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Wind turbine — Kean W. Stimm (US9194371B2)

Kean W. Stimm · Google Patents

Google Patents · Patents · License: Open Access

patent, google patents, intellectual property, US9194371B2, Kean W. Stimm, en, 2015

ABSTRACT

Abstract

A wind turbine having a set of curved blades mounted on a central rotatable huh. Each of the blades has a defined pitch angle, to a rotational axis of the hub, along the blade from the hub to the tip. A curve is provided on the wind contact surface along each of the blades over the blade surface from the leading edge of the blade to the trailing edge of the blade by an amount between about 6 and about 24 degrees. The defined pitch angle from any point along the leading edge of the blade being defined by the arc-sine of a ratio of blade velocity to apparent wind velocity, with a variance of Â±30 percent of the complementary angle to the arc-sine; and apparatus for varying the velocity of the blade to control power output so that it is within fifteen percent of maximum obtainable power of the blade most distant from the hub.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 13/221,656 filed Aug. 30, 2011, which is a continuation-in-part of PCT Application PCT/US2010/039487 filed Jun. 22, 2010, which in turn claims priority from U.S. Provisional Application 61/269,183, filed Jun. 22, 2009 and which U.S. patent application Ser. No. 13/221,656 further claims priority from U.S. Provisional Application 61/402,451 filed Aug. 30, 2010. Priority is claimed from all of the above applications, all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention broadly relates to wind turbines, more specifically to a wind turbine designed to extract energy from the wind.

Mankind has been using various types of rotary devices to extract energy from the wind for centuries. The types of mechanisms used include a multiple blade arrangement that rotates around a central axis. The apparatus may be configured with either a vertical axis or a horizontal axis. The horizontal axis type includes both windmills and wind turbines. The vertical axis devices generally provide methods that have more resistance to the wind on one side of the axis and less resistance on the other half such that the difference in wind resistance allows the unit to turn, and as a result, they exhibit significant inefficiencies. Horizontal axis windmills are usually open blade mechanisms such as for example, the old four blade Dutch windmills, Or the modern windmill with three blades, which has been proliferating around the world. The Dutch windmills are, effectively, a reaction type apparatus that relies on the impact of the wind on the angled blade to cause a force to turn the rotor. They are quite inefficient but if made large enough, they can supply some useful work.

Another type of wind device is the multi blade unit used to provide farmers with a means to pump water. This device might have 20, 30, or more blades and develop enough torque to turn a pump. This configuration is, also, a reaction type windmill driven, primarily, by the impact of the wind on an angled blade. This type is very inefficient over a broad wind spectrum and they are noisy and fragile and need to be shut down during periods of sustained high winds

The use of three-blade windmills has become very prominent around the world, Multiple three-blade windmills are usually arranged to establish âWind Farmsâ. A large wind farm may consist of a few dozen to several hundred individual three-blade windmills, and may cover an extended area of hundreds of square miles. The windmills used for wind farms are of enormous size with a blade swing diameter that ranges around 300 foot. They often rise to heights of 300 feet to 400 feet and require large amounts of land. They utilize the force from Bernoulli's Theorem as it is used to create the lift force on an airplane wing. However, the blades of three-blade turbines occupy only 5% of the blade swing area. Hence, 95% of the kinetic energy in the air mass passes between the blades and is lost. Adding more blades is not the answer as just one more blade causes the efficiency to become even worse. This is because of the enormous turbulence surrounding each blade thus causing interference with the other blades.

The three-blade windmills convert less than 1.4% of the kinetic energy in the wind to useful electrical energy; Yet, three-blade windmills are considered the most economically viable method currently available for generating significant electrical power from the wind. Because three-blade windmills are extremely expensive while being very inefficient, it is mathematically impossible for them to have a reasonable return on investment or a competitive cost for a kilowatt hour of electrical power without government subsidies, grants, and tax abatements. Further, their huge size dominates the skyline so that they are intrusive and can be annoying with flickering shadows, TV interference, and sometimes humming noises. Their very complex design involves thousands of parts, and, usually, adjustable pitch blades driven by expensive servomechanisms.

U.S. Pat. No. 4,021,135 (Pedersen), and U.S. Pat. No. 4,140,433 (Eckel) disclose a device attempting to enhance the Bernoulli effect as used by three-blade windmills by using fixed shrouds around the outside of the blades to funnel more air around the blades. This approach encourages some of the air mass to diverge around the windmill because it perceives a funnel as an obstacle thereby causing a net loss of available kinetic energy. These devices have rotatable blades that are in close proximity to a non rotating shroud, and as a result will experience serious drag and turbulence and thus a loss in efficiency.

Alternate configurations that attempt to provide higher efficiency are disclosed in U.S. Pat. No. 4,611,125 (Stone Jr.), which teaches a concept, which improves airflow, however, still allows a large percentage of the kinetic energy in the wind to bypass the structure unused. In U.S. Pat. No. 7,396,207 (DeLong), the use of sails to augment the amount of wind energy captured is commendable excepting for the practical problems associated with the complexities of continuous adjustment of the sails, handling of storms, and contending with ice and snow. In U.S. Pat. No. 4,150,301 (Bergey), the object has been to provide rotation speed regulation at considerable expense to efficiency. There is little evidence that demonstrates that any of these methods improve efficiency, simplicity, or cost.

U.S. Pat. No. 7,214,029 (Richter) discloses a device that initiates the acceleration of the air mass and implies that the kinetic energy is increased by diverting the air mass around a frontal structure to cause it to concentrate and speed up as it enters a funnel shape and then onto the many multiple blades. This, of course does not increase the kinetic energy in the air mass as per the laws of conservation of energy. Also, this system relics on the reaction force of the wind air mass impacting the angled blades. This is an inefficient method of extracting energy from the wind. Further, the wind will view any structure placed in an open-air environment as an obstacle and divert a substantial percent of that air mass around the obstacle. This is substantially different from such designs being placed in a long tube with forced air being driven through.

United States Patent Application No. 2008/0232957 (Presz), discloses a fixed shroud that surrounds a set of stator blades that direct airflow around a three bladed impeller rotor with mixer air diffused into the after area of the impellers. It is implied that this will increase the energy output of the impeller system by two to three times. However, despite the unsupported allegation, no hard evidence is provided for any such result. It is also implied that the configuration permits the airflow velocity to increase by use of the diffuser system located after the impeller rotor. This supposed increase in velocity, however, becomes a problem for three blade impellers, operating by use of Bernoulli's Theorem, since they cannot tolerate higher air velocity speeds without self destruction. They are also limited by the requirement that the blade tip velocity be seven times the wind speed in order to achieve reasonable efficiency. Further, pitch control of the blades and stator is essential to maximize performance in variable winds. All of this leads to an extremely complicated and costly device for which no actual improvement is shown. The huge shroud portrayed would add substantial weight and structural requirements to this wind turbine and the device would need to have tremendous strength to withstand even ordinary winds. The rotation of the impeller blades within the fixed shroud would generate significant drag and turbulence between the blade tips and shroud due to air mass being flung outward due to centrifugal and other forces caused by rotation of the impeller rotor and the extraction of energy. It is truly questionable whether any improvements resulting from the device could offset the increased costs and the environmental intrusion of such a structure.

U.S. Pat. No. 4,140,433 (Eckel) discloses a system that provides complex multistage turbines to cause each stage to enhance the wind power. The wind; however, sees this whole turbine as an obstacle to get through. Hence, some of the air stream, and energy, approaching the rotor will divert around the turbine. This theory works for power turbines where hot gasses are forced through as in aircraft jet engines. This approach is highly complex and very expensive without gaining credible efficiency because the many blades also cause drag and turbulence. It should also be noted, that the increased cost and complexity hardly justifies multiple stages, since each subsequent stage must extract energy from air from which energy has already been extracted.

Vertical axis windmills, which rely on providing greater force on one side of the axis than on the other. Examples of vertical axis windmills are shown in U.S. Pat. No. 5,525,037 (Cummings) and U.S. Pat. No. 4,619,585 (Storm). These windmills are notoriously inefficient since there is always drag on the side returning against the wind, which subtracts from the power generating side. Another approach is shown by U.S. Pat. No. 7,362,004 (Becker) utilizing a complex structure to control rotation speed at the expense of drag, turbulence, poor airflow, and many obstructions all of which reduce efficiency. U.S. Pat. No. 7,116,006 (McCoin) provides an ingenious arrangement to convert horizontal airflow to vertically mounted, counter rotating blades, which balance torque on the tower and maximize rotor speed. This is accomplished at great cost to efficiency in part due to the reaction blade system used. These types of mechanisms, generally, create significant turbulence, drag, and interference with the air stream. The many efforts for improvement by adjusting the differential forces on each side of the axis can only be slightly effective since there are so many other factors that can spoil the efficiency. The many patents involving windmills and wind turbines represent attempts at improving ways of better utilizing Bernoulli's theorem, or ways of better using reaction or impact methods as an air mass strikes a surface. Only minor gains are achieved as the basic theorems are highly limited as to the theoretical maximum efficiencies achievable. Further, the many efforts to gain greater efficiency and solve vexing problems, as presented in so many patents, involve astonishingly complex mechanisms which can be troublesome in the harsh environment of windmills. This raises serious questions of long-term cost and maintenance. The calculation of efficiency for a windmill or a wind turbine can be demonstrated by starting with a theoretical maximum output of â100â and then applying the known losses as follows:

Three-blade windmills using the Bernoulli Theorem:

Efficiency=100Ã5%Ã95%Ã45%Ã65.5%=1.4%

5% is the area of the blades in contact with the wind.

95% is the wind utilized and not bypassed around the blades.

45% is the conversion of kinetic energy to rotor horsepower output.

65.5% remainder after gearbox (10% loss and losses of generator/inverter).

Thus, there is a long felt need for a properly designed wind turbine that can deliver 35% and as much as 55% of the wind kinetic energy into useful electrical power, which is about 25 to almost 40 times greater than the typical three-blade windmill efficiency of only 1.4%.

There is a further long felt need for a wind turbine that can start generating power at lower wind speeds and continue producing power even during high speed wind storms. Currently, at low wind speeds and during storms, loss of wind power by a three-blade windmill can be estimated at as much as 50%.

There is a further long felt need for a wind turbine designed much smaller than a three-blade windmill for the same annual megawatt hour output.

BRIEF SUMMARY OF THE INVENTION

The wind turbine in accordance with the invention causes a moving mass of air, as wind, to be driven out of its path of motion to create the force that drives the turbine smoothly and efficiently with little turbulence by use of Newton's First Law of Linear Motion. The wind turbine of the invention may be a wind turbine having a rotatable hub with an enclosure surrounding the tips of the blades, and being connected to them, which blades cause a moving mass of air, as wind, to be driven out of its path of motion to create the force that drives the turbine smoothly and efficiently with little turbulence.

More particularly, the invention is a wind turbine having a set of curved blades mounted on a central rotatable hub. Each of the blades has a length from the hub to a tip and a wind contact surface defined by a leading edge and a trailing edge and a defined pitch angle, to a rotational axis of the hub along the blade from the hub to the tip. A curve is provided on the wind contact surface along each of the blades over the blade surface from the leading edge of the blade to the trailing edge of the blade by an amount between about 6 and about 18 degrees;

The defined pitch angle from any point along said the leading edge of each of the blades is defined by the arc-sine of a ratio of blade velocity to apparent wind velocity, with a variance of Â±30 percent of the complementary angle to the arc-sine.

Apparatus for varying the velocity of the blade is to control power output so that it is within fifteen percent of maximum obtainable power.

The pitch angle is at least 20 degrees and not greater than 85 degrees, and the pitch angle closest to the hub is at least fifteen degrees less than the pitch angle of most distant from the hub.

Preferably, the apparatus for varying the velocity of the blade varies the velocity such that velocity and drive force are each within at least 40 percent of maximum. A cone is desirable provided as part of the hub to direct wind around the hub to the blades.

It is to be understood that âhubâ means a central part to which blades are attached and also is intended to include portions of the blade proximate the hub which do not have a pitch angle as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and mode of operation of the present invention will now be more fully described in the following detailed description a preferred embodiment of the invention taken with the accompanying drawing figures, in which:

FIG. 1 is a front view of a preferred embodiment of a turbine of the present invention;

FIG. 2 is a top view of the preferred embodiment of the turbine shown in FIG. 1 ;

FIG. 3 is a top cross-sectional view of a turbine blade used in the turbine of the preferred embodiment of the present invention taken on line 3 - 3 of FIG. 5 ;

FIG. 4 is a side cross-sectional view of a turbine blade used in the turbine of the preferred embodiment of the present invention taken on line 4 - 4 of FIG. 5 ;

FIG. 5 is a front view of the turbine of a preferred embodiment of the present invention;

FIG. 6 is a view of airflow relative to a turbine blade;

FIG. 7 is a front view illustrating a hub of a preferred embodiment of the present invention;

FIG. 8 is a side view illustrating a hub of a preferred embodiment of the present invention;

FIG. 9 is a front view illustrating a structural flared enclosure of a preferred embodiment of the present inven

CROSS REFERENCE TO RELATED APPLICATIONS

BACKGROUND OF THE INVENTION

The invention broadly relates to wind turbines, more specifically to a wind turbine designed to extract energy from the wind.

Three-blade windmills using the Bernoulli Theorem:

Efficiency=100Ã5%Ã95%Ã45%Ã65.5%=1.4%

5% is the area of the blades in contact with the wind.

95% is the wind utilized and not bypassed around the blades.

45% is the conversion of kinetic energy to rotor horsepower output.

65.5% remainder after gearbox (10% loss and losses of generator/inverter).

There is a further long felt need for a wind turbine designed much smaller than a three-blade windmill for the same annual megawatt hour output.

BRIEF SUMMARY OF THE INVENTION

Apparatus for varying the velocity of the blade is to control power output so that it is within fifteen percent of maximum obtainable power.

