GB2467295A - Wind turbine blades having flow indicators which emit light at a predetermined wavelength - Google Patents

Wind turbine blades having flow indicators which emit light at a predetermined wavelength Download PDF

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Publication number
GB2467295A
GB2467295A GB0900987A GB0900987A GB2467295A GB 2467295 A GB2467295 A GB 2467295A GB 0900987 A GB0900987 A GB 0900987A GB 0900987 A GB0900987 A GB 0900987A GB 2467295 A GB2467295 A GB 2467295A
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GB
United Kingdom
Prior art keywords
flow indicators
blade
light
light source
flow
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.)
Withdrawn
Application number
GB0900987A
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GB0900987D0 (en
Inventor
Carsten Hein Westergaard
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.)
Vestas Wind Systems AS
Original Assignee
Vestas Wind Systems AS
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 Vestas Wind Systems AS filed Critical Vestas Wind Systems AS
Priority to GB0900987A priority Critical patent/GB2467295A/en
Publication of GB0900987D0 publication Critical patent/GB0900987D0/en
Publication of GB2467295A publication Critical patent/GB2467295A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/02—Indicating direction only, e.g. by weather vane
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/02—Blade-carrying members, e.g. rotors
    • F01D5/021—Blade-carrying members, e.g. rotors for flow machines or engines with only one axial stage
    • 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
    • F03D17/00—Monitoring or testing of wind motors, e.g. diagnostics
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/0006—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/02—Indicating direction only, e.g. by weather vane
    • G01P13/025—Indicating direction only, e.g. by weather vane indicating air data, i.e. flight variables of an aircraft, e.g. angle of attack, side slip, shear, yaw
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/001—Full-field flow measurement, e.g. determining flow velocity and direction in a whole region at the same time, flow visualisation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/02—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer
    • 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
    • F05B2270/80—Devices generating input signals, e.g. transducers, sensors, cameras or strain gauges
    • F05B2270/804—Optical devices
    • F05B2270/8041—Cameras

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Wind Motors (AREA)

Abstract

A system to monitor airflow over a wind turbine blade 10, comprising, flow indicators 20, emitting light at a predetermined wavelength mounted on the blade 10, and an imaging device 22, with a band pass filter which passes only light at the frequency emitted by the flow indicators 20. The flow indicators may be optically dirty. The system may include an optical fibre network 28 to transmit light from a light source 26 to the flow indicators 20 which may be optical fibres 24. The light source 26 may be a laser light source or may be light emitting diodes (34, Fig 3). The flow indicators may be tufts. The light emitted by the light source may be polarized. The system is particularly suited to a commercial wind turbine since the flow indicators are visible at any time of the day or night in any weather conditions.

