SUMMARY OF THE INVENTION
According to a first aspect, the present disclosure relates to a fluid turbine comprising a rotor having an array of rotor blades disposed circumferentially thereabout. The rotor has an axis of rotation, and comprises at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle. A pitch control mechanism is operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation. The pitch of each rotor blade is controlled via an actuating rod running from the blade to the rotor hub.
According to a second aspect, the present disclosure relates to a fluid turbine comprising a rotor and a pitch angle control mechanism. The rotor has an axis of rotation, and comprises at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a first end, a second end, a first mounting point, a second mounting point, a pitch axis and a variable pitch angle, each of the first and second mounting points being disposed inboard of the first and second ends. The pitch angle control mechanism is operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.
According to a third aspect, the present disclosure relates to a fluid turbine comprising a rotor and a pitch angle control mechanism. The rotor has an axis of rotation and comprises a first hub, a second hub, an array of at least two struts, having strut covers disposed thereabout, extending from each of the first and second hubs, and at least two rotor blades, each secured to the distal end of a strut and having a pitch axis and a variable pitch angle. The mechanism is operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of a fluid turbine according to certain embodiments of the present disclosure;
FIG. 2 is a view of the underside of a rotor blade according to certain embodiments of the present invention;
FIG. 3 is a cutaway view of the rotor blade of FIG. 2 showing the blade attachment mechanism and pitch control linkage;
FIG. 4 is a section view of a second embodiment of a rotor blade having a different attachment mechanism from the rotor blade of FIGS. 2 and 3;
FIG. 5 is a section view of a third embodiment of a rotor blade having a different attachment mechanism from the rotor blades of FIGS. 2-4;
FIG. 6 is an isometric view of the pivot assembly shown in FIG. 4;
FIG. 7 is an isometric view of the pivot assembly shown in FIG. 5;
FIG. 8 is a section view of the pivot assembly shown in FIGS. 5 and 7;
FIG. 9 is a front section view of a rotor blade showing the receiving pocket for a pivot assembly of the type shown above;
FIGS. 10 and 11 are views of a first embodiment of a turbine blade strut cover; and
FIGS. 12 and 13 are views of a second embodiment of a turbine blade strut cover.
DETAILED DESCRIPTION OF THE DRAWINGS
A system and method of the present patent application will now be described with reference to various examples of how the embodiments can best be made and used. Like reference numerals are used throughout the description and several views of the drawings to indicate like or corresponding parts, wherein the various elements are not necessarily drawn to scale.
FIG. 1 is an isometric view of a fluid turbine 100 according to certain embodiments of the present disclosure. Structurally, turbine 100 consists of a rotor assembly comprising a torque tube 102. Torque tube 102 is designed to prevent rotor hubs 108 from rotating independently of one another. Torque tube 102 is oriented along a central axis which is intended to be disposed generally perpendicular to the direction of fluid flow. The turbine 100 comprises arrays of radially-disposed struts 104, each mounted to one of rotor hubs 108 at its proximal end and a rotor blade 106 at its distal end. The rotor blades 106 shown in FIG. 1 are high aspect ratio airfoils/hydrofoils having a clearly defined leading and trailing edge. Turbine 100 shown in FIG. 1 comprises 10 blades, but alternate embodiments may have more or fewer blades, depending on the application. Each rotor blade 106 is attached to a strut 104 in such a manner as to allow the rotor blade 106 to be individually pivoted with respect to the axis of rotation of turbine 100, thus altering the pitch angle of each rotor blade 106 with respect to the direction of fluid flow through turbine 100. The angle of the rotor blades may be controlled via mechanical linkages, hydraulics, pneumatics, linear or rotary electromechanical actuators, or any combination thereof. In certain embodiments, the rotor pitch angle profile may be controlled by a cam-and-follower mechanism operating in concert with one or more of the above systems of actuation.
FIG. 2 is an oblique detail view of the underside of a rotor blade. FIG. 3 is an oblique cutaway view of the rotor blade showing the blade attachment mechanism and pitch control linkage. As seen in FIGS. 2 and 3, each rotor blade 106 is secured to a strut 104 by means of a pivot joint 252 allowing the rotor blade 106 freedom of movement to be moved to different pitch angles. As described above, the pitch angle of each rotor blade is controlled by an actuation rod 208 secured to the rotor blade at rod end 254. The actuation rod 208 is connected at its other end to a pitch control mechanism, such as a cam-and-follower mechanism, disposed in the rotor hub 108. Using the actuation rod 208, the pitch control mechanism is able to vary the pitch of the blade 106 as it moves through the fluid stream.
FIG. 4 is a section view of a second embodiment of a rotor blade 106 having a different attachment mechanism from the rotor blade 106 of FIGS. 2 and 3. FIG. 5 is a section view of a third embodiment of a rotor blade 106. FIG. 6 is an isometric view of a first embodiment of a pivot assembly 300 shown in FIG. 4. FIG. 7 is an isometric view of a second embodiment of a pivot assembly 300 shown in FIG. 5. FIG. 8 is a section view of the pivot assembly 300 shown in FIGS. 5 and 7. FIG. 9 is a front section view of the rotor blade 106 of FIGS. 4 and 5 showing the receiving pocket for the pivot assembly 300 of FIG. 8.
As seen in FIGS. 4-9, rotor blade 106 has a pivot assembly 300 disposed in a receiving pocket 306 in the center thereof. The pivot assembly 300 is pivotably secured to a strut rod end 302 and an actuation rod end 304, which pass through a slot 308 on the underside of rotor blade 106. In a similar manner to that described above, strut rod end 302 functions to maintain the position of rotor blade 106, while actuation rod end 304 functions to control the pitch of rotor blade 106 as it moves radially about the rotor.
In order to improve aerodynamic efficiency and protect the structural integrity of the mechanism, each strut 104 and actuation rod 208 are disposed within a strut cover 212. Certain embodiments of strut covers are shown in FIGS. 10-13. As seen in these figures, each strut 104 may be disposed within a centrally-located and axially-aligned strut aperture 256, and each actuation rod 208 may be disposed within a parallel actuation rod aperture 258.
It is believed that the operation and construction of the embodiments of the present patent application will be apparent from the detailed description set forth above. While the exemplary embodiments shown and described may have been characterized as preferred, it should be readily understood that various changes and modifications could be made therein without departing from the scope of the present invention as set forth herein.
Patent Application
20120134819