The pitch angle is at least 20 degrees and not greater than 85 degrees, and the pitch angle closest to the hub is at least fifteen degrees less than the pitch angle of most distant from the hub.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a preferred embodiment of a turbine of the present invention;

FIG. 2 is a top view of the preferred embodiment of the turbine shown in FIG. 1 ;

FIG. 3 is a top cross-sectional view of a turbine blade used in the turbine of the preferred embodiment of the present invention taken on line 3 - 3 of FIG. 5 ;

FIG. 4 is a side cross-sectional view of a turbine blade used in the turbine of the preferred embodiment of the present invention taken on line 4 - 4 of FIG. 5 ;

FIG. 5 is a front view of the turbine of a preferred embodiment of the present invention;

FIG. 6 is a view of airflow relative to a turbine blade;

FIG. 7 is a front view illustrating a hub of a preferred embodiment of the present invention;

FIG. 8 is a side view illustrating a hub of a preferred embodiment of the present invention;

FIG. 9 is a front view illustrating a structural flared enclosure of a preferred embodiment of the present invention;

FIG. 10 is a top view illustrating the structural flared enclosure of a preferred embodiment of the present invention;

FIGS. 11 a through 11 d are top views illustrating the wind flow without blade displacement of the wind;

FIGS. 12 a through 12 d are top views illustrating the wind flow with blade displacement of the wind;

FIG. 13 is a side cross-sectional view of a main housing assembly of the present invention;

FIG. 14 is a side cross-sectional view of a main column and cap assembly of a preferred embodiment of the present invention;

FIG. 15 is a side view of a preferred embodiment of a forward partition and lock down system of the present invention;

FIG. 16 is a front view of a preferred embodiment of a forward partition and a main bearing of the present invention;

FIG. 17 is a side view of a preferred embodiment of a rear partition and a main bearing of the present invention;

FIG. 18 is a front view of a preferred embodiment of a rear partition and a main bearing of the present invention;

FIG. 19 illustrates vectors of true wind, blade speed and apparent wind;

FIG. 20 is a side view of a wind vane and rear cone door assembly of a preferred embodiment of the present invention; and,

FIG. 21 illustrates alternative blade shapes of a preferred embodiment of the present invention showing apparatus controlling braking.

FIG. 22 shows a curve illustrating blade speed, torque and power output relative to blade pitch angle.

FIG. 23 shows a graph of true wind velocity against blade velocity permitting calculation of input angle of the blade.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a wind turbine as previously described. It is to be understood that the pitch angle on the blades need not necessarily extend along the entire leading edge of the blades. In such a case the wind turbine may be more particularly described as follows:

A wind turbine for operation within a circular area including:

A set of curved blades mounted on a central rotatable hub. Each of the blades has a length from the hub to the tip and a wind contact surface defined by a leading edge and a trailing edge and a defined pitch angle, to a rotational axis of the hub, along at least a portion of the blade from the hub to the tip such that the at least a portion of the blades passes through at least 85 percent of said circular area.

A curve is provided on the wind contact surface along the at least a portion each of the blades having an increasing pitch angle of the blade, over the blade surface from the leading edge of the blade to the trailing edge of the blade by an amount between about 6 and about 18 degrees.

The defined pitch angle from any point along the leading edge of the at least a portion of each of the blades being defined by the arc-sine of a ratio of blade velocity to apparent wind velocity, with a variance of Â±30 percent of the complementary angle to the arc-sine; and apparatus is proved for varying the velocity of the blade to control power output so that it is within fifteen percent of maximum obtainable power.

The pitch angle is at least 20 degrees and not greater than 85 degrees, and the pitch angle closest to the hub, of the at least a portion of the blade, is at least fifteen degrees less than the pitch angle of the at least a portion of the blade most distant from the hub.

In one embodiment, the present invention is a wind turbine having a set of curved blades mounted on a central rotatable hub. An enclosure surrounds and is attached to the tips of the blades. The enclosure is arranged to rotate with the hub and the blades. The blades have a fixed pitch such that a pitch angle Ï of each of the blades at the tip end of the leading edge is from 50 degrees to 80 degrees to a rotational (central) axis of the hub. A preferred leading edge pitch angle Î± of each of the blades at a hub end is defined by the formula: Î±=(Arctan of (Tan ÏÃhub diameter))/turbine tip diameter. The leading edge pitch angle of the blade at the hub is usually from about 28 to 49 degrees to the rotational axis but may vary considerably depending upon the diameter of the hub. In general, the leading edge pitch angle at the hub increases with increasing hub diameter. The preferred leading edge pitch angle

is the same as the apparent wind angle. The apparent wind angle at any location along the length of the blade can be clearly derived from FIG. 19 and from FIG. 19 the apparent wind angle may clearly be determined by the formula

=arctan (blade velocity/true wind velocity) where blade and wind velocities are in the same linear units per unit time (or multiplied by a conversion factor to make it so), e.g. feet per second, miles per hour, meters per second, etc. Since the apparent wind angle is a function of blade speed, as shown in FIG. 19 , the apparent wind angle may be controlled by controlling blade speed thus making it possible to utilize fixed pitch blades, i.e. blades that that have a fixed pitch that varies over their length and width but do not change pitch during operation.

