 10). Likewise, FIG. 10 shows the second and sixth blades 4,104 each canted forward as the result of: each of those blades being canted rearward about respectively the second-blade canting axis 34 and the sixth-blade canting axis 134 (these axes are shown in FIG. 9, but not in FIG. 10) relative to respectively the first and third hub portions 162,164 (the third hub portion being hidden in FIG. 10), and the first and third hub portions each being canted forward about respectively the first hub canting axis 166 and the third hub canting axis 168 (these axes shown in FIG. 9 but not in FIG. 10) relative to the hub plane 31.
In the embodiment shown in FIGS. 8-10, the magnitude of the angle by which each of the second, fourth, sixth and eighth blades 4,7,104,107 is canted rearward (relative to its respective hub portion 162,163,164,165) is the same as the rearward canting angle 133, and the magnitude of the angle by which each of the first, second, third and fourth hub portions 162,163,164,165 is canted forward (relative to the hub plane 31) is the amount needed to bring the blade (to which that hub portion is connected) to the forward canted angle shown in FIG. 10 as distorted angle 139′ (which appears distorted from its true magnitude—not shown—since the view in FIG. 10 is not in the same direction as the second-blade, fourth-blade, sixth-blade or eighth-blade canting axes 34,38,134,138, as seen in FIG. 9). In the embodiment shown in FIGS. 8-10, all the canting axes except for the second-blade, fourth-blade, sixth-blade and eighth-blade canting axes are located and oriented to be wholly within the hub plane 31. The second-blade, fourth-blade, sixth-blade and eighth-blade canting axes 34,38,134,138 deviate from the hub plane since they are displaced due to the first, second, third and fourth hub portions 162,163,164,165 being canted forward. And, although the forward canted angles for the second and sixth blades 4,104 are not shown in FIG. 10 (even as distorted angles) because in that figure those blades are seen end on, the forward canted angles for the second and sixth blades 4,104 are the same as the forward canted angle for the fourth and eighth blades 7,107, as is evident by a comparison of those blades to one another in FIG. 9 (showing their sizes, shapes and orientations) and in FIG. 10 (showing their displacements relative to the hub plane 31).
For the embodiment in FIGS. 8-10, FIG. 9 shows first, second, third, fourth, fifth, sixth, seventh, and eighth chord planes 40,41,42,43,140,141,142,143, each of which passes through respectively one of the first through eighth blades 3,4,6,7,103,104,106,107. Each of the first through eighth chord planes shown in FIG. 9 (like the first through fourth chord planes 40,41,42,43 discussed above in connection with FIG. 2) is normal to a reference radial that extends at a right angle from the spin axis 30. FIG. 9 shows first, second, third, fourth, fifth, sixth, seventh and eighth radials 44,45,46,47,144,145,146,147, each of said radials being normal to its respective one of the first through eighth chord planes 40,41,42,43,140,141,142,143 (thus, each chord plane is also perpendicular to the hub plane 31). (In FIG. 10, the orientation of the chord planes is exemplified by the fourth and eighth chord planes 43,143, each of which is shown passing through its respective one of the fourth and eighth blades 7,107 at a right angle to the hub plane 31.) Preferably, as shown in FIG. 9, each of the first through eighth chord planes are located and oriented (in relation to the chord plane's respective one of the first through eighth blades) for the chord plane's respective one of the first through eighth radials, or a parallel radial, to bisect what would be the blade's planform (i.e., if the blade were uncanted) at the chord plane.
Each of the blade canting axes 32,34,36,38,132,134,136,138 is shown in FIG. 9 oriented other than perpendicular to its respective radial 44,45,46,47,144,145,146,147. FIG. 9, shows undistorted first-blade, third-blade, fifth-blade and seventh-blade canting axis angles 48,50,148,150 (to indicate the orientation of respectively the first-blade, third-blade, fifth-blade and seventh-blade canting axes 32,36,132,136), and shows distorted second-blade, fourth-blade, sixth-blade and eighth-blade canting axis angles 49′,51′,149′,151′ (to indicate the orientation respectively of the second-blade, fourth-blade, sixth-blade and eighth-blade canting axes 34,38,134,138) —with the blade canting axis angles shown at a magnitude of 45 degrees for the undistorted blade canting axis angles, but slightly more than 45 degrees for the distorted blade canting axis angles due to the forward cant of their respective hub portions 162,163,164,165. FIG. 9 also shows the radials for each of the first blade pair, second blade pair, third blade pair, and fourth blade pair 5,8,105,108 separated by respectively a first-pair radial separation angle 52, second-pair radial separation angle 53, third-pair radial separation angle 152, and fourth-pair radial separation angle 153, all of which are shown in FIG. 9 as having the same magnitude of 45 degrees.
