US20070098555A1 - Wind turbine comprising elastically flexible rotor blades - Google Patents

Wind turbine comprising elastically flexible rotor blades Download PDF

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Publication number
US20070098555A1
US20070098555A1 US11/611,319 US61131906A US2007098555A1 US 20070098555 A1 US20070098555 A1 US 20070098555A1 US 61131906 A US61131906 A US 61131906A US 2007098555 A1 US2007098555 A1 US 2007098555A1
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US
United States
Prior art keywords
rotor blade
wind turbine
rotor
blade
wind
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.)
Abandoned
Application number
US11/611,319
Inventor
Sonke Siegfriedsen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Aerodyn Engineering GmbH
Original Assignee
Aerodyn Engineering GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Aerodyn Engineering GmbH filed Critical Aerodyn Engineering GmbH
Assigned to AERODYN ENERGIESYSTEME GMBH reassignment AERODYN ENERGIESYSTEME GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SIEGFRIEDSEN, SONKE
Publication of US20070098555A1 publication Critical patent/US20070098555A1/en
Abandoned legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D1/00Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/06Rotors
    • F03D1/0608Rotors characterised by their aerodynamic shape
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00Components
    • F05B2240/20Rotors
    • F05B2240/202Rotors with adjustable area of intercepted fluid
    • F05B2240/2022Rotors with adjustable area of intercepted fluid by means of teetering or coning blades
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00Components
    • F05B2240/20Rotors
    • F05B2240/21Rotors for wind turbines
    • F05B2240/221Rotors for wind turbines with horizontal axis
    • F05B2240/2213Rotors for wind turbines with horizontal axis and with the rotor downwind from the yaw pivot axis
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00Components
    • F05B2240/20Rotors
    • F05B2240/30Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • F05B2240/31Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor of changeable form or shape
    • F05B2240/311Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor of changeable form or shape flexible or elastic
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2280/00Materials; Properties thereof
    • F05B2280/50Intrinsic material properties or characteristics
    • F05B2280/5001Elasticity
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2280/00Materials; Properties thereof
    • F05B2280/60Properties or characteristics given to material by treatment or manufacturing
    • F05B2280/6003Composites; e.g. fibre-reinforced
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05CINDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2251/00Material properties
    • F05C2251/02Elasticity
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05CINDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2253/00Other material characteristics; Treatment of material
    • F05C2253/04Composite, e.g. fibre-reinforced
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • Y02E10/72Wind turbines with rotation axis in wind direction

Definitions

  • the problem of the invention is to provide a wind turbine of the aforementioned type, where limited loads are applied to the overall wind turbine structure due to wind pressure under extreme wind conditions.
  • this problem is solved by the construction of the at least one rotor blade with a flexural strength of the blade profile in the force application direction, allowing the elastic deflection of the rotor blade by more than half its total length.
  • the flexural strength of the rotor blade permits the deflection by more than twice its length.
  • the considerable deflection is made possible by the use of thin aerodynamic profiles in conjunction with the use of high strength materials, and at the same time a low modulus of elasticity. Thus, even in the case of pronounced deflections, the permitted material stresses and strains are not exceeded.
  • the preferably used relative profile thickness i.e. the ratio of the absolute profile thickness to the absolute profile depth, is between 0.05 and 0.15.
  • the profile thickness and profile depth are constant over the entire blade length.
  • FIG. 1 shows a side view of the wind turbine comprising elastically flexible rotor blades with the rotor in a non-bent position and the wind direction indicated by an arrow.
  • FIG. 2 shows a side view of the embodiment of FIG. 1 with the wind turbine in a decelerated state and the rotor blades in a bent position from extreme winds.
  • FIG. 3 shows an exploded view of the rotor blade in an extruded position directed by the wind force indicated by the letter S.
  • FIG. 4 shows a diagrammatic representation of the deflection rate of the rotor blade at different wind speeds.

Abstract

The invention relates to a wind turbine having a tower, a nacelle that is mounted on the tower and can be rotated about the axis of the tower, and a rotor which is carried by the nacelle on the lee side and having at least one rotor blade. The flexural strength of the at least one rotor blade permitting the elastic flexure of said blade by more than half of its extension and allowing deflection by more than two thirds of its total length.