The blade is provided with a surface that curves into the path of the apparent wind. (the angle of the wind seen by the moving blade) impinging upon the blade at a wind entry location of the blade. This curve may be referred to as the âmaintenance curveâ. The maintenance curve maintains surface contact with the apparent wind to deviate the apparent wind from its path thus extracting energy from the apparent wind. The maintenance curve effectively gradually increases the pitch angle of the blade as the wind flows along the blade surface. The maintenance curve of the surface preferable increase the pitch angle of the blade, over the blade surface from the leading edge of the blade to the trailing edge of the blade, usually by an amount between 6 and 18 degrees. It is believed that a preferred pitch increase is about 12 degrees.

The turbine is further provided with an apparatus that controls speed of rotation of the turbine so that the angle of the apparent wind to the blades can be adjusted relative to the pitch angle of the blades to obtain at least 50% of maximum energy that can be extracted using the turbine where angle of apparent wind preferably matches the angle of blade at location of contact with the blade. In all cases the angle of apparent wind approximates the pitch angle of the blade at contact. âApproximatesâ as used in this context means a variance of 3 degrees or less. As is apparent from FIG. 6 , it should be understood that the blade angle at the leading edge should usually not be less than the angle of apparent wind since apparent wind would then strike the back of the blade.

Stated in another way, the pitch angle of the blades is an angle that approximates a constant apparent wind angle and the apparent wind angle is kept constant by controlling the rotational speed of the blades relative to incoming wind speed and the angle of the blade is between 30 and 80 degrees to the rotational axis

In some embodiments, the enclosure includes a circumferential sidewall about a central axis, the circumferential sidewall includes a front opening being adapted to face true wind and a rear opening. The sidewall slopes from the front opening to the rear opening such that the rear opening has a larger diameter than the front opening. The sidewall slopes from the front opening to the rear opening at an angle to a plane of the front opening between 100 degrees to 135 degrees and preferably from 107 degrees to 112 degrees.

In some embodiments, each of the blades includes a leading edge and a trailing edge having a surface for receiving wind, wherein the number of blades is sufficient to entirely redirect direct wind impinging upon the turbine. For example, the leading edge of each of the blades may overlap the trailing edge of an adjacent blade by an amount between 14% and 20% of its surface area, but in some circumstances overlap may be as much as 60%.

In some embodiments, each of the blades are twisted such that the tip end of the blade is twisted at an angle to the central axis of an amount between 54 degrees to 64 degrees. Each of the blades, in some embodiments is twisted such that the hub end of the blade is twisted at an angle to the central axis of an amount between 28 degrees to 49 degrees.

In some embodiments, the turbine includes a nose cone at the front of the turbine face covering the hub, and which is streamlined to transfer an air mass approaching the turbine to be directed around the hub and into the blades so that kinetic energy in the air mass is captured.

In some embodiments, the turbine is connected to a multi-pole generator having poles connected in series and of sufficient size to provide a higher output voltage relative to the output of a dipole generator. In some embodiments, an inverter is connected to the generator output with means to provide the maximum electrical output of the generator under all normal wind conditions for delivery to the user.

In some embodiments, the control of turbine speed is regulated by a controller that measures generator power output and modifies field current of the generator to load its rotor to regulate rotation speed of the turbine to obtain at least 50% and, preferably at least 80%, of maximum generator power output under all wind conditions.

In some embodiments, the set of fixed pitch blades are shaped with a curvature on a first side and a different curvature on a reverse side to affect the apparent wind as seen by the moving blades of the turbine.

It is an object of the present invention to provide a wind turbine that is Â½ to 1/7th the diameter of a three-blade windmill having the same annual megawatt hour output.

It is a further object of the present invention to provide a wind turbine where up to 95% of the wind is utilized and not bypassed around the turbine and at least 35 percent and as much as 50 percent or more is used for the conversion of kinetic energy to rotor horsepower output. After electro-mechanical losses at least 70 percent of the rotor horsepower output can be converted to useful work, e.g., in the form of useful electrical power. The wind turbine of the invention using Newton's First Law of Linear Motion may thus converts as much as 35 percent or more of wind kinetic energy to useful electrical power:

100Ã95%Ã51%Ã72.5%=35.1%

95% is the wind utilized and not bypassed around the turbine. 51% is the conversion of kinetic energy to rotor horsepower output. 72.5% remainder after electro-mechanical losses of generator/inverter. No gearbox.

