WO1999013221A1

WO1999013221A1 - Wind turbine carried by tethered wing

Info

Publication number: WO1999013221A1
Application number: PCT/NL1998/000506
Authority: WO
Inventors: Theodorus Istvan Van Bakkum
Original assignee: Theodorus Istvan Van Bakkum
Priority date: 1997-09-05
Filing date: 1998-09-04
Publication date: 1999-03-18
Also published as: WO1999013220A1; AU9007698A; AU4223597A

Abstract

Wind turbine assembly consisting of a wind turbine mounted in a wing profile. The aim is to fix the wing profile to the ground surface with the aid of a cable and to allow such a wing profile to float at an appreciable height above the ground surface. As a result the maximum amount of wind can be caught. The wind turbine consists of a turbine having a horizontal shaft, the blades being constructed as flexible webs which change in shape depending on the rotational position thereof.

Description

WIND TURBINE CARRIED BY TETHERED WING

The present invention relates to a wind turbine assembly according to the preamble of claim 1. A wind turbine assembly of this type is disclosed in NL 8602793 A. This publication describes a wind turbine to be fixed to a mast. This wind turbine consists of a horizontal blade construction with outer wheel and inner wheel. The latter are arranged eccentrically with respect to one another and rotate at the same angular velocity. The blades, consisting of webs of flexible material, extend between outer wheel and inner wheel. The shape of the webs will change depending on the position of outer wheel with respect to inner wheel, that is to say the degree of eccentricity. It has been found that wind energy can be utilised by this means in a particularly effective manner, that is to say using a relatively compact form. Other generally known wind turbines are fixed propellers of the Darrieus and Panemoon type. In order to capture appreciable quantities of energy, propellers of this type must have an appreciable surface area and be positioned at great height to be able to catch sufficient wind. The same applies in the case of the construction described in the abovementioned Netherlands Application 8602793.

Consequently it is necessary to provide the mast construction used for these turbines with a substantial foundation, whilst mast constructions of this type contribute to an appreciable extent to a blot on the landscape. In view of the above, wind energy is now usefully used only in locations close to the coast where there are also elevations such as dykes. Because such locations are relatively scarce, the decision to erect a series of wind turbines on such sites is frequently taken.

From EP-0 391 601 a wing profile is known to be connected to the earth by a cable connection in the wing profile a low revolution generator set is provided connected to blades having a fixed shape.

The aim of the present invention is to provide a less expensive wind turbine assembly which, because of the construction thereof, can also be used in locations other than along coasts and which gives rise to less of a blot on the landscape and which provides a higher efficiency. This aim is realized with a wind turbine assembly as described above having the characterising features of claim 1.

The invention is based on the insight of no longer using a mast construction but incorporating the wind turbine according to Netherlands Pa- tent Application 8602793. which gives a relatively compact construction, in a wing profile and fixing this with respect to the ground surface with the aid of a cable. As a result it is possible to operate the wind turbine at appreciably greater heights than has been customary hitherto without taking special constructional measures. After all, cables for fixing components with appreciable strength and length are generally known in the prior art. Thus, it is possible to mount the wind turbines at a height of approximately 100 metres above ground level. Because no masts are present there is no question of a blot on the landscape, whilst the fixing construction can be of much lighter and simpler design, as a result of which the cost price per turbine falls. Because of the greater height, the field of application of the wind turbine is appreciably enlarged, with the result that the latter can no longer be used only along coasts and the like. Through securing the extremities of the blades in a fixed position with regard to the blade wheels it has surprisingly be shown that the efficiency of the wind turbine assembly increases. This can be further improved by having either the inner wheel or webs provided with windows to prevent obstruction of the air flow. According to an advantageous embodiment of the invention, the underside of the wing profile tapers from the front section thereof in the direction of the rear section. As a result an inlet opening for the air which enters the wind turbine is delimited on the underside of the rear section.

According to a further development of this embodiment, the wing profile is provided with side walls which do not taper to the same degree as the underside, with the result that said side walls protrude laterally. As a result it is possible to fix tips or other blade-like parts in said side walls to improve the stability of the construction. It is possible to mount further means, such as spoilers, in the rear section of the wing to provide the construction with optimum stability. The spoiler means or diffuser blades can be made adjustable. In order, in particular, to facilitate rising, it is possible to provide the wing profile with a chamber to be filled with gas, the gas, of course, having a lower relative density than the ambient air.

The generator can be mounted in any position in the wing profile, but it is preferred to mount said generator laterally on the outside with respect to the wing profile. As a result the flow over the wing profile is disturbed as little as possible and optimum cooling of the generator is provided.

It has been found that both large and small wind turbine assemblies can be produced using the construction according to the present invention.

