Patent Publication Number: US-2022228552-A1

Title: Wind turbine blade spar structure

Description:
TECHNICAL FIELD 
     The present invention relates generally to wind turbine blades and more specifically to an improved shear web for a wind turbine blade and method for assembling the same. 
     BACKGROUND 
     Modern wind turbine blades comprise a longitudinally extending spar to increase the structural rigidity of the blade. In some wind turbine blades, the spar structure comprises a shear web attached between opposed spar caps. The shear web may be substantially I-shaped, comprising a web panel arranged between flanges that extend along longitudinal edges of the panel. The flanges may be manufactured off-line and integrated with the web panel during manufacture of the shear web, for example in a lamination process. Typically, the flanges comprise a base and an upstand extending away from the base. The flanges are attached to the spar caps in an assembled spar. 
     Optimally designed wind turbine blades typically twist along their spanwise length, between a root and a tip of the blade, to capture energy from the incident wind more effectively. The shear webs must be designed to accommodate blade twist. Known solutions involve varying the angle of the flange base with respect to the flange upstand along the length of the shear web, or alternatively maintaining a constant base-upstand angle and using additional adhesive in certain regions to fill the resultant gaps in bondlines between the flanges and the spar caps. In the former case, a number of different flange profiles must be manufactured to accommodate twist along the blade. In the latter case, blade weight is increased due to the use of additional adhesive, and variations in the bondline thickness can result in unfavourable structural characteristics for the spar. 
     It is against this background that the present invention has been developed. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the invention there is provided a wind turbine blade shear web comprising an elongate web panel and a mounting flange extending along a longitudinal edge of the panel. The mounting flange comprises a base for bonding the shear web to a surface of a wind turbine blade shell and an upstand extending transversely to the base. The upstand is adhesively bonded to a side surface of the web panel and inclined relative to the side surface such that a bond gap is defined between the upstand and the side surface. The bond gap is at least partially filled with adhesive and one or more spacers are located in the bond gap, wherein the one or more spacers are configured to set an angle of inclination between the panel and the base of the mounting flange. 
     The bond gap may be substantially triangular when viewed in transverse cross section. The one or more spacers may be substantially triangular in transverse cross section. The one or more spacers may be shaped as wedges. 
     The base of the mounting flange may be substantially parallel to the surface of the blade shell. 
     The mounting flange may comprise first and second spanwise flange sections bonded respectively to first and second spanwise sections of the panel, the first and second flange sections being substantially identical in transverse cross section. The base of the first flange section may be inclined at a first angle to the panel and the base of the second flange section may be inclined at a second angle to the panel, the second angle being different to the first angle. A first spacer may be arranged in the bond gap between the first flange section and the panel, and a second spacer may be arranged in the bond gap between the second flange section and the panel. The first spacer may have a different size and/or shape to the second spacer. 
     The angle of inclination between the panel and the base of the mounting flange may vary in a spanwise portion of the shear web, and an angle between the base and the upstand of the mounting flange may be substantially constant throughout the spanwise portion. This may be achieved as described above, wherein a portion of the shear web comprises a plurality of flange sections having a substantially identical transverse cross section, with the bases of the flange sections being inclined at different angles to the panel. Alternatively, a single spanwise flange section may define a plurality of angles between the panel and the base of the spanwise flange section in the spanwise portion of the shear web. 
     The shear web may comprise a mounting flange having a suitable torsional flexibility such that a single flange section may twist along its spanwise length, defining a plurality of angles between the shear web panel and the base of the mounting flange section along the length of said section. A plurality of spacers having different sizes and/or shapes may be located in the bond gap between the upstand of such a flange section and a side of the shear web panel. 
     The angle of inclination between the panel and the base of the mounting flange may vary along the length of the shear web, and an angle between the base and the upstand of the mounting flange may be substantially constant along the length of the shear web. 
     In a spanwise portion of the blade, the shear web may comprise a plurality of mounting flange sections wherein the angle between the base and the upstand of each flange section is different, the flange sections being dissimilar in transverse cross section. The angle between the base and upstand of a first flange section may therefore be different to the angle between the base and upstand of a second flange section in some spanwise portions of the blade. 
     The mounting flange may be substantially L-shaped in transverse cross section. 
