Hybrid vertical axis turbine apparatus
A multi-stage hybrid Darrieus-modified-Savonius (HDMS) vertical axis wind or water turbine (VAWT) for aero-hydro energy harvesting. The HDMS VAWT can continuously harvest fluid energy, including wind and water energy, provides excellent self-starting capability, has enhanced structural stability, and a high energy harvesting efficiency.
1. A hybrid vertical fluid turbine apparatus, comprising:
(a) a first rotor system positioned in a central region and rotatable about a central axis, wherein the first rotor system comprises:
(i) at least two blade-sets stacked vertically along the central axis, each blade-set comprising a plurality of first blades that are equiangularly spaced about the central axis, wherein the at least two blade-sets are mounted upon a shaft with bearings along the central axis, wherein each first blade extends from a position proximate to the central axis out to a position distal to the central axis and has a concave shape that allows fluid to push on a concave side of each first blade, and
(ii) a hydraulic brake system that is mounted upon the shaft with bearings; and
(b) a second rotor system positioned in an annular region surrounding the first rotor system in the central region, wherein the second rotor system comprises a plurality of second blades equiangularly spaced about the central axis, wherein each of the second blades is positioned substantially parallel to the central axis and attached to at least one blade-set of the first rotor system using at least two supporting struts, wherein the cross-section of the second blade is a substantially symmetrical airfoil shape.
2. The hybrid vertical fluid turbine of claim 1 , wherein each blade-set includes a circular top plate and a circular bottom plate, wherein the circular plates are substantially perpendicular to the central axis, and wherein the plurality of first blades are positioned therebetween.
3. The hybrid vertical fluid turbine of claim 1 , wherein the plurality of second blades are straight-bladed.
4. The hybrid vertical fluid turbine of claim 1 , wherein each blade-set comprises three first blades located at approximately 0 degrees, 120 degrees, and 240 degrees about the central axis.
5. The hybrid vertical fluid turbine of claim I, wherein the first blades in each blade-set are offset about 20-60 degrees about the central axis from the first blades in each other blade-set.
6. The hybrid vertical fluid turbine of claim 1 , wherein the hybrid vertical fluid turbine apparatus rotates about the central axis in at least one of a clockwise manner or a counter clockwise manner.
7. The hybrid vertical fluid turbine of claim 1 , wherein the shaft is a static non-turning shaft, and the first rotor system is mounted upon, and rotates around, the static non-turning shaft.
8. The hybrid vertical fluid turbine of claim 1 , wherein the shaft is a rotating shaft, and the first rotor system is attached to the rotating shaft, and the rotating shaft rotates about the central axis.
9. The hybrid vertical fluid turbine of claim 2 , wherein each first blade is rectangular and has a first blade length and a first blade height, wherein the first blade height is equal to the distance between the circular top and bottom plates in the blade-set, and wherein the first blade length is greater than a radius of the circular top and bottom plates, leading to the concave shape.
10. The hybrid vertical fluid turbine of claim 1 , wherein the first rotor system comprises at least three blade-sets.
11. The hybrid vertical fluid turbine of claim 1 , wherein one plate-set can share a circular plate with another plate-set.
12. The hybrid vertical fluid turbine of claim 1 , wherein a ratio of a radius R o of the second blades about the central axis relative to a radius R i of the first blades about the central axis is in a range from about 1.5 to about 4.
13. The hybrid vertical fluid turbine of claim 1 , wherein a ratio of a radius R o of the second blades about the central axis relative to a radius R i of the first blades about the central axis is in a range from about 2.5 to about 3.5.
14. The hybrid vertical fluid turbine of claim 1 , wherein a ratio of a radius R o of the second blades about the central axis relative to a chord length of the second blades is in a range from about, 1.5 to about 4.
15. The hybrid vertical fluid turbine of claim 1 , wherein a ratio of a radius R o of the second blades about the central axis relative to a chord length of the second blades is in a range from about 2.5 to about 3.5.
16. The hybrid vertical fluid turbine of claim 1 , wherein a nonlinear interaction exists between the first rotor system and the second rotor system.
17. The hybrid vertical fluid turbine of claim 1 , wherein the greatest energy harvesting efficiency is achieved at a tip speed ratio (TSR) values greater than about 2.0.
18. The hybrid vertical fluid turbine of claim 1 , wherein a tip of the first blade of the first rotor system is aligned with an aerodynamic center of a corresponding second blade of the second rotor system.
19. The hybrid vertical fluid turbine of claim 1 , wherein the fluid is air.
20. The hybrid vertical fluid turbine of claim 1 , wherein the fluid is water.