Title: System for Enhancement of Fluid Foil Performance
The present invention applies to a general improvement of the dynamic performance of the wings in fluids using fluid-induced jet streams.
The present invention applies to systems for the capture of renewable energy such as natural or artificial is the present and the utilization of the electrical energy. The invention applies in particular to methods for improving the properties of wind turbines.
Wings in fluids have, since the invention of the propeller and motorized aviation, seen few innovations when it comes to dynamic optimization of the wing or surface effectiveness. Examples of known technology are variable pitch, flaps, slats. Example of static technology for efficiency is the vortex generators.
Wind turbines have during the last few years become a viable technology for commercialized supply of electric power. The main principles for the technology has not changed significantly since the first wind turbines, more than a hundred years ago.
Some attempts have been made to make wind turbines with similar principles as the jet engines. These trials have not been particularly successful, although some of them have become commercial products, but to a very small extent.
By far the dominant technology for wind turbines are two-and three-blade propeller coupled to a generator directly or through transmission gears.
This technology provides physical designs and sizes that often are less compatible with modern environmental considerations. The reason is that the wind capturing with known technology requires large rotational area of the propeller wings and that this area must be elevated to the highest possible in order to exploit the most laminar wind field above the more turbulent and weakening wind field influenced by surface friction and terrain.
The same parameters also mean complicated fabrication of turbines, large investment costs, high costs, difficult logistics operations, and a whole host of other problems and challenges. Not least, suffer such turbines stalls and must be shut off when they can give the most energy and fastest repayment of
investments, namely in strong winds.
Also facilities for other types of renewable energy exhibit similar
disadvantages and obstacles where the physical size of the plants is always a challenging factor, not least financially.
If we look at nature itself, we know that very often it can create enormous amounts of energy over very local areas without the help of physical structures that may correspond to man-made facilities such as wind turbine parks, for example. To recreate or mimic artificially certain natural phenomena has always been man's dream. This has proven very difficult in practice. An example is water current and wave power, which, with few exceptions, have given marginal energy harvesting in relation to investments, given that the energy output overall has been positive over time.
But there are examples of techniques that mimic such meteorological phenomena on a smaller scale. An example is the so-called swing doors where air knives establishes a barrier between warm and cold air.
OBJECT OF THE INVENTION
There is a general need for dynamic improvement of the efficiency and behavior of the wings, surfaces and profiles in fluids.
There is a need for a new technology for wind turbines that is considerably more environmentally friendly, can be manufactured cheaper, is less expensive in operation and simplifies logistics operations.
Furthermore, there is a need for a new wind turbine technology that is significantly cheaper to deploy across large areas. Thus, the technology is not required to provide very high efficiency in general, because reduced investment costs means that the same amount or higher overall long term efficiency, as through one year, may be achieved through numbers and volume to exploit a larger horizontal area. Efficiency can therefore be regarded as the ratio of power hours per year to investments.
It follows that a purpose of the invention is to harvest renewable energy at a greater height above the ground without the need to have structural installations at the same height.
Furthermore, an object is to achieve such a positive environmental profile that new areas can be developed with wind turbines, that are currently excluded for environmental reasons.
Another object is to achieve such a mechanically robust technology that today's problems and challenges with known wind turbine technology is overcome to such an extent that new areas can be developed. One purpose is also, as far as possible, in whole or in part, to avoid high, costly masts for installation of wind turbines and thereby reduce the extent of structure further, with the positive impact that follows. On land, such as on mountain tops, a significant reduction of visibility is achieved with a very low height of the voluminous structures. At sea, a certain higher mast height is necessary to protect equipment from waves, salt spray and to avoid turbulence when sea is rough. Despite this, the total height of the massive structure is reduced by a very significant and cost-saving factor.
Known technology uses energy delivered to fluid foils in the form of fluid flow to improve their ability to maintain laminar fluid flow across the foil profiles. The present invention uses energy supplied in the form of fluid jet stream where the fluid jet stream's power is crucial. The invention can find applications for new turbine types and for existing turbine designs. That includes the most prevalent types today for commercial exploitation of wind power, namely the horizontal axis, three blade turbines, HAWT.
In contrast to prior art, the invention is based on arrangements that are fed by energy in order to achieve increased harvesting of renewable energy across a given, horizontal area. Furthermore, in some embodiments the invention achieves this using a very low vertical installation height of structures. The invention in some embodiments make use of the physical mechanisms that will not be visible. One of the advantages of the invention is that in many cases it will not be perceived as visible or provocative. Some embodiments of the invention would to the layman be
called invisible wind turbines. The structures will thus largely be less visible and affect the environment less. The cost of mechanical structures will be significantly lower. One reason is that expensive, mechanical designs for the suspension of heavy objects at large heights in extreme weather conditions is avoided.