Description

    PRIOR APPLICATIONS
  • This application is a continuation-in-part of International Application No. PCT/DE2005/001547, filed on Sep. 5, 2005, which in turn bases priority on German Application No. 10 2004 045 401.9, filed on Sep. 18, 2004.
  • BACKGROUND OF THE INVENTION
  • 1. Field of Invention
  • The invention relates to a wind turbine having a tower, a nacelle mounted on the tower and rotatable about its axis, and a rotor having at least one rotor blade mounted in a rotary manner in the nacelle, and rotating on the lee side relative to the tower.
  • 2. Description of the Prior Art
  • Over the last few decades, wind power technology has developed very dynamically, relating only from average size to very large turbines for main parallel operation. However, there have been no advances in the last twenty years in the development of small power systems in the kilowatt range. Therefore, the turbines are still very expensive and have, consequently, not entered the market. Wind power use could play an important part in supplying two billion people without access to electricity. For such cases, there is a great need for turbines with a power level of 1 to 10 kW, but these must be extremely robust, inexpensive, easy to erect and largely maintenance-free.
  • However, existing small turbines are unable to fulfill these requirements because they are too expensive and/or too fault-prone. A particular problem arises in that the turbines must be designed in such a way as to withstand extremely high wind forces (typhoons, hurricanes, etc.). The designed wind speeds are up to 70 meters per second. With such wind speeds, the turbine is decelerated and is at a standstill.
  • In order to achieve this, solutions are known in which the rotor blades are rotated about their longitudinal axis so as to reduce shear. In other turbine types the entire nacelle is rotated out of the wind with the aid of a wind vane or by a pivoting device in which the complete rotor is brought into helicopter mode. It is a common feature of all these solutions that they are expensive, and also fault-prone, so that they are unsuitable for more widespread use. The same applies with regards to turbines which have to absorb high, extreme loads using very rigid blades, and transfer the same to the overall turbine and into the foundation.
  • DE 298 80 145 U1 discloses a wind turbine with an elastically flexible rotor blade.
  • The problem of the invention is to provide a wind turbine of the aforementioned type, where limited loads are applied to the overall wind turbine structure due to wind pressure under extreme wind conditions.
  • SUMMARY OF THE INVENTION
  • According to the invention, this problem is solved by the construction of the at least one rotor blade with a flexural strength of the blade profile in the force application direction, allowing the elastic deflection of the rotor blade by more than half its total length. In a preferred embodiment, the flexural strength of the rotor blade permits the deflection by more than twice its length.
  • It is particularly advantageous to have a fixed attachment of the rotor blade to the hub without any adjustability by means of bearings or joints, so that fault-proneness is minimized.
  • As a result of this pronounced deflection there is, firstly, a considerable decrease in the projected wind application surface, and secondly, the resistance coefficient is significantly reduced as a result of the pronounced outward curvature of the blades associated with the flexure or deflection. As a result of these two effects, under extreme wind conditions the wind shear on the entire turbine can be reduced by half compared with those turbines using rigid blades. This economized materials for the load-transferring components, such as the rotor shaft, machine casing, vertical bearing, tower, anchoring and foundation, so that the total turbine production costs are significantly decreased.
  • The considerable deflection is made possible by the use of thin aerodynamic profiles in conjunction with the use of high strength materials, and at the same time a low modulus of elasticity. Thus, even in the case of pronounced deflections, the permitted material stresses and strains are not exceeded. The preferably used relative profile thickness, i.e. the ratio of the absolute profile thickness to the absolute profile depth, is between 0.05 and 0.15.
  • In a preferred embodiment, the profile thickness and profile depth are constant over the entire blade length. This development makes it possible for the at least one rotor blade to be an extruded fiber composite profile. If the fiber composite material is a glass fiber plastic composite, the requirement for high strength and, at the same time, relatively low modulus of elasticity is fulfilled.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • Further features and advantages of the present invention can be gathered from the following descriptions of the preferred embodiment with reference to the attached drawings, wherein:
  • FIG. 1 shows a side view of the wind turbine comprising elastically flexible rotor blades with the rotor in a non-bent position and the wind direction indicated by an arrow.
  • FIG. 2 shows a side view of the embodiment of FIG. 1 with the wind turbine in a decelerated state and the rotor blades in a bent position from extreme winds.
  • FIG. 3 shows an exploded view of the rotor blade in an extruded position directed by the wind force indicated by the letter S.
  • FIG. 4 shows a diagrammatic representation of the deflection rate of the rotor blade at different wind speeds.
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • FIG. 1 illustrates the wind power turbine with tower 10 and tower anchor 12. The nacelle 14 is mounted so as to rotate about the axis of tower 10. In nacelle 14 is mounted the rotor 16, which rotates on the lee side, i.e. on the side of tower 10 that is remote from the wind. When the rotor 16 is stationary because of limited wind conditions, and with the turbine operating, the blades are not or only slightly deflected. The blades are fitted to the hub with a cone angle, i.e. a tilted arrangement in the wind direction, so that when the turbine is operating the centrifugal forces and wind shear forces are such that there are roughly no bending movements on the blade root. For wind speeds above the cut-out speed, the turbine is decelerated and brought to a standstill.
  • As illustrated in FIG. 2, the wind power turbine of FIG. 1 is shown in the decelerated state under extreme wind speeds. As a result of the wind shear, the blades are deflected by more than two thirds of their total length. As a result of this pronounced deflection, the wind load is significantly reduced because the wind application surface is reduced. In addition, the resistance coefficient of the profile is decreased compared with the flow direction due to the marked inclination of the blade.
  • FIG. 3 illustrates a thin aerodynamic profile of the rotor blade with a relative profile thickness of approximately 8%, i.e. the value of the greatest profile thickness 20 relative to the profile depth 22 is 0.08. As a result, the profile cross-section has a limited rigidity in the force application direction, and the wind loading can significantly bend the blade in the force application direction.
  • As illustrated in FIG. 4, the deflection of the flexible rotor blade is determined by the prevailing wind speed. The flexural strength is chosen in such a way that at wind speeds of 70 meters per second, it allows an elastic deflection of the blades of 70% of the total blade length.

