WO2012126625A1

WO2012126625A1 - Blade assembly of wind power plant having vertical rotation axis

Info

Publication number: WO2012126625A1
Application number: PCT/EP2012/001260
Authority: WO
Inventors: Pawel WIECZOREK; Ryszard FUHRMANN
Original assignee: Wieczorek Pawel; Fuhrmann Ryszard
Priority date: 2011-03-22
Filing date: 2012-03-22
Publication date: 2012-09-27
Also published as: PL394308A1; PL226073B1

Abstract

The present invention relates to the blade assembly of wind power plant with vertical rotation axis perpendicular to the direction of flow comprising at least one set of blades consisting of at least three identical blades distributed evenly on the power plant circumference and equidistant from its axis, wherein the blade (1) is in the form of a curved bowl, which has the shape of irregular spherical segment with the projection similar to a rectangle with rounded edges, fixed rotationally to at least one arm (3).

Description

Blade assembly of wind power plant having vertical rotation axis

The present invention relates to the blade assembly of wind power plant having vertical rotation axis perpendicular to the direction of wind flow. It is used especially in small wind power plants generating electric current, for instance for household needs. It proves to be particularly useful in the areas where there are light winds, but sometimes hurricane winds occur.

The turbine, which is equipped with at least two blade rotors situated one above the other, relative to the common rotation axis is known from the Polish patent application P386834. Each of the rotors has at least two horizontal extension arms with the wings fixed rigidly at the arms ends, where each of the wings has the bottom blade and the upper blade, which are bent outside at an angle in relation to extension arm. The rotors are fixed on coaxial shafts with independent bearings or they are connected by one shaft, whereby the upper rotor is rigidly fixed to the shaft and the bottom one is connected to the shaft by clutch.

The wind power plant with vertical bearing shaft on which the rotor shaped ascylinder is mounted is also known from the Polish patent application P387537. Identical coupled rotatable wings, mounted in pairs, are distributed on the rotor evenly on its circumference. The wing's curvature is similar to the curvature of the cylinder and the rotation axis of both wings are moved away from the cylinder axis by a constant radius R. The wing is made in such a way that it is a first order lever having the shape of the letter "L" with the rotation axis in bend. The longer arm constitutes part of the wing transferring the wind pressure, while the other, shorter arm is connected through the connecting link to the arm of the second wing opposite the first one. The length of connection link is the same and it is not longer than the distance between the holes axes in the shorter arms of the wing, reduced by the distance between the wing rotation axis and the hole axis in the shorter arm of the wing in the position, in which the rotation axis of one of the wings and the holes axes in the shorter arms wings are in alignment. The angle formed between the plane passing through the rotation axis of wing and the edge of wing, and the straight line passing through the rotation axis of wing and the hole axis in the shorter arm of the wing is not greater than 90°.

Moreover, the rotor consisting of three blades with a specially designed aerodynamic profile is known from the Polish patent application P376726. It is fixed to the hub in such a way that it is possible to change the angle in order to ensure steady revolutions of rotor in the working range of the wind speed, which is required by the cooperating generator assembly. The speed governor mechanism adjusts precisely the blades angle of attack according to wind conditions. Preferably, the wind power plant rotor having vertical rotation axis for wind energy transformation, especially low speed wind, integrated with the governor mechanism is especially appropriate for the cooperation with generators having permanent magnets. The blades have the form of a bowl, having side surface similar to the shape of a cylinder. Its diameter at the middle part, at the level of flange decreases downwards and upwards forming an interior angle of about 15°. External vertical edges of the bowl are slightly, obliquely deflected outside forming a concave angle on one side, and they meet in the middle of the bowl forming a convex angle on the other side. The bowl is closed at the top and bottom with flat upper and lower bottoms, having shape similar to a triangle, wherein these bottoms are perpendicular to the axis of power plant.

The known blade assemblies of the wind power plant with vertical rotation axis perpendicular to the direction of the wind flow have a low efficiency in light wind conditions, which is the result of a small efficiency of their aerodynamic profiles in light and very light wind conditions. They have also a relatively high speed at which the production of electric energy starts. Moreover, the known blade assemblies do not operate during very strong winds, which limits their applications. The known wind power plant blade assemblies having vertical rotation axis are characterized by complex fastening and adjustment systems, which increase their cost and make them less reliable. The disadvantages mentioned above considerably limit their applications in practice.