The main principles of the invention can be used for several different renewable energy sources such as wind, water waves, water currents, visible and invisible light.
Embodiments of the present invention are suggested for the exploitation of wind energy. Similar embodiments will be possible for other forms of energy.
Numerous other embodiments of the invention will be seen by experts in the relevant fields.
The invention is based on all energy having some form of wave character and thus obeying more or some of the laws that apply to wave propagation. The energy flux will always have a direction of movement and a front, more or less diffuse, depending on conditions and type of energy. Mathematically, the invention is described with aerodynamic laws, which is an offspring of hydrodynamics.
Maxwell's equations also apply, in which the diffusion parts are particularly important. Herein lays the invention utilizing deflection of energy in the wave motion to achieve the concentration of the energy flux density. Thus the invention achieves a reduction of material consumption for the system. Deflection for all wave propagation is related to changes in the medium impedance, magnetic or gravity. In air, the impedance change for various reasons such as changes in density or changes purely of the electrical properties. Changing in density of the medium affects the impedance for wind, sound and electromagnetic wave propagation. Change of density is used for example to detect wind shear near highly instrumented and congested airports. Wind shear are winds that abruptly change direction. Wind shear and many other typical aerodynamic and
meteorological phenomena often have hysteresis mechanisms and occur during addition of foreign or induced energy. The method used for detection of wind shear is radar using very high frequencies that give reflections from the density variations. At shorter distances ultrasound detection could also be used, even subsonic sound feasible. In the same way that wind shear can produce density gradients or contrasts in air, one can imagine that the induced density gradients
can produce wind shear. This is one of the principles that the invention is based on. Since water is an incompressible fluid, mechanisms of ocean waves and water currents may be slightly different, but the principles are applicable.
It follows from the principles of the invention that the pressure gradients do not need a large supply of energy for a gradient to change the direction of airflow. Similarly, an air density gradient or barrier or membrane also change the direction of any type of electromagnetic energy due to change in the pressure gradient epsilon. An example of existing technology with the use of air barriers, is air knives in connection with swing doors or door gates. One challenge is to achieve a pressure increase in mostly in a two-dimensional plane. Correspondingly an air stream devoted to establish a barrier or membrane of significant extent requires high air velocity. Typically it will be possible to achieve 0.6 x the speed of sound or higher. This plane or air knife can then function in approximately the same manner as a plane that consists of a solid matter. Similarly, the invention may use alternative and similar methods. Such methods may be vortex guns swept to form a plane. Since the aerodynamic or pneumatic conditions for the deflection of air flows that are to be achieved have hysteresis characteristics, the sweep rate is not necessarily required to be as high as to make system too complex. Such planes as mentioned can be used for deflection of wind flux. Other possible methods are subsonic sound which again will work similarly to vortex generators or the like, as well as ultrasound. The principle can also be seen as a way to achieve venturi effect, similar to that occurring when the wind speed increases across terrain curvatures. One principle of the invention is used to harvest the wind at a significantly greater height above ground or sea level than the height of the major, heavy parts of the invention with respect to mechanical arrangements and installations. Furthermore, the devices required to create air knife features will be significantly less bulky and lighter than the wind turbines. They can thus be elevated significantly without too costly installations or undesired environmental consequences. The invention also shows that the air knife can establish a membrane between two different, but often relatively identical fluids such as a membrane between fluids with different salinity. In weightlessness and vacuum and at low temperature, fluid such as water mist, can be frozen in place into a static surface plane with the desired shape and surface.
The principles of the invention with the introduction of the fluid jet stream can also be used to improve the efficiency and utilization of wind turbines and other generators of renewable energy with known technology. This is especially true for wind turbines at lower wind speeds to improve the power curve, and possibly lowering cut-in wind speed. The invention can thus extend the power curve region for optimum performance from the power generator.
Furthermore, the invention allow increased generator power for existing size of wind turbine rotor blades of provided that they can withstand loads and bending.
Improvement of prior art for compact wind accelerating wind turbines, CWAT as described above, is just one of many groups of embodiments of the invention. A group of embodiments of the invention is when used for improving the performance of existing wind turbines with minimal material addition and without increasing the rotor area. This group of embodiments is a further embodiment of the invention with sweeping jet stream, for example, using air knife. It is also a further embodiment of the invention with a strengthening of the venturi effect, advantageously both in downwind and upwind direction or only one of these.