These and other objects and advantages of the present invention will be readily appreciated from the following description of preferred embodiments of the invention and from the accompanying drawings and claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the an to which this invention belongs. It should be appreciated that the term âtrue windâ is defined as the actual speed in the direction of the wind as it approaches the turbine. The direction of true wind is usually along the same axis as the rotation axis of a horizontal windmill or turbine. The term âapparent windâ as used herein means the speed and relative direction from which the wind appears to blow with reference to a moving blade. The âangle of the apparent windâ is the angle between the direction of the apparent wind relative to true wind. It should be appreciated that the term âwind turbineâ is defined as an apparatus having an internal rotor having angular blades, surrounded by a circumferential wall, that generates rotary mechanical power from the energy in a stream of fluid. The âfront blade surfaceâ is a surface of the blade receiving true wind. The âreverse blade surfaceâ is a surface of the blade shielded from true wind. The central axis is also equivalent to the rotational axis and can be used interchangeably. The âleading edgeâ is the edge of the blade that strikes air as a result of blade rotation and is the edge of the blade surface furthermost on the blade in the direction of rotation. The âtrailing edgeâ is the edge of the blade opposite the leading edge and follows the leading edge in the direction of rotation.

At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered the preferred embodiments, it is to be understood that the invention as claimed is not limited to the disclosed embodiments.

Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and, as such, may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

Referring now to the figures, FIGS. 1 thru 2 illustrates a preferred embodiment of a turbine assembly 1 having plurality of fixed pitch blades 1 A mounted on hub 1 B with axle 1 C and attached within enclosure 1 D as a single stage turbine and as a single rotating part. It should be understood that hub 1 B which maybe an axle or may form a part of an axle. Axle 1 C is projected forward and is enclosed within nose cone 1 E which also rotates with the turbine. Specifically, the turbine has eight fixed pitched blades. Each blade 1 A includes tip end 20 and hub end 21 . Each tip end 20 is equally spaced at angle (Î¸) of about 45Â° to central axis a-aâ². Blade 1 A further comprises leading edge 22 and trailing edge 23 defining front surface 28 for receiving wind, wherein the number of blades is sufficient to entirely redirect direct wind impinging upon the turbine. Leading edge 22 of each blade 1 A overlaps trailing edge 23 of an adjacent blade defining overlap surface 29 . Preferably, leading edge 22 of each blade 1 A overlaps trailing edge 23 of an adjacent blade by an amount between 5% and 60% and more preferably from 14% and 20% of its surface area. Each blade 1 A having a fixed pitch such that pitch angle (Î) of the blade at the tip end is from a range between 54 degrees to 75 degrees to rotational (central) axis a-aâ².

In the present embodiment, enclosure 1 D surrounds tip end 20 of the blades and is attached thereto. Enclosure 1 D is arranged to rotate with hub 1 B and blades 1 A about central axis a-aâ². Enclosure 1 D includes circumferential sidewall 25 defining front opening 26 and rear opening 27 . Front opening 26 is adapted to face true wind 31 . Circumferential sidewall 25 is arranged about central axis a-aâ². In should be understood that for the purpose of illustration true wind 31 is a direction along central axis a-aâ². Sidewall 25 slopes from front opening 26 to rear opening 27 such that the rear opening has a larger diameter than the front opening. Preferably, sidewall 25 slopes from front opening 26 to rear opening 27 at angle (Î¨) to a plane of the front opening between 100 degrees to 135 degrees, preferably from 107 degrees to 112 degrees. FIGS. 1 and 2 further illustrate top and front views of turbine assembly 1 . It should be appreciated that preferably, the turbine, itself, could be one solid casting. However, the individual parts of the turbine can be made separately and assembled to become one part with final assembly in the field. The components may be fabricated out of any substantially rigid material such as, for example metal or a reinforced plastic. Preferably, all of the components should be the same color. Nose cone 1 E is shaped to deflect air mass at the hub diameter into blades 1 A so that little of the kinetic energy is lost. The shape and curvature of the nose cone are determined for maximum efficiency. The axis supports the nose cone, which has a cast in receptacle to fit the axis. The aft end of nose cone 1 F is bolted and sealed to hub 113 . The output signal of the wind direction servo 1 F is telemetered through the axis to orient the turbine into the wind by use of the gear motor shown in FIG. 14 . In a preferred embodiment, the nose cone is cast up in a mold using reinforced plastic.