The aim of the present invention is to develop wind power plant blade assembly having vertical rotation axis perpendicular to the direction of wind flow, free of the described disadvantages, so that it could be used especially in small wind power plants generating electric current, for instance, for the needs of households, and especially so that it could be used in the areas where there are usually light winds, but sometimes hurricane winds occur. The aim of invention was fulfilled by means of blade assembly of wind power plant having vertical rotation axis perpendicular to the direction of flow comprising at least one set of blades consisting of at least three blades distributed evenly on the circumference of power plant and equidistant from its axis, wherein the blade is in the form of a curved bowl, which has the shape of irregular spherical segment with the projection similar to a rectangle with rounded edges, fixed rotationally of at least one arm.

Preferably, the blade assembly comprises at least two sets of blades, wherein distances between blades and power plant axis in individual sets are different.

Preferably, the blade is in the form of a bowl with the chord (the width at the base) of the blade to its total height ratio ranging from 0,25 to 2.5, more preferably from 0.4 to 0.8, the most preferably equal to about 0.5.

Preferably, the blade is in the form of a bowl with the ratio of the plane sector height at the base of blade to its chord ranging from 0 to 1.3, more preferably from 0,2 to 0.4, the most preferably equal to about 0,22.

Preferably, the blade is in the form of a bowl with the blade chord to the length of its external sheathing circumference at the base ratio ranging from 0.3 to 1.0, more preferably from 0.5 to 0.8, the most preferably equal to about 0.7.

Preferably, the blade is in a form of a bowl with the displacement of the blade middle plane in the length of blade in parallel to the blade chord to its chord ratio ranging from 0 to 0.5, more preferably from 0.05 to 0,2, the most preferably equal to option about 0.1.

Preferably, the blade is in a form of a bowl with displacement of the blade plane in the blade length perpendicularly to the chord of blade to its chord ratio ranging from 0 to 0.5, more preferably from 0.02 to 0.1 , the most preferably equal to about 0.05.

Preferably, the blade is in a form of a bowl with the maximum protrusion height of the blade centre to its chord ratio ranging from 0 to 1.0, more preferably from 0.4 to 0.8, the most preferably equal to about 0.5.

Preferably, the blade is in the form of a bowl with the rounding of the blade end to its chord ratio ranging from 0 to 1.0, more preferably from 0.2 to 0.5, the most preferably equal to about 0.25.

Preferably, the blade is in the form of a bowl with the length of external sheathing circumference of the centre of blade to the length of its external sheathing circumference at the base ratio ranging from 0.5 to 2.0, more preferably from 0.7 to 1.7, the most preferably equal to about 1.4. The blade can be fixed rotationally to the arms ends. It can be fixed rotationally to the ends of two arms, which are rigidly connected together. Usually, it is rotationally fixed to at least one arm by means of at least one support rod propped in several places of the bowl.

The number of blades distributed evenly on the circumference of power plant can be calculated according to the formula

K=S/A * Wk

where:

- number of blades,

S - maximum circumference of power plant with closed blades,

A - chord of blade,

Wk - coefficient of the number of blades,

wherein the result is rounded to natural number and the coefficient of the number of blades Wk has the value ranging from 0.3 to 0.9.

Preferably, besides the usual three blades, the blade assembly may comprise five or six blades distributed evenly on the power plant circumference.

Preferably, the blade is stabilized by damper mounted between blade and the arm or rotor.

The blade assembly of wind power plant having vertical rotation axis perpendicular to the direction of wind flow, according to the present invention, is characterized by high efficiency in light wind conditions, which is mainly a result of the high efficiency of aerodynamic profiles of the blades with in light and very light winds conditions, even in case of wind speed below 1.3 m/s. It also has a relatively low speed at which the production of electric energy starts and it operates also during very strong winds, even hurricane winds, which makes the range of its application broader. The wind power plant blade assembly with vertical rotation axis perpendicular to the direction of wind flow, according to the present invention, is characterized by a cheap and simple fixing and adjustment system .

The invention will be described and presented in preferable examples presented on the drawings, where

Figure 1 shows in schematic manner, the bottom view of blade according to the present invention,

Figure 2 shows in schematic manner, the axonometric view of blade according to the present invention, Figure 3 shows in schematic manner, bottom view of the cross-section of blade in Figure 1 in the middle plane,

Figure 4 shows in schematic manner, the wind power plant with the blade assembly according to the present invention,

Figure 5 shows in schematic manner, the model of a different embodiment of wind power plant with the blade assembly according to the present invention,

Figure 6 shows in schematic manner, the assembly of three blades according to the present invention,

Figure 7 shows in schematic manner, the assembly of five blades according to the present invention, and

Figure 8 shows in schematic manner, the assembly of six blades according to the present invention.

Figure 9 shows in schematic manner, the assembly according to the present invention comprising two sets of blades, each consisting of three blades.

Figure 10 shows in schematic manner, the assembly according to the present invention comprising two sets of blades, the first consisting of three blades and the second consisting of six blades.

Figure 1 1 shows in schematic manner, the another embodiment of assembly according to the present invention comprising two sets of blades, the first consisting of three blades and the second consisting of six blades.

Figure 12 shows in schematic manner, the assembly according to the present invention comprising two sets of blades, the first consisting of three blades and the second consisting of twelve blades.

As can be seen in Figure 1 , the blade has a form of a curved bowl, which has the shape of irregular spherical segment with the projection similar to a rectangle with rounded edges (see also Figures 2, 4 and 5). Said blade is rotationally mounted to at least one arm 3.

Blade 1 has a form of bowl with the ratio of chord A (the width at the base) of blade 1 to its total height B (see Figure 2), defined as width coefficient at the base Wa, which ranges from 0.25 to 2.5, more preferably from 0.4 top 0.8, the most preferably equal to about 0.5.

The bowl has the ratio of height C of the plane sector at the blade base 1 to its chord A ranging from 0 to 1.3, more preferably from 0.2 to 0.4, the most preferably equal to about 0.22, defined as height coefficient of the plane sector of the base of blade Wc. The ratio of chord A of blade 1 to the length D of its external sheathing circumference at the base ranges from 0.3 to 1.0, more preferably from 0.5 to 0.8, the most preferably equal to about 0.7 and it is defined as Wd.

The ratio of displacement E of the middle plane 2 of blade 1 in the length B of blade 1 in parallel to the chord A of blade 1 to chord A ranges from 0 to 0.5, is more preferably than 0.05 to 0.2 and the most preferably equal to about 0.1 and it is defined as We.

The ratio of displacement F of the middle plane 2 of blade 1 in the length B of blade 1 perpendicularly to the chord A of blade 1 to chord A which ranges from 0 to 0.5, more preferably from 0.02 to 0.1, the most preferably equal to about 0.05 and it is defined as Wf.

The ratio of the highest protrusion G of the middle of blade 1 to its chord A ranges from 0 to 1.0, more preferably from 0.4 to 0.8, the most preferably equal to about 0.5 and it is defined as Wg.

The ratio of rounding H of the blade 1 ends to its chord A ranges from 0 to 1.0, more preferably from 0.2 to 0.5, the most preferably equal to about 0.25 and it is defined as Wh.

The ratio of length I of sheathing circumference of the centre of blade to the length D of its sheathing circumference at the base ranges from 0.5 to 2.0, more preferably from 0.7 to 1.7, the most preferably equal to about 1.4 and it is defined as Wi.

As is shown in Figure 4, each of the blades 1 is rotationally mounted to at least one arm 3, by means of holder 4 (see Figure 3), but it can also be rotationally mounted to the ends 5 of two arms 3, which are rigidly connected together (as in Figure 5), forming one integral rigid set of arms. Blade 1 is usually rotationally mounted to at least one arm 3 by means of at least one support rod 6 propped in several places of the bowl by means of side bars 7.

The number of blades distributed evenly on the power plant circumference can be calculated based on the formula

K=S/A * Wk

where:

- number of blades,

S - maximum circumference of power plant with closed blades,

A - chord of a blade, Wk - coefficient of the number of blades,

wherein the result is rounded to a natural number and the coefficient of the number of blades Wk has the value ranging from 0.3 to 0.9, Said coefficient Wk depends on the blades shape and has been examined experimentally.

Besides the usual three blades 1 (as shown in Figure 6) the set of blades 1 may comprise five (as shown in Figure 7) or six (as shown in Figure 8) blades 1 distributed evenly on the power plant circumference Blades 1 are shown in Figures 6, 7 and 8 both in the closed the open position. As can be seen in these figures, blades 1 are rotationally mounted to arms 3, which are fixed to the rotor 8 on their other end.