Downwind jet stream is also also useful for CWAT turbines in the same way as upwind jet stream. Such improvement, particularly for HAWT, takes place by means of induced fluid jet stream, preferably using air knife technology, where the propeller wings are provided with nozzles for jet streams mounted in or on the propeller blades, preferably at the tip of the blades. The supply of pressurized air can usually be done through the propeller hub through a rotary joint that seals off the fluid. In mentioned embodiments the air gradient funnel formed takes a sort of cone shape. The invention is particularly suitable for such improvement of HAWT horizontal axis wind turbines, which are almost exclusively three-blade propeller. Such embodiments allow not only new, more efficient wind turbines without increasing rotor area or propeller diameter. But it can also be used to increase performance through modifications of existing wind turbines. The propeller blades of HAWT are hollow inside for the sake of weight and material consumption, and are therefore relatively easy to apply for hosting air hoses out to for example propeller blade tips, where a jet air nozzle is installed. Compressed air can come from compressors powered by the mains voltage. Similar embodiments of the invention is possible for propellers for propulsion in fluids, as with aircrafts and
ships. Also reducing induced drag and improving the performance of wings and of stabilizing surfaces of aircrafts, is correspondingly feasible with the invention. In these cases, examples of possible embodiments are jet stream nozzles arranged at the tip end of fixed or moving aircraft wings, pointing with or against the direction of movement. The invention may in particular improve the "power curve" of wind turbines.
Fluid knives, such as air knives, are obligated to be classified as jet nozzles that generate fluid jet stream.
In addition to new turbine designs, one group of embodiments of the invention that also particularly concerns improvement of the performance and operation of prior art wind turbines, are turbines that already are installed or manufactured. This group of embodiments include wind turbines getting jet or air knife fluid streams implemented from areas far out on the rotor blades, often from the blade tip. An important feature of these designs is the exploitation of the force arm torque from said nozzle having a jet flow angle where the jet force works with the direction of rotation. This feature can be combined with embodiments of the invention that aim to increase the effective area for the wind turbine, because here also the torque effect will be present with most jet flow angles for the nozzles. Such increase in torque provides at least two benefits. One is to compensate for thermal losses and to increase the efficiency of converting energy to nozzle air. The other is in addition, an increase in turbine efficiency, especially when the efficiency of converting energy to nozzle air is high. The said feature can serve a number of purposes. Such purposes are feedback regulators in control loops yielding a wide feedback loop bandwidth. The invention can thus serve the regulating tasks to at least include controls for turbine cut-in, weak wind operation, sub rated power operation, tip-speed ratio optimization, improvement of the coefficient of performance (Cp), stalling, runaway, turbulence, wind direction deviation, storms, and low voltage ride thru (LVRT). The latter, LVRT, especially concerns turbulent wind conditions and wind direction deviation where the invention can make fast compensations for low voltage before the grid is affected and requires disconnecting. For LVRT the invention can also be used to achieve soft disconnection. Such regulating tasks with the invention has particular applications in wind farm optimization. This can also, completely or partially,
replace the functions of different types of transmission gears, as with mechanical, pneumatic, electrical and hydraulic gears. Most HAWT are optimized for maximum "tip speed ratio" where blade tip speed for the largest turbines approach super sonic speeds, whereby further increase in performance with greater speed is not possible. Such further increase can be done with increase in torque, which is possible with the invention.
Groups of embodiments of the invention is thus when power taken from the "grid" or turbine generator as before mentioned, is fed back as a force acting with the direction of rotation and positioned far from the hub, on one or more rotor blades. The working principle is that a certain amount of the wind energy, generated by a mean force arm from the hub and torque, is re-used to move the mean force further out on the rotor blade, resulting in increased total torque and power efficiency. The available power - arm is to be considered a loss-free gear that is already available. It can also be considered as a continuously adjustable transmission gear through pneumatic control and controlled power bleeding for the conversion to pneumatic energy. Control can also be done in conjunction with adjustments of the pitching of rotor blade. All other types of transmission gears will posses intrinsic losses. Any force increase at a given distance from the hub will provide a net increase in torque which in turn leads to increased efficiency. The losses involved will be from the extraction of energy until it is converted to force on the arm (rotor blade). Thus it is possible to achieve a coefficient of performance, Cp, which is closer to or up to Betz' constant at 59%. For traditional turbine designs this will enable higher performance for wind speeds below rated power wind speed of the turbines. For the lowest wind speeds it means improved start control. Although the energy of the wind is low for those speeds, they make up a large energy potential because the occurrence of such wind speeds tend to represent more than 50% of operating time during one production year. Hereby, the invention can achieve a cost-benefit factor that is very attractive.
I follows that the tip-speed ratio is increased for wind speeds below turbine rated power wind speed or correspondingly that lift is increased resulting from the angle of attack being changed. Consequently the ratio of induced to parasitic drag is altered. In total this will result in a higher performance coefficient of the turbine when the angle between the foil chord and attacking wind actively is optimized.