FIGS. 3 through 5 illustrate a plurality of turbine blades 1 A. Preferably, each of the blades is configured to include a precise compound curve. The primary curve determines the amount of displacement of the air mass as it passes through the turbine and is about eleven to twelve degrees with an eight-blade configuration, but may vary somewhat as related to the number and shape of the blades, the size of the turbine, and its determined rotation speed. The secondary curve is a twist from the blade tip to the blade base to accommodate the change in the blade circumference and its relative travel speed. Preferably, tip end 20 of blade 1 A is twisted at pitch angle (Î) to the rotational (central axis) a-aâ² of an amount between 54 degrees to 75 degrees. Even more preferably from 58 degrees to 64 degrees. Specifically, the blade angle at the tip end may be twisted to 60 degrees. The blades are twisted such that hub end 21 of blade 1 A is twisted at angle (Î±) to rotational (central) axis a-aâ² of an amount between 28 degrees to 49 degrees. Specifically, the blade angle at the hub end may be 34 degrees. Even more specifically, the pitch of each of the blades at hub end 21 is defined by a product of a ratio, of hub radius R 1 divided by turbine radius R 2 , multiplied by a pitch angle at the tip. The pitch can vary, somewhat, in accordance with the relative hub diameter, the desired turbine rotation speed, and the established power curve for a specific turbine. It should be understood that many modifications of the blade configuration may be made without departing from the scope of the appended claims. For example, increasing or decreasing the number of blades and increasing or decreasing the overlap of the blades is well within the concept of the invention. Likewise, it is to be expected a somewhat different curvature of the blades may be determined that will further enhance efficiency.

FIG. 6 is a top view of turbine blade 1 A as the airflow of apparent wind 30 moves along the blade as the blade rotates. Turbine blade 1 A includes compound curve 24 . As seen in FIG. 6 , the angle of the apparent wind is approximately the same as the angle of the blade at the location of input of apparent wind.

FIG. 7 is a front view illustrating the hub of the present invention and FIG. 8 is a side view illustrating the hub of the present invention. Turbine hub 1 B is secured to axle 1 C with the blades are mounted on hub 1 B outer periphery in a manner that provides structural integrity. Preferably, the base of the blades is secured from inside of the hub. Preferably, the turbine hub is to be essentially an aluminum pipe with end caps on the front and back to support axle 1 C. The back of the hub supports disc brake surface 1 C that is used to lock down the turbine. Axle 1 C is an aluminum pipe, which extends from the forward inside part of nose cone 1 E to the back end of generator armature 5 B. The wall thickness, diameter, and temper, are determined in accordance with good engineering practice for the loads and stresses expected with hurricane force winds for a specific turbine size.

FIGS. 9 and 10 illustrate the structural flared enclosure

D having sidewall 25 sloping from front opening 26 to rear opening 27 such that the rear opening has a larger diameter than the front opening. Enclosure 1 D is supported by a plurality of blades that are secured to the enclosure in a structurally integrated manner. Preferably, the blades are secured to the enclosure by drilling a bolt through the enclosure and down into the blade. Enclosure 1 D provides high strength and ruggedness to the turbine assembly since both ends of the blades are fully supported. Enclosure 1 D flans outward from the front opening toward the back opening. The angle of flair is mathematically determined to expand the volume of the turbine from front to back by an amount proportional to the percent of energy extracted from the wind. For example, if 50% of the energy were extracted, the volume of the space within the turbine would need to increase by about 30% to prevent the air mass from slowing down. It is envisioned that the structural flared enclosure be made with a reinforced plastic to match the blades.

For purpose of illustration FIGS. 11 and 12 show successive âsnap shotâ paths of true wind 31 as it impinges on the face of the turbine blade 1 A. FIGS. 11 a through 11 d are top views illustrating the wind flow without blade displacement of the wind. The figures show how air mass 32 passes straight through the turbine without touching blade 1 A if there is no blade curvature and blade 1 A are moving to match apparent wind 30 . The blades, effectively, move out of the way just in time. FIGS. 12 a through 12 d are top views illustrating the wind flow with blade displacement of the wind. True wind 31 is forced out of its path of motion by a curved blade with the same conditions as in FIG. 11 . As can be seen in FIG. 12 a , the speed of the turbine blade is set so that the angle of apparent wind 30 initially approximately matches the angle of the pitch of blade 1 A.

FIG. 13 is a side cross-sectional view of the main housing assembly of the present invention. The rear portion of axle 1 C is supported within housing 2 which contains two partitions

3 A and 3 B at front and partly back, each containing main axle bearings

4 A and 4 B. The aft end of axle 1 C is attached to <figure-callout id="5B" label="generator armature" filenames="US09194371-20151124-D00005.png" state="{{s

CLAIMS

Claims ( 20 )

What is claimed is:

1. A wind turbine for operation within a circular area comprising:

a set of curved blades mounted on a central rotatable hub, each of said blades having a length from the hub to the tip and a wind contact surface defined by a leading edge and a trailing edge and a defined pitch angle, to a rotational axis of the hub, along at least a portion of the blade from the hub to the tip such that said at least a portion of said blade passes through at least 85 percent of said circular area;

a curve on the wind contact surface along said at least a portion each of said blades having an increasing pitch angle of the blade, over the blade surface from the leading edge of the blade to the trailing edge of the blade by an amount between about 6 and about 24 degrees;

said defined pitch angle from any point along said leading edge of said at least a portion of said blade being defined by the arc-sine of a ratio of blade velocity to apparent wind velocity, with a variance of Â±30 percent of the complementary angle to said arc-sine; and

apparatus for controlling the velocity of the blade to control power output so that it is within forty percent of maximum obtainable power under normal wind conditions;

provided that, said pitch angle is at least 20 degrees and not greater than 85 degrees, and provided that the pitch angle closest to the hub, of said at least a portion of the blade, is at least fifteen degrees less than the pitch angle of said at least a portion of the blade most distant from the hub.

