FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMLPLETE SPECIFICATION
[See section 10, Rule 13]
APPARATUS AND PROCESS FOR
MEASUREMENT OF LEADING EDGE CONTOUR OF WIND TURBINE BLADES;
SUZLON ENERGY LIMITED, WHOSE ADDRESS IS UNIT NO. 6, BLOCK NO. 93, VILLAGE: VADASALA-VARNAMA, N.H.NO.8, DISTRICT VADODARA -391242, GUJARAT, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IS TO BE PERFORMED.

Field of invention:
The present invention relates to an apparatus and process for measurement of leading edge contour of turbine blades, and more particularly to an apparatus that includes C-shaped plates having a plurality of radial sticks to develop a current profile leading edge contour of wind turbine blades that is compared with a standard profile to identify if the current profile lies in predefined tolerances.
Background of the invention:
In the field of wind energy generation, the shape of the turbine blades carries lot of importance. It has been observed that after demolding, the turbine blades may have a different profile than required profile. The deformities might be present at more than one location on the blade. One has to frequently monitor the profile of wind turbine blades. People in wind energy generation industry monitor the profile of the blades to find out deviation from the standard profile. Visual inspection is one of the most common procedures to inspect the contour of blade. However, this method is error prone and not an accurate method of inspection.
Generally templates having predefined profile are employed to measure the profile of turbine blades, templates that are used for measuring leading edge profile of turbine blades are called as leading edge contour templates. It is to be noted that for each location of wind turbine blade, a separate leading edge contour template is required. For example, for one blade type there could be 10 to 15 or even more predefined locations at which blade leading edge contour measurement templates having predefined shapes are employed. Each of the

blades needs is verified against such templates at various locations. Based on the results of the measurement by the templates, a decision of repair is taken.
In the prior art various designs of leading edge contour templates are available. However, the major drawback of the templates in the prior art is that for each location on the blade different template is needed. One template couldn't be used for multi locations on the blade for measurement of profile. Further while deciding the location of the template on the blade, a user may not position the template accurately by considering length, chord width, angle of inclination and leading edge parting line simultaneously which may lead to inaccurate results. Further, results are obtained from such templates are with intervals of approximately 100mm due to which it becomes difficult to identify the profile of the blade between two consecutive locations. If the distance between two locations is reduced then in that case the time required to observe the profile increases.
It is also observed that the results obtained from the leading edge contour templates in the prior art are not comparable with that of the dimensions obtained by using CAD profiles. Hence one cannot compare the measured numeric profile with standard CAD profile. It is also observed that the templates in the prior art has to be positioned on the blades surface for longer time for measurement which is done with vernier /filler gauge/ tapper gauge and same is hectic and undesirable.
For each position a separate template is required. A person having ordinary skill in the art will appreciate that one may not be able to measure blade profiles of locations for which templates are not available. Gap between template & blade is generally measured by tapper gauge which itself is time consuming and hectic job. Use of tapper gauge may lead to inaccurate results.
EP 1590552 to Holder discloses a template apparatus for assessing damaged areas on an aircraft turbine blade includes a set of marks indicating maximum area of damages

allowed on a blade. A profile guide enables the inspector to align the templates in proper position against the blade for accurate visual inspection of the damaged areas. However, there are few problems associated with this device. For example, if the template is placed on the blade by using positioning guide and the blade defect location is out of the range of the marks shown on the template then template will fail to perform the intended work. Template will not work if it is not made with transparent material. The results with such template rely on visual inspection which may lead to errors. Template doesn't show the blade profile variations but checks if the damaged area is in predefined tolerances.
EP1451522 to Phuly discloses a method and apparatus for obtaining templates used in pipe end cutting essential in fabricating saddle and mitered pipe connections. The template is made by an array of z-shaped pins arranged radially to form the shape of a stepped cylinder. However, the apparatus is limited to pipes.
There is a need of an apparatus for accurate and easy measurement of leading edge contour profile of wind turbine, further an apparatus is needed that can measure leading edge contour at various locations on the wind turbine blade with highest accuracy and precision.
Summary
An apparatus for leading edge contour measurement of turbine blade for inspecting the profile of leading edge of wind turbine blades is disclosed that includes a template, a plurality of sticks, at least two pairs of plurality of pins, and a pair of clamps. The template includes a C-shaped groove and a plurality of through holes having predefined shape. The pluralities of sticks are preferably radially positioned on the template in association with a holder.

The pairs of pins are also radially positioned on the template in association with the holder at a predefine location on the blade. The pair of clamps is used for positioning the apparatus on a wind turbine blade. The through holes in the template are preferably of circular, triangular, square shape and the like. The holder includes a plurality of radial holes receiving the sticks and the pins to position the respective sticks and pins in a plane of the template that also includes apparatus location information.
The stick holder is being positioned in the plane of the template and hence the template and the holder are approximately coplanar. The stick is a long and thin piece of metal having a point at one end. The sticks are positioned in the holder such that the sticks are adjacently touching to each other in the plane of template. The endpoints of the adjacent sticks define a locus of points that define a profile that is identical with a profile of the leading edge contour profile of the blade at a predefined location where the apparatus is being positioned. The sticks and the pins are movable through respective through hole defined in the holder along a central axis of respective stick.
A wind turbine rotor blade in accordance with the present invention includes a plurality of pairs of marks that are defined on a pressure side of blade and suction side of the blade per location. The pairs of marks are defined per location on the blade surface such that a first pair of marks is on the pressure side, and a second pair of marks is on the suction side of the blade. A plurality of first pairs of marks are defined on the pressure side, and a plurality of second pairs of marks are defined on the suction side of the blade. The plurality of pairs of marks are defined in a moulding process with a predefined mould having a plurality of pairs of marks on the mould. In another embodiment, the blade contour measurement apparatus includes a plurality of sticks that are grouped in at least three groups that are radially positioned along C-groove of the template. A first and a third group are positioned such that a second group is positioned between the first and third group. The blade

contour measurement apparatus is positionable on a blade with the three groups and fixed in the position with the pair of clamps.
A preferred process for measuring blade edge contour profile comprising steps of defining a plurality of pairs of marks on a blade, the marks being defined in the form of pairs; positioning a leading edge contour measurement apparatus on the blade; positioning a plurality of adjacent radial sticks on the blade such that a pointed end of each stick touches the blade profile; developing a current profile according to the shape defined by the pointed ends of the sticks on a predefined graph paper; and comparing the current profile with a standard profile on the graph paper.
Positioning the leading edge contour measurement apparatus on the blade includes positioning at least two pairs of pins in accordance with the pairs of marks on the blade. The graph paper includes at least three profiles and a plurality of shapes being defined on the graph paper. The graph paper includes a standard profile and at least two tolerance profiles. The step of comparing the standard profile with the current profile includes identifying if the current profile lies within the predefined tolerances profile on the graph paper.
Brief description of the drawings
FIG. 1 is a front perspective view of a leading edge contour measurement apparatus in accordance with a preferred embodiment of the present invention;
FIG. 2 is top perspective view of a typical wind turbine rotor blade;
FIG. 3A is a top view of a wind turbine rotor blade mould including predefined pairs of marks in accordance with the present invention;

FIG. 3B is a front perspective view of a turbine blade having a plurality of marks that is manufactured using the mould of FIG. 3,
FIG. 4 a leading edge contour measurement apparatus with two pairs of opposed pins positioned on a wind turbine blade of FIG. 3B in accordance with the present invention;
FIG. 5 shows a graph that shows a standard leading edge contour profile, and two tolerance profiles of leading edge of blade in permanent form at a predefined position for a specific blade in accordance with the present invention;
FIG.6 is front perspective view of another embodiment of a leading edge contour measurement apparatus of FIG. 1 including at least three groups of sticks;
FIG. 7 is a front perspective view of another embodiment of a leading edge contour measurement apparatus of FIG. 1 that has at least four pairs of opposed pins; and
FIG. 8 is a graph of FIG. 5 that shows current blade contour profile developed in accordance with a preferred process and apparatus of FIG. 1.
Detailed description of the invention:
Although specific terms are used in the following description for sake of clarity, these terms are intended to refer only to particular structure of the invention selected for illustration in the drawings, and are not intended to define or limit the scope of the invention.
Referring to FIG.l, a leading edge contour measurement apparatus 100 in accordance with a preferred embodiment of the present invention is described. The leading edge contour measurement apparatus 100 includes a template 102, a pair of clamps 104, a first pair of pins 106-106□, a second pair of pins 107-107 □, a plurality of sticks 108, and a stick holder 110.

