DE202011002702U1 - Double Darrieus rotor - Google Patents

Abstract

Apparatus for converting a fluid flow into usable motive power, comprising a first Darrieus rotor having a first high speed number and a second Darrieus rotor having a second high speed number which is smaller than the first high speed number, the second Darrieus rotor providing a starting aid to the first Darrieus rotor is.

Description

Technical area

The invention relates to a device for converting a fluid flow into usable driving force, wherein the device comprises at least one Darrieus rotor.

State of the art

Devices for utilizing fluid flows are known in a variety of variations. A particularly interesting basic principle is the Darrieus rotor to mention, to which many design proposals and developments exist.

A well-known feature of the Darrieus rotor in wind turbines is the high start-up speed, ie the Darrieus rotor does not run on its own or only at relatively high wind speeds. There are many attempts in the literature to improve this property, it is proposed, for example, to use a generator connected to generate electricity as a motor and to start the Darrieus rotor by means of electricity (ie to set in rotation). In other approaches, rotor blades are made so modifiable that the rotor blades at low fluid velocities have a higher fluid-dynamic resistance and start the Darrieus rotor, and take at higher fluid velocity a shape and / or position with reduced fluid-dynamic resistance to one to achieve good efficiency. The rotor blades can be designed, for example expandable or hinged. In this sense, z. B. the DE 298 04 581 U1 to provide expandable elements (wings etc.) or changeable elements (eg profile thickness and / or profile shape). Movement possibilities are also known relative to the flow direction of the fluid (twisting, tilting, etc.). Likewise, permanently installed additional elements such. B. a front of the flow receptor, ie rotor blade, mounted trough-shaped front sheet (such as in DE 41 20 908 A1 ) or one or more Savonius rotors (such as in TW 2007 16862 A ) achieve an advantageous fluid-dynamic effect. Again other approaches use wind deflectors for guiding and bundling the wind (such as in WO 2006/132923 A2 or otherwise attempt to increase the relative fluid velocity. Other approaches combine a Darrieus rotor with another device, such as a Savonius rotor, which starts by itself at lower fluid velocities and drives the Darrieus rotor.

In the prior art are also variants of Darrieus rotors with provisions to increase performance and efficiency. These include z. As the previously mentioned wind deflectors, but also about elements to prevent unwanted stalling of rotor blades, such. B. a freely rotating second Darrieus rotor, which lies within the first Darrieus rotor ( DE 10 2006 040 006 A1 ).

All of these approaches have their specific disadvantages; z. B. requires a motorized starting a relatively complicated measurement and control technology. Any reversible change in the fluid dynamic resistance of the rotor blades by technical and in particular mechanical measures is complex, prone to failure and expensive, especially for relatively small rotor blades (which means "relatively small" sizes of up to several meters).

Wind deflectors or fluid guide elements increase the space requirement of the device unreasonably, and the additional space required could possibly be exploited more efficiently by a larger Darrieus rotor. Additional low-speed startup fluid velocity devices (such as a trough-shaped front blade in front of the rotor blades or one or more Savonius rotors) slow the Darrieus rotor at the higher fluid velocities in which the Darrieus rotor typically and efficiently operates becomes.

If the additional device designed by the Darrieus rotor decoupled, so the total space requirement of the overall device increases and the coupling is complicated, prone to failure and expensive. And a freely rotating second Darrieus rotor to prevent unwanted stall edges does not reduce the stall margins well enough to allow a significant increase in the efficiency of the first Darrieus rotor and thereby justify the added design effort.

Presentation of the invention

The object of the invention is to provide a device belonging to the technical field mentioned above, which starts at the lowest possible fluid speeds by itself, works efficiently at high fluid velocities and compact, stable or robust and can be realized inexpensively.

The solution of the problem is defined by the features of claim 1. According to the invention, a device for converting a fluid flow into usable driving force comprises a first Darrieus rotor with a first High-speed number and a second Darrieus rotor with a second high-speed number. The second high-speed number is smaller than the first high-speed number, and the second Darrieus rotor serves as a starting aid for the first Darrieus rotor.