     The shear web may comprise a further mounting flange extending along the longitudinal edge of the panel, said further mounting flange comprising a base and an upstand extending transversely to said base, said upstand being adhesively bonded to an opposite side surface of the web panel and inclined relative to the opposite side surface such that a further bond gap is defined between said upstand and the opposite side surface. The further bond gap may be at least partially filled with adhesive and one or more spacers may be located in the further bond gap. 
     The respective bases of the two mounting flanges may be substantially coplanar when the shear web is viewed in transverse cross section. 
     The mounting flange may comprise a further upstand extending transversely to the base, and the longitudinal edge of the panel may be received between the upstands such that a further bond gap is defined between the further upstand and an opposite side surface of the shear web panel. The further bond gap may be at least partially filled with adhesive and one or more spacers may be located in the further bond gap. The mounting flange may be substantially pi-shaped (π) in transverse cross section. 
     Both bond gaps may taper in width and one of the bond gaps may taper in an opposite sense to the other bond gap when the shear web is viewed in transverse cross section. 
     In another aspect of the present invention there is provided a wind turbine blade comprising the shear web as described herein. The blade shell may have a twisted profile and the angle of inclination between the panel and the base of the mounting flange may vary along the length of the shear web to accommodate the twisted profile of the blade shell. 
     The wind turbine blade may comprise an adhesive bondline between the base of the mounting flange and the surface of the blade shell. The height of the bondline from the blade shell surface to the mounting flange base may be substantially uniform along the length of the shear web as a result of the varying angle of inclination between the panel and the base of the mounting flange which sets the angle of inclination between the mounting flange base and the shear web panel to substantially match the twisted profile of the blade shell. 
     In a further aspect of the present invention there is provided a method of making a wind turbine blade shear web. The method comprises providing an elongate web panel, providing a mounting flange having a base and an upstand extending transversely to the base, and providing one or more spacers. The method further comprises setting an angle of inclination between the panel and the base of the mounting flange by arranging the one or more spacers between the upstand and a side surface of the panel and bonding the upstand to the side surface of the panel. 
     The method may further comprise curing adhesive between the upstand and the side surface. 
     The method may further comprise arranging a second mounting flange with a longitudinal edge of the shear web panel, the second mounting flange being arranged with its upstand inclined relative to a second side surface of the shear web panel. The method may further comprise applying adhesive between the upstand and second side surface and arranging one or more spacers between the upstand and second side surface of the panel to support the upstand of the additional mounting flange in inclined relation to the second side surface of the web panel. 
     The method may further comprise forming a compression joint clamping the upstand of a mounting flange to the shear web panel. 
     The method may further comprise arranging a mounting flange having a further upstand extending transversely to the base. Arranging the mounting flange with a longitudinal edge of the panel may comprise arranging the shear web panel between the upstands. The method may further comprise arranging one or more spacers between each of the upstands and the shear web panel to set an angle of inclination between the panel and the base of the mounting flange. 
     The method may further comprise supporting the shear web in a vertical orientation and applying a compressive force in a direction substantially parallel to the shear web panel, wherein the arrangement of the spacers serves to self-locate the mounting flange at the correct orientation with respect to the shear web panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described in further detail by way of nonlimiting examples only with reference to the following figures in which: 
         FIG. 1 a    is a schematic perspective view of part of a wind turbine blade comprising a shear web in accordance with the prior art; 
         FIG. 1 b    is a detailed view of the region marked i in  FIG. 1   a;    
         FIG. 1 c    is a detailed view of the region marked ii in  FIG. 1   a;    
         FIG. 2 a    is a schematic perspective view of part of a further wind turbine blade comprising a shear web in accordance with the prior art; 
         FIG. 2 b    is a detailed view of the region marked iii in  FIG. 2   a;    
         FIG. 2 c    is a detailed view of the region marked iv in  FIG. 2   a;    
         FIG. 3  is a schematic view of an example of a shear web in a transverse cross section; 
