EP0070857A1

EP0070857A1 - Fluid driven rotor

Info

Publication number: EP0070857A1
Application number: EP19820900410
Authority: EP
Inventors: Anders Lundqvist
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-02-09
Filing date: 1982-02-09
Publication date: 1983-02-09
Also published as: SE8100876L; WO1982002747A1

Abstract

Un rotor entraine par un fluide, specialement pour fonctionner au vent, consiste en des aubes (4) situees autour de la generatrice d'un tronc de cone et s'etendant dans son sens longitudinal. L'invention est caracterisee en ce que la distance entre deux aubes adjacentes (4, 5, 45) est plus petite que la largeur de l'aube respective, et qu'au moins l'un des organes de support (2, 3) est ouvert et permet une communication entre l'interieur du rotor et le milieu ambiant, et que les aubes (4, 5, 45) sont inclinees suivant un angle compris entre 20 et 30 par rapport a l'axe du rotor.A rotor driven by a fluid, especially to operate in the wind, consists of blades (4) located around the generator of a cone trunk and extending in its longitudinal direction. The invention is characterized in that the distance between two adjacent blades (4, 5, 45) is smaller than the width of the respective blade, and that at least one of the support members (2, 3) is open and allows communication between the interior of the rotor and the surrounding environment, and that the blades (4, 5, 45) are inclined at an angle between 20 and 30 relative to the axis of the rotor.

Description

Fluid driven rotor

This invention relates to a fluid driven rotor, particularly but not exclusively intended to be driven by the wind, Rotors and turbines of different types for utilizing the energy inherent in the wind are known. Of such devices substantially two types exist, viz. the type at which the turbine blades extend substantially perpendicularly from the turbine shaft (propeller type), and the type at which the turbine blades extend substantially in parallel with the turbine shaft. In order to be able to obtain any useful effect by these devices, wind velocities of up to 6 m/s are required. At lower wind velocities the devices are non-productive. Both these types of devices, moreover, have the characterizing feature that their rotational speed is very low compared with the wind velocity.

There exists also one type of turbine with vertical shaft at which the turbine blades extend in arc-shape from the lower portion of the shaft to its upper point. The number of blades normally are three. This design comprises a light rotor part, which implies that the turbine rotates relatively rapidly. Owing to the design of the blades, however, this type of device has a relatively low torque, which in its turn implies that the wind velocity must be high for gaining a useful effect from the device.

The present invention relates to turbines of the type, which comprises a vertical shaft with blades rotating about the same. The invention as it is defined in the characterizing clauses of the attached claims provides a fluid driven rotor or turbine, which is characterized by high rotational speed and which has an efficient torque already at wind velocities of 2 m/s, irrespective of the wind direction.

The invention is described in greater detail in the following by way of an example, with reference to the accomp anying drawing, in which

Fig. 1 is a schematic lateral view of a device according to the present invention,

Fig. 2 is a schematic section through the device according to Figs. 1 and 3, and

Fig. 3 shows another embodiment of the invention.

The rotor according to the invention in principle comprises a shaft 1, which downwardly carries a support member 2 and upwardly carries a support member 3. The support members 2 and 3 have the form of spoked rings, and the diameter of the support member 2 exceeds that of the support member 3. Between the peripheral portions of the support members extend turbine blades in uniformly spaced relationship along the respective periphery and in such a number, that the distance between two adjacent blades is smaller than the blade width, the blade chord. In Fig. 1, for reason of simplicity, only two blades are shown. The respective blade here consists of a forward stay 5, seen in the rotation direction of the turbine, which is braced between ween the two support members, and a sail 4 extending from the stays. See also the lower portion of Fig. 2. The sail may be of a suitable material, such as fabric, plastic dacron ^(R) or the like, The sail in its turn is braced in extended position at the support members by suitable fastening means 6. Due to the fact that at least one of the support members 2 and 3 is fixed on the shaft 1, the turbine, for example, can drive a generator (not shown) positioned in the base 7.

Seen as an entirety, the blades with the support members form a truncated cone, the "shell" of which shall form an angle α to the shaft of about 20-30°, preferably 25-26°, which has proved to be an optimum angle range. At greater or smaller angles the rotational speed of the rotor decreases. When the wind blows against the blade, in usual manner a higher pressure is formed on the front side of the blade met by the wind, and a negative pressure is formed on the rear side of the blade, and the turbine will rotate. Due to the venturi effect between the blades, the air there increases its speed, whereby the dynamic pressure drops. The air flows out of the device through the open support members 2,3, while within the turbine at the rotation a permanent negative pressure is formed which exceeds the negative pressure on the leeside of the turbine. No braking effect, therefore, arises from air flowing through the turbine and, consequently, a high rotation speed can be achieved compared with the wind velocity.

