The invention relates to a turbine system in accordance with the preamble of claim 1.
Savonius turbines are known (see also
A decisive unbalance as a result of the cyclically varying load strength from the flow during rotation is characteristic of the Savonius rotor, even when the weight distribution is perfectly balanced. This unbalance due to load alternation can be minimized by arranging a larger number of blades, generally three, instead of two. However, this greatly reduces the efficiency of the Savonius rotor, by approximately 30%.
By comparison with the known three-blade wind generators having a horizontal axis of rotation and aircraft-type blades, a radial turbine has the major advantage of operating independently of the direction of the incident wind. Thus, the radial turbine having a vertical axis of rotation does not have to be turned to the wind.
In a particularly economical embodiment, the radial turbine is provided with deflector plates that collect the wind energy and deflect it onto the blades of the radial turbine in a concentrated form. However, this has the drawback that, because of the deflector plate, independence from the wind direction is no longer achieved. The radial turbine comprising a deflector plate therefore has to be tracked to the wind.
If the Savonius turbine is equipped with deflector plates, it gains at low wind speeds, but loses all the more at higher wind speeds.
Object of the invention: much better use is to be made of the wind energy, with a much higher efficiency than in conventional Savonius turbines. It should still be possible to use the wind turbine even when the wind would be too weak to drive conventional Savonius turbines.
The wind turbines should operate with no noise and very little vibration, in such a way that they can even be used on residential buildings in urban areas.
A radial turbine is also to be used which comprises a deflector plate and which automatically turns to an optimum angular position with respect to the incident wind, and is thus self-tracking, without a tracking arrangement being necessary for this purpose. The advantages of the deflector plate in the radial turbine are thus to be combined with the independence of the radial turbine from the incident wind direction.
A minimum unbalance with high performance is to be ensured by way of the special construction and geometry.
This object is achieved in accordance with the invention by the features of claim 1.
Advantageous embodiments of the invention are specified in the dependent claims.
It is known that the Savonius rotor and the Darrieus rotor do not gain in performance as a result of deflector plates. The Savonius rotor gains in weak wind, but this is conditional on speed, and leads to losses at higher wind speeds. Since the turbine is dependent on the wind direction, it decreases in overall efficiency.
This problem is solved by the invention.
As a result of the specific shape and arrangement of the turbine blades in connection with the wind splitter in accordance with the parameter ranges given in claim 1, rotational speeds up to three times higher than in known Savonius turbines are obtained, along with an efficiency of up to 66%, by contrast with the efficiency of 28% achieved by conventional turbines. The turbine according to the invention can be used even in very weak wind which would no longer be sufficient to drive conventional Savonius turbines.
By contrast with the Savonius rotor, the wind turbine according to the invention does not have an unbalance of the type described above, even in a particularly advantageous embodiment where three turbine blades are provided.
It is particularly expedient to combine the geometry according to the invention of the turbine blades with a deflector surface according to claim 2, also known as a wind splitter.
Another important consideration: suppose there are two turbines in a system enclosed by deflector plates and having additional beveled concentration plates and/or wind guide plates which are attached above and below the turbines. As a result of the closed system and the additional concentration plates and/or wind guide plates, optimum use is made of what is known as the Magnus effect, and as a result the system according to the invention, which is mounted on a mast, can rotate to the wind automatically and thus always receive an optimum wind flow. This “turning to the wind” has been demonstrated in a number of specific models in natural wind.
The Magnus effect, named after Heinrich Gustav Magnus (1802-1870), who discovered it, is a phenomenon in fluid mechanics, specifically the transverse force effect (force) experienced by a round rotating body (cylinder or ball) in a flow.
