THREE-VANE DOUBLE ROTOR FOR VERTICAL AXIS TURBINE

Abstract

A double rotor for vertical axis turbine includes two single three-vane rotors separated by a horizontal or separation plate, wherein such plate provides two different access areas to the propelling fluid, wherein between each of the three vanes of each of the single rotors it is determined surface continuity attenuated by curves in the fluid flow direction preventing parasitic flows during rotation thereof.

Claims

1. A double rotor for vertical axis turbine comprising two single rotors with three vanes with equal height, separated by a horizontal or separation plate, wherein such plate provides two different access areas for the propelling fluid and between each of the three vanes of each of the single rotors, there is surface continuity attenuated by curves in fluid flow direction preventing parasitic flows during rotor rotation.

2. The double rotor according to claim 1, wherein the two single three-vane rotors comprise the so-called upper rotor and lower rotor according to their relative spatial positions within such vertical axis turbine, having each rotor hollow cores.

3. The double rotor according to claim 3, wherein the hollow cores are covered below and above, leaving an opening through which the vertical axis of the turbine passes and such axis is joined to the upper and lower rotors.

4. The double rotor according to claim 3, wherein the upper rotor is separated from the lower rotor by means of the horizontal or separation plate which is joined to such rotors and passed by the vertical axis of the turbine.

5. The double rotor according to claim 4, wherein both the upper rotor and the lower rotor have their vanes separated by means of an angle of 120 degrees.

6. The double rotor according to claim 5, wherein each vane of the upper rotor is displaced with respect to each vane of the lower rotor by means of an angle of 60 degrees.

7. The double rotor according to claim 6, wherein each of the three vanes that make up each of the rotors, upper and lower, are arranged on the outside of a R radius circumference around the vertical axis which has an inner wall which makes up the hollow core of each single rotor.

8. The double rotor according to claim 7, wherein the farthest area from the vertical axis of each vane belonging to each rotor, upper and lower, during rotation, generates a 4R radius circumference equal to the radius of the horizontal or separation plate which separates such upper rotor from the lower rotor.

9. The double rotor according to claim 8, wherein each of the vanes that make up the upper and lower rotors have dolphin fin shape thus having an aerodynamic design profile like a plane wing, wherein such profile has a convex area in the extrados and a concave area in the intrados.

10. The double rotor according to claim 9, wherein both on the upper rotor and the lower rotor, the convex area in the extrados of one of the vanes joins with the concave area of the intrados of the next vane through a 0.5R radius circumference.

11. The double rotor according to claim 10, wherein the convex area in the extrados of each of the vanes corresponds to a portion of 5R radius circumference taken as center a first point on the 4R radius circumference generating the outermost portion of each vane when rotating around the vertical axis.

12. The double rotor according to claim 10, wherein the concave area in the intrados of each of the vanes corresponds to a portion of 4R radius circumference taken as center a second point on the 4R radius circumference generating the outermost portion of each vane when rotating around the vertical axis.

13. The double rotor according to claim 11, wherein the separation between the first point and the second point on the 4R radius circumference, generating the outermost portion of each vane when rotating around the vertical axis, is 1.20R.

14. The double rotor according to claim 12, wherein the separation between the first point and the second point on the 4R radius circumference, generating the outermost portion of each vane when rotating around the vertical axis, is 1.20R.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to understand this description, the attached drawings show an example of embodiment, but not limited, of the object of this invention:

[0030] FIG. 1 shows two side views of the three-vane double rotor for a vertical axis turbine.

[0031] FIG. 2 shows two top side views of each single rotor that makes up the three-vane double rotor for a vertical axis turbine; in the top view, the hollow core is shown while in the bottom view such hollow core is covered and the hole for the insertion of the vertical axis turbine can also be seen.

[0032] FIG. 3 shows a top view of each single rotor that makes up the three-vane double rotor for vertical axis turbine wherein the 120-degree separation between each vane is shown.

[0033] FIG. 4 shows a top view of the two single rotors that make up the three-vane double rotor for vertical axis turbine wherein the 60-degree separation between the vanes of the upper rotor and the ones of the lower rotor is shown.

[0034] FIG. 5 shows a top view of each single rotor that makes up the three-vane double rotor for vertical axis turbine wherein its dimensions with respect to the R radius are shown.

[0035] FIG. 6 shows two plain side views of the three-vane double rotor for vertical axis turbine.

[0036] FIG. 7 shows on top the three types of rotors used in wind tunnel tests and at the bottom the layout of the model within the wind tunnel.

[0037] FIG. 8 shows a top view of each single rotor that makes up the three-vane double rotor for vertical axis turbine wherein the circumferences generated by the 4R, 0.5R and 1.2 R radius are shown.

