GB2098671A - Dumping rotor blades for high speed wind power rotors - Google Patents
Dumping rotor blades for high speed wind power rotors Download PDFInfo
- Publication number
- GB2098671A GB2098671A GB8214460A GB8214460A GB2098671A GB 2098671 A GB2098671 A GB 2098671A GB 8214460 A GB8214460 A GB 8214460A GB 8214460 A GB8214460 A GB 8214460A GB 2098671 A GB2098671 A GB 2098671A
- Authority
- GB
- United Kingdom
- Prior art keywords
- profile
- centre
- rotor blade
- blade
- leading edge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005484 gravity Effects 0.000 claims abstract description 10
- 230000001133 acceleration Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Wind Motors (AREA)
Abstract
In a rotor blade for high speed rotors of wind power stations the centre of gravity 10 of the profile of the blade the centre of shear forces 9 of a supporting brace 15 and the wind aerodynamic centre 11 of the profile are arranged one after another in the section through the profile of the blade, starting from the leading edge of the profile. The position of the centre of gravity 10 of the blade may be determined by making parts of the blade of different materials. Alternatively weights (13, Figs 3 and 4 not shown) may be provided at, or in front of, the leading edge of the profile. <IMAGE>
Description
SPECIFICATION
A rotor blade for high speed rotors
The present invention relates to a rotor blade construction for high speed rotors of wind power stations, and more particularly to slim rotor blades with thin profiles which are resilient and are reinforced by a supporting brace or tie.
In construction of this type the problem is that the rotor blades are very resilient in the direction of the rotor axis. When they are subject to different loads during operation, for example because of gusts, they wobble. This may lead to disturbing resonance if the vibration frequency of blade strokes is close to the rotor speed or the vibration frequency of the windmill tower. In order to overcome this problem, the frequencies of the critical components are balanced at considerable cost by means of refinements in design, calculations and tests. The aim is to arrive at a large gap between the natural vibration frequencies of the components and to keep these as far as possible from the energising frequency of the rotor.
However, when the rotor speed changes, for example when starting up and slowing down the plant, this sort of arrangement is subject to resonance and critical operating conditions.
In known rotor blades the supporting brace is usually in the thickest part of the profile, in order to make the best possible use of the material and achieve a large drag moment. As a result the aerodynamic centre is usually in front of the centre of shear forces of the supporting brace so that there is even greater wobble when twisting occurs.
It is an object of the present invention to provide a rotor blade which introduces a damping effect simply, and automatically reduces flexure caused by different loads and can ensure fault-free operation at different speeds.
According to the present invention there is provided a rotor blade having a supporting brace wherein, in a section through the profile of the rotor blade, the centre of gravity of the profile, the centre of shear forces of the supporting brace and the aerodynamic centre of the profile are arranged one after another starting from the leading edge of the profile.
The aerodynamic force engaging behind the centre of shear forces produces a torque which reduces the angle of attack of the blade profile as the force increases and therefore reduces the aerodynamic force. If the rotor blade is accelerated in the direction of the aerodynamic force, the centre of gravity which lies in front of the centre of shear forces generates a moment which reduces the angle of attack of the blade profile and therefore causes a reduction in the aerodynamic force.
It is proposed to provide balance weights in the region of the leading edge of the profile or, via rods, in front of the leading edge of the profile to define the centre of gravity of the profile for the purpose of readily shifting the centre of gravity. Alternatively the rotor blade may be formed over its profile depth or chord from different materials, in orderto define the centre of gravity of the profile. Of course both these measures may be used together.
In order to affect the centre of shear forces position the supporting brace may be arranged in the area of the leading edge of the profile for shifting the centre of shear forces.
Preferred embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, of which Fig. 1 shows a plan view of a rotor blade;
Fig. 2a shows a section through the profile along the line ll-ll in Fig. 1 on a larger scale;
Fig. 2b shows a diagram illustrating the angle ratios;
Fig. 3 shows a section through the profile of a rotor blade with balance weights in the tip of the profile; and
Fig. 4 shows a section through the profile of a rotor blade with balance weights on a rod in front of the profile tip.
The rotor blade 1 as shown is mounted at its root on a hub (not shown in detail ) and is pivotally arranged about a horizontal axis3 providing a rotor plane 4 which is blown at in a wind direction 5. The profile of the rotor blade 1 has a leading edge 6 and a trailing edge 7 and takes up a blade angle 8 with respect to the rotor plane 4.