The template 102 includes a C-shaped groove, and a plurality of through holes such that the C-shaped groove is on a first end, and the plurality of through holes are defined on a second end of the template 102. The template 102 defines the body of leading edge contour measurement apparatus 100 that includes a plurality of through holes. In this preferred embodiment, the template 102 includes least two through holes 112 and 114.
Stick holder 110 includes a plurality of radial holes such that each hole receives a stick 108. The sticks 108 are radially on template 102 along the C-shaped groove of template 102. Sticks 108 are positioned in holder 110 such that each of the sticks 108 is in the plane of Template 102. The sticks are movable through respective through hole in holder 110 on application of predefined amount of force. The sticks are movable along a central axis of the respective stick 108.
In this one preferred embodiment, the leading edge contour measurement apparatus 100 is preferably positioned with approximately 20 to 30mm offset from the blade profile. It is, however, understood that the offset distance of leading edge contour measurement apparatus 100 depends upon the profile of blade at a particular location. The thickness of leading edge contour measurement apparatus 100 is approximately 3mm and apparatus 100 is preferably made from materials such as aluminum, steel, acrylic etc.
Template 102 preferably includes apparatus location information 116 of the blade that indicates positioning information of the apparatus 100 on a predefined blade. Such information is preferably permanently stamped on the Template 102. For example, in this preferred embodiment, pressure side/suction side, blade type, and location in millimeters etc. is imprinted on each Template 102.
The stick 108 is a long and thin piece of metal having a point at one end. Each of the sticks is slidably positionable in holder 110. Each of the sticks 108 is movable in the holder 110 on application of external force only, otherwise the stick continues with a current

position. Stick holder 110 is preferably approximately coplanar with the plane of Template 102. The sticks 108 are positioned in the holder such that they are adjacently touching to each other in the plane of template 102. The stick length is defined in such way that when stick 108 touches to blade leading edge profile, a substantial portion is seen out of holder 110. Stick length is more if single leading edge contour measurement apparatus 100 is used for more than one locations of leading edge contour measurement to cater smaller leading edge profile of bade 350.
The sticks 108 are positioned on the leading edge of the blade such that the profile of the blade is covered by sticks 108. Sticks 108 are positioned such that a pointed end of each of the stick 108 is rested on the blade without any gap between two consecutive sticks. Hence the pointed end of each of the sticks rests on the blade leading edge. The pointed ends of the adjacent sticks advantageously 108 define a locus of points that is identical with a nose contour profile of the blade at a predefined location where the apparatus is positioned. The sticks 108 are approximately identical.
Now referring to FIG. 2, a typical wind turbine rotor blade 200 is shown. The blade 200 includes a root 202, a trailing edge 204, a leading edge 206, and a leading edge parting line 208. The leading edge 206 is defined along the parting line 208. The leading edge parting line 208 divides the blade into two parts such as pressure side 210 and suction side 212. The pressure side 210 is also referred as X-side. The suction side 212 is also referred as O-side.
Referring to FIGS. 3A and 3B a wind turbine rotor blade mould 300 and a wind turbine rotor blade 350 made from mould 300 in accordance with the preferred embodiment of the present invention is shown. Blade mould 300 includes a plurality of marks 302 defined on a pressure side 304, and a suction side 306 as per the standard design on the mould 300.