[0038] FIG. 9 shows a vane with R radius inner circumference and 5R radius circumference generated by the extrados, 4R radius circumference generated by the intrados, 1.2R radius circumference generated by the separation of points A and B on the 4R radius circumference and 0.5R radius circumference that joins the intrados of such vane with the extrados of the next one.

DETAILED DESCRIPTION OF THE INVENTION

[0039] This invention is related to a three-vane (4) double rotor (1) for vertical axis turbine driven by propelling fluids such as wind or liquids, including water.

[0040] The double rotor of this invention comprises two three-vane single rotors, wherein one of the single rotors is called the upper rotor (2) and the other one is called the lower rotor (3) according to their relative spatial positions in such vertical axis turbine, the upper rotor is located in a position above the other single rotor, called lower rotor, both of them are separated by a horizontal or separation plate (5), wherein such plate (5) provides two different access areas for such propelling fluid. Both rotors, the upper rotor (2) and the lower rotor (3), that make up the double rotor (1) move together with the horizontal plate (5) around a vertical axis due to the action of the propelling fluid, such as wind or liquids, which in turn operates the vanes thereof.

[0041] The vanes of each of the single rotors (upper rotor and lower rotor) that make up the double rotor are separated from each other at an angle of 120 degrees (FIG. 3).

[0042] Each vane of the upper rotor (2) is displaced from the corresponding vanes on the lower rotor (3) at an angle of degrees (FIG. 4). This displacement optimizes the torque produced by a fluid stream and it also prevents cyclic vibrations when distributing propulsion along the whole rotor.

[0043] Each of the three vanes that make up each of the single rotors or the double rotor is situated in a R radius circumference around the vertical axis that produces the hollow core of each single rotor. These hollow cores of each single rotor are covered (7) above and below leaving an opening (8) in order that the vertical axis passes so that the fluid does not enter into such hollow cores (6).

[0044] Each of the vanes (4) that make up the upper rotor (2) and the lower rotor (3) have dolphin fin shape, having a profile with aerodynamic design like a plane wing, wherein such profile has the so-called extrados and intrados.

[0045] The farthest area from the vertical axis of each vane (4) of each of the rotors (upper rotor and lower rotor) that make up the double rotor (1) generates, during rotation around the vertical axis, a 4R radius circumference.

[0046] Considering the aerodynamic profile of each vane that makes up each of the rotors (upper rotor and lower rotor), such as a plane wing, it has a convex area in the extrados and a concave area on the intrados.

[0047] On each rotor (upper rotor and lower rotor (2, 3)) the convex area in the extrados of one of the vanes is joined to the concave area in the intrados of the next vane across a portion of 0.5R radius circumference.

[0048] The convex area in the extrados of each of the vanes corresponds to a portion of 5R radius circumference taken at a point A on the 4R radius circumference generated by the outermost portion of each vane during rotation around the vertical axis.

[0049] The concave area in the intrados of each of the vanes corresponds to a portion of 4R radius circumference taken at a point B on the 4R radius circumference generated by the outermost portion of each vane during rotation around the vertical axis.

[0050] The separation between point A and point B for the same vane corresponds to a distance equal to 1.20R.

[0051] According to the above, the relations regarding sizes of each single three-vane rotor that makes up the double rotor (1) of this invention can be unambiguously defined based on a R constant corresponding to the radius of the central circumference of each of the single rotors; each of the three vanes of each of the single rotors is joined to such central circumference.

[0052] This central R radius circumference corresponds to the center of each rotor which is hollow (hollow core rotor (6)), which makes the structure lighter and the start easier due to the action of the fluid. This R radius circumference has an inner wall that makes the structure stronger; inside such structure it is located the so-called hollow core of each single rotor. Such hollow cores are covered below and above, leaving an opening for the vertical axis passing so that the fluid does not enter into such hollow cores (6).

[0053] This way, having defined each of the single rotors that make up the double rotor (1) of this invention, it is determined continuity of the attenuated surface through curves between each vane in the flow direction of the fluid, resulting in the easier start of the turbine, elimination of parasitic flows like vortices (parasitic flow stopping rotor movement) in the area near the rotor axis leading to a higher performance thereof; in addition, it makes easier fluid outflow and decreases turbine's noise where this double rotor is installed. This continuity of the attenuated surface through curves between each vane (4), in the direction of the propelling fluid inlet, is maximized for a three-vane rotor; the increase of vanes in rotors (more than three) produces no attenuated joining curves thus giving rise to tangential surfaces that increase noise and vibration when the turbine using them is in operation.