         FIG. 4  is a schematic view of the shear web of  FIG. 3  shown in a further transverse cross section; 
         FIG. 5  is a schematic view of part of a shear web arrangement in accordance with a further example in a transverse cross section; 
         FIG. 6  is a schematic view of a stage in the manufacture of a shear web shown in a transverse cross section; 
         FIG. 7 a    is a schematic perspective view of a portion of a wind turbine blade comprising an example of a shear web; 
         FIG. 7 b    is a detailed view of the region marked v in  FIG. 7   a;    
         FIG. 7 c    is a detailed view of the region marked vi in  FIG. 7   a;    
         FIG. 8  is a schematic view of a further portion of a shear web in a transverse cross section; 
         FIG. 9  is a schematic view of part of a shear web arrangement in accordance with a further example in a transverse cross section; and 
         FIG. 10  is a schematic view of a stage in the manufacture of the shear web arrangement of  FIG. 9  in a transverse cross section. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1 a    is a schematic perspective view of a spanwise portion  10  of a wind turbine blade  12  comprising a shear web  14  according to the prior art. The wind turbine blade  12  comprises a shell  16  which extends in a spanwise direction (S), and in a chordwise direction (C) between a leading edge  18  and a trailing edge  20 . The shear web  14  extends in the spanwise direction (S) to provide structural reinforcement to the blade  12 . In the spanwise portion  10  shown, the blade shell  16  comprises an airfoil profile when viewed in a transverse cross section. Transverse cross sections  22 ,  24  in first and second spanwise sections  26 ,  28  of the shear web  14  are shown in  FIG. 1 a   . As described by way of background, the blade  12  twists along its spanwise (S) length in order to maximise the capture of energy from wind incident on the blade  12 . The twist of the blade  12  can be seen in a comparison of the cross sections  22 ,  24  in the first and second spanwise sections  26 ,  28  respectively, wherein the airfoil profiles are rotated in relation to one another. 
       FIGS. 1 b  and 1 c    respectively show enlarged views of the regions annotated i and ii in  FIG. 1 a   . As shown in  FIGS. 1 b  and 1 c   , the prior art shear web  14  comprises a web panel  30  arranged between upper and lower flanges  32 ,  34 . The flanges  32 ,  34  are substantially T-shaped, comprising a base  36  and an upstand  38 . The upstands  38  of the flanges  32 ,  34  are integrated with the shear web panel  30  in a lamination process and the shear web  14  accordingly comprises a composite structure wherein the web panel  30  and flanges  32 ,  34  are sandwiched between two outer laminate layers  40 . The flanges  32 ,  34  of the shear web  14  are bonded to a surface  42 ,  44  of the blade shell  16  by a layer of adhesive  46 . 
     The T-shaped profile of the flanges  32 ,  34  and their orientation are consistent along the length of the shear web  14 , as can be seen in a comparison of  FIGS. 1 b  and 1 c   . Similarly, the orientation of the shear web panel  30  is consistent along the length of the blade  12  due to its rigid planar form. The configuration of each flange  32 ,  34  is optimised in the first spanwise section  26  (as shown in  FIG. 1 b   ) such that a uniform adhesive bondline thickness T 1  is achieved between the base  36  of each flange  32 ,  34  and the blade shell surface  42 ,  44  to which it is bonded. However, the configuration of each flange  32 ,  34  is not optimised for bonding in the second spanwise section  28  due to the twist of the blade  12  and the variation in airfoil geometry. 
     The adhesive bondline  46  between the flanges  32 ,  34  and the blade shell surface  42 ,  44  in the second spanwise section  28  (as shown in  FIG. 1 c   ) varies in thickness T 2  across the chordwise (C) width of each flange  32 ,  34 . Additional adhesive  46  is required in the bondline to fill the space between the base  36  of each flange  32 ,  34  and the blade shell surface  42 ,  44 . This can result in unfavourable structural characteristics as the adhesive bondline thickness T between the shear web  14  and the blade shell surface  42 ,  44  is inconsistent along the length of the shear web  14 , and also results in increased adhesive use, increasing the weight of the blade  12 . 
       FIG. 2 a    is a schematic perspective view of a spanwise portion  110  of a wind turbine blade  112  comprising a shear web  114  according to a further example of the prior art, with  FIGS. 2 b  and 2 c    showing detailed views of transverse cross sections  122 ,  124  in first and second spanwise sections  126 ,  128  respectively. Contrary to the prior art example described with reference to  FIGS. 1 a  to 1 c   , the adhesive bondline thickness T between the shear web  114  and the blade shell surface  142 ,  144  is consistent along the length of the shear web  114  in the present example. A comparison of  FIGS. 2 b  and 2 c    shows that the bondline thickness T 3 , T 4  is substantially uniform throughout both the first and second spanwise sections  126 ,  128  of the shear web  114 . 