The 302 marks are preferably defined in pairs such that a first pair of marks is on X-side or pressure side 304, and a second pair marks is defined on O-side or suction side 306 of the mould 300. A plurality of first pairs and second pairs are defined on the pressure and suction sides 304, 306 respectively. It is to be noted that the FIG. 3B shows only first pairs defined on the pressure side and the second pairs on the suction side 306 are not seen in the FIG. 3B.
In this one preferred embodiment, preferably four marks 302 are defined per location such that a first pair of marks is on suction side 306 and a second pair of marks is defined on pressure side 304. The marks 302 are defined by considering the suction side 306, the pressure side 304, and the angle of inclination of the Template for each location. The marks 302 are defined on the mould surface where the leading edge contour of the blade needs to be measured. The marks 302 in accordance with the preferred embodiment are denoted by '+' symbol, however any other symbol such as X, -, etc. might be used as per the convenience.
It is to be understood that the marks 302 on the mould are reproduced on the blade 350 during the moulding process, and hence the blade 350 also includes marks 352, suction side 354 and pressure side 356. The marks 352 are preferably permanent in nature. It is to be understood, however, that the marks 352 are preferably produced on the blades 350 during the moulding process of blade 350 using the mould 300 in accordance with the present invention.
The marks 352 that are in close proximity with leading edge parting line 358 are preferably defined to guide a user to position the template 102 (Ref. FIG. 1) guidance of template with blade particularly for defining an angle of inclination. Marks that are away from leading edge parting line guide the template 102 in terms of angle of inclination, and leading edge profile measurement length along Y-direction of blade. The marks indicate location of the template along the Z-direction (lengthwise) of the blade 350, location of the template 102 along the Y-direction (chord wise) of the blade 350, and location of template

102 by considering angle of inclination of each leading edge contour measurement apparatus 100 with respect to blade. The use of marks advantageously avoids positioning errors of template on the blade.
As shown in FIG. 4, at least two pairs of pins 402, 402' and 404, 404' are positioned on Template 102 in association with holder 110. The first pair of pins 402 and 402D is close to leading edge parting line. It is to be noted that the pair of pins 402, 402D is angularly positioned on the Template 102. The first pair 402,402a is positioned on the Template 102 such that first pin 402 is positioned on pressure side 356 but approximately half of length of leading edge profile measurement, and second pin 402' is positioned on suction side 354 but approximately half of length of leading edge profile measurement for that particular position of the Template 102.
An up and down movement of each pin 402, 402' and 404, 404 □ along respective central axis through respective holes in holder 110 is achievable by application of manual force on the respective pin 402, 402 □ and 404, 404 □. Each of the pins 402, 402 □ and 404, 404□ is positioned on the template 102 such that the respective pin guide the positioning of template 102 on a predefined leading edge profile of wind turbine blade on which the template 102 is being positioned. Each of the pins is preferably positioned on the template 102 such that pointed ends of the pins 402,402', 404, 404' rest on a predefined mark of blade 350. It is to be noted that marks on the blade are permanent marks that are defined on the blade in a predefined fashion at the time of manufacturing of the blade in accordance with the present invention.
A second pair of pins 404, 404' is not close to leading edge parting line. The second pair is positioned on the Template 102 such that a first pin 404 of second pair is positioned on end of length of leading edge profile on pressure side 356 of template 102, and other second

pin 404D of second pair is positioned on end of length of leading edge profile of template 102 on suction side 354. Each of the pins 404, 404a of the second pair is positioned at a predefined location on the Template 102. The second pair of pins 404, 404D is used for proper alignment of template with blade as well as to indicate leading edge profile measurement length along- Y direction from leading edge parting line of blade. Each of the pins 402,402 □ and 404,404□ is positioned on the Template 102 such that pins are aligned with the predefined marks on the blade surface.
Referring to FIG. 5, a graph paper 500 in accordance with a preferred embodiment of the present invention is shown. For each position of leading edge contour measurement, a separate preferably tear proof graph paper 500 is required. The graph paper 500 includes at least three profiles 502, 504, and 506. The leading edge contour profiles 504 are in accordance with the standard drawing preferably developed using CAD tools for a predefined position. The scale is preferably 1:1. The second profile 502 and third profile 506 defines tolerances of the first profile 504. The second and third profiles 502, 506 preferably have different colour than that of the first profile 504. It is, understood, however that identification means, for example, colours of profiles 502 and 506 can have different line type than first profile 504. It is to be noted that the tolerance profiles 502, 506 have predefined scale preferably 1:1 in accordance with the present invention.
The graph paper 500 also includes predefined shapes 508 and identity information 510. It is to be noted that the shapes 508 on the graph paper 500 are approximately identical to that of shape of through holes on the respective Template 102 (Ref. FIG. 1). The shapes 508 are used to position the template 102 on the graph 500 to draw the leading edge contour profile. The shape 508 in this embodiment is triangular, however, shape 508 can be any other shape such as circular, rectangular etc.