Claims (8)

1-7. (canceled)
8. A wind turbine having a tower, a nacelle located on the tower and rotatable about its axis, and a rotor having at least one rotor blade rotating on the lee side and carried by the nacelle by a hub, the wind turbine comprising:
a) the at least one rotor blade firmly connected to the hub and fabricated from a high strength material having a low modulus of elasticity thereby giving the at least one rotor blade a flexural strength for allowing their elastic flexure by more than half a total length of said at least one rotor blade and a constant profile thickness and profile depth over said total blade length.
9. The wind turbine of claim 8, wherein the flexural strength of the at least one rotor blade allows for deflection thereof by more than two-thirds of the total length of said at least one rotor blade.
10. The wind turbine of claim 8, wherein the constant profile thickness of said total blade length of said at least one rotor blade has a relative profile thickness between 5% and 15%.
11. The wind turbine of claim 8, wherein the at least one rotor blade is made from an extruded composite fiber profile.
12. The wind turbine of claim 11, wherein the at least one rotor blade is an extruded profile of fiber glass-reinforced plastic.
13. The wind turbine of claim 8, wherein the at least one rotor blade comprises two rotor blades disposed in outwardly opposed directions from said hub.
14. The wind turbine of claim 8, wherein the at least one rotor blade comprises more than two rotor blades disposed in outwardly directions from said hub.
US11/611,319 2004-09-18 2006-12-15 Wind turbine comprising elastically flexible rotor blades Abandoned US20070098555A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE102004045401.9 2004-09-18
DE102004045401A DE102004045401A1 (en) 2004-09-18 2004-09-18 Wind energy plant with elastically flexible rotor blades
PCT/DE2005/001547 WO2006029593A1 (en) 2004-09-18 2005-09-05 Wind turbine comprising elastically flexible rotor blades
WOPCT/DE05/01547 2005-09-05

Publications (1)

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US20070098555A1 true US20070098555A1 (en) 2007-05-03

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US11/611,319 Abandoned US20070098555A1 (en) 2004-09-18 2006-12-15 Wind turbine comprising elastically flexible rotor blades

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US (1) US20070098555A1 (en)
EP (1) EP1789677A1 (en)
CN (1) CN1997822A (en)
DE (1) DE102004045401A1 (en)
WO (1) WO2006029593A1 (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009073191A1 (en) * 2007-12-05 2009-06-11 Wagner Thomas V Wind turbine rotor assembly
US7582977B1 (en) * 2005-02-25 2009-09-01 Clipper Windpower Technology, Inc. Extendable rotor blades for power generating wind and ocean current turbines within a module mounted atop a main blade
US20100303631A1 (en) * 2009-05-29 2010-12-02 Vestas Wind Systems A/S Wind Turbine Rotor Blade Having Segmented Tip
US20110120108A1 (en) * 2009-11-25 2011-05-26 Pioneer Energy Products, Llc Wind turbine
US20140112782A1 (en) * 2011-06-30 2014-04-24 Educational Foundation Bunri Gakuen Propeller windmill for small-sized power generator
US9509036B2 (en) 2015-03-05 2016-11-29 Pioneer Energy Products, Llc Communications units with high capacity low profile antenna arrangements
US9709029B2 (en) 2011-06-21 2017-07-18 University Of Virginia Patent Foundation Morphing segmented wind turbine and related method