As shown in Fig. 2a a supporting brace 15 is in the form of a double "T" support and has a centre of shear forces 9 which is positioned between a centre of gravity 10 of the profile and a aerodynamic centre 11 to which a resultant aerodynamic force 12 is applied. In order to displace the centre of gravity 10, in suitable weights 13 are provided which are arranged in one instance in the area of the leading edge 6 and in the other via a rod 14 in front of the leading edge 6, see Figures 3 and 4. The supporting brace 15 is also arranged in the area of the leading edge 6 in order to achieve a forward centre of shear forces 9.
The diagram shown in Fig. 2b shows the relative position of the wind force 5, the resulting aerodynamic force 12, the component 16 of the peripheral speed of the rotor blade 1 in the rotor plane4 and the direction 17 in which the rotor blade 1 is blown which arises from the position of the resultant of the wind force 5 and the component 16 of the peripheral speed. The direction 17 defines the angle 18 relative to the rotor plane 4. Furthermore, the direction 17 and the profile line 19 together form the inflow angle or angle of attack 20.
Due to the relative arrangement of points 9, 10 and 11, there is an increase in the blade angle and therefore a reduction in the inflow angle 20 when there is an increase in wind force and therefore the resultant aerodynamic force applied is reduced. If there is a reduction in wind force there is a reduction in the blade angle 8 and therefore an increase in the inflow angle 20 and in the applied resultant aerodynamic force 12.
Similarly, when there is an acceleration of the blade in the direction of the wind force there is a reduction in the inflow angle 20 due to mass forces.
Therefore an acceleration of the blade contrary to the direction of the wind force causes an increase in the inflow angle.
This measure has a damping effect and attenuates any energisation of resonance transverse to the rotor plane by means of aerodynamic forces.
Claims (6)
1. A rotor blade having a supporting brace wherein, in a section through the profile of the rotor blade, the centre of gravity of the profile, the centre of shear forces of the supporting brace and the aerodynamic centre of the profile are arranged one after another starting from the leading edge of the profile.
2. A rotor blade as claimed in claim 1 wherein balance weights are arranged at the leading edge of the profile.
3. A rotor blade as claimed in claim 1 wherein balance weights are arranged on rods in front of the leading edge ofthe profile.
4. A rotor blade as claimed in any preceding claim wherein the rotor blade is formed over its profile chord from different materials.
5. A rotor blade as claimed in any preceding claim wherein the supporting brace is arranged in the region of the leading edge of the profile.
6. A rotor blade substantially as herein described with reference to Figs. 1 and 2, Fig. 3 or Fig. 4 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813119780 DE3119780A1 (en) | 1981-05-19 | 1981-05-19 | ROTOR BLADE TRAINING FOR HIGH SPEED ROTORS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2098671A true GB2098671A (en) | 1982-11-24 |
| GB2098671B GB2098671B (en) | 1984-06-27 |
Family
ID=6132626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8214460A Expired GB2098671B (en) | 1981-05-19 | 1982-05-18 | Dumping rotor blades for high speed wind power rotors |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3119780A1 (en) |
| DK (1) | DK189382A (en) |
| GB (1) | GB2098671B (en) |
| SE (1) | SE8203038L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20230020641A1 (en) * | 2019-12-23 | 2023-01-19 | Vestas Wind Systems A/S | Modular wind turbine blade with vibration damping |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7153090B2 (en) * | 2004-12-17 | 2006-12-26 | General Electric Company | System and method for passive load attenuation in a wind turbine |
-
1981
- 1981-05-19 DE DE19813119780 patent/DE3119780A1/en not_active Withdrawn
-
1982
- 1982-04-28 DK DK189382A patent/DK189382A/en not_active Application Discontinuation
- 1982-05-14 SE SE8203038A patent/SE8203038L/en not_active Application Discontinuation
- 1982-05-18 GB GB8214460A patent/GB2098671B/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20230020641A1 (en) * | 2019-12-23 | 2023-01-19 | Vestas Wind Systems A/S | Modular wind turbine blade with vibration damping |
Also Published As
| Publication number | Publication date |
|---|---|
| SE8203038L (en) | 1982-11-20 |
| DK189382A (en) | 1982-11-20 |
| GB2098671B (en) | 1984-06-27 |
| DE3119780A1 (en) | 1982-12-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |