WO2011105887A1 - Windmill propeller blades with built-in extendable flaps - Google Patents

Windmill propeller blades with built-in extendable flaps Download PDF

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Publication number
WO2011105887A1
WO2011105887A1 PCT/NL2010/000032 NL2010000032W WO2011105887A1 WO 2011105887 A1 WO2011105887 A1 WO 2011105887A1 NL 2010000032 W NL2010000032 W NL 2010000032W WO 2011105887 A1 WO2011105887 A1 WO 2011105887A1
Authority
WO
WIPO (PCT)
Prior art keywords
blade
flaps
blades
profile
wind
Prior art date
Application number
PCT/NL2010/000032
Other languages
French (fr)
Inventor
Hugo Karel Krop
Original Assignee
Hoofdweg Managements Bv
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 Hoofdweg Managements Bv filed Critical Hoofdweg Managements Bv
Priority to PCT/NL2010/000032 priority Critical patent/WO2011105887A1/en
Publication of WO2011105887A1 publication Critical patent/WO2011105887A1/en

Links

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
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/022—Adjusting aerodynamic properties of the blades
    • F03D7/0232—Adjusting aerodynamic properties of the blades with flaps or slats
    • 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
    • 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
    • F05B2240/305—Flaps, slats or spoilers
    • F05B2240/3052—Flaps, slats or spoilers adjustable
    • 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
    • F05B2270/00—Control
    • F05B2270/30—Control parameters, e.g. input parameters
    • F05B2270/32—Wind speeds
    • 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

  • Windmill propeller blades with built-in extendable flaps Windmill propeller blades with built-in extendable flaps.
  • the lift on a cambered aerofoil shaped wing is primarily the result of its shape (in particular its camberline) and its angle of attack. When either or both are positive, the resulting flow field about the aerofoil has a higher average velocity on the upper surface than on the lower surface. This velocity difference is necessarily accompanied by a pressure difference, via Bernoulli's principle, which in turn produces the lift force.
  • Modern wind generators are equipped with blades being rotated by both dynamic and aero dynamic wind power.
  • a dynamic section (usually around the axis, where rotary velocity will not attain aerodynamically relevant values) sets the windmill rotor into motion.
  • This brushing wind flow is the most relevant wind flow, not the wind driving the dynamic part of the rotor with a perpendicular force.
  • the dynamic part will soon be less relevant compared to the aerodynamic forces driving the outer circle of the wing surface as a result of the lower speed of revolutions at the center of the total wing surface (when in motion).
  • Modern wind generator blades are shaped with a well pre-chosen shape, allowing both forces to act when most appropriate.
  • the choice is usually such that a rotor will function at its most efficient in wind forces of 5-8 Bft.
  • the wind force formula is such that increasing wind velocities will augment torque in a windmill drive axis to the third power. In decreasing wind force conditions the opposite is true.
  • This dynamically active surface in existing windmill blades is usually about 1 ⁇ 4 of the length of the blade, positioned at the relatively slow moving axis part.
  • Our invention proposes to employ retractable flaps in the mid section of a windmill blade, at the trailing edge.
  • the surface of the aero dynamically effective part of the blade (usually 3 ⁇ 4 of the blade, from midsection to tip) is thereby partly made into a temporarily dynamically responsive blade, leaving the blade tip parts (the fast moving remaining 1 ⁇ 4 surface at the tip) functioning aero dynamical.
  • This brushing wind is what drives the generator for the most part. It is to be distinguished from the naturally available (perpendicular) wind force that drives the dynamical parts of the blades.
  • the blades At a pre-chosen point (depending on the mill design) the blades will revert to their original shape. This will occur when wind velocity has improved to mill efficient values (at 5-8 Bft, usually).
  • the wind generator blades will continue to function as they were designed, for optimal wind conditions. Retracted, the blades will adopt their original curvature and (aerofoil) shapes.
  • a control mechanism will drive 3 electric motors present in the axis section of the 3 wing blades and will cause extension or retraction of protruding movable blade sections along the length of the rotor blades at the appropriate moment.
  • Airplanes are known to use flaps in their wings to be able to lift from a runway before it ends. At that point a temporary dynamically active function is added to the aerodynamic function of the wings, providing additional lift at the appropriate time. When attaining more speed, the wings usually revert to fully aero dynamical shape. The same flaps act as brakes when descending. Before the airspeed is too low to provide an aero dynamical function and the plane risks a stall condition, the added dynamical lift will keep the plane in the air while landing in a controlled fashion.
  • Airplane wings are brushed by the same overall wind speed along their length.
  • Rotary functioning wings such as in windmills, experience a varying wind velocity as the airspeed varies along with the diameter of the wing.
  • the flaps described in this invention are not involved in braking the rotor speed.
  • Patents exist describing movable sections of wings and windmill blades to adapt to different wind conditions.
  • WO2009095758 (retractable wing flaps) describes (quote) "an outer aerodynamic module with a telescoping feature which, when extended out, increases the airfoil or blade diameter or length and generates more lift forces or, in the case of power- generating device rotor blades, captures more wind energy during periods of lower winds, and telescopes in (retracts) to reduce wind energy exposure in higher winds.”
  • a patent US4017041 exists describing an air flow control mechanism as part of an aircraft wing (quote): "the provision of retractable foils extending upwardly and/or downwardly from the aircraft airfoil, preferably at or close to an end thereof, aligned parallel, if desired, to the longitudinal centerline of the aircraft ."
  • This patent describes a wingtip vortex control mechanism, a substantially different kind of provision, in order to improve airfoil functioning of a wing with the purpose of diminishing turbulent wakes of large aircraft. It mentions side benefits such as “providing for an increased rate of climb at a given engine setting and improving the air flow characteristics of the airfoil.”
  • a patent US 20081 5220 exists describing "A helicopter rotor blade having a blade body that defines a confined space and a control flap that is secured to the blade body that moves through a range of motion. An electric machine is secured inside of the rotor blade body that rotates a motor shaft.”
  • This patent describes a substantially different kind of airflow control mechanism, not enlarging the dynamic surface of a blade.
  • the herein proposed addition to windmill wing blades, temporarily extending flaps at the trailing edge of the midsection of the blades consists of a (set of) movable blade(s) movably fitting into the profile of the trailing edge of the blades longitudinally, a control mechanism with blade speed and wind speed sensors and a means of extending and retracting those flaps into the aerofoil cambered blade profile, such as an electric motor or solenoid or any other mechanical, pneumatical or hydraulic means.
  • Sensors will give the necessary feedback information about the position of the movable blade parts at all times to a control mechanism coordinating the parameters.