[0054] It is worth mentioning that on the configuration of the double rotor of this invention, the fluid (wind or liquid) that causes movement of such rotor always hits two vanes of a single rotor and one vane of the other single rotor separated by a horizontal or separation plate, simultaneously; this determines that three vanes will always be in optimum position or easily achieve such optimal position to start (two on one side of the horizontal or separation plate and the other on the other side) in the turbine where it is installed. If we consider a single three-vane rotor of this invention only, it will have at most two vanes facing the fluid (for example, wind or water) since the remaining vane shall be in opposite position; at the same time, due to the displacement of 60 degrees between the upper and lower vanes of each single rotor, a vane of the other single rotor will also be in position to receive the fluid. That is, three vanes (2+1) will always be in position for driving the turbine axis in the double rotor of this invention regarding such turbine that has a single three-vane rotor only. This means that the turbine using the double rotor of this invention has 50% more starting power than one that uses a single three-vane rotor, which implies a start with less fluid speed.

[0055] Among the materials used for the construction of the double rotor of this invention, the followings are preferred: metal, plastic, or wood, any material used in construction and their combination.

[0056] These materials may also be used in combination to construct the single rotors that make up the double rotor.

Wind Tunnel Tests

[0057] Comparative tests of the rotor of this invention against other single and double rotors without continuity of the attenuated surface through curves between vanes were done.

[0058] The rotors used in each case had a diameter of 20 cm and a height of 0.5 m with hollow core. The turbine used in all tests had a height of 0.5 m and a diameter of 0.415 m.

[0059] In order to achieve the objective, the tests were conducted in a wind tunnel with a test section of 1.83 m×2.6 m×19 m and adjustable speed. Measurements were done with variable starting speeds, depending on the direction of the turbine with respect to the direction of wind, and maximum speed of 18 m/s. On each test, the following performance information of the turbine was obtained:

1. Free starting current speed (m/s).
2. Mechanical torque (Nmm) generated by the rotor.
3. Angular speed (rpm).

[0060] The three directions of the turbine are shown on top of FIG. 7, including the model layout diagrams inside the wind tunnel for each test; in the center of each direction, vanes to perform the tests are arranged.

Equipment

[0061] a) Turbulent boundary layer wind tunnel, test section 1.83 m×2.6 m×19 m, adjustable speed.
b) Portable hot wire anemometer, TESTO 512.
c) Torque wrench RT2USB, AEP.

d) Digital Tachometer, HEPTA.

Methodology

Test Preparation

[0062] a) Placement, alignment and leveling of the supporting structure the turbine.
b) Placement and leveling of torque wrench.
c) Placement of digital tachometer.

Test Procedure

Starting Speed Measurement

[0063] Start speeds in each case were determined; firstly, for the turbine without load, that is the axis free, and secondly, for the turbine with load, being the load the resistance to rotation exerted by the torque wrench on the rotor axis.

[0064] In the first case, turbine without load, angular speed measurements were performed using a HEPTA digital tachometer.

[0065] Measurement of torque and rotation speed (rpm)

[0066] Torque and rpm general procedure consisted in the measurement of speeds between 7 and 18 m/s. The first measured speed corresponds to the starting speed and it depends on each individual case on the direction of the turbine and on the fact of being load or not (if connected or not the torque wrench).

[0067] The above procedures were applied to the following rotors:

i) 6-blade single rotor (with vanes without surface continuity attenuated by curves)
ii) 3-blade single rotor (with vanes with surface continuity attenuated by curves)
iii) Double rotor comprising two 3-blades single rotors (vanes with surface continuity attenuated by curves corresponding to the rotor of this invention)

Test Results

[0068] i) Test on 6-Blade Single Rotor (with Vanes without Surface Continuity Attenuated by Curves)

[0069] The formation of a six-blade rotor causes that joining surfaces between the vanes can not be attenuated by curves; the distribution of six vanes around the rotor center determines cutting surfaces that generate parasitic flows during rotation thereof (see upper FIGURE).

Start Speed:

[0070] Start speeds obtained for the three directions of the wind are summarized in the following Table 1:

TABLE-US-00001 TABLE 1 start speeds (m/s), assisted or autonomous With load of torque Without load wrench Direction Assisted Autonomous Assisted Autonomous of turbine start start start start No. 1 10 >18 10 >18 No. 2 7 18 7.5 12 No. 3 7.5 >18 7 18

Angular Speeds for Each Direction:

[0071] Angular speeds obtained for the three directions of the wind are summarized in the following Tables 2, 3 and 4:

TABLE-US-00002 TABLE 2 RPM for direction No. 1 Rotor with Speed (m/s) Free rotor torque wrench 10 20 — 11 29 — 12 38 — 13 48 — 14 60 — 15 90 — 16 140 — 17 210 — 18 320 —

TABLE-US-00003 TABLE 3 RPM for direction No. 2 Rotor with Speed (m/s) Free rotor torque wrench 7 19 — 8 37 — 9 50 — 10 60 — 11 108 — 12 140 — 13 170 — 14 240 — 15 270 — 16 310 — 17 390 — 18 430 —

TABLE-US-00004 TABLE 4 RPM for direction No. 3 Rotor with Speed (m/s) Free rotor torque wrench 7.5 19 — 8 27 — 9 37 — 10 51 — 11 68 — 12 79 — 13 110 — 14 150 — 15 205 — 16 360 — 17 400 — 18 470 —

Torque:

[0072] It was done the measurement of torque for direction 3, wherein manual start under this condition reached 18 m/s. The results are summarized in Table 5:

TABLE-US-00005 TABLE 5 Torque (Nmm) for direction No. 3: Speed (m/s) Rotor with torque wrench 8 — 9 — 10 — 11 — 12 — 13 — 14 — 15 — 16 — 17 — 18 18

[0073] ii) Test on 3-Blade Single Rotor (with Vanes with Surface Continuity Attenuated by Curves)

[0074] A single three-blade rotor was used just like the one corresponding to each of the single rotors composing the upper rotor and the lower rotor of this invention; the height is the same.

Start Speed:

[0075] Start speeds obtained for the three directions of the wind are summarized in Table 6:

TABLE-US-00006 TABLE 6 start speeds (m/s), assisted or autonomous With load of torque Without load wrench Direction Assisted Autonomous Assisted Autonomous of turbine start start start start No. 1 7 >18 13 >18 No. 2 5.5 11 11 15 No. 3 4.5 14.5 12 >18

Angular Speeds and Torque for Each Direction:

[0076] Angular speeds and torque obtained for the three directions of the wind are summarized in the following Tables 7, 8, 9, 10, 11 and 12:

Results for direction No. 1

TABLE-US-00007 TABLE 7 RPM for direction No. 1 Rotor with Speed (m/s) Free rotor torque wrench 7 85 — 8 200 — 9 305 — 10 691 — 11 895 — 12 1010 — 13 1328 61 14 1494 123 15 2000 173 16 — 243 17 — 448 18 — 1268

TABLE-US-00008 TABLE 8 Torque (Nmm) for direction No. 1 Speeds (m/s) Rotor with torque wrench 14 21.49 15 22.34 16 23.18 17 24.49 18 25.93
Results for direction No. 2

TABLE-US-00009 TABLE 9 RPM for direction No. 2 Rotor with Speed (m/s) Free rotor torque wrench 5.5 100 — 6 185 — 7 275 — 8 370 — 9 630 — 10 830 — 11 975 — 12 1140  93 13 1310 115 14 1475 211 15 1595 267 16 1783 382 17 — 583 18 — 750

TABLE-US-00010 TABLE 10 Torque (Nmm) for direction No. 2 Speeds (m/s) Rotor with torque wrench 12 16.52 13 17.35 14 18.89 15 20.04 16 21.93 17 25.04 18 27.70

[0077] Results for direction No. 3

TABLE-US-00011 TABLE 11 RPM for direction No. 3 Rotor with Speed (m/s) Free rotor torque wrench 4.5 120 — 5.5 207 — 6 307 — 7 500 — 8 703 — 9 835 — 10 1065 — 11 1250 — 12 1430 — 13 1554 236 14 1930 409 15 2250 795 16 2500 982 17 — 1201  18 —

TABLE-US-00012 TABLE 12 Torque (Nmm) for direction No. 3 Speeds (m/s) Rotor with torque wrench 13 12.84 14 15.24 15 19.58 16 22.45 17 26.57 18 26.86

[0078] Based on the above results the following power curve was done. See the following table 13:

Preliminary Conclusions:

[0079] The single three-blade rotor with vanes with surface continuity attenuated by curves has better performance than a single 6-blade rotor since it needs less wind speed in some assisted start configurations, being almost equal the behavior in autonomous start.

iii) Test on 3-Blade Double Rotor (Vanes with Surface Continuity Attenuated by Curves)

[0080] A three-blade double rotor, just like the model of this invention, was used.

