WO1992001865A1 - Wind turbine blade and rotor incorporating same - Google Patents
Wind turbine blade and rotor incorporating same Download PDFInfo
- Publication number
- WO1992001865A1 WO1992001865A1 PCT/GB1991/001265 GB9101265W WO9201865A1 WO 1992001865 A1 WO1992001865 A1 WO 1992001865A1 GB 9101265 W GB9101265 W GB 9101265W WO 9201865 A1 WO9201865 A1 WO 9201865A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- wind turbine
- blade
- span
- turbine blade
- aerofoil
- Prior art date
Links
- 238000005457 optimization Methods 0.000 description 7
- 230000008901 benefit Effects 0.000 description 3
- 230000003416 augmentation Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000003190 augmentative effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- RLQJEEJISHYWON-UHFFFAOYSA-N flonicamid Chemical compound FC(F)(F)C1=CC=NC=C1C(=O)NCC#N RLQJEEJISHYWON-UHFFFAOYSA-N 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor
- F03D1/06—Rotors
- F03D1/0608—Rotors characterised by their aerodynamic shape
- F03D1/0633—Rotors characterised by their aerodynamic shape of the blades
- F03D1/0641—Rotors characterised by their aerodynamic shape of the blades of the section profile of the blades, i.e. aerofoil profile
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2240/00—Components
- F05B2240/20—Rotors
- F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
- F05B2240/301—Cross-section characteristics
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Definitions
- the wind turbine rotor in accordance with the present invention uses a plurality of aerofoil section blades having this characteristic and set at an appropriate incidence with respect to the rotor hub so that wind passing through the rotor disc will generate a rotation force on the blades which exceeds any drag component and therefore maintains the rotor in rotating motion with adequate power extraction from the kinetic energy of the wind.
- Figure 3 shows a third form of blade section in accordance with the present invention in which the high camber trailing part of the aerofoil section is again relatively smoothly integrated with the front part of the chord but now there is a slot 5 between the main part 6 of the aerofoil and the trailing part 7. The existence of this slot 5 further increases the C- ⁇ max value and results in an increased C-T/C Q ratio.
Abstract
A wind turbine blade has an aerofoil section resembling that of an aircraft wing with a high lift device (for example a slotted flap (7) defining a slot (5)). The wind turbine rotor is provided with a plurality of such blades set at an appropriate angle of incidence so that the blades are operating close to the stalling angle. The blade cross-section has a CL?/CD? of at least 75, and a CL?max of at least 1.8 at a stalling angle of no more than 12.
Description
WIND TURBINE BLADE AND ROTOR INCORPORATING SAME
The present invention relates to a rotor blade for a wind turbine, and to a wind turbine rotor incorporating such blades. It is known that the performance coefficient Cp of a wind turbine rotor is greater when the aerofoil used is one which has a high lift to drag ratio (C*/CD) . Traditionally the aerofoils used for such high C-T/CQ wind turbine blades are carefully designed so as to offer high lift to drag ratios in the "clean" configuration (without the operation of any high lift devices or deflection of any camber flaps) .
It is also known to provide high lift devices to augment the lift of an aircraft wing aerofoil in the landing and take-off configurations (particularly with regard to landing) , in order to allow the speed to be reduced without loss of lift. This implies both high angles of attack and high CL by virtue of deployment of the lift augmentation means. However, normal cruising flight will reguire the aerofoil to be in its clean configuration. Traditionally the designers of both lift surfaces and stabilizer surfaces on aircraft and of wind turbine blades have striven for optimum performance of the aerofoil in its clean configuration. In the case of the aircraft designer, he has the knowledge that he can rely on lift augmentation devices for landing and take-off; the wind turbine designer has no need for such measures as the rotor is designed to operate only in its cruising mode (clean configuration) .