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2484148A (en) * 2010-10-02 2012-04-04 Duncan James Parfitt Windmill with apertured flexible vanes
DE102014204591B3 (en) * 2014-03-12 2015-04-02 Voith Patent Gmbh Bidirectional flowable horizontal rotor turbine with passive overload protection
CN104343643B (en) * 2014-09-24 2017-01-25 王东明 Lift type elastic synergistic windmill blade

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US4050246A (en) * 1975-06-09 1977-09-27 Gaston Bourquardez Wind driven power system
US4366387A (en) * 1979-05-10 1982-12-28 Carter Wind Power Wind-driven generator apparatus and method of making blade supports _therefor
US20040052640A1 (en) * 2002-09-12 2004-03-18 Ghazi Khan All weather windmills

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DE8122496U1 (en) * 1981-07-31 1985-10-31 Lepoix, Louis L., 7570 Baden-Baden Device for converting the kinetic energy of the wind into another type of energy, preferably into electrical energy
DK100497A (en) * 1997-09-04 1997-09-04 Novo Nordisk As Chemical compound
DE19807477C2 (en) * 1997-09-30 2000-01-13 Deutsch Zentr Luft & Raumfahrt rotor
WO2002073031A1 (en) * 2001-03-14 2002-09-19 Benny Klemar A wind turbine wing

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Publication number Priority date Publication date Assignee Title
US4050246A (en) * 1975-06-09 1977-09-27 Gaston Bourquardez Wind driven power system
US4366387A (en) * 1979-05-10 1982-12-28 Carter Wind Power Wind-driven generator apparatus and method of making blade supports _therefor
US20040052640A1 (en) * 2002-09-12 2004-03-18 Ghazi Khan All weather windmills

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7582977B1 (en) * 2005-02-25 2009-09-01 Clipper Windpower Technology, Inc. Extendable rotor blades for power generating wind and ocean current turbines within a module mounted atop a main blade
WO2009073191A1 (en) * 2007-12-05 2009-06-11 Wagner Thomas V Wind turbine rotor assembly
US20090148304A1 (en) * 2007-12-05 2009-06-11 Wagner Thomas V Wind turbine rotor assembly
US8430636B2 (en) 2007-12-05 2013-04-30 Thomas V. Wagner Wind turbine rotor assembly
US20100303631A1 (en) * 2009-05-29 2010-12-02 Vestas Wind Systems A/S Wind Turbine Rotor Blade Having Segmented Tip
US20110120108A1 (en) * 2009-11-25 2011-05-26 Pioneer Energy Products, Llc Wind turbine
US8596978B2 (en) 2009-11-25 2013-12-03 Pioneer Energy Products, Llc Wind turbine
US9709029B2 (en) 2011-06-21 2017-07-18 University Of Virginia Patent Foundation Morphing segmented wind turbine and related method
US11466660B2 (en) * 2011-06-21 2022-10-11 University Of Virginia Patent Foundation Morphing segmented wind turbine and related method
US20140112782A1 (en) * 2011-06-30 2014-04-24 Educational Foundation Bunri Gakuen Propeller windmill for small-sized power generator
US9039367B2 (en) * 2011-06-30 2015-05-26 Educational Foundation Bunri Gakuen Propeller windmill for small-sized power generator
US9509036B2 (en) 2015-03-05 2016-11-29 Pioneer Energy Products, Llc Communications units with high capacity low profile antenna arrangements

Also Published As

Publication number Publication date
WO2006029593A1 (en) 2006-03-23
EP1789677A1 (en) 2007-05-30
DE102004045401A1 (en) 2006-03-30
CN1997822A (en) 2007-07-11

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Owner name: AERODYN ENERGIESYSTEME GMBH, GERMANY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SIEGFRIEDSEN, SONKE;REEL/FRAME:018640/0501

Effective date: 20061115

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO PAY ISSUE FEE