Abstract

A system of temporarily extending flaps at the trailing edge of the midsection of individual windmill blades consisting of a (set of) movable blade(s) movably fitting into the profile of the trailing edge of the blades longitudinally a built-in mechanism to extend and retract flaps, a control mechanism with blade speed and wind speed sensors, and a means of extending and retracting those flaps into the aerofoil cambered blade profile, such as an electric motor or solenoid or by any other mechanical, pneumatical or hydraulic means. These flaps are designed to provide a positive angle of attack.

Description

Windmill propeller blades with built-in extendable flaps.
In order for a wing to produce lift it has to be at a positive angle to the airflow. In that case a low pressure region is generated on the upper surface of the wing which draws the air above the wing downwards towards what would
otherwise be a void after the wing had passed. On the underside of the wing a high pressure region forms, accelerating the air there downwards out of the path of the oncoming wing. The pressure difference betwee these two regions produces an upwards force on the wing, called lift.
This is a dynamic phenomenon.
The lift on a cambered aerofoil shaped wing is primarily the result of its shape (in particular its camberline) and its angle of attack. When either or both are positive, the resulting flow field about the aerofoil has a higher average velocity on the upper surface than on the lower surface. This velocity difference is necessarily accompanied by a pressure difference, via Bernoulli's principle, which in turn produces the lift force.
Modern wind generators are equipped with blades being rotated by both dynamic and aero dynamic wind power.
A dynamic section (usually around the axis, where rotary velocity will not attain aerodynamically relevant values) sets the windmill rotor into motion.
Once the rotor is turning over, the tip of the blades will soon attain speeds invoking an aero dynamical effect. The flowfield of the brushing wind flow, created by the rotary motion of the blades, makes the rotor turn faster and thereby generates torque at its axis.
This brushing wind flow is the most relevant wind flow, not the wind driving the dynamic part of the rotor with a perpendicular force. The dynamic part will soon be less relevant compared to the aerodynamic forces driving the outer circle of the wing surface as a result of the lower speed of revolutions at the center of the total wing surface (when in motion).
Modern wind generator blades are shaped with a well pre-chosen shape, allowing both forces to act when most appropriate. The choice is usually such that a rotor will function at its most efficient in wind forces of 5-8 Bft. The wind force formula is such that increasing wind velocities will augment torque in a windmill drive axis to the third power. In decreasing wind force conditions the opposite is true.
Consequently, modern wind generators are not very efficient at low wind velocities, at e.g. 1-5 Beaufort. The total of fully operational hours per year is usually around 26% of its theoretical capacity. This figure describes conditions in which the available power generating capacity is used efficiently. It is a relevant component in a cost/profit calculation.
The peak conditions mostly contribute to the performance. A wind generator is usually equipped with power generating capacities just right for those conditions. Another point we make, is that wind conditions of Bft 1-5 occur a lot more frequently than conditions of Bft 5-8.
A considerable part of the capacity is wasted in low wind conditions, one might say.
This can be remedied for a large part by temporarily adding to the dynamically active blade surface. This dynamically active surface in existing windmill blades is usually about ¼ of the length of the blade, positioned at the relatively slow moving axis part. Our invention proposes to employ retractable flaps in the mid section of a windmill blade, at the trailing edge.
The surface of the aero dynamically effective part of the blade (usually ¾ of the blade, from midsection to tip) is thereby partly made into a temporarily dynamically responsive blade, leaving the blade tip parts (the fast moving remaining ¼ surface at the tip) functioning aero dynamical.
As a result of improved responsiveness to perpendicular dynamic wind force the propeller is pushed to a better speed, causing an improved brushing wind speed at the tip parts of the blades, causing augmentation of torque at the axis.
This brushing wind is what drives the generator for the most part. It is to be distinguished from the naturally available (perpendicular) wind force that drives the dynamical parts of the blades.
At a pre-chosen point (depending on the mill design) the blades will revert to their original shape. This will occur when wind velocity has improved to mill efficient values (at 5-8 Bft, usually). The wind generator blades will continue to function as they were designed, for optimal wind conditions. Retracted, the blades will adopt their original curvature and (aerofoil) shapes.