[0081] Those skilled in the art will note the possibility of adding various modifications and variations to the invention without excluding the spirit or scope thereof. Angular speeds and torque for each direction: Angular speeds and torque obtained for the three directions of the wind, as well as the power curve, are summarized in

[0082] Tables 14, 15, 16, 17, 18, 19, 20 and 21:

TABLE-US-00013 TABLE 14 start speeds (m/s), assisted or autonomous With load of torque Without load wrench Direction Assisted Autonomous Assisted Autonomous of turbine start start start start No. 1 4 5 7 7 No. 2 4 5 7 7 No. 3 4 4 7 7

Results for Direction No. 1

[0083] Angular Speeds (rpm)

TABLE-US-00014 TABLE 15 RPM for direction No. 1 Rotor with Speed (m/s) Free rotor torque wrench 4 17 — 5 44 — 6 74 — 7 119 22 8 173 54 9 248 98 10 346 170 11 467 252 12 575 362 13 695 455 14 800 588 15 909 742 16 1025 830 17 1120 921 18 1240 1035

TABLE-US-00015 TABLE 16 Torque (Nmm) for direction No. 1 Speeds (m/s) Rotor with torque wrench 7 18 8 19 9 19 10 20 11 21 12 21 13 22 14 23 15 24 16 25 17 26 18 27

[0084] Results for direction No. 2

[0085] Angular Speeds (rpm)

TABLE-US-00016 TABLE 17 RPM for direction No. 2 Rotor with Speed (m/s) Free rotor torque wrench 4 8 — 5 33 — 6 56 — 7 83 28 8 129 54 9 196 91 10 248 133 11 301 183 12 390 276 13 548 360 14 640 499 15 775 646 16 870 771 17 935 852 18 1100 962

[0086] Torque (Nmm)

TABLE-US-00017 TABLE 18 Torque (Nmm) for direction No. 2 Speeds (m/s) Rotor with torque wrench 7 19 8 20 9 20 10 22 11 22 12 23 13 25 14 26 15 27 16 28 17 30 18 29

Results for Direction No. 3

[0087] Angular Speeds (rpm)

TABLE-US-00018 TABLE 19 RPM for direction No. 3 Rotor with Speed (m/s) Free rotor torque wrench 4 14 — 5 31 — 6 53 — 7 80 48 8 118 93 9 169 141 10 240 226 11 303 338 12 405 438 13 485 598 14 626 702 15 723 830 16 800 959 17 930 1093 18 1100 1243

Torque (Nmm)

[0088]

TABLE-US-00019 TABLE 20 Torque (Nmm) for direction No. 3 Speeds (m/s) Rotor with torque wrench 7 18 8 19 9 21 10 22 11 23 12 25 13 27 14 27 15 29 16 29 17 30 18 31

[0089] Based on the above results, the power curve shown on the following table 21 was done.

Final Conclusions:

[0090] As shown in all rpm tables above mentioned, and as expected, an increase in wind speed means increases in the rotor's rpm or torque or angular speed, in each case, and therefore an increase in power.

[0091] It is worth mentioning that the operation and performance of the turbine are directly related to its direction with respect to the prevailing wind direction, highlighting that direction No. 3 is the one showing best results in terms of power (this aspect should be considered when defining the location of the device).

[0092] If analyzed separately, rpm and torque variations allow drawing some conclusions. On the one hand, it is difficult to define a noticeable rpm value behavior pattern, since according to the tables, the best direction from the point of view of rpm, it changes depending on the fact if there is a load or torque or not (a load may affect the internal fluid dynamic field due to the interaction between the rotor speed and its geometry). On the other hand, from the point of view of torque, the results show that the best direction is No. 3.

[0093] Please note that the double rotor design for vertical axis turbine comprising two simple rotors with three vanes of equal height of this invention allows autonomous start speeds lower than those of the other rotors, i) and ii), as shown in Table 14. This is shown either if loaded or not.

[0094] A further comparative advantage of this model iii) with respect to the rotors i) and ii) is the noticeable reduction of noise emissions.

[0095] In comparison, it can be concluded that this rotor design achieved substantial improvements in start speeds due to the displacement between the two sections that make up the rotor. This allows a start less influenced by the position of the rotor vanes with respect to the direction of the wind.

[0096] The fluid dynamic model used determines the rotor behavior is also comparable regarding different types of fluids, such as liquid and semiliquid fluids.

NUMERICAL REFERENCES

[0097] 1: Double rotor comprising two single rotors with three vanes with equal height for vertical axis turbine.

2: Upper Rotor

3: Lower Rotor

4: Vane

5: Horizontal or Separation Plate

[0098] 6: Hollow core
7: Covered hollow core
8: opening passed by the vertical axis of the turbine.

[0099] As a result of the above, it is understood that this invention covers the modifications and variations thereof as long as they are within the scope of the attached claims and their equivalents.