According to the present invention we now provide a wind turbine blade having a tip and a root end, in which over at least half of the span the aerofoil section of the blade is one having a C-*-/CD ratio of at least 75 and a C^max of at least 1.8 at a stalling angle of attack which is less than or equal to 12°. The invention also relates to a wind turbine rotor incorporating a plurality of such blades mounted for
rotation about an axis, and set with an angle of incidence appropriate to allow the blade to operate close to its stalling angle of attack when rotated by wind passing through the rotor disc. In order that the present invention may more readily be understood the following description is given, merely by way of example, reference being made to the accompanying drawings, in which:-
FIGURE 1 is a section of an aerofoil of a wind turbine blade in accordance with the present invention, the aerofoil being designed to have a section similar to that of a conventional integral aerofoil with a camber flap deflected to an incidence of +20°;
FIGURE 2 is a section of an alternative aerofoil in which the trailing part of the aerofoil section has been designed with a more curved form, but again with a very high camber portion reminiscent of the deflected camber flap shown in Figure 1; and
FIGURE 3 is a view similar to Figure 2 but showing a slot through the aerofoil section making the high camber trailing part of the aerofoil section operate in the manner of a slotted trailing edge flap.
As indicated above, the present invention provides an aerofoil section wind turbine blade adding a high lift configuration reminiscent of an aircraft wing in its landing or take-off configuration, but fixed with such high lift configuration for all operating regimes. Figure 1 shows the blade 1 as having the usual rounded nose 2 and a deflected trailing edge portion 3 reminiscent of a plain aircraft wing flap or an aileron, at positive incidence (deflected downwardly) . The wind turbine rotor in accordance with the present invention uses a plurality of aerofoil section blades having this characteristic and set at an appropriate incidence with respect to the rotor hub so that wind passing through the rotor disc will generate a rotation force on the blades which exceeds any drag component and therefore
maintains the rotor in rotating motion with adequate power extraction from the kinetic energy of the wind.
Whereas the aircraft designer traditionally aims for high lift without being too concerned about the drag in the landing configuration (although he may to some extent aim for avoiding high drag in the take-off configuration and will certainly aim for optimum C;Q/CD in the cruising configuration for considerations of power consumption) , we now propose to use the aerofoil section in its high lift configuration throughout the operating regimes of the rotor, and to aim for a high Cj*/CD ratio in this high lift configuration. By "high lift to drag ratio" or "high CL/CD" we mean ratios of at least 75.
We aim for a maximum C- , of at least 1.8, when the aerofoil is at its stalling angle of attack, and we aim that this stalling angle should be no greater than 12°.
Traditionally the aircraft designer will aim for a high stalling angle in order to allow the aircraft to he operated with maximum safety on take-off and landing and when manoeuvring at low speeds on the approach path, whereas we aim to keep the stalling angle low so that in normal operation the wind turbine blade is close to its stalling angle and this enables the wind turbine to be operated safely in that in the event of wind gusts there will be no overspeed of the rotor because its blades will already be working near the stalling angle and they will simply stall due to the changing angle of attack resulting from the high wind speed.
This feature of operating near the stall is quite different from the considerations of aircraft design where avoidance of the stall in cruising flight makes it necessary to operate well below the stalling angle, and where a high lift configuration in cruising flight will mean that there are no means of still further augmenting lift for landing. Figure 2 shows an aerofoil which has a camber similar to that of Figure 1 but is more smoothly curved so
that the "permanently deployed high lift device" comprising the high camber trailing section is more smoothly integrated with the front part of the chord of the aerofoil. Clearly, such an aerofoil would be of no use to the aircraft designer because of the inability of an aerofoil with such a permanently high camber section to cruise effectively. However, for a wind turbine rotor blade with such a cross- section operates effectively close to the stalling angle and with its high C*/CD ratio and high CLmax value at stall. Figure 3 shows a third form of blade section in accordance with the present invention in which the high camber trailing part of the aerofoil section is again relatively smoothly integrated with the front part of the chord but now there is a slot 5 between the main part 6 of the aerofoil and the trailing part 7. The existence of this slot 5 further increases the C-^max value and results in an increased C-T/CQ ratio.
Still further forms of permanently deployed high lift devices may be found to give the desired C- CΓJ ratios of at least 75 and a C-^max value of at least 1.8. For example, a leading edge slat may be found to give the desired results, or possibly a permanently deployed leading edge flap may be used.