The blade assembly may include at least one set of blades, wherein set of blades consists of at least three blades. Within each individual set, blades are distributed evenly on the circumference of power plant and equidistant from its axis.

If the blade assembly comprises more than one set of blades, for example two or more such sets, distances between blades and power plant axis in individual sets may be different. For example, as shown on fig. 9, assembly may contain two sets of blades, each consisting of three blades. The distance between power plant axis and blades of first set is larger, than the distance between power plant axis and blades of second set.

It is also possible to combine several blade assemblies, having the same or different blade 1 sizes, within one power plant, on the same or different levels.

Fig. 10 shows a blade assembly comprising two sets of blades, wherein the first set consists of three blades and the second ser consists of six blades. Blades of first assembly are located closer to the power plant axis and they are smaller than the blades of the second set.

Another embodiment of the invention is shown on Fig. 1 1. The presented blade assembly comprises two sets of blades, wherein the first set consists of three blades and the second ser consists of six blades. Blades of first assembly are located closer to the power plant axis and they are larger than the blades of the second set.

Further embodiment of the invention is shown on Fig. 12. This particular blade assembly comprises two sets of blades, wherein the first set consists of three blades and the second set consists of twelve blades. Similarly as in the previously described embodiment, blades of first assembly are located closer to the power plant axis and they are larger than the blades of the second set. Blades 1 are mounted to arms 3 of the rotor 8 in such manner that it is possible to correctly set the angle of attack of blade 1 to the wind. The geometry of blade 1 (its physical properties of surface and weight), and the aerodynamics ( face of attack relative to the wind and working surface during the operation), enables the control of blade 1 (closing/opening) by wind and at the same time by the change of revolutions (decrease/increase of centrifugal forces).

L and M denote parts of the blade surface and indices of centrifugal forces (FL_; FM) on the blade with the rotor turning.

In the very light wind conditions (scale 1) when the blade 1 is open (angle about 20 degrees relative to the arm), the wind exerts thrust on part L of blade 1 to the greater extent than on part M (FL > FM) (see Figure 3). As a result, blade 1 is "opened" and exerts thrust on arms 3 of the rotor 8 which induces a torque on the shaft of power plant. Since centrifugal forces of parts L and M are similar, and L>M, and the wind exerts thrust mostly on "L", the power plant does not close the blades, andonly its rotor revolves.

In the light wind conditions (scale 2), the revolutions increase and centrifugal forces of the parts of blade 1 change, wherein L=M, but the thrust on the surface of part L still turns the rotor 8 of power plant (a torque is induced) (FL>FM).

In the average wind conditions (scale 3), the revolutions increase and centrifugal forces of blade 1 change, wherein M>L. Part M starts to shut off slowly "the access" of the wind stream (it turns blade 1 slightly), so the thrust of wind on part L decreases (FL = FM) and the revolutions of power plant stabilize.

In the strong wind conditions (scale 4), the revolutions increase and centrifugal forces of blade 1 change, wherein M»L Part M shuts off "the access" of the part of wind stream and the thrust of wind on part L still decreases (FL < FM) , the power plant stabilizes and shuts off the excess of wind.

Blade 1 in its geometry changes the position to about 70-80 degrees relative to arm 3 , which causes change in geometry of the whole blade assembly and at the same time increases the tip speed ratio of the power plant of a particular class, and as a result the greater power is transferred to the power plant shaft.

In the hurricane conditions (scale 5), the revolutions stabilize and centrifugal forces of blades change, wherein M»>L (M considerably bigger than L). Part M shuts off the "access" of the wind stream and the thrust of wind on part L still decreases (FL < < FM). .The power plant gets stabilized and shut off the excess of wind. The external part of blade 1 also helps to achieve it, as it helps "closing" blade 1 with greater force. Blade 1 in its geometry changes the position to about 80-90 degrees relative to arm 3, which causes the change in geometry of the whole power plant and in the same time increases the tip speed ratio of the power plant of a particular class, and as a result the greater power is transferred to the power plant shaft.

The whole power plant can be additionally stabilized by damper 9 (see Figure 5) mounted between arm 3 or rotor 8 and blade 1 , preferably its grip 4 which usually is a part of the support rod 6. The purpose of the damper 9 is to eliminate sudden changes of blade geometry relative to arm 3 which are the result of sudden gusts of wind, and to close all blades evenly.

