Abstract
An apparatus for inspecting an adhesive layer applied about the leading edge of a wind turbine rotor blade is provided, which apparatus includes a heating assembly configured to direct heat at a portion of the adhesive layer between the outer edges of the adhesive layer; an infrared imaging means arranged to obtain an infrared image of a heated portion; and a displacement means adapted to move the inspection apparatus alongside the rotor blade during operation of the heating assembly and the infrared imaging means to facilitate infrared imaging of the adhesive layer.
Claims
1. An apparatus for inspecting an adhesive layer applied about the leading edge of a wind turbine rotor blade, which apparatus comprises a heating assembly configured to direct heat at a portion of the adhesive layer between the outer edges of the adhesive layer; an infrared imaging means arranged to obtain an infrared image of a heated portion; a displacement means configured to move the inspection apparatus alongside the rotor blade during operation of the heating assembly and the infrared imaging means to facilitate infrared imaging of the adhesive layer.
2. The inspection apparatus according to claim 1, wherein the displacement means comprises a guide assembly configured to maintain an essentially constant distance between the heating assembly and the adhesive layer.
3. The inspection apparatus according to claim 1, wherein the displacement means comprises a number of spring-mounted rollers configured to roll along the surface of the rotor blade.
4. The inspection apparatus according to claim 1, wherein the heating assembly is mounted on a telescopic support.
5. The inspection apparatus according to claim 1, comprising an image processing module configured to detect an anomaly in the adhesive layer from evaluation of the infrared images.
6. The inspection apparatus according to claim 1, comprising a defect reporting module configured to report a detected anomaly and the position of that anomaly.
7. The inspection apparatus according to claim 1, comprising a position tracking means configured to determine the position of the infrared imaging means relative to the rotor blade.
8. The inspection apparatus according to claim 1, wherein the heating assembly comprises a plurality of heat sources arranged in a U-shaped configuration.
9. The inspection apparatus according to claim 1, wherein the infrared imaging means comprises a plurality of cameras, and comprises at least one camera arranged to obtain an image of the heated portion of the adhesive layer on the suction side of the rotor blade and at least one camera arranged to obtain an image of the heated portion of the adhesive layer on the pressure side of the rotor blade.
10. The inspection apparatus according to claim 1, wherein the displacement means is configured to move the inspection apparatus at an essentially constant rate.
11. The inspection apparatus according to claim 1, wherein at least the heating assembly and the infrared imaging means are mounted on a wheeled support and the displacement means comprises a motor configured to drive the wheels of the support.
12. The inspection apparatus according to claim 1, comprising a temperature sensing means arranged to measure the temperature of the heated portion.
13. A method of inspecting an adhesive layer applied about the leading edge of a wind turbine rotor blade using the apparatus of claim 1, which method comprises A) actuating the heating assembly to direct heat at a portion of the adhesive layer; B) actuating the infrared imaging means to obtain a number of infrared images of the heated portion; and displacing the apparatus alongside the rotor blade over the extent of the adhesive layer while repeating steps A and B.
14. The method according to claim 13, wherein the infrared imaging means comprises a plurality of cameras, and the method comprises a step of joining images to obtain a composite image of a heated portion of the adhesive layer.
15. The method according to claim 14, comprising a step of joining multiple composite images of the heated portions to obtain a composite image for the entire adhesive layer.
Description
BRIEF DESCRIPTION
[0040] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:
[0041] FIG. 1 shows an embodiment of the inventive inspection apparatus in place below a wind turbine rotor blade;
[0042] FIG. 2 is a perspective view of an embodiment of the inventive inspection apparatus;
[0043] FIG. 3 illustrates a first of two consecutive steps of embodiments of the inventive method;
[0044] FIG. 4 illustrates a second of the two consecutive steps of embodiments of the inventive method;
[0045] FIG. 5 is a simplified schematic of an exemplary infrared image generated in the course of embodiments of the inventive method;
[0046] FIG. 6 shows a simplified block diagram of an exemplary embodiment of the inventive inspection apparatus;
[0047] FIG. 7 shows exemplary images of a leading edge region of a rotor blade;
[0048] FIG. 8 shows an embodiment of the inventive inspection apparatus and a pre-bent rotor blade; and
[0049] FIG. 9 shows an embodiment of the inventive inspection apparatus and a swept rotor blade.