For a 10% increase in performance for lower wind speeds from the theoretical increase in torque alone, and hence turbine power output, required efficiency of grid power to the jet stream is 0.7 to 0.8. With said efficiency only slightly over 0.5, which is common for traditional air compressors with high thermal losses, the theoretical turbine efficiency gain increase is 0%, when the increase of the angular velocity or lift are not included. With the increase of the angular velocity or angle of attack added, the net performance increase can still approach 10-20% for annual production in kWh. Increased performance will decline at a reduced angle of attack and be close to zero at the angle of attack for the rated power wind speed. The invention can thus cause "runaway", but in addition to the jet stream being capable of being switched on and off and being regulated, nozzle effect may include several nozzles or nozzles with adjustable angles that may act as air airbrakes to prevent runaway and serve other purposes. This principle, in embodiments of the invention can effectively be used for storm control, i.e.
allowing increased wind speed for cut-out that will smooth the power curve towards the cut-out.
There is a plurality of applications of the invention with respect to regulation. One example is the component showing the most frequent failures during operation of HAWT and rectification of AC generator voltage, being the smoothing capacitor following the rectifier. It's main purpose is the smoothing effect on the most rapid wind flux variations. Employing the present invention, this capacitor may be completely abolished or given reduced capacitance in order to extend it's lifetime.
In some embodiments for high efficiency the invention provides nozzle air from air pump instead of the conventional compressor. The air pump has one or more rotors, turbine wheels or impellers where circulation of air is arranged from the pressure side to the inlet side, similar to a "bypass" principle. A portion of the air on the pressure side are supplied as nozzle air in a regulated fashion, while inlet air is supplied sufficiently regulated, either through pipes or ventilation. Other bypass solutions with the invention are also possible. In accordance with the invention being applicable not only to air as fluid, turbines installed by or at water, can be using water or sea as the jet fluid, whereby the fluid density makes it easier to achieve the necessary power. Pumps with the invention can be realized so
small that they can be placed inside the rotor blades and derive electrical power via slip rings or become mechanically driven by the rotor rotation or a combination thereof. Similarly, air pumps can be driven by the rotor blade centrifugal force, for example, using devices inside the blades that utilize weights bodies.
Disturbance of laminar air flow near the tips of rotor blades due to the jet nozzles can be minimized with "flush" mounting or other aerodynamic solutions. In addition, the jet stream itself reduces the "wing-tip" turbulence and makes this problem more trivial. The invention also makes it possible to optimize the jet streams to avoid adverse wake effects. Under certain conditions, the air flows over the outer portion of the rotor blade thus will remain in contact with foil surface. Not least, nozzle angles can be actively used here, even to introduce turbulent fluid flows in connection with for example storm control.
The force on the outer portion of the rotor blade with the invention may be substantially larger in absolute value than the normal angle of attack force.
Increased stress on the fluid foil due to the invention, however, is reduced or becomes negligible. This follows from the vectors of the momentum on the rotor blade becoming not very different from perpendicular to the trailing edge of the foil or aligned with the foil chord. The vector of momentum perpendicular to the foil surface caused by the nozzle force, will in most cases be small. Thus, the elasticity considerations are also considerably simplified.
The invention, when it comes to wind turbines, can be summarized as consisting of two parts that can have different weights with different embodiments of the invention.
One part is a fluid jet stream from the rotor blades that provide a force acting in the direction of rotation, in some cases against, and achieves both control of turbine performance and an average improvement of its performance. With force against the rotation direction and speed braking, either adjustable jets in the trailing edge of the foil capable of giving the necessary force vector, or nozzles installed in leading edge of the foil is required for this purpose.
The second part combines the first part with optimization of jet stream angle of attack to increase the turbine effective area, equivalent to a turbine with a physically larger rotor diameter.
The first part can achieve COP of up to Betz 'constant and extend the range of wind speeds, where the coefficient is high. The other may increase the coefficient to exceed 59.25% when the real actuator disc is considered to correspond to the rotor swept area.
Acoustic noise from the jets can be reduced with one or more of several possible measures with bypass air flow around the cylindrical jet stream, not unlike that of a turbofan jet engine. Commutating or modulated jet flows will also reduce noise and is easy to realize. Commutator or modulator can be induced on nozzle force as well as beam angle.
The considerations of the invention having been made for HAWT wind turbines can also be applied to a variety of other fluids, and most fluid foil applications including oscillating foils.
The considerations of the invention having been made for HAWT wind turbines can also be applied to other types of wind turbines, both horizontal and vertical axis turbines.
The considerations of the invention having been made for CWAT compact wind turbines can also be applied to corresponding devices for other types of fluids.