By using a second Darrieus rotor as a starting aid for the first Darrieus rotor, both rotors can be optimized for their respective task. The first Darrieus rotor is of widely known type and is designed to have maximum efficiency in a given speed range of performance of the fluid (eg 5-15 m / s) and the second Darrieus rotor is designed so that it begins to rotate at a predetermined start-up speed range of the fluid (eg, 2-5 m / s). The starting speed range is below the predetermined speed power range, i. H. the two areas are adjacent to each other or close to each other. In practice, these areas may also partially overlap.

The second Darrieus rotor has according to its function, for example, a thicker wing profile than the first Darrieus rotor. The second Darrieus rotor can also have slats or flow-through wings. The inventive double Darrieus rotor consisting of the first and second Darrieus rotor, which are suitably functionally coupled, can start for this reason alone at low fluid velocities. Because both rotors operate on the same principle, the dimensioning of the device and the implementation are simplified in the technical details (similarity of the components and elements used), which simplifies their manufacture and reduces costs.

As an optional feature, the second Darrieus rotor has a smaller radius than the first one.

With a smaller radius, the second Darrieus rotor can be made compact, reducing the overall size of the whole device. Radii of different sizes also make it possible, in the case of identical or closely spaced axes of rotation, to arrange respective rotor blades offset transversely, thereby achieving a compact construction.

Alternatively, the first and second Darrieus rotors may also have the same radii, and in an extreme case, even the second Darrieus rotor may have a larger radius than the first, the latter being advantageous only in very rare cases.

Optionally, the second Darrieus rotor is at least partially within a rotational shell of the first.

The device can be made particularly compact, if the second Darrieus rotor lies at least partially within the rotational envelope of the first Darrieus rotor. It is particularly advantageous if the second Darrieus rotor is completely in the rotational envelope of the first, since the space occupied by the device can be used optimally in this way. By rotational envelope of the first Darrieus rotor is meant the boundary of the space which is traversed by the rotating first Darrieus rotor. In a rotor with straight wings with a constant distance to the rotation axis over its length, the rotation envelope is a circular cylinder. For curved wings, the rotational envelope is a rotational volume with a correspondingly shaped wing surface rotation surface.

Alternatively, the second Darrieus rotor may also lie outside the rotational envelope of the first Darrieus rotor, for example lying adjacent to it (eg up or down or right or left or rear or front) on the axis of rotation of the first Darrieus rotor or also next to it.

As another optional feature, the ratio of the high speed numbers corresponds to the ratio of the radii of the Darrieus rotors.

If the radii of the Darrieus rotors are equal to each other as their respective high-speed numbers, then both Darrieus rotors have the same rotation period, ie. H. both Darrieus rotors require the same time to fully rotate once around their axis. With high-speed number here the ratio of the peripheral speed of a rotor blade at the outer end of the rotor to the fluid velocity meant (professional definition). Coupling of both Darrieus rotors with each other is greatly simplified when both Darrieus rotors have the same rotation period because this eliminates the need for mechanical transmissions, variable electronic couplings, fluid gearing, and other couplings. Deviations from the ideal ratio are still within the scope of the optional feature if they have practically negligible effects (eg if they are below 10%).

Alternatively, the ratio of the high-speed numbers of the Darrieus rotors may be smaller or larger than the ratio of the radii.

Optionally, the two Darrieus rotors are mechanically rigidly coupled.

A rigid coupling of both Darrieus rotors has the advantage of being simple, stable and inexpensive to implement. A rigid coupling can usually be made very compact, lightweight and robust (less prone to interference). It is particularly easy to realize a rigid coupling when both Darrieus rotors have the same period of rotation.

Alternatively, a clutch can be used which z. B. as a freewheel (a so-called. Overrunning clutch, such as in the rear hub of a bicycle) decouples the two Darrieus rotors as soon as the first Darrieus rotor begins to rotate faster than the fluid-dynamically more decelerated at high rotational speeds second Darrieus rotor , A variable coupling (eg freely selectable, linear and / or nonlinear) with and / or without a defined coupling profile can also be used, depending on the intended use and field of application.

As a further optional feature, the second Darrieus rotor may have flow-through rotor blades.