2. The wind turbine of claim 1 wherein the apparatus for controlling the velocity of the blade controls the velocity such that velocity and drive force are each within at least 40 percent of maximum.

3. The wind turbine of claim 1 wherein the hub comprises a cone that directs wind to the blades.

4. The wind turbine of claim 3 further comprising an enclosure surrounding the tips of the blades and attached thereto, which enclosure is arranged to rotate with said hub.

5. The wind turbine recited in claim 4 , wherein the enclosure has a circumferential sidewall about a central axis, said circumferential sidewall defining a front opening being adapted to face true wind, and a rear opening; said sidewall sloping from said front opening to said rear opening such that the rear opening has a larger diameter than the front opening.

6. The wind turbine recited in claim 5 , wherein said sidewall slopes from said front opening to said rear opening at an angle to a plane of said front opening between 100 degrees to 135 degrees.

7. The wind turbine recited in claim 1 , wherein the control of turbine speed is regulated by a controller that measures generator power output and modifies field current of the generator to load rotor to regulate rotation speed of the turbine to obtain at least 50% of maximum available power under normal wind conditions.

8. The wind turbine recited in claim 4 having a number of blades sufficient to entirely redirect direct wind impinging upon the turbine.

9. The wind turbine recited in claim 8 , wherein the leading edge of each of the blades overlaps the trailing edge of an adjacent blade by an amount between 5% and 60% of its surface area.

10. The wind turbine recited in claim 4 , wherein each of said blades is twisted such that the tip end of said blade is twisted at an angle to the central axis of an amount between 58 degrees to 64 degrees.

11. The wind turbine recited in claim 10 , wherein each of said blades is twisted such that the hub end of said blade is twisted at an angle to the central axis of an amount between 28 degrees to 49 degrees.

12. The wind turbine recited in claim 4 , wherein the nose cone is provided at the front of the turbine face covering the hub, and is streamlined to transfer an air mass, approaching the turbine, to be directed around said hub and into said blades so that kinetic energy in said air mass is captured.

13. The wind turbine recited in claim 1 wherein, the turbine is connected to a multi-pole generator having a rotor and having poles connected in series and of sufficient size to provide a higher output voltage relative to the output of a dipole generator.

14. The wind turbine recited in claim 13 , wherein the control of turbine speed is regulated by a controller that measures generator power output and modifies field current of the generator to load rotor to regulate rotation speed of the turbine to obtain at least 40% of maximum available wind power under normal wind conditions.

15. The wind turbine recited in claim 14 , wherein the control of turbine speed is regulated by a controller that measures generator power output and modifies field current of the generator to load rotor to regulate rotation speed of the turbine to obtain at least 80% of maximum generated power output under normal wind conditions.

16. The wind turbine recited in claim 15 , wherein an inverter is connected to the generator output with apparatus to provide the maximum electrical output of the generator under all normal wind conditions for delivery to the user.

17. The wind turbine recited in claim 4 , wherein said set of fixed pitch blades are shaped with a curvature on a front blade surface and a different curvature on a reverse blade surface to affect the apparent wind as seen by the moving blades of said turbine.

18. The wind turbine recited in claim 9 , wherein the leading edge of each of the blades overlaps the trailing edge of an adjacent blade by an amount between 14% and 20% of its surface area.

19. A wind turbine comprising:

a curve on the wind contact surface along each of said blades over the blade surface from the leading edge of the blade to the trailing edge of the blade by an amount between about 6 and about 24 degrees;

said defined pitch angle from any point along said leading edge being defined by the arc-sine of a ratio of blade velocity to apparent wind velocity, with a variance of Â±30 percent of the complementary angle to said arc-sine; and

apparatus for controlling the velocity of the blade to control power output so that it is within forty percent of maximum obtainable power;

provided that, said pitch angle is at least 20 degrees and not greater than 85 degrees, and provided that the pitch angle closest to the hub is at least fifteen degrees less than the pitch angle most distant from the hub.

20. The wind turbine of claim 1 where normal wind conditions are between 8 and 30 MPH.

US14/633,937

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Wind turbine

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2010-08-30

US13/221,656

US9004864B2

( en )

2009-06-22

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( en )

2015-04-14

US20120034082A1

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WO2013033326A1

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US20150184635A1

( en )

2015-07-02

AU2012301930A1

( en )

2014-03-20

AU2012301930A2

( en )

2014-03-20

Wind turbine — Kean W. Stimm (US9194371B2)

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