The invention will be explained in more detail below with reference to an illustrative embodiment shown in the drawings. In the drawings:

Fig. 1 shows a side view of the wind turbine assembly according to the invention;

Fig. 2 shows a perspective and partially exposed view of the construction according to Fig. 1, and

Fig. 3 shows a detail in perspective of the assembly according to the invention. In the figures a wind turbine assembly is indicated in its entirety by 1. The assembly consists of a wing profile 2, a wind turbine 3 being mounted in the rear section thereof. The front section of the wing profile 2 is provided with eyes 6 for fixing a cable thereto. A blade construction is indicated by 9- This blade construction consists of two shafts 8 and 10 which rotate at the same angular velocity and in the same direction and are linked to one another via means which are not shown in more detail. An inner wheel 12 is mounted around shaft 8 on either side of the wing profile. A wheel 11 is connected to shaft 10 on either side of the wing profile. A number of flexible blades 13. constructed as webs of material, extend between the wheels 11 and 12. The blades are drawn in various positions in the figures. These different positions are imposed by the relative positions of inner wheel 12 and outer wheel 11. The flexible blades are secured in a fixed position to both the wheels 11 and 12 at their respective ends . It is possible to perform a rotary movement at se- veral hundred revolutions per minute with a construction of this type.

The outer wheel 11 is also provided with toothing, which is not shown in more detail and engages on a gear wheel 16 which, in turn, is connected to a generator 17 which is located outside the actual wing profile 2. On the other side of wing profile 2 a further generator 17 connected to a gear wheel 16 is provided. These generators 17 can be high frequency power generators. For example it is possible to use generators having an operational area between 10.000-60.000 rpm. Such generators have a relatively low weight at a relatively high output. This means that gear wheel 16 or other transmission should be appropriately designed. By providing gene- rators on both sides of the device (torsional) loading of the outer wheel is balanced as much as possible.

The rear section of the wing profile comprises two wind vanes 21 , which are located some distance apart and between which a spoiler 18 extends. This spoiler is of adjustable construction. The adjustment can be wind-dependant to render optimum positioning of the rear section with respect to the front section 4 possible. That is to say, as a result of adjustment the rear section can be located higher or lower with respect to the front section, which has an influence on the amount of air admitted to the wind turbine 3« In this way the wind turbine 3 is always able to function in the optimum operating range thereof, which is also promoted by the use of a diffuser 25.

The front section 4 of the wing profile 2 consists of an upper section and an underside 22. A chamber 23 is delimited between the two, which chamber can optionally be closed off so that it can be filled with gas. The underside 22 does not extend down as far as the side walls 20. The side walls 20 are provided with tips 24 which generate turbulence to stabilise the wing profile. From fig. 3 it is clear that inner wheel 12 is provided with a number of windows 30. Through the presence of these windows air flow will not be severely restricted and during rotation a flexible blade 13 which is about to be engaged by the air flow will be prepositioned and pre- engaged through air flowing through the related window 30.

By means of the construction shown here an installation is obtained which has a particularly high efficiency, which is of an efficient shape and is simple and economical to operate, self-starting and provided with speed control. Moreover, said construction is self-orienting to the optimum wind direction. Optimum adjustment to the conditions can be provided by variation of the height of the installation according to the invention. Speed-limiting characteristics are achieved with a wind turbine constructed in this way. The power take-up is also constant over a wide range of wind speeds.

It is possible to generate virtually constant electric power using the constructions described above. This is particularly so because the wind turbine assembly can be used at great height.

It will be understood that as well as for generating energy the installation described above can also be used for commercial purposes . These purposes can comprise operation as an advertising carrier, use as a transmitter/receiver or use as an accumulator. After reading the above it will be understood that the wing profile shown here is only a preferred embodiment of the present invention. Many variants thereto are possible without going beyond the scope of the present invention and said variants will be obvious to those skilled in the art after reading the description and fall within the scope of the appended claims.

Claims

1. Wind turbine assembly (1) comprising a wind turbine (3) and a mounting connected thereto, the wind turbine comprising an inner (12) and outer (11) blade wheel rotatable about an essentially horizontal shaft wherein vanes (13) extend between said blade wheels (11, 12) and being formed by flexible web sections which change in shape depending on the position with respect to the mounting, generator means (17) for generating electric current being connected to said horizontal shaft, characterised in that said mounting comprises a wing profile (2) having a width which essen- tially corresponds to the width of the wind turbine, and having a front lift-producing section (4) which is provided with a fixing (6) for a cable (7) to be connected to the ground, as well as a rear section (5) in which said turbine is mounted, and wherein the extremities of said vanes are secured in fixed position to said blade wheels (11,12).

2. Wind turbine assembly according to Claim 1 , wherein the underside (22) of the wing profile (1) tapers from the front section (4) to the top in the direction of the rear section.

3. Wind turbine assembly according to Claim 2, wherein said wing profile is provided with side walls (20) which extend lower than the underside (22) in the tapering section of said underside.

4. Wind turbine assembly according to Claim 3. wherein elements (24) generating turbulence are mounted in that part of the side wall which is lower than the underside.

5. Wind turbine assembly according to Claim 4, wherein said elements generating turbulence comprise blade-like parts.

6. Wind turbine assembly according to one of the preceding claims, wherein the wing profile is provided at the rear with a diffuser blade (25) and an adjustable spoiler (18).

7. Wind turbine assembly according to one of the preceding claims , wherein a compartment (23) to be filled with gas is delimited between the underside and the top of the wing profile.

8. Wind turbine assembly according to one of the preceding claims, wherein at least one generator (17) is mounted on the rear of the wing profile at the sides thereof.

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