To allow the start of the second Darrieus rotor at the lowest possible fluid velocities, its rotor blades can be advantageously constructed as a flow-through rotor blades. When the rotor blades flow through the profile of the rotor blade is not only flows around, but flows through, thereby reducing the necessary for starting fluid velocity decreases and the efficiency increases. A simple variant of a flow-through rotor blade is a rotor blade with a trough-shaped front blade mounted in front of it, but any other conceivable version of rotor blades which are at least partially flowed through is also explicitly included.

Alternatively, instead of through-flow rotor blades quite different precautions are taken to reduce the speed necessary for starting, such. As a variation of the profile thickness (rotor blades with thicker profiles run in principle at lower fluid velocities), a change in the position of the rotor blades with respect to the flow direction of the fluid or other precautions such as already listed in the prior art. It is not decisive whether the precaution is firmly mounted or the change is reversible executable. The known disadvantages of the corresponding precautions do not affect the efficiency of the device according to the invention to a relevant extent because the precautions are taken only on the second Darrieus rotor, but not on the first. The disadvantages are not particularly significant when the second Darrieus rotor has a much smaller surface exposed to the fluid than the first Darrieus rotor, has a smaller radius and / or in particular at high speeds of the first Darrieus rotor of selbigen can be decoupled.

As a further optional feature, the first and / or the second Darrieus rotor are designed as H-Darrieus rotors.

A H-Darrieus rotor has rotor blades that are parallel to the rotor axis and not the curved rotor blades known from the classical Darrieus rotor, which run towards the rotor axis at their ends. The rotor blades are mounted with support arms and can take depending on the design with the support arms together an H-shaped form. The H-Darrieus rotor can be made simpler and / or cheaper compared to the classic Darrieus rotor or many other shapes because of the straight rotor blades, and has greater torque because the lever arm of the rotor blades is long and the space through the rotor maximized at a certain rotor height and optimally used.

Alternatively, various other shapes may be used for the first and / or second Darrieus rotor, for example, the classic curved blade shape, oblique helical blades, cup-shaped blades, and many more. Depending on requirements, the first and second Darrieus rotor may have a different shape.

As a further optional feature, the first and second Darrieus rotors each have 3 rotor blades.

The advantage of three rotor blades in each case is that on the one hand Darrieus rotors with at least three rotor blades start better by themselves and at lower fluid speeds than with one or two rotor blades. Because the rotor blades are usually evenly spaced to avoid imbalances, at least one rotor blade is in a fluid-dynamic favorable position and can start the Darrieus rotor. On the other hand remain relatively large gaps between the rotor blades with only three rotor blades, which are particularly advantageous if in a preferred embodiment, the rotor blades of the second Darrieus rotor are at least partially within the rotational envelope of the first Darrieus rotor and the fluid for driving the Rotor blades of the second Darrieus rotor to pass through the gaps between the rotor blades of the first Darrieus rotor.

Alternatively, however, it is also possible to use one, two, four or more rotor blades, and counterweights etc. can be used to avoid imbalances.

As another optional feature, the high speed number of the first Darrieus rotor is at least twice that of the second Darrieus rotor.

A high speed number allows a high efficiency of the Darrieus rotor, however, with a high speed number greater than 3 no self-starting is possible. By the speed of the first Darrieus rotor is selected at least twice as high as the speed of the second Darrieus rotor, on the one hand, the efficiency of the first Darrieus rotor is correspondingly high, while the speed of the second Darrieus rotor is chosen so that it automatically can start and the first Darrieus rotor serves as a start-up aid. Depending on the size, shape and / or coupling of both Darrieus rotors, the ratio of the two high-speed numbers can be optimized so that an independent start at low wind speeds through the second Darrieus rotor is possible, but the first Darrieus rotor achieves good efficiency, without vom second Darrieus rotor to be slowed down too much.

Depending on the expected flow rates, the speed of rotation of the first Darrieus rotor may also be less than twice that of the second Darrieus rotor.

As a further optional feature, the first and second Darrieus rotates about vertical axes, and in particular about the same vertical axis, and most preferably, the entire device is supported on a support at a single point (pivot).