The many regulatory and control benefits of the invention can be best utilized with substantially more advanced local wind prediction than with simpler sensor platforms such as with anemometer at the individual turbines and other locations. Therefore, in some embodiments of the invention microwave sensor concepts are used as an alternative to known radar technology, such as airport wind shear detection radar and similar for "near cast". The invention comprises substantially less expensive solutions with high measurement resolution that use transponders scattered in the terrain or on buoys at sea and oceans. At or near the turbines transmitter receivers (transceivers) are installed that form base lines for phase comparison. When the distance between the transmitter-receivers is large, the phase resolution becomes high. Also the distance between the transponders can be used to form base lines in a system for distance
measurement and positioning. Transponders need sufficiently low power so that they can operate continuously over years powered by solar cells. A central processor detects the different phase noise signatures from the different
transponders. Autonomous intelligence correlate signatures with the wind statistics accumulated, often centralized. Along with real-time measurement of speeds, accelerations and positions of the signatures, it uses the accumulated database, together with real-time signature detection to predict wind conditions at all turbines. Here it will be possible to track a wind field and provide a number of predictions at least tens of seconds before the wind changes occur at each turbine. The method will not only provide data for the line of sight between the transponder and the turbines, but also to greater heights, which will have their own signatures. With antenna directivity at one end or both, in particular parts of the transmission medium within the Fresnel Zone will affect the phase measurements and produce signatures. The invention may provide different signatures for density changes and water concentrations depending on frequency selection. This feature can be further improved with frequency diversity as with two or more frequencies. The invention can provide multidimensional signatures, for example, consisting of both amplitude and frequency spectrum for phase changes. The invention can accordingly also be thought used to monitor the wake from the turbines, where measures may be trying to reduce adverse wake effects.
Experts in the relevant areas will be able to see that further embodiments and applications of the invention are possible.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 shows the principle (101 ) for the deflection of the laminar wind (103) to a certain height above the ground, whereby the deflected wind energy (105) is led down to a wind turbine facility (106) standing at the end of the deflection area (104) and relatively close to the ground or sea level (102).
Figure 2 shows the principle (201 ) for an embodiment of the invention in which a deflection surface is replaced with air knife effect (21 1 , 212). The air knife generator (209) fed by the installation (201 ) own energy (210). Turbine or turbines (206) also has the ability to acquire the installation own energy when it is necessary to establish aerodynamic effects with hysteresis characteristics to maximize the power of the generator associated with the turbine installation (206).
Figure 3 shows a wind turbine with a prior art design (301 ) and familiar technology, its horizontal and vertical areas.
Figure 4 shows an embodiment (401 ) of the invention as a wind turbine, its horizontal and vertical area.
Figure 5 shows an embodiment (501 ) of the invention as wind turbine, side view, cross-wind direction. Above the turbine (502) is the air knife unit (503) and alternative micro-wave radar (504) for monitoring and control loop for the air knife (506) and deflected wind (507, 508).
Figure 6 shows an embodiment (601 ) of the invention where several rows of smaller turbines (604, 614) are stacked on top of each other with an air knife device fitted at the top (606) and suspended with a relatively low mast (606).
Figure 7 shows how certain embodiments (701 ) of the invention an air knife vortex cannon or similar device (702) can be swept (703, 704, 705, 707) in a sector to create a wide air knife (706) with high pressure and speed.
Figure 8 shows how an embodiment (801 ) of the invention for wind turbine that uses multiple air knives (808, 818, 828), suspended at different heights above the turbine arrangement by means of mast (810, 81 1 ) of moderate dimensions.
Figure 9 shows an embodiment (901 ) of the invention for wind turbine with air knives (908, 918, 928) in various heights, as viewed from the side, where the turbine arrangement (904) and associated air knife arrangements are suspended with a fairly low mast (906).
Figure 10 shows an embodiment of the invention for wind turbine where the turbine arrangement (1004) is fitted with air knives encircling in a rectangular shape (1005, 1002, 1004, 1006, 1007) to form a horn-like structure (1010) for the air knife and the wind harvesting.
Figure 1 1 shows (1 101 ) how the principle of the invention is explained by the Coanda effect between two fluids, in this case, an air knife fluid jet stream (1 106) and wind fluid kinetic energy field (1 109, 1 1 10, 1 1 1 1 ).
Figure 12 shows (1201 ) a further embodiment of the invention where the wind speed is accelerated by the pressure in the center of the turbine (1202) is being lowered by means of circular pressure chamber (plenum) (1212) and Coanda effect and circular nozzle (1209, 1210).
Figure 13 shows (1301 ) a further embodiment of the invention with installed adjustable air knife (131 1 ), air amplifier (1314), compressor air intake (1319),
"bleeder" (1320) for turbine outlet air (1324) with an adjustable choke (1321 , 1322).
Figure 14 exemplifies that a commercially available wind turbine (1402) can be the basis for the various embodiments of the invention using retrofitting and modifications.