The identity information 510 includes blade type, position of template, blade number, date etc. The identity information 510 such as date, and blade number is to be filled by a person who uses the process of the present invention. Further relevant information on the graph paper 500 is preferably pre-printed with a scale 1:1.
Referring to FIG.6, another embodiment of leading edge contour measurement apparatus 600 in accordance with a preferred embodiment of the present invention is described. The embodiment 600 is identical to that of the preferred embodiment 100, except arrangement of sticks 108 (Ref. FIG. 1). In this embodiment, the leading edge contour measurement apparatus 600 includes a template 602, a clamp 604, a plurality of pairs of pins 606-606D, at least three groups of sticks 608, 610, 612, and at least three stick holders 614, 616, 618. The Template 602 defines the body of leading edge contour measurement apparatus 600 that includes at least two through holes 620 and 622.
The first group of sticks 608 and third group of sticks 612 are opposedly positioned on Template 602. Second group of sticks 610 is positioned approximately centrally relative to first group of sticks 608 and third group of sticks 612. The sticks in the three groups 608, 610, and 612 are radially arranged along a C-shaped groove of the template 602.
The first group of sticks 608 is securely positioned with a first holder 614. Similarly the second and third groups of sticks 610, 612 are securely positioned by second and third holders 616, 618 respectively. The sticks in each group 608, 610, and 612 are positioned in accordance with the leading edge profile of a wind turbine blade. The axis-X is approximately normal to second holder 616. Axis-Y is approximately normal to first and third holders 614 and 618. It is to be understood, however that the sticks in first group 608 and third group 612 are parallel to axis-Y, and sticks in the second group 610 are approximately parallel to axis-X. The sticks in each group are movable inside and outside the respective holders 614, 616, 618, on application of external force preferably manually, such

that sticks in the first group 608 and third group 612 are parallel to axis-Y and sticks in second group 610 are parallel to axis-X. The sticks are movable through respective holders 614, 616, 618 on application of external axial force from any side, however the sticks in groups 608, 610, 612 continue a current position on absence of external force.
Referring to FIG. 7, one more embodiment 700 of the leading edge contour template measurement apparatus 100 is shown. In this embodiment, the leading edge contour template measurement apparatus 700 includes at least four pairs of opposed pins 702-702□, 704-704 □, 706-706 □, and 708-708 □. The embodiment 700 is identical to that of the preferred embodiment 100, except any one pairs of pins 704, 704' to 708, 708' and number of pair of through holes 712. The present embodiment 700 is advantageously useful to measure leading edge contour at predefined two different locations on a specific blade.
Referring to FIGS. 3B and 7, the leading edge contour measurement apparatus 700 is usable for two different locations for leading edge profile measurement, for example, a first location Z16000, and a second location Z20000. For, first location Z16000 related leading edge profile measurement, through hole 710 are preferred. However, for the second location Z20000 related leading edge profile measurement, the through holes 712 are preferred.
For first location related Z16000 leading edge blade profile measurement with template 700, marks 352 close to leading edge parting line 358 align with the pins 706 and 706' which indicates placement of apparatus 700 on blade 350. As well for same location marks 352 those are away from leading edge parting line 358 of blade 350 align with pins 702 and 702' which indicates placement of apparatus 700 on blade 350, and same shows leading edge contour measurement length along Y-direction of blade 350.
Leading edge contour measurement apparatus 700 is used for leading edge measurement profile of blade 350 for other location Z20000 also. Marks 352 on blade surface