Description

Flow Indicators for Wind Turbine blades This invention relates to wind turbines, and in particular to flow indicators used on wind turbine blades to monitor airflow at various points on the wind turbine blade surface.
Various flow indicators are known and have been used for some while to observe airflow over wind turbine blades and other aerofoils such as aircraft wings. One common type of flow indicators is a tuft or tickler which is typically a length of thread or wool attached to the surface of a wind turbine blade. The tuft is free to extend in the flow direction and so flow patterns and changes in flow patterns can easily be observed. When the airflow at the tuft is on the point of stalling, the tuft will vibrate giving an easily observed indication of the onset of stall. Tufts can be filmed over time using a video camera or other device to determine flow properties such as streamlines, stalls and transitions. From these properties other flow parameters can be determined. Tufts have been used to visualise flow for many decades although improved tufts have been proposed, for example in US 4,567,760 Crowder. This document discloses a tuft intended for use on an aircraft wing and comprising a cone shaped member attached at its apex to a support via a thread or cord. This type of tuft is intended to reduce flow disturbances and avoid self-excited whipping motions exhibited by simple thread tufts.
Another type of flow indicators is the stall flag which is described in US 6,065,334 Corten. A stali flag is a small sheet of material, for example plastics, which is fixed to the blade surface along one side and is free to flip over about that fixed side so that it lies with its opposite surface upwards to indicate a change in flow direction, It is known to make the two surfaces of the flags either a different colour or to have different properties, for example one shiny the other matt, to aid detection. It has also been proposed to use several types of flag or several different colours on a single surface to aid observation of different phenomena. These flags may be used on the surface of a wind turbine blade.
While the use of flags and tufts is well known, usage tends to be confined to research or experimental stations and none of the known techniques are well suited to use in a practical, commercial environment where a wind turbine is running constantly, day and night, often in very hostile conditions. The use of a video camera to image tufts, flags and other flow indicators on wind turbine suffers from severe problems caused by changing background contrast. On a bright day, as a blade rotates, the background seen by the camera may change from bright sunshine to dark ground making it very difficult for an image processing system to distinguish movement of flow indicators. Tufts tend to be made of dark material, and the wind turbine blades of white material but the enormous changes in background contrast makes it difficult to optimise the image.
This in turn makes the automated image processing required for remote monitoring of tufts very cumbersome. Where tufts are used for research or experimental purposes there may be some flexibility as to when measurements are made and the operator can wait for suitable weather conditions. However, in a commercial wind turbine, any system used must be able to operate day or night in any weather conditions.
The present invention, therefore, aims to address this problem and to provide a flow monitoring system that is suitable for use with a commercial wind turbine.
According to the invention there is provided a system for monitoring airflow over a wind turbine blade, comprising an imaging device mounted for rotation with the blade, and a plurality of flow indicators mounted on the blade to indicate airflow at points on the blade, the flow indicators emitting light at a predetermined wavelength, wherein the imaging device includes a filter for passing light at the frequency emitted by the flow indicators.
I
Embodiments of the invention have the advantage that high contrast images of the flow indicators may be formed and that the flow indicators are visible at any time of day in any weather conditions. The imaging device will only see the flow indicators and will be unaffected by changing
background.
Preferably, the flow indicators are optically dirty. This may be achieved by doping the flow indicators with a dye or by trapping impurities or air in the material of the flow indicators. Optically dirty flow indicators will scatter light making them more easy to detect.
In a preferred embodiment of the invention the system comprises an optical fibre network arranged in the blade and extending from a light source to the flow indicators. The light source may be a laser light source and may be mounted in the blade. This embodiment has the advantage that the light passed to the flow indicators is laser light of an accurately is defined wavelength. This light is emitted by the flow indicators and the filter used as the imaging device may be selected to have a very narrow bandpass essentially only transmitting light at the wavelength of the laser light. This has the advantage of further improving the contrast of the images produced by the imaging device.
The flow indicators may comprise the ends of optical fibres which extend through the skin of the blade as lengths of optical fibre which can plug into the optical fibre network from connectors mounted on the blade surface.
The latter is particularly preferred as it enables the fibres to be fitted after the blade has been assembled and mounted as a wind turbine, so minimising the risk of damage.
Preferably, the light source emits polarised light and the imaging device comprises a complementary polarising filter for passing polarised light enabled by the flow indicators. This has the advantage of further increasing the contrast of images of the flow indicators that can be obtained.
In another preferred embodiment, the light source, preferably light emitting diodes, is mounted at the flow indicators. This arrangement has the advantage of being inexpensive. Preferably, the flow indicators are doped with a dye which emits light at a specific wavelength, which may be s different from the wavelengths of light emitted by the LED and will be in a narrower band than the LED so enabling higher contrast images to be obtained.
Preferably, the flow indicators are each attached to an optical coupling mounted in a respective recess in the blade. This arrangement ensures minimal disruption to the airflow over the blade.
Preferably, the flow indicators are tufts. The tufts may comprise a length of plastics film, preferably polyvinyl. This has the advantage of being strong and capable of surviving in the harsh climatic conditions in which wind turbines after have to operate.
Embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a first embodiment of the invention and shows a wind turbine blade having a plurality of tufts; Figure 2 is a cross-section through a wind turbine blade showing an optical coupling to a tuft; Figure 3 is a cross-section through a wind turbine blade showing an alternative arrangement to that of figure 2; Figure 4 shows a second embodiment of the invention showing an alternative method of illuminating a tuft; and Figure 5 shows a variant on the embodiment of figure 4; Figure 1 shows an illustrative wind turbine blade 10 having upper and lower surfaces 12, 14, a tip end 16 and a root end 18. The actual configuration of the blade is not important and many different blade designs are used in practice depending on the manufacturer and the location of the wind turbine. A plurality of tufts 20 is arranged at points on the upper surface 12 of the blade. The number and spacing of the tufts will depend on the size of the blade and the type of flow conditions desired to be monitored.
In order to monitor the position of the tufts in an airflow, an imaging device, for example, a CCD camera 22 is mounted on the blade towards the blade root 18. The camera has a field of view which includes the tufts to be monitored or is steerable so that it can be focussed on a part of the wind turbine blade. The camera may also have a zoom control so that an individual tuft or group of tufts may be selected for viewing. The camera may be mounted within a protective housing and, as it is mounted on the blade, will rotate with the blade making it relatively easy to view the tufts when the wind turbine blades are rotating. The same advantage may be * gained by mounting the camera on another rotating part of the wind turbine, such as the spinner. In some respects this is preferred as it is easier to weatherproof a spinner mounted camera and easier to connect the electrical cabling required for the camera to communicate with other electronics in the wind turbine such as the turbine controller and a power source. However a spinner mounted camera is inevitably further away from the tufts it is observing which may be disadvantageous. The imaging device acquires successive images of the tuft or tufts from which flow patterns and phenomena may be determined.
An optical fibre 24 extends from a light source 26 at the blade root 18 to the individual tufts. The light source is preferably arranged at the blade root but could be arranged on the rotor hub or further down the blade towards the tip. As shown in figure 1, a single fibre extends along the length of the blade which a branch 28 extending out from the main fibre to each of the tufts. Thus light from the light source can be communicated to the tufts to illuminate them. Alternatively, a bundle of individual fibres may extend from the light source each to a respective tuft.
The light source used may be a fibre laser, for example of the type used in telecommunications networks emitting light in the order of l500nm, other laser devices may be used, for example a laser diode emitting light t between 850-890 nm.
The laser light from source 26 is distributed via the network of optical fibres to a plurality of tap holes in the surface of the blade. The number of tap holes may exceed the number of tufts. The tap holes may be embedded in the blade skin so that only a small optical connector actually passes through the skin. This arrangement is shown in more detail in figure 2 which shows a small recess 30 provided in the upper surface of the blade which receives the end of the optical fibre. This end is connected to the tuft via an optical coupling 32 which is preferably flush is mounted.
The tufts may be made from any suitable material but it is presently preferred to use a polyvinyl plastic film. The tufts may be made optically dirty by one or more means. The term optically dirty refers to the material having impurities added to it to alter its optical characteristics. For example, the tufts may be doped with a narrow bandwidth fluorescent dye which fluoresces when it is in contact with light from the light source. To aid detection, a length of the tuft in the order of 10cm is dyed. The camera 22 is also provided with a corresponding narrow band filter to enable it to detect only light emitted from the fluorescing tufts.
An alternative way of making the tufts optically dirty is to include impurities such as particles or air bubbles in the tufts which will increase the contrast of these free ends. In this case the narrow band filter used on the camera 22 is chosen to pass light at the frequency of the laser light source 261n both cases described, the use of a narrow band filter on the camera ensures that the camera only sees the tuft enabling a high contrast image to be obtained regardless of background conditions. The contrast may be further enhanced by using polarised light at the light source 26, in which case the camera is additionally provided with a polarising filter. A polariser is advantageous regardless of whether the light source is a laser.
S The tufts may be attached to the optical coupler by pulling an end of the plastic film and gluing the rounded end to the optical coupler 32. The coupler may then be fitted into the tap hole in the blade. This type of snap on coupling is advantageous as it is easy to service and may be replaced simply should the plastic film break. This is common as the tufts could be reasonably delicate and operate in hostile weather environments. It is preferred to install more tufts than are required so that when some fail or become damaged, no maintenance is required. A tuft made of polyvinyl plastics material will typically last for a few years, for example 3 years.
Instead of using a separate material for the tufts, the tufts could be formed as an extension of the optical fibres 28 which extend through the tap holes, removing the need for an optical coupler. As the optical fibres are delicate and prone to break, fibres sticking out of the blade surface are likely to be damaged during transportation and assembly. To avoid this problem, a length of optically dirty optical fibre may be used in place of the polyvinyl film and attached to the optical coupler so that it can be plugged into place when the blade is in place on the wind turbine during assembly.
In either of these arrangements, the portion of the optical fibre that functions as the tuft may be doped with dye or filled with air bubbles or impurities over the last few centimetres as described above.
It will be appreciated that the use of a fluorescent dye in the tuft provides one example of a tuft which emits light at a wavelength different to that of the illuminating light.
The embodiment described has the advantage that high contrast images of the tufts can be obtained regardless of the conditions in which the wind turbine is operating.
S
The embodiment of figure 3 provides a low cost alternative to the use of optical fibres and positions a light emitting diode (LED) 34 in the recess 30 under the tuft. A transparent cover 36 may be placed above the LED under the tuft. The LED illuminates the tuft. Compared to the laser light source of figure 1, the LED emits a broader wavelength light. To enable the tufts to be detected, they are doped with a dye which is excited by the LED light to emit a narrow bandwidth of light at a different wavelength.
The filter on the camera is selected to pass only this wavelength.
Rhodamine is an example of a suitable dye. This combination of LED and selected dye may enable an even narrower band filter to be used on the camera so improving the contrast of images of the tufts that may be obtained. A disadvantage of the figure 3 embodiment is the need to provide electrical wiring to the LEDs at a plurality of points along the blade.
Electrical wiring is prone to corrosion and lightning damage. However, this disadvantage may be outweighed by the overall cost reduction compared to the embodiment of figures 1 and 2.
The embodiments of figures 4 and 5 provide an even simpler solution. In these embodiments, the recess 30 and optical couplings are removed and the LED 34 (Figure 4) or optical fibre 28 (Figure 5) are embedded in the skin of the upper blade surface. Thus, the tuft is illuminated through the blade skin. This solution does not require any alteration to the tufts which, although they may still be optically dirty as described above, are fitted to the blade in the same way as a conventional tuft. Moreover, as the illumination is embedded in the skin, it is very robust. Preferably, a microlens is applied to the LED or the end of the optic fibre to enable a sufficiently large area to be illuminated. This is necessary as the tuft is moving about its fixed end in the direction of the oncoming wind.
The embodiments described may be installed into a blade during the manufacturing process such that the optical fibres or wiring, and the recesses and tap holes to which it extends, are fitted before the two moulded halves of the blade are assembled together. Where plug-in tufts are used, these may be either assembled on site or in advance. It is possible to retrofit the embodiments of the invention to existing assembled blades as the size of commercial wind turbine blades is sufficiently large as to enable a fitter to gain access to the inside of the blade over much of S its length. However, it may be difficult to retrofit fibres or wiring towards the blade tips where the internal space is narrow.
Thus, embodiments of the invention provide a system which enables an imaging device such as a camera to image tufts with a high contrast regardless of the background conditions or the time of day. Although described in respect of tufts, embodiments of the invention may also be used with other flow indicating devices including, but not limited to, stall flags.
Embodiments of the invention have the advantage of enabling detailed measurements of flow conditions to be made without requiring sophisticated sensors which can be expensive and delicate.
Embodiments of the invention are suitable for use on wind turbines located in harsh climatic conditions without requiring frequent maintenance.

Claims (19)

  1. ICLAIMS1. A system for monitoring airflow over a wind turbine blade, comprising an imaging device mounted for rotation with the blade, and a plurality of flow indicators mounted on the blade to indicate airflow at points on the blade, the flow indicators emitting light at a predetermined wavelength, wherein the imaging device includes a filter for passing light at the frequency emitted by the flow indicators.
  2. 2. A system according to claim 1, wherein the flow indicators are optically dirty.
  3. 3. A system according to claim 2, wherein the optically dirty flow indicators include fluorescent dye.
  4. 4. A system according to claim 2 or 3, wherein the optically dirty flow indicators include air bubbles or other impurities in the material of the flow indicator.
  5. 5. A system according to claim 1, comprising an optical fibre network arranged in the blade for transmitting tight from a light source to the flow indicators, the network extending from the light source to the flow indicators.
  6. 6. A system according to claim 5, wherein the light source is a laser light source and the filter on the imaging device passes light at the wavelength of light emitted by the laser.
  7. 7. A system according to claim 5 or 6, wherein the light source is mounted within the blade.
  8. 8. A system according to claim 5, 6 or 7, wherein the flow indicators comprise fibres of the optical fibre network extending through the skin of the blade.S
  9. 9. A system according to claim 5, 6 or 7, wherein the flow indicators comprise optical fibres coupled to fibres of the optical fibre network at the blade skin.
  10. 10. A system according to any of claims 5 to 9, wherein the light source emits polarised light and the imaging device comprises a complementary polarising filter for passing polarised light emitted by the flow indicators.
  11. 11. A system according to any of claims I to 4, comprising a light source mounted adjacent each of the flow indicators.
  12. 12. A system according to claim 11, wherein the light sources comprise light emitting diodes.
  13. 13. A system according to claim 11 or 12, wherein the flow indicators are doped to emit light at a wavelength different from that of the light source.
  14. 14. A system according to any preceding claim, wherein the flow is indicators are each attached to an optical coupling mounted in a respective recess in the blade.
  15. 15. A system according to any preceding claim, wherein the flow indicators are tufts.
  16. 16. A system according to claim 15, wherein the tufts comprise a plastics film.
  17. 17. A wind turbine having a rotor comprising a plurality of blades and at least one system according to any of claims I -16.
  18. 18. A system for monitoring airflow over a wind turbine blade substantially as herein described with respect to Figures 1 and 2, 3, 4 or 5 of the accompanying drawings.
  19. 19. A wind turbine having a rotor having a plurality of blades and a system for monitoring airflow over at least one of the blades substantially as herein described with reference to Figures 1 and 2, 3, 4 or 5 of the accompanying drawings.
GB0900987A 2009-01-21 2009-01-21 Wind turbine blades having flow indicators which emit light at a predetermined wavelength Withdrawn GB2467295A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0900987A GB2467295A (en) 2009-01-21 2009-01-21 Wind turbine blades having flow indicators which emit light at a predetermined wavelength

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0900987A GB2467295A (en) 2009-01-21 2009-01-21 Wind turbine blades having flow indicators which emit light at a predetermined wavelength

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GB0900987D0 GB0900987D0 (en) 2009-03-04
GB2467295A true GB2467295A (en) 2010-07-28

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2353320A1 (en) * 2008-02-08 2011-03-01 GAMESA INNOVATION & TECHNOLOGY S.L. Wind turbine blade with a ligth beacon at the tip
WO2012082324A1 (en) * 2010-12-16 2012-06-21 Inventus Holdings, Llc A method for determining optimum vortex generator placement for maximum efficiency on a retrofitted wind turbine generator of unknown aerodynamic design
GB2488123A (en) * 2011-02-15 2012-08-22 Vestas Wind Sys As System and method for detecting damage to a wind turbine blade
CN104568968A (en) * 2015-01-13 2015-04-29 西安交通大学 Method and system applied to in-situ crack detection of wind generator blade
CN107091120A (en) * 2016-02-18 2017-08-25 通用电气公司 Turbo blade centroid motion method and system
WO2018086908A1 (en) * 2016-11-09 2018-05-17 Wobben Properties Gmbh Method for detecting flow characteristics of a wind turbine rotor blade, reflector unit, and wind turbine
WO2019011489A1 (en) * 2017-07-14 2019-01-17 Siemens Gamesa Renewable Energy A/S Determining at least one characteristic of a boundary layer of a wind turbine rotor blade

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6636320B1 (en) * 2000-10-18 2003-10-21 Lockheed Martin Corporation Fiber optic tufts for flow separation detection

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6636320B1 (en) * 2000-10-18 2003-10-21 Lockheed Martin Corporation Fiber optic tufts for flow separation detection

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2353320A1 (en) * 2008-02-08 2011-03-01 GAMESA INNOVATION & TECHNOLOGY S.L. Wind turbine blade with a ligth beacon at the tip
US8038401B2 (en) * 2008-02-08 2011-10-18 Gamesa Innovation & Technology, S.L. Wind turbine blade with a light beacon at the tip
WO2012082324A1 (en) * 2010-12-16 2012-06-21 Inventus Holdings, Llc A method for determining optimum vortex generator placement for maximum efficiency on a retrofitted wind turbine generator of unknown aerodynamic design
GB2488123A (en) * 2011-02-15 2012-08-22 Vestas Wind Sys As System and method for detecting damage to a wind turbine blade
US9255886B2 (en) 2011-02-15 2016-02-09 Vestas Wind Systems A/S System and method for detecting damage to a wind turbine blade
CN104568968A (en) * 2015-01-13 2015-04-29 西安交通大学 Method and system applied to in-situ crack detection of wind generator blade
CN107091120A (en) * 2016-02-18 2017-08-25 通用电气公司 Turbo blade centroid motion method and system
CN107091120B (en) * 2016-02-18 2021-10-01 通用电气公司 Turbine blade centroid migration method and system
WO2018086908A1 (en) * 2016-11-09 2018-05-17 Wobben Properties Gmbh Method for detecting flow characteristics of a wind turbine rotor blade, reflector unit, and wind turbine
WO2019011489A1 (en) * 2017-07-14 2019-01-17 Siemens Gamesa Renewable Energy A/S Determining at least one characteristic of a boundary layer of a wind turbine rotor blade
CN110869609A (en) * 2017-07-14 2020-03-06 西门子歌美飒可再生能源公司 Determining at least one characteristic of a boundary layer of a wind turbine rotor blade
CN110869609B (en) * 2017-07-14 2021-08-24 西门子歌美飒可再生能源公司 Determining at least one characteristic of a boundary layer of a wind turbine rotor blade
US11378487B2 (en) * 2017-07-14 2022-07-05 Siemens Gamesa Renewable Energy A/S Determining at least one characteristic of a boundary layer of a wind turbine rotor blade

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