The axis of rotation of Darrieus rotors should ideally be transverse to the flow direction of the fluid. But the rotor can just as easily be vertical, horizontal or oblique in space. A vertical axis of rotation offers the advantage, in particular in wind turbines, that one end of the axis of rotation points in the direction of the ground and is thus very easy to reach, especially with axial lengths of a few meters and more, and heavy components such as generators, etc. can be arranged at the bottom end. It is particularly advantageous if the axes of rotation of both Darrieus rotors are identical, because the power transmission is simplified, the overall size is compact (in particular with at least partially overlapping or containing rotating sleeves) and the storage or attachment to the ground, for example, by a common foundation is simplified. In particular, if the entire device according to the invention is supported on the ground only at a single point, such as a common rotation axis end, the installation, maintenance and construction of the device are simplified.

Alternatively, the axes of rotation of the first and / or second Darrieus rotor may also be horizontal or oblique, and the axes of rotation need not be superposed. The attachment of the device can also take place at two or more locations. Noteworthy is the horizontal installation in the area of a roof and / or side edge of a multi-storey building or a skyscraper or skyscraper and the assembly between such buildings or, for example, across valleys on opposite slopes.

The invention is particularly suitable as a wind turbine for decentralized electrical energy supply. Of course, variable water flows (eg tidal currents) can also be converted into electrical energy with the invention.

From the following detailed description and the totality of the claims, further advantageous embodiments and feature combinations of the invention result.

Brief description of the drawings

The drawings used to explain the embodiment show:

1 Schematic representation of a section perpendicular to the axes of rotation of both Darrieus rotors of the device.

Ways to carry out the invention

The in 1 illustrated schematic horizontal section across the inventive device shows two rigidly connected H-Darrieus rotors, which have the same vertical axis of rotation 3 exhibit. The device is designed as a wind energy plant. The first H-Darrieus rotor has three rotor blades 1.1 - 1.3 on which in orbit 4 around the axis 3 rotate. The second H-Darrieus rotor has three rotor blades 2.1 - 2.3 on which in orbit 5 around the axis 3 rotate.

The rotor blades 1.1 - 1.3 such as 2.1 - 2.3 are straight in shape and run parallel to the axis of rotation 3 , wherein they are shaped in profile as a wing of an aircraft wing. The rotor blades 1.1 - 1.3 and 2.1 - 2.3 can be inexpensively made of extruded aluminum profiles and are stable, lightweight and typically a few meters long. The rotor blades 1.1 - 1.3 can, as shown here in shape and size have the same profile as the rotor blades 2.1 - 2.3 , while still in each case in the direction of rotation (here: counterclockwise) in front of the rotor blades 2.1 - 2.3 trough-shaped front leaves 6.1 - 6.3 are mounted. The rotor blades 2.1 - 2.3 of the second Darrieus rotor are therefore of the type flowed through and the second Darrieus rotor points 1.2 a lower speed number than the speed of the first Darrieus rotor on (here three sevenths), the second Darrieus rotor can, however, independently and at low wind speeds of z. B. 2 m / s start.

The rotor blades 1.1 - 1.3 are regularly in orbit 4 distributed and are with the brackets 7.1 - 7.3 on the axis 3 attached. The brackets 7.1 - 7.3 Stand in mutually offset by 120 degrees angles from the axis and consist of aluminum. In the direction of rotation, the brackets 7.1 - 7.3 streamlined profiles on.

The rotor blades 2.1 - 2.3 are regularly in orbit 5 distributed and are with the brackets 8.1 - 8.3 on the axis 3 attached. The brackets 8.1 - 8.3 Stand in mutually offset by 120 degrees angles from the axis and lie in the bisector between the adjacent brackets 7.1 - 7.3 , Also the brackets 8.1 - 8.3 consist of aluminum and have streamlined profiles in the direction of rotation.

The diameter of the orbit 5 is three-sevenths of the diameter of the orbit 4 , or generally speaking, the ratio of the diameters of the orbits corresponds to the ratio of the high-speed numbers of the respective Darrieus rotor. The diameter of the orbit 5 is 2.3 meters. The rotational envelope of the second Darrieus rotor lies within the rotational envelope of the first Darrieus rotor, since all rotor blades are of equal length, run parallel to one another and are bounded by the same normal sectional plane to the common axis of rotation.