nearer to leading edge parting line of blade 350 align with the pins 708 and 708' which indicates placement of template on blade 350. For same location, marks 352 on blade surface that are away from leading edge parting line of blade 350 align with pins 704 and 704' which indicates placement of apparatus 700 on blade 350 as per standard profile developed, preferably using any CAD tool and the same shows leading edge contour measurement length along Y-direction of blade 350.
Numbers of through holes and pins in apparatus preferably depend upon the number of locations for which the apparatus 100 is to be used for leading edge contour measurement. For example, if the apparatus 100 is to be used for three different locations for leading edge contour measurement then the apparatus 100 includes at least six the through holes 112 such that one pair of holes is usable for one location, and twelve pins 106 such that two pairs of pins for one location are required.
Referring to FIG. 8, graph paper 500 is shown that includes a fourth profile 800 in addition to the three profiles 502, 504, 506. The profile 800 is a measured profile of leading edge contour of blade 350 for particular position in accordance with the present invention. This profile 800 is preferably developed by using a pencil such that while drawing the profile the pencil follows a locus defined by the pointed ends of the sticks 108. The profile 800 is approximately coincident with the profile developed by the locus of pointed ends of sticks 108 while the sticks 108 are rested on the profile of the blade. Profile 800 is the desired profile in accordance with the present invention.
Referring to FIGS. 1, 3B and 4, a preferred process of positioning the leading edge contour measurement apparatus 100 of the present invention is described. While positioning the Template 102 on the blade, position of pins 402, 402 □ and 404, 404 □ is adjusted by an up and down movement of the respective pin along respective central axis. The adjustment of position of each of the pins 402, 402 □ and 404, 404 □ is preferably separately done by

application of manual forces on the respective pins 402, 402□ and 404, 404D by a user. The pins 402, 402 □ and 404,404 □ are movable along their respective central axes. When pointed ends of all four pins 402, 402 □ and 404, 404 □ align with the predefined marks 352 of blade 350 for a particular position, then the specific Template 102 is supposed to be positioned on the blade properly by considering length, cord and inclination. After positioning the pins 402,402□ and 404, 404□ on accordance pairs of marks 352, sticks 108 are manipulated such that a pointed end of the each of the sticks 108 is rested on the surface of blade 350. This positioned of the apparatus 100 is locked with the clamps 104.
Referring to FIGS. 1 and 8, now a process of measuring the leading edge blade contour profile in accordance with present invention is described. It is to be noted that for each of the blades, leading edge contour measurement is done at predefined locations of the blade with the leading edge contour measurement apparatus 100. These predefined locations marks 352 are impressed on the surface of blade 350 during the process of manufacturing of the respective blade from mould 300.
For example, the predefined locations of marks 352 on a particular type of blades are 20000, 23000, 25000, 30000, 33000, 36000, 37000, 38000, 39000, 40000, 41000, and 42000. If these twelve locations are considered then for at least three successive locations one leading edge contour apparatus 100 of the present invention is needed. In other words, if these locations are considered, then at least four templates are needed to measure leading edge profile at these twelve locations. However, in accordance with prior art templates and methods at least twelve templates were needed for such twelve locations. It is to be noted that, if distance between two locations is minimum, then maximum locations can be covered in one template & vice versa. It is also noted, however, that in the prior art wrong placement (lengthwise, widthwise, angle of inclination) of a template on blade would have provided inaccurate readings.

To position the leading edge contour template apparatus 100 correctly reference marks 302 are made on blade moulds. As a result the impression of each mark 302 is achieved on each blade 350 in the form of marks 352. One can position the template apparatus 100 with reference to the predefined marks 352. It is understood that the reference marks 352 are made available on the blade 350 at the location where contour templates are to be positioned by means of pins 106-106□, 107-107□. In accordance with the present invention at least two marks are provided on pressure side 356 and at least two are on suction side 354.
The measurement begins from a first mark 352 either from a root or a last mark 352 from tip of the blade. The positions of the marks 352 are noted on the blade 350. A leading edge contour apparatus 100 of particular position of the blade for which leading edge contour needs to be measure is selected. The template apparatus 100 is positioned on the leading edge of the blade surface for which leading edge profile is to be measured. Now at that particular location of blade for which leading edge contour needs to be measured, at least four marks 352 are located such that two marks 352 are on suction side and two marks 352 on pressure side. Now the blade type for which apparatus 100 is made, is insured. Then the template location is matched with the mark 352 on the blade. It is insured that suction and pressure surface of apparatus 100 matches with suction and pressure surfaces of blade.
Then pins 106-106', 107-107* are moved towards marks 352 by hand such that pins 106-106% 107-107' align with respective marks 352. The apparatus 100 is positioned on the blade with clamp 104. All sticks 108 are radially moved towards blade leading edge such that each of them makes a contact with the blade surface.
The apparatus is removed from the blade surface. A graph paper 500 is taken for the location of measured leading edge profile of blade with particular template type and measured location are insured with graph paper 500. Then the blade number for which