Figure 15 shows an example of embodiment (1501 ) of the invention which may be use various types of control devices (1506, 1508, 151 1 , 1512, 1513, 1514, 1515, 1516) in one or more control loops to optimize the performance of the invention in which signals (1509) from one or more sensor platforms (1510) are included.
Figure 16 shows (1501 ) a simplified, passive embodiment of the invention where the incoming wind (1608) using annular plenum chamber (1605) and using the Coanda profile produces self-regulated air-knife effect directly (1607), often in a funnel-like shape.
Figure 17 shows a horizontal axle wind turbine propeller HAWT front view (1701 ) and side view (1702). Jet streams are displayed from the wingtips of the propeller wings (1707-1709, 1727-1730).
Figure 1 shows the principle (101 ) for the deflection of the laminar wind (103) to a certain height above the ground, whereby the deflected wind energy (105) is led down to a wind turbine facility (106) standing at the end of the deflection area (104) and relatively close to the ground or sea level (102).
Figure 2 shows the principle (201 ) for an embodiment of the invention in which a deflection surface is replaced with air knife effect (21 1 , 212). The air knife generator (209) fed by the installation (201 ) own energy (210). Turbine or turbines (206) also have the ability to acquire the installations own energy when it is necessary to establish aerodynamic effects with hysteresis characteristics to maximize the power from the generator associated with the turbine installation (206). Such a possibility is to supply electrical energy to the generator which is connected to the turbine shaft so that it can be accelerated up to speed to trigger the desired aerodynamic or pneumatic power.
Figure 3 shows a wind turbine with a prior art design (301 ) and familiar technology, its horizontal and vertical areas. The figure also suggests the extent of air trapping area (305). The turbine section can rotate (309) 360 degrees in agreement with wind direction.
Figure 4 shows an embodiment (401 ) of the invention as a wind turbine, its horizontal and vertical area. Wind Harvesting Area (405) is suggested to extend up to a height several times higher than the total height of the device itself, the arrangement can be rotated 360 degrees (409) and aligned towards the direction of the wind. The turbine installation itself can take many shapes and designs. An efficient solution is to use many smaller turbines stacked together. These may have a high rotational speeds that will increase the possibility of achieving hysteresis characteristics for the wind to be harvested. Each turbine can have several sets of rotors, not unlike jet and turbofan engines. Controlled bypass devices can thus be used to optimize power output compared to the available power from the wind. Furthermore, a wide array of turbines allow generators connected in series to obtain high voltages directly without energy conversion and step-up transformation.
Figure 5 shows a design (501 ) of the invention as wind, side view, cross- wind direction. Figure 5 shows an embodiment (501 ) of the invention as wind turbine, side view, cross-wind direction. Above the turbine (502) is the air knife unit (503) and alternative micro-wave radar (504) for monitoring and control loop for the air knife (506) and deflected wind (507, 508). Thus, the various control devices in the system is controlled using the sensor information from the radar (504) and generator (502) to optimize in real-time the capture of renewable energy. Air knife attack angle can be controlled for optimization purposes and is preferably a part of the control loop using the radar information. In some embodiments of the invention also the angle of attack of the turbine device itself is varied and controlled for maximum energy harvesting.
Figure 6 shows an embodiment (601 ) of the invention where several rows of smaller turbines (604, 614) are stacked on top of each other with an air knife device fitted at the top (606) and suspended with a relatively low mast (606). The turbine wheels and turbine wings can be realized in a variety of ways and experts in the field will see that other embodiments of the invention are possible. Also
turbines or generators that are more optimized on the basis of the venturi effect and Bernoulli's equation, are possible arrangements of the invention. Bypass arrangements with the turbines as an alternative to variable pitch simplifies the construction of the invention and keeps production cost low.
Figure 7 shows how certain embodiments (701 ) of the invention an air knife vortex cannon or similar device (702) can be swept (703, 704, 705, 707) in a sector to create a wide air knife (706) with high pressure and speed. Since the aerodynamic or pneumatic conditions for the deflection of air flows to be accomplished have hysteresis characteristics, the sweep rate does not necessarily have to be complicating high. By accelerating the turbine itself up in revolution speed using its own energy, the task of establishing wind deflection is facilitated.
Figure 8 shows how an embodiment (801 ) of the invention for wind turbine that uses multiple air knives (808, 818, 828), suspended at different heights above the turbine arrangement by means of mast (810, 81 1 ) of moderate dimensions. In these embodiments of the invention the limited physical size requirement for air knives of the facility exploits the limited requirement for high volume or mass, thus allowing suspension at height at low cost relative to wind turbines with known technology suspended at considerable height. Such conditions also means that the visibility of the facilities is kept moderate to meet most environmental requirements. The purpose of the air knives or similar devices at different heights is to increase efficiency by compensating for the air flow from air knife being decreased with distance from it.