DETAILED DESCRIPTION
[0050] FIG. 1 shows a rotor blade 2 arranged at a height above ground and supported by a suitable holding arrangement (not shown). The leading edge LE of the rotor blade 2 is covered by a leading edge protector 3, which can comprise a flexible shell 3 that is glued onto the rotor blade 2 using a suitable adhesive 30. An embodiment of the inventive inspection apparatus 1 is shown. Details of the heating assembly and imaging assembly will be given in FIGS. 2-4. Here, the diagram indicates how the inspection apparatus 1 may move relative to the rotor blade 2, to capture infrared images of the heated adhesive layer 30 along the entire length of the leading edge protector 3. Once the inspection apparatus is placed in a suitable starting position (near the inboard short edge of the LEP, for example), it commences to move autonomously along the rotor blade, maintaining a constant rate of movement and a constant distance to the heated surface as will be explained below, until it reaches the other end of the LEP (the outboard end near the tip, for example).
[0051] FIGS. 2-4 show an exemplary realization of embodiments of the inventive inspection apparatus 1 and a section of a (complete) rotor blade 2 which has a leading edge protector 3 bonded in place by an adhesive layer 30 (collectively indicated by a stippled pattern). The diagrams show a heating assembly 1H with number of heat sources 10, for example infrared curing lamps. The diagrams also show a camera assembly 1IR with a number of infrared cameras 11. The heat sources 10 are arranged in an essentially U-shaped fashion so that the adhesive layer 30 of the LEP 3 is covered from edge-to-edge, i.e., the heat sources 10 direct thermal energy at all of the current portion of the adhesive layer 30 on the suction side 2S, the pressure side 2P and at the transition 2.sub.LE between suction side and pressure side. Of course, the heat sources 10 can direct thermal energy beyond the long edges of the adhesive layer 30 onto the rotor blade surface, but this is not relevant. The cameras 11 are also arranged in an essentially U-shaped fashion so that the heated adhesive layer 30 can be imaged correctly.
[0052] FIG. 2 also shows a support assembly 13, in this case a trolley with wheels which can be turned by an electric motor 13M. To ensure a constant distance between heat source 10 and the surface of the region to be imaged, the inspection apparatus 1 is equipped with an arrangement of spring-loaded rollers 12A, 12B arranged to ensure that a desired distance is maintained between the heat sources 10 and the surface of the rotor blade; and to ensure that a desired distance is maintained between the cameras 11 and the surface of the rotor blade. In this exemplary embodiment, a pair of spring-loaded rollers 12A maintains contact with the leading edge of the rotor blade 2 as the support assembly 13 is moved along the rotor blade 2. The spring-loaded rollers 12A and the heating assembly 1H are realized as a single unit so that any upward or downward displacement of the rollers 12A results in a corresponding vertical displacement D.sub.10 of the heaters 10. The diagram also shows a distance sensor 19 arranged to sense a distance between the rotor blade surface and the heating assembly 1H. A control unit 14 (not shown) receives the measurement data and issues control commands to any actuators (adjustable telescopic support columns 10S, 11S) are indicated here) in order to maintain the sensed distance at a constant value.
[0053] The diagram also shows a temperature sensor 18 arranged to monitor the temperature of the heated portion P.sub.hot. The control unit 14 receives the sensed temperature and adjusts the travel speed of the apparatus 1 in order to maintain the sensed temperature at a constant value.
[0054] A second spring-loaded roller arrangement 12B maintains contact with the leading edge of the rotor blade 2 as the support assembly 13 is moved along the rotor blade 2. The spring-loaded roller 12B and the imaging assembly 1IR are realized as a single unit so that any upward or downward displacement of the roller 12B results in a corresponding displacement of the imaging assembly 1IR.
[0055] A position tracking means 15 assists in determining the geometrical coordinates of a detected anomaly. A position tracking means 15 can be realized for example as an encoder of the displacement means 13M and can have a favorably low resolution so that the position of the inspection apparatus 1 can be precisely established relative to a certain reference, for example relative to the beginning of the adhesive layer 30.
[0056] FIG. 3 shows a cross-section through a rotor blade 2 during embodiments of the inventive method. The diagram shows how the adhesive layer 30 may be heated by an arrangement of heat sources 10 such as curing lamps. Here, an arrangement using three heaters 10 is shown. However, an arrangement using only two heaters 10 is equally possible.
[0057] FIG. 4 shows a cross-section through a rotor blade 2 during a subsequent stage of embodiments of the inventive method and shows how the heated adhesive layer 30 is imaged by cameras 11 of an infrared imaging assembly. Here, an arrangement using three cameras 11 is shown. However, an arrangement using only two cameras 11 is equally possible, for example two image sensors, each with a favorably wide field of view, may be arranged relative to the leading edge to capture images covering the entire adhesive layer 30.