By way of frictional effects, a rotating roller induces rotation in the fluid surrounding it. If there is additionally a flow over the roller, the different speeds of fluid overlap. As a result, the fluid flows around the rotating roller faster on one side than on the other (in the rest system of the roller). On the side of the roller where the frictional effects are greater, it is as if the fluid were flowing more rapidly. This results in “deflection” of the roller, pushing the roller downwards (see
According to the invention, high performance is achieved in combination with low installation costs, in such a way that the cost-effectiveness, in terms of power output, is much greater than in the known wind generators comprising a horizontal shaft and blades of the aircraft-wing type.
To increase the cost-effectiveness, a ring generator is provided for power generation. In addition, to increase the cost-effectiveness further, the mast and the wind splitter can be used as advertising space.
With the blade shape according to the invention of the individual turbines and the specific arrangement of the two turbines with respect to one another, it is particularly advantageous that the two turbines do not obstruct one another, but can instead boost one another, even at low wind speeds, assisted by the low-frequency pressure oscillation taking place in the rear cavity of the V-shaped wind splitter.
By contrast with the known wind generators comprising a horizontal shaft and three blades, the radial turbine according to the invention can be operated even at relatively low wind speeds. As a result of the Magnus effect, the radial turbine according to the invention “pulls” the wind in, as it were, and amplifies low wind speeds. For example, the radial turbine according to the invention can also be used in circulating winds, in which the wind speed is greater below at a low height than at the large height at which the three-blade wind generators have to be operated simply because of the blade size. A wind speed which is too low for the known three-blade turbines in any case is sufficient for energy production with the radial turbine according to the invention.
In the event of fluctuations in the wind direction, the radial turbine according to the invention adjusts itself automatically, partly as a result of the Magnus effect, and immediately rotates to the optimum direction, even at wind speeds of less than 1 m/s. Rapid adaptations of this type of the generator are not possible with the known three-blade turbines.
Since the radial turbine according to the invention only takes up a small amount of space, it can be used as an add-on to pre-existing parts of buildings or structural elements, for example as an attachment to a street light.
In the following, a plurality of embodiments of the invention are described in greater detail by way of drawings. Like reference numerals have the same significance in all of the drawings and are therefore only be explained once.
In the drawings:
a shows a grid mast construction that is and/or can be used for the special accumulator and turbine mounting system,
b is the section A-A,
Wind flows onto the wind turbine according to the invention of
A grid mast construction is provided above the rotary connection, and is used and can be used as a frame for the special accumulator mounting system and turbine system.
A safety space, which is protected and grounded by the outer shell of the mast, preferably a thick-walled steel tube, and may contain various sensitive technological components, is located below the rotary connection, without any additional costs. The use according to the invention of the turbine system makes it possible to create safety spaces, and to use wind generators in the pre-existing infrastructure (streets, rails etc.), in areas where construction would otherwise be impossible.
It can clearly be seen that in a wind speed range from approximately 0.7 to 1.8 m/s a conventional Savonius turbine is stationary, but the wind turbine according to the invention rotates at rotational speed of 50 to 150 revolutions per minute. In the wind speed range from approximately 1.7 to 2.7, the wind turbine according to the invention rotates at approximately 2 to 15 times the rotational speed of the conventional Savonius turbine.
A series of measurement results for the properties of the wind turbine according to the invention and for a conventional Savonius wind turbine, which were both exposed to the same wind conditions, is shown graphically in
As regards the prior art, it can additionally be established that 2 basic types of wind generators have achieved success:
The inventive solution disclosed herein relates primarily to VAWTs, although horizontal mounting with an incident wind flow transverse to the axial direction is also possible in special cases.
There are also many variations/modifications among commercially available VAWT systems, starting from 2 basic types (see for example German Wikipedia “Windturbine”):
Savonius rotor
Giromill/Darrieus rotor
Unlike the turbine according to the invention, the Savonius rotor cannot run faster as a result of a deflector plate or deflector surface. However, this can be demonstrated with the invention.
The variations relate to the number and the special shape of the rotor blades, the attachment of wind guide elements, and in some cases a screw-shaped configuration for achieving a more constant speed during rotation. The solution according to the invention thus relates to particular, relatively precisely determined shapes and arrangements which have been found to be particularly efficient in the development process.