Monitoring wind speed and rotary speed of a 3 blade generator, a control mechanism will drive 3 electric motors present in the axis section of the 3 wing blades and will cause extension or retraction of protruding movable blade sections along the length of the rotor blades at the appropriate moment.
Airplanes are known to use flaps in their wings to be able to lift from a runway before it ends. At that point a temporary dynamically active function is added to the aerodynamic function of the wings, providing additional lift at the appropriate time. When attaining more speed, the wings usually revert to fully aero dynamical shape. The same flaps act as brakes when descending. Before the airspeed is too low to provide an aero dynamical function and the plane risks a stall condition, the added dynamical lift will keep the plane in the air while landing in a controlled fashion.
Airplane wings are brushed by the same overall wind speed along their length. Rotary functioning wings, such as in windmills, experience a varying wind velocity as the airspeed varies along with the diameter of the wing.
This describes the same phenomenon. Our invention suggests using midsection flaps for a different purpose, as explained above, fitting into the design of modern windmill blades.
The flaps described in this invention are not involved in braking the rotor speed.
An embodiment is described in fig 1 (cross section of wing profile, flaps in) and 2 (idem, flaps out) and figs 3 and 4 (wing profile, all flaps in and out).
Existing art:
Patents exist describing movable sections of wings and windmill blades to adapt to different wind conditions.
WO2009095758 (retractable wing flaps) describes (quote) "an outer aerodynamic module with a telescoping feature which, when extended out, increases the airfoil or blade diameter or length and generates more lift forces or, in the case of power- generating device rotor blades, captures more wind energy during periods of lower winds, and telescopes in (retracts) to reduce wind energy exposure in higher winds."
This is a different approach to the solution of the low wind problem. It suggests to temporarily enlarge the radius of the windmill wingspan, extending the tip of the blades.
This is not very effective as it does not contribute to improving the brushing wind speed (in a vertical plane), the driving force of the generator. Low wind speeds will not rotate a wind generator any faster with an enlarged aerodynamic
wingspan, of which the tip is a part.
WO2009090537 suggests a similar solution to the problem.
The same line of criticism might apply.
A patent US4017041 exists describing an air flow control mechanism as part of an aircraft wing (quote): "the provision of retractable foils extending upwardly and/or downwardly from the aircraft airfoil, preferably at or close to an end thereof, aligned parallel, if desired, to the longitudinal centerline of the aircraft ..."
This patent describes a wingtip vortex control mechanism, a substantially different kind of provision, in order to improve airfoil functioning of a wing with the purpose of diminishing turbulent wakes of large aircraft. It mentions side benefits such as "providing for an increased rate of climb at a given engine setting and improving the air flow characteristics of the airfoil.".
A patent US 20081 5220 exists describing "A helicopter rotor blade having a blade body that defines a confined space and a control flap that is secured to the blade body that moves through a range of motion. An electric machine is secured inside of the rotor blade body that rotates a motor shaft."
This patent describes a substantially different kind of airflow control mechanism, not enlarging the dynamic surface of a blade. The herein proposed addition to windmill wing blades, temporarily extending flaps at the trailing edge of the midsection of the blades consists of a (set of) movable blade(s) movably fitting into the profile of the trailing edge of the blades longitudinally, a control mechanism with blade speed and wind speed sensors and a means of extending and retracting those flaps into the aerofoil cambered blade profile, such as an electric motor or solenoid or any other mechanical, pneumatical or hydraulic means.
These flaps are designed to provide a positive angle of attack. The herein proposed addition to windmill wing blades is described in a prior patent application NL 1035525.
Sensors will give the necessary feedback information about the position of the movable blade parts at all times to a control mechanism coordinating the parameters.
In order to maintain full control of the mechanism no wind force or momentum force is used to move the blades.
An option exists to render this mechanism independent of any other power source or mechanism than present in each blade embodiment, e.g. using a solar or gravity activated charger and batteries.