For the embodiment in FIGS. 8-10, each blade has a constant basic (parallelogram) airfoil shape, with a constant chord at radial distances outboard of its wing root and its trailing edge V-angle. The airfoil shape for the first, third, fifth and seventh blades 3,6,103,106 is represented by a reverse first airfoil shape 54R (as best seen in FIG. 9A); and, the constant chord for the each of those blades is represented by a reverse first chord 55R (as best seen in FIGS. 9 and 9A). And, the airfoil shape for the second, fourth, sixth and eighth blades 4,7,104,107 is represented by the reverse second airfoil shape 154R (as best seen in FIG. 9B); and, the constant chord for the each of those blades is represented by a reverse second chord 155R (as best seen in FIGS. 9 and 9B). (Although, as noted above, having a constant airfoil shape and/or constant chord is entirely optional.) And, for the embodiment in FIGS. 8-10, a reverse first-chord pitch angle 56R (relative to the hub plane 31) is shown in FIG. 9A for the first blade 3 (as viewed through sectional cut III-III), which serves as an example of the reverse chord pitch angle for each of the first, third, fifth, and seventh blades 3,6,103,106 (at the blade's respective chord plane 40,42,140,142) —since in this embodiment each of those blades has the same reverse chord pitch angle. (The term “reverse” is used in regard to the chord pitch angles in the 8-blade device 100 shown in FIGS. 8-10 simply because those chord pitch angles are for making the 8-blade devise 100 spin in the reverse—counterclockwise—direction from the clockwise spin direction of the 4-blade devices 1,60 shown in FIGS. 1-5, 6 and 7.) By reference to FIGS. 8-10, particularly FIG. 9, in view of FIG. 9A and the above discussions relating to those figures, it can be seen that the first-blade canting axis angle 48 and the first blade's rearward canting angle 133 determine the magnitude of the reverse first-chord pitch angle 56R.
Furthermore, for the embodiment in FIGS. 8-10, the second, fourth, sixth, and eighth blades 4,7,104,107 each have the same chord and the same reverse chord pitch angle as that of the second blade 4. FIG. 9B shows, in regard to the second blade 4 (as viewed through sectional cut IV-IV), the reverse second chord 155R and a reverse second-chord pitch angle 156R (relative to the hub plane 31). By reference to FIGS. 8-10, particularly FIG. 9, in view of FIG. 9B and the above discussions relating to those figures, it can be seen that the magnitude of the reverse second-chord pitch angle 156R is determined by both the second-blade canting axis angle (indicated in FIG. 9 as distorted second-blade canting axis angle 49′) and the orientation of the first hub canting axis 166 as well as by the degree to which the second blade 4 is canted rearward, relative to the first hub portion 162, about the second-blade canting axis 34 and the degree to which the first hub portion 162 is canted forward about the first hub canting axis 166. (The second-blade canting axis angle appears distorted in FIG. 9 since the second-blade canting axis 34 is placed at an angle relative to the hub plane 31 by the forward cant of the first hub portion 162.) Preferably, as it is in the embodiments shown herein, one or more of the device's blades has a blade pitch angle (which in these embodiments is the same as the blade's single chord pitch angle) that is the same as the blade pitch angle of another of the device's blades; but, the pitch angle of any blade (and of the blade's one or more chord pitch angles) is independent of, and thus may be different from, the pitch angle of any other blade (and of the other blade's one or more chord pitch angles).
In other embodiments, there may be a different number of blades, and one or more of the blades may be sized, shaped, orientated, and/or canted differently from the blades shown and/or described herein and/or differently from some or all of the other blades. And, in other embodiments having a star-shaped hub, one or more blades may be connected to the hub with the blade's canting axis collinear with (or parallel to) and the blade's trailing edge adjacent the leading-edge side of a star point, rather than (as shown in FIGS. 8-10) with the blade's canting axis collinear with (or parallel to) and the blade's leading edge adjacent the trailing-edge side of the star point, for a reversed blade pitch. Thus, for example, if this were done in regard to the forward canted blades shown in FIGS. 8-10, an appropriate chord pitch angle for the counterclockwise spin of those blades could be achieved without canting their respective hub portions forward, but rather by simply canting those blades forward about their respective repositioned canting axes.
The present invention contemplates and includes all conventional adjustments and modifications to the embodiments described or shown herein, including alternate embodiments of the present invention that have conventional differences in size, shape, proportion, orientation, or direction of movement from those described or shown herein, without departing from the present invention.
Accordingly, the invention claimed is not limited to the embodiments described or shown herein but is limited only by the claims, which encompass any and all embodiments within the scope of the claims and their equivalents.
Patent Application
20120321481