Figure 9 shows a side view of an embodiment (901 ) of the invention for wind turbine with air knives (908, 918, 928) at various heights, where the turbine arrangement (904) and associated air knife arrangements are suspended with a fairly low mast (906). The figure also shows that the turbine device (904) and the various air blades (908, 918, 928) may have different angles of attack, as mentioned for Figure 8.
Figure 10 shows an embodiment of the invention for wind turbine where the turbine arrangement (1004) is fitted with air knives encircling in a rectangular shape (1005, 1002, 1004, 1006, 1007) to form a horn-like structure (1010) for the air knife and the wind harvesting. It will thus be better conditions for creating venturi effects that can increase the utilization of wind energy.
Experts in various fields will be able to see other possible embodiments of the various arrangements used in the invention.
Figure 1 1 shows (1 101 ) how the principle of the invention is explained by the Coanda effect between two fluids, in this case, an air knife fluid jet stream (1 106) and wind fluid kinetic energy field (1 109, 1 1 10, 1 1 1 1 ). The jet stream (1 106) from the air knife (1 103) binds through the Coanda effect to the wind field (1 109) and both fluid flows are deflected (1 108, 1 1 10) towards the wind turbine (1 102) and brings about a concentration of wind energy flux to towards turbine (1 102). Thus, the invention achieves that the energy capture to material consumption ratio increases. For the deflection to occur, the air knife flow must be adjusted in strength and direction relative to the wind field to be deflected. The deflection is also depending on the turbine (1 102) creating a pressure decrease. The cut in threshold can be lowered by the turbine (1 102) being accelerated in rotational speed in order to establish lower pressure in the turbine and thus the characteristic hysteresis deflection effect. The acceleration can be achieved with a load change, supplied electrical energy or changes in the aerodynamic conditions in and around the turbine. For wind turbines that are placed at the coast or out at sea, and in further embodiments of the invention with induced gradients or surfaces by the help of fluids, air knife may be replaced correspondingly by using water as fluid, the principles being similar. The desired effect occurs through, among other things, he Coanda effect occurring between water flow and air flow. In the case of water, this may well be in the form of vapor or mist.
Figure 12 shows (1201 ) a further embodiment of the invention where the wind speed is accelerated by the pressure in the center of the turbine (1202) is being lowered by means of circular pressure chamber (plenum) (1212) and Coanda effect and circular nozzle (1209, 1210). The plenum chamber is pressurized (1205) using compressed air supply (121 1 ). Accelerated air passes through the circular nozzle (1210) along a Coanda profile and further back in the turbine. This increases the amount of supplied air (1206, 1207) to the turbine and thus the air speed. The compressed air (121 1 ) can be generated by the turbine (1202) itself, or an independent compressor or a combination thereof.
Figure 13 shows (1301 ) a further embodiment of the invention with installed adjustable air knife (131 1 ), air amplifier (1314), compressor air intake (1319),
"bleeder" (1320) for turbine outlet air (1324) with an adjustable choke (1321 , 1322). Air amplifier is supplied with air to increase the airflow through an interface (1317), for example, the ambient air. From the air amplifier a regulated (1318) amount of air (1315) is transported to the turbine plenum chamber (1312) and the air knife plenum chamber (1316). As an alternative or supplement, an independent air compressor may supply compressed air to the mentioned devices (1319). The air knife (131 1 ) should have individual control (1325) of air velocity and control (1325) of the air knife angle.
Figure 14 exemplifies that a commercially available wind turbine (1402) can be the basis for the various embodiments of the invention using retrofitting and modifications. The challenge will partly lie in getting the turbine to withstand the increased power output. In some embodiments of the invention this is solved with additional turbines of smaller size for the same power output integrated in a wind turbine farm system. In other embodiments of the invention it is used to improve the power curve for a specific type of wind turbine. Such improvement is possible with turbines with free running propellers and annular turbines, that is low pressure turbines that accelerate the wind speed.