     However, the T-shaped profile of the flanges  132 ,  134  and their orientation are not consistent along the length of the shear web  114 . The configuration of each flange  132 ,  134  is optimised in both the first and second spanwise sections  126 ,  128  of the shear web  114  such that a uniform adhesive bondline thickness T 3 , T 4  is achieved between the base  136  of each flange  132 ,  134  and the blade shell surface  142 ,  144  to which they are bonded. Whilst it is desirable to achieve a substantially uniform bondline thickness T along the length of the shear web  114 , a number of different flange profiles  132   a ,  132   b ,  134   a ,  134   b  must be provided in order to match the inclination of the blade shell surface  142 ,  144  with respect to the shear web panel  130  in different spanwise (S) locations. A wind turbine blade shear web  114  according to such a prior art example is therefore relatively expensive, requiring a large number of unique flange sections  132   a ,  132   b ,  134   a ,  134   b  having different geometries along the length of the shear web  114 . 
       FIG. 3  is a schematic view showing an example of a wind turbine blade shear web  210  in a transverse cross section. The shear web  210  comprises an elongate web panel  212  which extends in a spanwise direction (S), perpendicular to the plane of the page in  FIG. 3 . 
     The shear web  210  comprises a mounting flange  214  extending along a longitudinal edge  216  of the panel  212 . In this example, the shear web  210  comprises mounting flanges  214  extending along both longitudinal edges  216 ,  218  of the web panel  212 . It will be understood that features in this example and the relations between these are substantially identical at both longitudinal edges  216 ,  218  of the web panel  212 , and the description will be provided in reference to the lower longitudinal edge  216  in the configuration depicted in  FIG. 3 . 
     The mounting flange  214  comprises a base  220  and an upstand  222  extending transversely to the base  220 . In this example, the mounting flange  214  is substantially L-shaped in transverse cross section. The mounting flange base  220  is bonded to a surface of a wind turbine blade shell in an assembled blade. The upstand  222  of the mounting flange  214  is adhesively bonded to a side surface  224  of the shear web panel  212 . 
     The upstand  222  of the mounting flange  214  is inclined relative to the side surface  224  such that a bond gap  226  is defined between the upstand  222  and the side surface  224 . The bond gap  226  is at least partially filled with adhesive  228  in order to bond the mounting flange upstand  222  to the shear web panel  212 . As shown in  FIG. 3 , the bond gap  226  is substantially triangular when viewed in a transverse cross section due to the inclined relation of the mounting flange upstand  222  with the side surface  224 . 
     The shear web  210  further comprises one or more spacers  230  located in the bond gap  226  between the mounting flange upstand  222  and the shear web panel  212 . The spacers  230  are configured to set an angle of inclination X between the panel  212  and the base  220  of the mounting flange  214 . In this example, the spacers  230  are shaped as wedges which are substantially triangular in transverse cross section. In this example, the mounting flange  214  is substantially rigid and the dimensions of the one or more spacers  230  therefore correspond directly to the orientation of the mounting flange  214 , thereby setting the angle of inclination X between the panel  212  and the base  220  of the mounting flange  214 . 
     As will be described in further detail below with reference to  FIGS. 7 a  to 7 c   , the angle of inclination X between the panel  212  and the mounting flange base  220  varies along the length of the shear web  210 . Spacers  230  having different sizes or shapes are therefore implemented in different spanwise (S) sections along the length of a blade such that the angle of inclination X between the panel  212  and the base  220  of the mounting flange  214  substantially matches an angle of inclination of a blade shell surface with respect to the panel  212  along the length of the shear web  210 . 
     Each of the one or more spacers  230  located in the bond gap  226  has a discreet spanwise length. For example, the spacers  230  may have a spanwise length in the range of 10 mm to 100 mm. Where a plurality of spacers  230  are located in the bond gap  226  along the length of the shear web  210 , the spacers  230  are distributed at spanwise intervals. For example, the spacers  230  may be located in the bond gap  226  at spanwise intervals in the range of 1 m to 2 m separation. 