leading edge profile needs to be measured and date are mentioned in the space provided in the graph paper 500.
In a next step, the template apparatus 100 is positioned on the graph paper. The holes 508 on the graph paper 500 is matched with the through holes in the template 112 and 114 of apparatus 100 to insure appropriate positioning of the template 100 on the graph paper 500. This step insures that template and graph paper are aligned. Now with marker or pencil, curve 800 is drawn manually by using end points of sticks 108. The curve/profile is developed 800 in accordance with the profile defined by the endpoints of adjacent sticks 108. The locus of the endpoints of the sticks defines the required profile 800 in accordance with the present invention. After this step the newly developed profile 800 is compared with the originally designed profile 504 of blade leading edge. In this step, it is seen if the new profile 800 lies in between two tolerances 502 and 506 blade leading edge curves or not. If new profile 800 lies in between two tolerance profiles 502 and 506, then it indicates that blade leading edge profile for that particular location is made correctly. It is in aerodynamic tolerance.
The preferred process is common for template 700 by considering Z16000 position, with pins 706, 706' and 702, 702'. The through holes are identified preferably with triangle. Now the above mentioned process is repeated for another location Z20000, preferably with another set of pins 708,708' and 704,704' and through holes shown by half circle using same edge contour measurement apparatus 700. Apparatus 100 can be used for more than one location of leading edge blade profile measurement but individual graph paper 500 is required for that particular location of blade for which profile is measured.
A user draws the profile 800 on graph paper 500 and checks if drawn profile is lies in between tolerances profile 502, 506. The user also checks the leading edge profile 504 of blade for that repaired position also. User may take a picture of the drawn profile along with CAD and tolerances profiles from graph paper for record. The newly developed profile 800 is

observed. If newly developed profile 800 is out of two tolerance profiles 502 and 506, then that is an indication of deviated leading edge profile. By using the deviated profile 800, one can repair the blade surface. For a next use of same graph paper 500, the details are erased preferably with an eraser to reuse the graph paper.
The pins 106-106' and sticks 108 are positioned in the holder 110 such that the pins 106-106' and sticks 108 are movable only on application of external force manually by a user. The pins 106-106' and sticks 108 continue to retain their current position when external force is not being applied. The advantage of the leading edge contour measurement apparatus 100 and process of the present invention is that the results are in the form of plots of profiles. The process and apparatus 100 of the present invention assist to decide if the blade profile lie in the given tolerances are not. There is no need of any measurement tool for getting plotted profile such as tape measure, vernier, tapper gauge etc. One leading edge contour template apparatus 100 can measure profile of any blade 350 for at least three locations. Further there is no need to hold template for longer time on blade as that of prior art.
Time consuming process of manual measurement is avoided by using this process and apparatus. The apparatus and process of the present invention advantageously saves man efforts and avoids mistakes/error that are observed in the prior art techniques. Apparatus 100 and the preferred process is very simple in operation due to which it avoids utilization of skill man power. Because of measurement tool like a Vernier caliper is not the part of this process and apparatus 100, less time is required to get the leading edge profile of blade 350. The holder 110 advantageously positions sticks 108 and pins 106,106', 107, 107' in the plane of the template 102.
The marks 352 advantageously indicate location of the leading edge contour templates apparatus 100 along the Z- direction (lengthwise) of the blade, and location of the leading edge contour templates apparatus 100 along the Y direction (chord wise) of the blade.

Marks 352 nearer to leading edge parting line 358 are defined for guiding template apparatus 100 with blade in terms of angle of inclination. Marks 352 away from leading edge parting line are also for guiding template apparatus 100 with blade in terms of angle of inclination and same indicates leading edge profile measurement length along Y-direction of blade from blade leading edge parting line.
It is to be noted that per location, there are four marks 352 such that two marks are on pressure side and the other two are suction side. These four marks position leading edge contour apparatus 100 correctly on the blade surface by considering a length (along Z direction), a chord (along Y direction), and an angle of inclination.
The embodiments of the invention shown and discussed herein are merely illustrative of modes of application of the present invention. Reference to details in this discussion is not intended to limit the scope of the claims to these details, or to the figures used to illustrate the invention.

