The present invention relates generally to electricity producing wind turbines, and in particular to wind turbines having airfoils.
Many conventional wind turbine designs already exist for producing electricity. Most commonly, such designs involve a single large propeller mounted at the top end of a vertical mast. Air flow across the propeller causes the propeller to turn, which in turn rotates a generator to produce electricity.
Such conventional wind turbines suffer numerous disadvantages. First, they involve large propellers that must are mounted a considerable distance above the ground. Thus, they require a tall and sturdy mast to which the propeller is mounted. A second disadvantage of large rotating propeller blade systems is that they tend to kill a large number of birds. A third disadvantage of such designs is that the generator is typically positioned at the center of the rotating blades. Thus, the generator is mounted at the top of the mast along with the propeller. This requires the mast to be sufficiently strong to support both the propeller and the generator. As a result, it is difficult to access the turbine for repairs and servicing. A fourth disadvantage of conventional propellers is that the blades rotate in a direction perpendicular to the wind direction. As a result, propeller blade velocity through the air increases with the distance from the center of rotation of the propeller. This unfortunately requires a variable and complex blade section geometry.
The present invention provides a wind turbine, comprising: a rotatable frame; a plurality of airfoils mounted to the rotatable frame, wherein the airfoils extend in a direction parallel to an axis of rotation of the rotatable frame; and an enclosure surrounding the rotatable frame, wherein the enclosure comprises a plurality of moveable members configured to direct air flow onto a first portion of the rotatable frame and to block air flow onto a second portion of the rotatable frame.
In accordance with the invention, air flow is only directed onto the first portion of the rotatable frame, thereby causing the rotatable frame to rotate. Preferably, the moveable members comprise pivotable louvers that are opened by being oriented in a direction parallel to the direction of the air flow. In various embodiments, the enclosure formed by the moveable members may be rectangular or square or round in shape.
Air flow perpendicular to the axis of rotation of the rotatable frame causes the rotatable frame to rotate. Preferably, the rotatable frame rotates about a vertical axis. Rotation of the rotatable frame can be used to generate electricity either by way of a generator drive wheel in contact with the rotatable frame, or by the rotatable frame itself serving as the rotor of an electric generator.
The present invention also provides a method of operating a wind turbine, comprising: positioning a plurality of moveable members to direct air flow over a first portion of a wind turbine and to block air flow over a second portion of the wind turbine, thereby causing the wind turbine to rotate, wherein the wind turbine comprises: a rotatable frame; and a plurality of airfoils mounted to the rotatable frame, wherein the airfoils extend in a direction parallel to an axis of rotation of the rotatable frame. In one aspect of the method, a plurality of pivotable louvers surrounding the wind turbine are opened in a direction parallel to the direction of air flow across the first portion of the wind turbine.
In accordance with preferred methods, the moveable members are preferably positioned such that the first and second portions of the rotatable frame are approximately equal in size (comprising opposite halves of the rotatable frame, divided by a line passing through an axis of rotation of the rotatable frame).
A first advantage of the present wind turbine is that it is ideally suited to be positioned on top of a building (especially a high-rise building, since winds are often stronger and steadier at heights farther above the ground). As will be seen, the center portion of the present wind turbine is empty. Therefore, the present wind turbine can be placed on top of a building leaving room on the center of the roof of the building for structures such as elevators, and HVAC and communication equipment. As will also be shown, the present wind turbine can be used for electricity generation while catching winds approaching the building from different directions. Moreover, when used in high-rise buildings, the present wind turbine can optionally be positioned between different floors of the building.
A second advantage of the present invention is that, by using airfoils, it uses both lift over the airfoil and drag across the airfoil to cause the rotatable frame to rotate.
A third advantage of using airfoils is that the same airfoil cross section can be used across the entire width of the airfoil. Therefore, power output of the wind turbine can be increased simply by increasing the height of the airfoils. In contrast, with conventional propeller systems, it is necessary to increase the diameter of the propellers to increase overall system power output.
A fourth advantage of the present invention is that is has a low center of gravity. Therefore, it is very stable. Moreover, the present system does not require a strong, heavy mast to support a propeller and turbine some distance above the ground. This considerably reduces the weight and size limitations of the present system, resulting in cost savings as compared to traditional designs. Furthermore, having the generator drive wheel (and the turbine itself) positioned close to the ground or floor or on the roof of a building permits easy access for turbine/drive system repairs and servicing.