This description of the invention is therefore supplemented by a further embodiment, in connection with a further narrowly defined parameter space analogous to Table 1 for describing the shape, as follows.
The further embodiment of the wind turbine according to the invention also corresponds to
For completeness, it is noted that the height (or length) of the turbine may be in a wide range of ratios to the radius. That is to say, depending on the place of use, the height or length of the turbine is approximately 0.3 to 100 times the turbine radius, it also being possible, for reasons of construction or stability, to understand a long or high turbine as a positive coupling of a plurality of turbines to a shaft which may optionally be connected by means of positive couplings.
The purpose of the turbine system is to obtain energy from wind in an optimum manner, priority being given to obtaining electrical energy. For this purpose, a generator is mechanically connected to the turbine shaft positively or non-positively, directly or indirectly via a transmission, in a manner adapted to the turbine system, said turbine shaft being positively or non-positively connected to the turbines so as to ensure force transmission from the turbine to the generator. In this context, one generator may be used for both turbines, or each turbine may be connected individually to one respective generator.
The generator is controlled in a manner adapted to the wind speed, in such a way that by regulating the generated power an electromagnetic braking torque is transmitted to the turbine, so as to set an optimum tip speed ratio (TSR) for energy conversion that is between 45% and 65% of the tip speed ratio of the unbraked turbine. This ensures that the maximum possible energy can always be “harvested”.
In the embodiment, a height:radius ratio of approximately 20 is set, the turbines on a shaft being mounted individually approximately every 5 m, and being interconnected via a flexible positive coupling and connected to the end of a shaft directly or indirectly via a transmission comprising a current generator.
For increased efficiency, two turbine deflector plate systems may advantageously be brought together with reflective symmetry as a wind splitter system, in such a way that for example with a vertical axis of rotation, the left deflector plate deflects the wind to the left turbine and the right deflector plate deflects the wind to the right turbine as seen in the primary wind direction. In this context, the deflector plates may advantageously be in the form of a “nose” with a rounded “bridge” as a connection between the two deflector plates, so as to form a closed wind guide system, the wind splitter.
Preferably, the distance between the V-shaped wind splitter and the turbines is variable and adjustable, so as to achieve optimum operating conditions for all wind conditions.
As a function of the wind speed, the V-shaped wind splitter is brought into the optimum position, based on the distance and inclination with respect to the turbine blades and the turbine shaft.
For an overall height of 20 m, the height of the turbines is 10 m. The turbines have a diameter of 1 m. The expected capacity for a site on the coast, where the wind generator captures the circulating coastal wind, is approximately 21,700 kWh, with an efficiency averaged over the year of 38%.
The rotary bearings 10, 11 on the one hand and 13, 14 on the other hand are kept at a distance by a spacer collar 23, 24. The spacer collar is in the form of a hollow tube.
Finally,
What is known as a thread test was carried out on the system according to the invention (
The significance of the reference numerals in
A side effect is the ping-pong ball which is “suspended” in an oblique airstream. As a result of the Coanda effect, the flow of the airstream is not stripped away from the ball, but encircles it (almost) completely without being stripped away. Since the ball is suspended slightly below the center of the airstream, the air does not flow around it symmetrically. More air is deflected downwards, since the flow speed and flow cross-section are lower at the underside of the ball than at the upper side. As a result, the ball experiences an upward force. This is superposed on the Magnus effect (the ball rotating). The two effects each prevent the ball from falling downwards and only allow it to “slip” along the underside of the airstream. The resistance of the ball to the flow holds it at a distance from the nozzle, and gravity prevents it from simply being blown away. Thus, the ball can float in a more or less stable position.
Evaluation of static and dynamic torque measurements on the wind turbine according to the invention of diameter 1 m and length 1 m in
The following data are taken into account, directly or indirectly, in the evaluation:
An eddy current brake, with which various braking forces could be set by varying the coil current, was also used during the dynamic measurements in each case.