Figure 15 shows an example of embodiment (1501 ) of the invention which may be use various types of control devices (1506, 1508, 151 1 , 1512, 1513, 1514, 1515, 1516) in one or more control loops to optimize the performance of the invention in which signals (1509) from one or more sensor platforms (1510) are included in arrangements for the control loop. The embodiment has adjustable azimuth angle (1506) and tilting angle (1508). Further the vertical angle is adjustable, possibly also the azimuth angle of the air knife arrangement (151 1 ). The various air actuators to both air knife (1512) and turbine air amplification (1513) is controlled. A further air actuator can be supply of compressed air (1514). A controlled dampers (1515) regulates the amount of output air from the turbine used to produce compressed air. Load regulation, possibly supply of electrical energy, regulates the speed of the turbine generator (1516), for example, to establish the deflection of the wind towards the turbine. Sensors (1510) of different types control through intelligent devices the various actuators. Examples of possible sensors are wind measurements in front of the turbine, similarly at the rear the turbine, generator power measurements, data from radar directed against
the wind direction and other relevant measurements or variable parameters. Best control of the invention will be obtained with measurement of the wind field dynamics at a certain distance in front of the turbine. The turbine can also be designed with different mitigating acoustic measures using known technology for different kinds of turbines. In some versions of the invention separate harvesting of wind can be used to produce compressed air instead of in addition to using the exhaust air from the turbine. The generator itself may have to be stretched in the longitudinal direction to be able to provide high power and to minimize restrictions on air flows. Alternatively, such an embodiment of the generator may be made up of a number of generators, connected in series and on the same axle.
Figure 16 shows (1501 ) a simplified, passive embodiment of the invention where the incoming wind (1608) using annular plenum chamber (1605) and using the Coanda profile produces self-regulated air-knife effect directly (1607), often in a funnel-like shape. The annular wall (1606) which forms the plenum chamber (1605), air knife nozzle (161 1 ) and wind intake (1612) may in some embodiments be omitted. Embodiments of the invention are likely to include adjustable angle for air knife flow (1607) through the device (1603) being aligned with the air knife plane and allowed to rotate about an axis (1604) and divided into sections.
Furthermore, a number of embodiments of the invention will have air knife only along a portion of the periphery of the turbine up wind side. That will make it easier to have adjustable air knife angle. The embodiment can, in some versions as in figure 12, 13 and 15 in addition use turbine annulus (1610) with a circular nozzle and circular Coanda profile at the turbine front and rear to further lower the pressure in the turbine and increase the wind speed and thus increase the amount of air with the kinetic energy that the turbine can convert into electrical energy. Figure 17 shows a horizontal axle wind turbine HAWT propeller front view (1701 ) and side view (1702). Jet streams from the shown propellers wind tips are swept with the propellers revolutions circling around the extension of the turbine axel in a cylindrical or cone shape. Jet streams (1727, 1728) are shown from the wingtips of the propeller wings (1707-1709), with a speed component towards the wind direction (1720). Option for embodiment of the jet stream with a speed component along the wind direction is (1702) indicated (1729, 1730).- The angles (1712) of the jet streams in the plane of the propeller is shown (1701 ) with the relationship
between the longitudinal axis of the wing (171 1 ) and direction of the jet stream (1707). The figure shows an embodiment of the invention in which the said angle of the said jet stream contributes to a torque working with the rotational direction (1710), on the propeller wings (1704-1706). The jet streams from the three propeller blades set up a funnel-shaped layer of fluid gradients, corresponding to an air funnel with a cone shape. Both downwind (1729, 1730) and upwind
(1727.1728) jet stream is usually pointing with a certain angle (1735, 1734) out from the turbine shaft line (1731 ) and as mentioned, while at a tilted angle relative to the shaft line, so that the momentum from the jet stream interacts with the propeller rotation (1710). The jet stream can be generated with air knife technology or other nozzle arrangement and the jet streams can have from small to moderate momental coverage, which means that for practical considerations it can be one-, two-or three-dimensional. Such choices are determined by several factors such as profiles, surfaces, wind optimization. Compressed air to the nozzles showed (1725, 1726) can be supplied via the propeller wing (1723, 1724) cavity (1733) through the propeller hub (1721 ) and the propeller shaft (1722) via a rotating joint (1732). The positioning of the nozzles on the propeller wings depends on the characteristics desired for the turbine, but for many cases, the jets have the most applicable impact when installed in the wingtips. For the initiation of propeller rotation at low wind speeds and smoothing of the rotation speed, preventing rotation stops, positions in the wingtips are the most effective. Air pressure flow supply to the nozzles, and preferably also jet stream directions, are preferably intelligently controlled for optimum efficiency for of the turbine. Advanced embodiments of the invention can have nozzles mounted in several places on the propeller wings. The air compressor can be electrical and supplied by grid power, but can also be powered by recycled air flow as with one or a number of venturi funnels. The effect set up by the jet streams has hysteresis characteristics and is most effective when it is intelligently controlled in relation to wind sensors, but even static solutions will provide significant increase of wind turbine efficiency. The increase will normally show up clearly in the turbine "power curve" as a result of maximum generator power becoming achieved at lower wind speeds through concentration of the wind flux. An important part of the behavior is the Coanda effect between wind fluid flux to jet stream fluid. With jet streams directed upwind,
from the propeller the venturi effect is increased. Correspondingly happens with jet streams directed downwind from the propeller. The two methods can be combined. Experts in the area will see that various different embodiments and applications of the invention are possible.