A fifth advantage of the present airfoil design is that each of the airfoils experience the same wind velocity along the entire length of their leading edge. Equal wind velocity at all points along the leading edge of the airfoil allows a single simplified airfoil cross section along the entire airfoil length. Thus, the wind turbine vertical height and not its horizontal diameter determines power generation. Moreover, having the airfoils disposed at the perimeter of the device results in the longest possible torque lever arm. This results in the most torque per unit of airfoil force generation.
The present invention provides a wind turbine that is ideally suited to operate in a horizontal position on top of a building.
Wind turbine 10 further includes an enclosure 20 surrounding rotatable frame 12. Enclosure 20 is formed from moveable members. As illustrated in
As will be shown in
Referring first to
Opening louvers in area 22A directs wind onto area 12A of rotatable frame 12. Opening louvers in area 22C permits the air flow (entering through area 22A) to exit the back of wind turbine 12. Closing louvers in area 22B blocks air flow onto area 12B of wind turbine 12. The louvers in area 22D can either be closed or open during normal operation, as is desired.
Referring next to
Referring next to
Referring next to
As can be seen throughout
Lastly,
In accordance with the present invention, the rotation of rotatable frame 12 can be used to generate electricity by a generator 30 in contact with one of wheels 18. An advantage of using the rotation of wheel 18 to generate electricity is that it offers gearing advantages due to the comparatively large sized rotatable frame 12 in contact with the comparatively small sized wheel 18. As a result, even a small speed of rotation of the frame 12 translates into a fast rotation of the wheel 18. In alternate embodiments, however, rotatable frame 12 may itself be a rotor of an electric generator.
In optional aspects of the invention, wind turbine 10 may further comprise an air flow direction sensor 40 such as a weather vane (
By continually adjusting the position of individual louvers 22 as the wind direction changes over time, wind turbine 10 can continue to generate a power output regardless of the wind direction.
Number | Name | Date | Kind |
---|---|---|---|
94641 | Piper | Sep 1869 | A |
103742 | Heald | May 1870 | A |
222256 | Dewees | Dec 1879 | A |
232558 | Smith | Sep 1880 | A |
273642 | Toombs | Mar 1883 | A |
293509 | Petersen | Feb 1884 | A |
485933 | Herman | Nov 1892 | A |
543462 | Bramwell | Jul 1895 | A |
1586914 | Palm | Jun 1926 | A |
2231749 | Damerell | Feb 1941 | A |
3697193 | Phillips | Oct 1972 | A |
4293274 | Gilman | Oct 1981 | A |
4551631 | Trigilio | Nov 1985 | A |
4598210 | Biscomb | Jul 1986 | A |
4659940 | Shepard | Apr 1987 | A |
4692098 | Razinsky et al. | Sep 1987 | A |
4818888 | Lenoir, III | Apr 1989 | A |
4832569 | Samuelsen et al. | May 1989 | A |
5083899 | Koch | Jan 1992 | A |
5463257 | Yea | Oct 1995 | A |
5591004 | Aylor | Jan 1997 | A |
5765990 | Jones | Jun 1998 | A |
6015258 | Taylor | Jan 2000 | A |
6064123 | Gislason | May 2000 | A |
6629815 | Lusk | Oct 2003 | B2 |
6634855 | Rollo | Oct 2003 | B1 |
20020015639 | Roberts | Feb 2002 | A1 |
20020079705 | Fowler | Jun 2002 | A1 |
20020187038 | Streetman | Dec 2002 | A1 |
20030025335 | Elder | Feb 2003 | A1 |
20030035725 | Sosonkina | Feb 2003 | A1 |
20030042743 | Gingras et al. | Mar 2003 | A1 |
20030049128 | Rogan | Mar 2003 | A1 |
20030056506 | Cutcher | Mar 2003 | A1 |
20030111844 | McDavid | Jun 2003 | A1 |
20030175109 | Brock et al. | Sep 2003 | A1 |
20030223858 | O'Connor et al. | Dec 2003 | A1 |
20030235498 | Boatner | Dec 2003 | A1 |
20040001752 | Noble | Jan 2004 | A1 |
20040036297 | John | Feb 2004 | A1 |
20040041407 | Petterson et al. | Mar 2004 | A1 |
20040042894 | Smith | Mar 2004 | A1 |
20040071541 | Rainbow | Apr 2004 | A1 |
20040141843 | Blank et al. | Jul 2004 | A1 |
20040141845 | Ohlmann | Jul 2004 | A1 |
20050079060 | MacManus | Apr 2005 | A1 |
20060216152 | Golinkin et al. | Sep 2006 | A1 |
20060275105 | Roberts et al. | Dec 2006 | A1 |
Number | Date | Country | |
---|---|---|---|
20070222224 A1 | Sep 2007 | US |