[0058] FIG. 5 is a simplified schematic to explain the interpretation of an infrared image 11.sub.IR obtained as described above. The sensor output of the cameras 11 shown in FIG. 2 and FIG. 4 are combined to give a composite image 11.sub.IR of a heated section of the adhesive layer 30. The leading edge LE is indicated by the dashed line overlaid on the image 11.sub.IR, and the image 11.sub.IR shows a section of the LEP 3 extending into the pressure side and also a corresponding section of the LEP 3 extending into the suction side. The different materials result in different intensities (or colors) in the infrared image 11.sub.IR. Here, regions of low intensity within the adhesive 30 indicate defects 30X in the adhesive layer 30. With this knowledge, the LEP 3 and adhesive layer 30 can be opened at precisely those locations in order to repair the defects and to obtain a high-quality adhesive layer prior before the rotor blade leaves the manufacturing facility.
[0059] FIG. 6 shows a simplified block diagram of an exemplary embodiment of the inventive inspection apparatus 1. The diagram shows a control unit 14 that choreographs the activities of a heating assembly 1H, an infrared imaging means 1IR and a drive unit 13M of the wheeled support 13 shown in FIG. 2. Images 11.sub.IR captured by the infrared imaging means 1IR are forwarded to an image processing module 16, which can detect anomalies in the adhesive layer as explained in FIG. 5 above. The image processing module 16 may also be configured to output a color-enhanced image 160 that can be shown in a computer display, for example. The diagram also indicates an optional temperature sensing means 18 which is provided to measure the temperature of the heated portion P.sub.hot. One or more temperature sensors 18 can be arranged at suitable positions in the inspection apparatus, for example these can be mounted to the heating assembly, downstream of the curing lamps as indicated in FIG. 2. The temperature sensors can deliver useful data regarding the actual temperatures in the heated portion P.sub.hot, and this information can be used to calibrate the inspection procedure, to assist in evaluating the infrared images, to choose colors for the false-color images, etc.
[0060] FIG. 7 indicates an exemplary collection of images 11.sub.IR collected by the imaging means of embodiments of the inventive inspection apparatus as described above. Starting from the left-hand short edge of the LEP 3 and its adhesive strip 30, images 11.sub.IR of each heated portion are collected as the inspection apparatus 1 is moved in the direction of the other short edge of the LEP 3 and its adhesive strip 30. For each heated portion P.sub.hot, three or more images 11.sub.IR may be collected. Each such group of images 11.sub.IR may be combined to give a composite image 11.sub.P_comp of that heated portion. Equally, all the images 11.sub.IR, or all the composite images 11.sub.P_comp of the heated portions, may be combined to give a composite image 11.sub.30_comp showing the entire adhesive layer.
[0061] FIG. 8 shows an embodiment of the inventive inspection apparatus 1 being used to inspect the adhesive layer underneath an LEP applied to a pre-bent rotor blade 2 according to embodiments. The diagram shows the assembly from above. The rotor blade 2 is held horizontally, with its chord plane vertical and its trailing edge 2.sub.TE pointing upwards. As the diagram shows, the trailing edge, and therefore also the leading edge, follows a curved trajectory instead of a straight line. The inspection procedure commences with the apparatus 1 at an inboard region of the rotor blade 2, and the apparatus 1 is moved towards the tip region. The displacement means controls the inspection apparatus 1 to follow the curved trajectory of the leading edge.
[0062] FIG. 9 shows an embodiment of the inventive inspection apparatus 1 being used to inspect the adhesive layer underneath an LEP applied to a swept rotor blade 2 (shown with considerable exaggeration) according to embodiments. The diagram shows the assembly from the side. Here also, the rotor blade 2 is held essentially horizontally, with its trailing edge 2.sub.TE pointing upwards and its leading edge 2.sub.LE pointing downwards. As the diagram shows, the leading edge 2.sub.LE follows a curved upwards trajectory instead of a horizontal straight line. The inspection procedure commences with the apparatus 1 at an inboard region of the rotor blade 2, and the apparatus 1 is moved towards the tip region. The displacement means controls the inspection apparatus 1 to rise upwards in order to follow the upwardly curved trajectory of the leading edge 2.sub.LE.
[0063] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. For example, the inspection apparatus could be adapted for inspection procedures of an adhesive layer on the leading edge of an already installed rotor blade. Furthermore, the inspection apparatus is not limited to the inspection of an adhesive layer on a wind turbine rotor blade but can be used to detect defects in an adhesive layer on essentially any curved body.
[0064] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.