The embodiment described is merely to be understood as an illustrative example, which can be expanded or modified as desired within the scope of the invention. In particular, all size information is easily scalable at least within a magnitude and usually also beyond proportional use.

The invention is not limited to H-Darrieus rotors, but can be applied to all other types and shapes of Darrieus rotors. An application may equally well be in wind turbines such as in tidal power plants, in flows of liquids (eg in rivers) or gases (eg in chimneys, exhaust pipes or ridges or gullies) or in other areas with dynamic fluids ,

The invention is not limited to Darrieus rotors with three rotor blades, but can also be applied to Darrieus rotors with one, two, four or more rotor blades. The rotor blades and their mounts may be partly or wholly made of various other materials besides aluminum, such as other metals and alloys, wood, plastic, composites (especially fiber-plastic composites), and other materials that provide a robust and lightweight construction allow.

The direction of rotation of the first and / or second Darrieus rotor can run both clockwise and counterclockwise, both Darrieus rotors rotate in the same direction with advantage, but can also move in opposite directions. The trough-shaped front leaves of the second Darrieus rotor can be replaced by other measures for better start-up at low fluid velocities, such as by other selected profile thicknesses and shapes or the like. The rotor blades of the first and / or second Darrieus rotor can be flowed through or flowed around depending on the application, and the second Darrieus rotos can also start at smaller or greater fluid velocities than 2 m / s.

The high-speed numbers of both Darrieus rotors may be fixed or variable in a smaller or larger ratio than seven to three, and the diameters of the orbits of the two Darrieus rotors may also be in a different relationship to each other than their high-speed numbers. In particular, the speed of rotation of the second Darrieus rotor may be less than or greater than 1.2 be. The two Darrieus rotors need not be rigidly coupled together, but can be connected to each other, for example via variable couplings or a freewheel.

The first and second Darrieus rotor can be designed and / or optimized for different fixed or even variable fluid speeds within the speed power range or starting speed range. Both Darrieus rotors may either rotate about the same or different axes of rotation, and the rotary shells of the Darrieus rotors may intersect, comprise, or be completely separate.

The rotor blades of a Darrieus rotor can be arranged irregularly and / or at other distances than with each 120 degrees offset in its orbit, and also the relative position of the rotor blades of both Darrieus rotors to each other can be fixed or variable and of different sizes.

The supports of the rotor blades may be designed differently than by radial struts, and the profile of the brackets may differ from a streamlined shape and in particular of a wing profile of an aircraft wing and be shaped, for example, round or square.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 29804581 U1 [0003]
• DE 4120908 A1 [0003]
• TW 200716862 A [0003]
• WO 2006/132923 A2 [0003]
• DE 102006040006 A1 [0004]

Claims (10)

Apparatus for converting a fluid flow into usable motive power, comprising a first Darrieus rotor having a first high speed number and a second Darrieus rotor having a second high speed number which is smaller than the first high speed number, the second Darrieus rotor providing a starting aid to the first Darrieus rotor is. Apparatus according to claim 1, characterized in that the second Darrieus rotor has a smaller radius than the first. Apparatus according to claim 1 or 2, characterized in that the second Darrieus rotor is at least partially within a rotational envelope of the first. Device according to one of claims 2-3, characterized in that the ratio of the high-speed numbers corresponds to the ratio of the radii of the Darrieus rotors. Device according to one of claims 2-4, characterized in that the two Darrieus rotors are mechanically rigidly coupled. Device according to one of claims 1-5, characterized in that the second Darrieus rotor through-flowed rotor blades ( 2.1 - 2.3 ) having. Device according to one of claims 1-6, characterized in that the first and / or the second Darrieus rotor are designed as H-Darrieus rotors. Device according to one of claims 1-7, characterized in that the first and the second Darrieus rotor each have 3 rotor blades ( 1.1 - 1.3 ) respectively. ( 2.1 - 2.3 ) exhibit. Device according to one of claims 1-8, characterized in that the speed of rotation of the first Darrieus rotor is at least twice as high as that of the second Darrieus rotor. Device according to one of claims 1-8, characterized in that the first and second Darrieus rotor about vertical axes and in particular about the same vertical axis ( 3 ), with particular advantage, the entire device is attached to a single point on a substrate.

Images