Effectively, the wind turbine blade in accordance with the present invention has a cross-section along the majority of the blade span which resembles that of an aircraft wing on landing and/or take-off, but that section is never "cleaned" during operation of the wind turbine. The normal approach to optimization of blade performance in propellers and wind turbines uses optimization of the product of the chord c and the lift coefficient CL at all points along the blade span. Clearly, when a higher value of ^ is possible, c can be reduced for the same product c.CL, and this results in a reduction of the installed blade area, both giving optimum aerodynamic performance and also avoiding high static loads arising on
the blade and tower structure of a wind turbine in the event of high winds while the blades are stationary. This benefit alone makes the present invention very attractive.
A further advantage of operating with high C]*/CD ratios is that the operating speed of the rotor can increase, giving a lower torque value on the hub and the transmission train.
Still a further advantage of the high lift to drag ratio used in the present invention is that the performance coefficient Cp can be increased, where desirable, in order further to enhance the overall efficiency of the wind turbine.
It is well known that for a wind turbine there is a theoretical maximum value of Cp of 0.58, the so-called "Glauert ideal" value, and that in practice wind turbines fail to match that value but can approach the Cp max condition with careful blade optimization. We believe that the blade optimization possibility open to the designer of a wind turbine rotor in accordance with the present invention provide for much closer approach to the ideal than was previously possible.
Blade optimization may result in varying the cross- section of the wind turbine blade along its span while still maintaining the optimum value of c.Cp, and it may be that the criteria of
greater than or equal to 1.8 may not be achieved at the inboard parts of the blade, but in accordance with the present invention the majority of the blade should comply with these criteria. in summary, the criteria of (i) high CL/CD, (ii) a
CLmax in excess of 1.8 and (iii) a reduced stalling angle result in greater energy capture by the wind turbine rotor, safer stall regulation of operation (by virtue of the lower stall angle) , and reductions in the required blade area which both reduce the static loading and facilitate blade construction in that a more simplified construction from
less expensive materials can be possible and can then reduce the manufacturing costs of the wind "turbine.
A preliminary investigation of the present invention has shown that the performance coefficient Cp can be increased from 0.45 to 0.48 simply by adopting the high lift to drag ratio and high C-^max proposed in accordance with the present invention, without indulging in any optimization of the rotor blade design. Such blade optimization (involving variation in the section and/or angle of incidence along the blade span) may result in still further increase of Cp closer to the Glauert ideal.
Since the root end of the blade span is not normally aerodynamically as effective as the tip end, we believe that the aerofoil section of this invention should be incorporated at least over the part of the span nearer the tip, preferably over at least the outboard 50% of the span, and more preferably the outboard 85%.
Claims
1. A wind turbine blade having a tip and a root end, in which over at least half of the span the aerofoil section of the blade is one having a C-/CΓJ ratio of at least 75 and a CLmax of at least 1.8 at a stalling angle of attack which is less than or equal to 12° .
2. A wind turbine blade according to claim 1 wherein over said at least half of the span the CL/CD ratio is at least 100.
3. A wind turbine blade according to claim 2, wherein over at least a part of the span the Cι/CD ratio is substantially 200.
4. A wind turbine blade according to claim 1, wherein said at least half of the blade span extends inwardly from the tip end of the blade.
5. A wind turbine blade according to claim 4, wherein said at least half of the span extends over 85% of the span.
6. A wind turbine blade according to any one of the preceding claims, wherein said aerofoil section over at least the majority of the span resembles an aircraft wing with a high lift device permanently deployed.
7. A wind turbine blade according to claim 6, wherein the blade resembles a wing having a trailing edge flap deflected.
8. A blade according to claim 7, wherein the section resembles that of a wing with a slotted flap deflected.
9. A wind turbine according to claim 2 or 3, wherein said at least half of the blade span extends inwardly from the tip end of the blade.