We Claim:
1. An apparatus for a leading edge contour measurement of a wind turbine blade for
inspecting a profile of the leading edge of wind turbine blades, the apparatus for
leading edge contour measurement of the wind turbine blade comprising:
a template, the template having a c-shaped groove and a plurality of through holes of a predefined shape, the template having a holder configured thereon;
a plurality of sticks, the sticks being radially positioned on the template in association with the holder through a plurality of radial holes defined therein;
a plurality of pair of pins, the pair of pins being radially positioned on the template in association with the holder through a respective pair of radial holes defined therein, the pair of pins positioning the template at a predefined location on the blade for developing a current profile of the leading edge contour of wind turbine blades; and
at least one pair of clamps for positioning the template on the leading edge of the wind turbine blade.
2. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the through holes are selected from one or more of the following a circular shape, a triangular shape, a square shape, and the like.
3. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the radial holes position the respective sticks and pins in a plane of the template.
4. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the template includes apparatus location information.
5. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the stick holder positions in the plane of the template.

6. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the stick is a long and thin piece of metal having a point at one end.
7. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the sticks are positioned in the holder such that the sticks are adjacently touching to each other along the plane of template.
8. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the current profile is defined by a locus of points of endpoints of the adjacent sticks.
9. The apparatus for leading edge contour measurement as claimed in claim 8, wherein the current profile is identical with a profile of the leading edge contour profile of the blade at a predefined location where the apparatus is being positioned.
10. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the sticks are movable through respective through hole defined in the holder along a central axis of respective stick.
11. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the pins are movable through respective through hole defined in the holder along a central axis of respective stick.
12. The apparatus for leading edge contour measurement as claimed in claim 1, wherein the plurality of sticks define at least three groups of sticks being radially positioned in respective holders.
13. The apparatus for leading edge contour measurement as claimed in claim 12, wherein a first group of sticks and a third group of sticks are positioned on the template in a substantially opposite manner.
14. The apparatus for leading edge contour measurement as claimed in claim 12, wherein a second group of sticks is positioned approximately centrally relative to the first group of sticks and the third group of sticks.

15. A wind turbine rotor blade comprising:
a plurality of pairs of marks being defined on a pressure side of blade and suction side of the blade per location.
16. The wind turbine rotor blade of claim 15, wherein the pairs of marks are defined per location on the blade surface such that a first pair of marks is on the pressure side, and a second pair of marks is on the suction side of the blade.
17. The wind turbine rotor blade of claim 16, wherein the plurality of pairs of marks are defined in a moulding process with a predefined mould having a plurality of pairs of marks on the mould.
18. A process for measuring blade edge contour profile comprising steps of: defining a plurality of pairs of marks on a blade, the marks being defined in the form of pairs;
positioning a template on the blade;
fixing the template on the blade using a pair of clamps such that pairs of pins align
with the pairs of marks on the blade;
positioning a plurality of adjacent radial sticks of the template on the blade such that a
pointed end of each stick touches the blade profile to achieve a current profile;
positioning the template on a predefined graph paper such that predefined through
holes on the template match with predefined shapes on the graph paper;
developing the current profile according to the shape defined by the pointed ends of
the sticks on the predefined graph paper; and
comparing the current profile with a standard profile on the graph paper.

19. The process for measuring blade edge contour profile as claimed in claim 18, wherein positioning the template on the blade includes positioning of at least two pairs of pins on the respective pairs of marks on the blade.
20. The process for measuring blade edge contour profile as claimed in claim 18, wherein the graph paper includes at least three profiles and a plurality of shapes being defined on the graph paper.
21. The process for measuring blade edge contour profile as claimed in claim 20, wherein the profiles include a standard profile and two tolerance profiles.
22. The process for measuring blade edge contour profile as claimed in claim 18, wherein the step of comparing the standard profile with the current profile includes identifying if the current profile lies within the predefined tolerance profiles on the graph paper.