Claims

Patent claims

The blade assembly of wind power plant with vertical rotation axis perpendicular to the direction of flow comprising at least one set of blades consisting of at least three identical blades distributed evenly on the power plant circumference and equidistant from its axis, characterized in that blade (1) is in the form of a curved bowl, which has the shape of irregular spherical segment with the projection similar to a rectangle with rounded edges, fixed rotationally to at least one arm (3).

The blade assembly according to claim 1, comprising at least two sets of blades, wherein distances between blades and power plant axis in individual sets of blades are different.

The blade assembly according to any of preceding claims, wherein blade (1) is in the form of a bowl with the chord (A) (width at the base) of blade to its total height (B) ratio ranging from 0.25 to 2.5, more preferably from 0.4 to 0.8, the most preferably equal to about 0.5.

The blade assembly according to any of preceding claims, wherein blade (1 ) is in the form of a bowl with the height (C) of the plane section at the base of blade (1) to its chord (A) ratio ranging from 0 to 1.3, more preferably from 0.2 to 0.4, the most preferably equal to about 0.22.

The blade assembly according to any of preceding claims, wherein blade (1 ) is in the form of a bowl with the chord (A) of blade (1 ) to the length (D) of its external perimeter of sheathing at the base ratio ranging from 0.3 to 1.0, more preferably from 0.5 to 0.8, the most preferably equal to about 0.7.

The blade assembly according to any of preceding claims, wherein blade ( 1 ) is in the form of a bowl with the displacement (E) of the middle plane (2) of blade (1 ) in the length of blade (1) in parallel to the chord of blade (1) to the chord (A) ratio ranging from 0 to 0.5, more preferably from 0.05 to 0.2, the most preferably equal to about 0.1 .

The blade assembly according to any of preceding claims, wherein blade (1 ) is in the form of a bowl with the displacement (F) of the middle plane (2) of blade (1 ) in the length of blade (1 ) perpendicularly to the chord (A) of blade (1 ) to the chord (A) ratio ranging from 0 to 0.5, more preferably from 0.02 to 0.1 , the most preferably equal to about 0.05. 8. The blade assembly according to any of preceding claims, wherein blade (1) is in the form of a bowl with largest protrusion height (G) of the centre of blade (1) to the chord (A) ratio ranging from 0 to 1.0, more preferably from 0.4 to 0.8, the most preferably equal to about 0.5.

The blade assembly according to any of preceding claims, wherein blade (1 ) is in the form of a bowl with rounding (H) of blade termination (1 ) to the chord (A) ratio ranging from 0 to 1 .0, more preferably from 0.2 to 0.5, the most preferably equal to about 0.25. 10. The blade assembly according to any of preceding claims, wherein blade (1 ) is in the form of a bowl with the length (I) of sheathing circumference of the centre of blade (1 ) to the length (D) of its external sheathing circumference at the base ratio ranging from 0.5 to 2.0, more preferably from 0.7 to 1.7, the most preferably equal to about 1.4.

11. The blade assembly according to any of preceding claims, wherein blade (1 ) is fixed rotationally to the ends (5) of arms (3).

12. The blade according to any of preceding claims, wherein blade (1 ) is fixed rotationally to the ends (5) of at least two arms (3) rigidly bound with each other.

13. The blade assembly according to any of preceding claims, wherein blade (1 ) is fixed rotationally to at least one arm (3) by means of at least one support arm (6) propped in several places of bowl.

14. The blade assembly according to any of preceding claims, wherein the number of blades (1 ) distributed evenly on the power plant circumference is calculated according to formula = S/A * Wk , where K is number of blades, S is maximum circumference of power plant with the blades closed, A is chord of blade, Wk is coefficient of the number of blades), where the result is rounded to natural number.

15. The blade assembly according to any of preceding claims wherein the coefficient of the number of blades (1) Wk has the value ranging from 0.3 to 0.9.

16. The blade assembly according to any of preceding claims, wherein it includes five blades (1) distributed evenly on the power plant circumference.

17. The blade assembly according to any of claims 1 -15 claims wherein it includes six blades ( 1 ) distributed evenly on the power plant circumference.

18. The blade assembly , according to any of preceding claims, wherein blade (1) is stabilized by damper (9) mounted between blade (1 ) and arm (3) or rotor (8).