10. A wind turbine rotor comprising a plurality of blades each constructed in accordance with any one of tne preceding claims, and mounted on a hub with the appropriate angle of incidence appropriate to allow the blade to operate close to its stalling angle of attack when rotated by wind passing through the rotor disc.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9016435A GB2246398A (en) | 1990-07-26 | 1990-07-26 | Wind turbine blade and rotor incorporating same |
GB9016435.1 | 1990-07-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1992001865A1 true WO1992001865A1 (en) | 1992-02-06 |
Family
ID=10679705
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1991/001265 WO1992001865A1 (en) | 1990-07-26 | 1991-07-26 | Wind turbine blade and rotor incorporating same |
Country Status (2)
Country | Link |
---|---|
GB (1) | GB2246398A (en) |
WO (1) | WO1992001865A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0690236A1 (en) * | 1994-06-27 | 1996-01-03 | COFIMCO S.p.A. | Untwisted blade for axial-flow fan |
CN102072080A (en) * | 2011-01-18 | 2011-05-25 | 华北电力大学 | High-performance blade of wind turbine |
EP1856408B1 (en) | 2005-02-22 | 2017-04-05 | Vestas Wind Systems A/S | Wind turbine blade |
EP2007981B1 (en) | 2006-04-02 | 2021-01-20 | Wobben Properties GmbH | Wind turbine with slender blade |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0001399D0 (en) * | 2000-01-22 | 2000-03-08 | Rolls Royce Plc | An aerofoil for an axial flow turbomachine |
EP2078852B2 (en) | 2008-01-11 | 2022-06-22 | Siemens Gamesa Renewable Energy A/S | Wind turbine rotor blade |
US8240993B2 (en) * | 2011-01-04 | 2012-08-14 | General Electric Company | System and method of manipulating a boundary layer across a rotor blade of a wind turbine |
CN103174604A (en) * | 2011-12-26 | 2013-06-26 | 珠海市洁源电器有限公司 | Small-size wind turbine blade airfoil family |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1547644A (en) * | 1921-10-31 | 1925-07-28 | Fed Engineering Company | Aerofoil |
US2441151A (en) * | 1945-04-12 | 1948-05-11 | Robert T Jones | Control surfaces with beveled trailing edge |
GB612413A (en) * | 1943-11-01 | 1948-11-12 | Wincharger Corp | Improvements in wind driven prime movers |
DE2322654A1 (en) * | 1972-05-04 | 1973-11-08 | Mc Donnell Douglas Corp | HIGH PERFORMANCE WINGS AND METHODS OF CONSTRUCTING THE SAME |
DE3045695A1 (en) * | 1980-12-04 | 1982-08-19 | Hans 5300 Bonn Müller | Wing design for wind-driven mechanism - has inclined auxiliary wing behind main wing, forming gap for increase of force |
DE3207539A1 (en) * | 1982-03-03 | 1983-09-08 | Leo 6800 Mannheim Maniura | Propeller with two double blades - for a wind power plant |
US4408958A (en) * | 1980-12-23 | 1983-10-11 | The Bendix Corporation | Wind turbine blade |
GB2186638A (en) * | 1986-02-05 | 1987-08-19 | Howden James & Co Ltd | Wind turbines |
AU598498B2 (en) * | 1986-12-12 | 1990-06-28 | Robert B. Wheat | High drag airfoil apparatus |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB299387A (en) * | 1927-10-25 | 1929-01-31 | Camille Edmond Outurquin | Improvements in air propellers |
GB944166A (en) * | 1960-03-02 | 1963-12-11 | Werner Hausammann | Rotor for turbines or compressors |
IT1141170B (en) * | 1980-02-06 | 1986-10-01 | Cofimco Sas | AXIAL FAN WITH BENDS NOT CROSSED AND WITH INCREASED TRACTION |
EP0082162B1 (en) * | 1981-06-19 | 1984-11-28 | KOLECKI, Jerzy | A propeller blade |
NL8203019A (en) * | 1982-07-28 | 1984-02-16 | Transinvest Bv | DEVICE FOR CONVERTING WIND ENERGY IN ANOTHER FORM OF ENERGY. |
-
1990
- 1990-07-26 GB GB9016435A patent/GB2246398A/en not_active Withdrawn
-
1991
- 1991-07-26 WO PCT/GB1991/001265 patent/WO1992001865A1/en unknown
