Vertical axis turbine
A vertical axis turbine includes a rotatable hub assembly that is configured to be connected to an energy sink and rotatable about an axis of rotation. At least two blades are mounted on the hub assembly, each blade including a leading edge and a trailing edge, the blades being oriented so that the respective leading edges face in a common rotational direction. Each blade further includes a straight section that is substantially parallel to the axis of rotation and two helical sections, the straight section being interposed between the helical sections, and the helical sections extending at least partially around the axis of rotation.
1. A vertical axis turbine that includes:
a rotatable hub assembly that is configured to be connected to an energy sink and rotatable about an axis of rotation; and
at least two blades that are mounted on the hub assembly, each blade including a leading edge and a trailing edge, the blades being oriented so that the respective leading edges face in a common rotational direction, and each blade further including:
a straight section that is substantially parallel to the axis of rotation; and
two helical sections, the straight section being interposed between the helical sections, the helical sections extending at least partially around the axis of rotation, and the helical sections being substantially identical to each other.
2. The vertical axis turbine as claimed in claim 1 , in which the blades are substantially identical to each other.
3. The vertical axis turbine as claimed in claim 1 , in which the blades are substantially equally spaced from each other.
4. The vertical axis turbine as claimed in claim 1 , in which the hub assembly includes a shaft and the helical sections of each blade extend in a common rotational direction about the shaft.
5. The vertical axis turbine as claimed in claim 1 , in which the helical sections constitute between 30% to 80% of a span of each blade.
6. The vertical axis turbine as claimed in claim 5 , in which the helical sections constitute two thirds of a span of each blade.
7. The vertical axis turbine as claimed in claim 5 , in which the helical sections constitute one third of a span of each blade.
8. The vertical axis turbine as claimed in claim 1 , in which the blades have a constant pitch angle along their lengths.
9. The vertical axis turbine as claimed in claim 1 , in which the pitch angle of the blades varies along their lengths.
10. The vertical axis turbine as claimed in claim 1 , in which the blades have a constant camber along their lengths.
11. The vertical axis turbine as claimed in claim 1 , in which the blades have a camber that varies along their lengths.
12. The vertical axis turbine as claimed in claim 1 , in which the blades are entirely without camber.
13. The vertical axis turbine as claimed in claim 1 , in which the helical sections are cambered while the straight sections are without camber.
14. The vertical axis turbine as claimed in claim 1 , in which the straight sections are cambered while the helical sections are without camber.
15. The vertical axis turbine as claimed in claim 1 , in which the blades each have end plates at their tips.
16. The vertical axis turbine as claimed in claim 1 , in which plates are provided at junctions between the helical and straight sections.
17. The vertical axis turbine as claimed in claim 1 , in which the hub assembly includes a shaft.
18. The vertical axis turbine as claimed in claim 1 , in which at least one strut connects each respective blade to the shaft.
19. The vertical axis turbine as claimed in claim 1 , which includes three blades.