The measurement values were checked for plausibility and evaluated using various averaging and filtering methods.
The result data for wind speeds of between 2 and 8 m/s are compiled in the following table.
Torque [Nm] vs. rotational speed [rpm]; parameter wind speed [m/s]
Key to graph:
♦ 2 m/s measurement
▴ 3 m/s measurement
X 4 m/s measurement
+ 5 m/s measurement
− 6 m/s from measurement
▪ 7 m/s from measurement
x 8 m/s from measurement
------- max. torque
- - - - ave. torque
Mech. Power
Extrapolation in the maximum power range with average PC=35%
Mechanical power [W] vs. torque [rpm]; parameter wind speed [m/s]
Key to Graph:
▪ 2 m/s eddy current brake
x 3 m/s eddy current brake
4 m/s eddy current brake
− 5 m/s eddy current brake
♦ 6 m/s from eddy current brake
▴ 7 m/s from eddy current brake
X 8 m/s from eddy current brake
Since the dynamic measurements thus far have only been carried out with relatively weak braking forces, the interpolation outside the measurement range that has been established thus far is shown in dashed lines. In this context, it has been assumed that at the maximum power point a power coefficient of 35% is achieved. From the dispersion of the result data, sufficiently precise calibration verification for the measurement technique used can provisionally be placed at approximately 30-40%. Otherwise, the systematic errors in the measurement technique have to be additionally taken into account. The power coefficient can be determined more precisely if further measurements at higher braking forces are taken into account.
The turbine system according to the invention can also advantageously be used in water for obtaining energy from the flow of water, that is to say as a marine turbine system.
In a further embodiment, a grid mast construction, which is and/or can be used as a frame for the special accumulator and turbine mounting system, is provided above the rotary connection that is fixed to a stationary mast (cf.
Since the lower region of the tower below the rotary connection is made from steel tubing, it forms a cavity which can be used for safely installing highly sensitive technology, since ventilation and/or heating and/or suitable air conditioning, particularly in relation to air humidity, can be provided.
The base part may be used in a configuration as a further energy store or as a water reservoir or oil store, and may be designed accordingly. Heat pumps (with heat pipes) may be integrated into the base part.
In the present invention, the turbine blades (air foils) are mounted on a plurality of milled support arms that in turn are fastened to a rotary part on the shaft on both sides by two “support hearts” which are screwed together. This reduces the weight and makes it possible for the turbine to reach full speed more quickly (cf.
In addition, the support hearts make it possible to replace the turbine blades individually by screwing. The very heavy fixed circular disks, which are entrained in rotation and are conventional in the Savonius turbine, are replaced with stationary grille face panels that are additionally rounded for better wind introduction. As a result, the weight of the rotating parts and the losses from the Thom effect are greatly reduced. The wind energy can thus be harvested with a high level of efficiency.
The support hearts which are used according to the invention are much lighter. The grille face panels are held together by a mast that is a functional replacement for the heavy frame construction conventional in the Savonius turbine.
It is advantageous to bring together a plurality of windtrackers to form a decentralized network-communicating energy supply system and other applications. It is therefore proposed to provide an arrangement of the turbine systems according to the invention and/or of the windtrackers along the traffic infrastructure, such as streets, motorways, railway lines and canals, which arrangement is additionally provided for telecommunications or for buffering current from the grid in times of low current uptake and/or for use as an advertising medium and/or as street lighting and/or for providing safety spaces.
Number | Date | Country | Kind |
---|---|---|---|
10 2010 045 915.1 | Sep 2010 | DE | national |
10 2010 054 365.9 | Dec 2010 | DE | national |
10 2011 010 176.4 | Feb 2011 | DE | national |
20 2011 101 729.3 | Jun 2011 | DE | national |
10 2011 109 215.7 | Aug 2011 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP11/04601 | 9/14/2011 | WO | 00 | 3/19/2013 |