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1547644A (en) * | 1921-10-31 | 1925-07-28 | Fed Engineering Company | Aerofoil |
GB612413A (en) * | 1943-11-01 | 1948-11-12 | Wincharger Corp | Improvements in wind driven prime movers |
US2441151A (en) * | 1945-04-12 | 1948-05-11 | Robert T Jones | Control surfaces with beveled trailing edge |
DE2322654A1 (en) * | 1972-05-04 | 1973-11-08 | Mc Donnell Douglas Corp | HIGH PERFORMANCE WINGS AND METHODS OF CONSTRUCTING THE SAME |
DE3045695A1 (en) * | 1980-12-04 | 1982-08-19 | Hans 5300 Bonn Müller | Wing design for wind-driven mechanism - has inclined auxiliary wing behind main wing, forming gap for increase of force |
US4408958A (en) * | 1980-12-23 | 1983-10-11 | The Bendix Corporation | Wind turbine blade |
DE3207539A1 (en) * | 1982-03-03 | 1983-09-08 | Leo 6800 Mannheim Maniura | Propeller with two double blades - for a wind power plant |
GB2186638A (en) * | 1986-02-05 | 1987-08-19 | Howden James & Co Ltd | Wind turbines |
AU598498B2 (en) * | 1986-12-12 | 1990-06-28 | Robert B. Wheat | High drag airfoil apparatus |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0690236A1 (en) * | 1994-06-27 | 1996-01-03 | COFIMCO S.p.A. | Untwisted blade for axial-flow fan |
EP1856408B1 (en) | 2005-02-22 | 2017-04-05 | Vestas Wind Systems A/S | Wind turbine blade |
EP2007981B1 (en) | 2006-04-02 | 2021-01-20 | Wobben Properties GmbH | Wind turbine with slender blade |
CN102072080A (en) * | 2011-01-18 | 2011-05-25 | 华北电力大学 | High-performance blade of wind turbine |
Also Published As
Publication number | Publication date |
---|---|
GB2246398A (en) | 1992-01-29 |
GB9016435D0 (en) | 1990-09-12 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4917332A (en) | Wingtip vortex turbine | |
US9555895B2 (en) | Motor pylons for a kite and airborne power generation system using same | |
US6726439B2 (en) | Retractable rotor blades for power generating wind and ocean current turbines and means for operating below set rotor torque limits | |
US4108403A (en) | Vortex reducing wing tip | |
US7789624B2 (en) | Methods and devices for improving efficiency of wind turbines in low speed sites | |
US20100303634A1 (en) | Fluid dynamic section having escapelet openings for reducing induced and interference drag, and energizing stagnant flow | |
US7424988B2 (en) | Use of aerodynamic forces to assist in the control and positioning of aircraft control surfaces and variable geometry systems | |
US20100215494A1 (en) | Wind Turbine Rotor Blade | |
EP2764238B1 (en) | Wind turbine having flow-aligned blades | |
US5772155A (en) | Aircraft wing flaps | |
EP2940293A1 (en) | Aerodynamic device for a rotor blade of a wind turbine | |
JPH06305492A (en) | Rotor blade | |
US9709026B2 (en) | Airfoil for a flying wind turbine | |
GB2186033A (en) | Wind turbine | |
US11225316B2 (en) | Method of improving a blade so as to increase its negative stall angle of attack | |
JPH0375398B2 (en) | ||
EP1984244A2 (en) | An airfoil for a helicoptor rotor blade | |
US5209643A (en) | Tapered propeller blade design | |
WO1992001865A1 (en) | Wind turbine blade and rotor incorporating same | |
CA3060758C (en) | Aircraft with rotating ducted fan | |
US11148794B2 (en) | Method of determining an initial leading edge circle of airfoils of a blade and of improving the blade in order to increase its negative stall angle of attack | |
US5433586A (en) | Tapered propeller blade design | |
EP0103478A1 (en) | Airfoil | |
US11713105B2 (en) | Wing integrated propulsion system | |
US11685519B2 (en) | Wing tips and wing tip construction and design methods |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): US |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IT LU NL SE |