Instead of blades in the form of stays and sails, the blade can be made homogeneous of metal, for example light metal, or reinforced plastic material. The blade 45 then preferably is slightly S-shaped and has a thin profile, see the upper part of Fig. 2. As the speed of the blade is higher downwardly at the turbine than upwardly, because of the inclination of the blades, the blade thickness for aerodynamic reasons should be greater at the upper support member 2 than at the lower support member.

It applies in general that the higher the wind velocity (wind forces), the more stretched the blades must be in order to achieve a high efficiency degree. By designing the upper and the lower support member rotatable relative to each other, for example by arranging the upper member 3 freely rotatable on the shaft, it is possible to automatically achieve this effect. Due to the fact, that the upper support member 2 has a smaller diameter than the lower support member and thereby, together with the upper blade portions, has less mass than the lower support member with its blade portions, the upper part of the turbine has the tendecy of rotating at a higher speed than the lower part and, therefore, a certain angle torsion between the support members will arise. This in its turn implies that the blade is subjected to a stretching in longitudinal direction, i.e. a stiffening.

At the embodiment according to Fig. 1 and the lower portion of Fig. 2, it is possible also to effect a stretching of the blade sails by anchoring them downwardly in sheet members, actuated for example by centrifugal governors .8 . The higher the wind velocity is , the faster is the rotation, which implies a more forceful stretching of the sails. Such arrangements can be brought about by applying known art, and therefore they are not part of the invention proper and here not described in detail either.

In Fig. 3 a turbine according to the invention is shown, which consists of two truncated cone-shaped partial turbines 9 and 10. As appears from Fig. 3, they are mounted on the same shaft 1 and face each other with their base surfaces. The turbine blades 45 (for reasons of clarity not all are shown in the Figure) are arranged so that the partial turbines rotate in opposed directions. By providing the adjacent support members with electric windings and magnets, which together form rotor and armature for an electric generator, the possibility is obtained of generating current in an efficient way with the turbine according to the invention. The parts of the generator are given a speed in relation to each other which is twice as high as the rotation speed of each of the partial turbines. The generator, which can be manufactured in conventional manner, is not a part of the invention, either, and therefore is not described in detail. At this embodiment, the air leaves the turbine through the uppermost and lowermost support member with smaller diameter.

It is also possible within the scope of the invention to make such an arrangement that the blades 45 can be given feathering position, depending on the wind velocity, and thereby to obtain maximum efficiency degree of the turbine at different wind velocities. The feathering position can be effected automatically or manually. The technical solution of such feathering does not involve, either, an inventor's work and can be realized in many different ways by applying known art. No feathering mechanism, therefore, is described in detail.

The double turbine shown in Fig. 3 also can be used to drive a generator in the foundation via the counterrotating shafts of the partial turbines. It is, of course, understood to fall within the scope of the invention that machines other than generators can be driven. The invention also can be used, for example, for driving the propeller of a boat.

As, due to the parameters determined by the invention, no cross-flow occurs in the turbine, and the air passes out of the rotor through the end surfaces, the invention, of course, can be combined with an axial fan, propeller, located at the wider support member 2 and designed so as to be driven by the air flowing out of the rotor. The support member 3 in that case preferably should be closed.

Claims

1. A fluid driven rotor, especially for wind operation, comprising blades. (4) located about the generatrix of a truncated cone and extending in the longitudinal direction thereof, which blades by a first support member (2) constituting the greater limit surface of the cone and a second support member (3) constituting the smaller limit surface of the cone are connected to the shaft (1) of the rotor, which shaft coincides with the axis of the truncated cone, c h a r a c t e r i z e d i n that the distance between two adjacent blades (4,5,45) is smaller than the width of the respective blade, that at least one of the support members (2,3( is open and permits communication between the interior of the rotor and the ambient, and that the blades (4, 5,45) are inclined through an angle between 20 and 30 in relation to the rotor axis.

2. A rotor as defined in claim 1, c h a r a c t e r i z e d i n that the angle is between 24° and 27°.

3. A rotor as degined in claim 1 or 2, c h a r a c t e r i z e d i n that the respective blade has the form of a sail (4), which at its forward edge seen in the direction of movement of the blade is stayed in a stay (5) stretched between the first (2) and the second support member (3), and that the rear edge of the sail is attached to the respective support member.

4. A rotor as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that two rotors are arranged coaxially with the first support member (2) of the respective rotor adjacent one another, and the blades (45) are positioned so that the rotors rotate in opposed directions.

5. A rtor as defined in claim 4, c h a r a c t e r i z e d i n that the support members (2) adjac ent one another carry rotor and, respectively, stator parts so as in co-operation to form an electric generator.

6. A rotor as defined in claim 1, 2 or 3, c h a r a c te r i z e d i n that the first support member (2) is attached to the shaft (1), which is mounted rotatably in a foundation (7) carrying the rotor, and that the second support member (3) is rotatable in relation to the shaft.

7. A rotor as defined in any one of the claims 3-6, c h a r a c t e r i z e d i n that the rear edge of the sail is connected to the first support member (2) by means known per se for automatic stretching, sheeting, the sail at increasing wind pressure on the sail.