Claims

Claims 1.
Windmill wing blades containing a (set of) movable blade(s), movably fitting into the profile of the blades longitudinally at the trailing edge and a means of extending and retracting those blades into the blade profile or enlarging a dynamical blade profile, therewith enlarging or diminishing the dynamically active part of a blade surface by temporarily extending flaps at the trailing edge of the midsection of the blades
2.
Mechanism present in a windmill blade, as described in claim 1, being activated and powered independently of any other mechanism (e.g. present in the windmill nacelle) within the confines of the same wing blade.
3.
Mechanism as described in claim 1, containing a control mechanism with blade speed and wind speed sensors, a (set of) movable blade(s) movably fitting into the profile of the trailing edge of the blades longitudinally and a means of extending and retracting those flaps into the blade profile, such as an electric motor or solenoid or by any other mechanical, pneumatical or hydraulic means.
These flaps are designed to provide a positive angle of attack.
PCT/NL2010/000032 2010-02-26 2010-02-26 Windmill propeller blades with built-in extendable flaps WO2011105887A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/NL2010/000032 WO2011105887A1 (en) 2010-02-26 2010-02-26 Windmill propeller blades with built-in extendable flaps

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/NL2010/000032 WO2011105887A1 (en) 2010-02-26 2010-02-26 Windmill propeller blades with built-in extendable flaps

Publications (1)

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WO2011105887A1 true WO2011105887A1 (en) 2011-09-01

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4017041A (en) 1976-01-12 1977-04-12 Nelson Wilbur C Airfoil tip vortex control
EP1375911A1 (en) * 2001-03-26 2004-01-02 Hitachi Zosen Corporation Propeller type windmill for power generation
US20080145220A1 (en) 2006-12-14 2008-06-19 Sikorsky Aircraft Corporation On-blade actuator for helicopter rotor blade control flaps
NL1035525A1 (en) 2008-06-03 2008-07-07 Hugo Karel Krop Windmill propeller with extendable profile parts.
WO2009050550A2 (en) * 2007-09-27 2009-04-23 Comandu Angelo Variable-geometry blade for an eolic generator
WO2009061478A1 (en) * 2007-11-06 2009-05-14 Flexsys, Inc. Active control surfaces for wind turbine blades
WO2009090537A2 (en) 2008-01-14 2009-07-23 Clipper Windpower Technology, Inc. A modular rotor blade for a power-generating turbine and a method for assembling a power-generating turbine with modular rotor blades
WO2009095758A2 (en) 2008-01-30 2009-08-06 Clipper Windpower Technology, Inc. Retractable blade structure with a split trailing edge

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4017041A (en) 1976-01-12 1977-04-12 Nelson Wilbur C Airfoil tip vortex control
EP1375911A1 (en) * 2001-03-26 2004-01-02 Hitachi Zosen Corporation Propeller type windmill for power generation
US20080145220A1 (en) 2006-12-14 2008-06-19 Sikorsky Aircraft Corporation On-blade actuator for helicopter rotor blade control flaps
WO2009050550A2 (en) * 2007-09-27 2009-04-23 Comandu Angelo Variable-geometry blade for an eolic generator
WO2009061478A1 (en) * 2007-11-06 2009-05-14 Flexsys, Inc. Active control surfaces for wind turbine blades
WO2009090537A2 (en) 2008-01-14 2009-07-23 Clipper Windpower Technology, Inc. A modular rotor blade for a power-generating turbine and a method for assembling a power-generating turbine with modular rotor blades
WO2009095758A2 (en) 2008-01-30 2009-08-06 Clipper Windpower Technology, Inc. Retractable blade structure with a split trailing edge
NL1035525A1 (en) 2008-06-03 2008-07-07 Hugo Karel Krop Windmill propeller with extendable profile parts.
NL1035525C1 (en) * 2008-06-03 2009-07-06 Hugo Karel Krop Adjustable rotor blade for e.g. wind turbine, includes extendible profile part such as flap or slat

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