     In some examples, a single spacer may have a spanwise length substantially similar to the length of the shear web, the single spacer thereby extending along the entire length of the shear web. 
       FIG. 4  is a transverse cross section of the wind turbine blade shear web  210  of  FIG. 3  in a spanwise section in between spacers  230 , i.e. where no spacer  230  is present in the bond gap  226 . In such a spanwise section, the bond gap  226  is substantially or at least partially filled with adhesive  228  to bond the upstand  222  of the mounting flange  214  to the side surface  224  of the shear web panel  212 . The upstand  222  of the mounting flange  214  is inclined relative to the side surface  224  of the shear web panel  212  as a result of the arrangement of one or more spacers  230  in the bond gap  226  in other spanwise sections along the length of the shear web  210 . 
       FIG. 5  is a schematic view of part of a wind turbine blade shear web  210  in accordance with another example shown in a transverse cross section. The shear web  210  in this example comprises a mounting flange  214   i , hereafter referred to as a first mounting flange, on a first side  232  of the shear web  210  as described in reference to  FIGS. 3 and 4 . The shear web  210  comprises a further mounting flange  214   ii , hereafter referred to as a second mounting flange, on a second side  234  of the shear web  210 , which extends along the same longitudinal edge  216  of the panel  212  as the first mounting flange  214   i . The second mounting flange  214   ii  comprises a base  220  and an upstand  222  extending transversely to the base  220 . In this example, the respective bases  220  of each of the mounting flanges  214   i ,  214   ii  are substantially coplanar when viewed in a transverse cross section as shown in  FIG. 5 . The base  220  of each mounting flange  214   i ,  214   ii  is bonded to a surface  236  of a wind turbine blade shell by a layer of adhesive  238 . 
     The upstand  222  of the second mounting flange  214   ii  is inclined relative to an opposite side surface  240  of the web panel  212 , the opposite side surface  240  being defined as the surface of the shear web panel  212  opposite to the previously-described side surface  224 . A further bond gap  242 , hereafter referred to as a second bond gap, is defined on the second side  234  of the shear web  210  between the upstand  222  of the second mounting flange  214   ii  and the opposite side surface  240 . The second bond gap  242  is at least partially filled with adhesive (not shown in  FIG. 5  for clarity) in order to adhesively bond the upstand  222  of the second mounting flange  214   ii  to the opposite side surface  240  of the web panel  212 . One or more spacers  230  are located in the second bond gap  242  and serve to set an angle of inclination Y between the base  220  of the second mounting flange  214   ii  and the shear web panel  212 . 
     In the present example, the second bond gap  242  is substantially triangular when viewed in transverse cross section. As shown in  FIG. 5 , each of the bond gaps  226 ,  242  taper in width W 1 , W 2  respectively, the width of a bond gap  226 ,  242  being defined as the distance in the chordwise direction (C) between the upstand  222  of a mounting flange  214   i ,  214   ii  and the respective side surface  224 ,  240  to which it is adhesively bonded. One of the bond gaps  226  or  242  tapers in an opposite sense to the other bond gap  242  or  226  when the shear web  210  is viewed in a transverse cross section. The opposite tapering of the bond gaps  226 ,  242  is resultant from the inclination X, Y of the base  220  of each mounting flange  214   i ,  214   ii  with respect to the shear web panel  212 , said inclination of the bases  220  being configured to best match the inclination Z of the surface  236  of the wind turbine blade shell with respect to the shear web panel  212 . 
       FIG. 6  is a schematic view in a transverse cross section showing a stage in the process of manufacturing a wind turbine blade shear web  210 . An elongate web panel  212  is provided and may be supported in a vertical orientation as depicted in  FIG. 6 , or may alternatively be oriented horizontally. 
     A mounting flange  214   i  is provided and arranged to extend along a longitudinal edge  216  of the shear web panel  212 . In the example shown in  FIG. 6 , a further mounting flange  214   ii  is arranged along the longitudinal edge  216  of the panel  212 . One or more spacers  230  are provided, and these are arranged in the bond gaps  226 ,  242  defined between the upstand  222  of each mounting flange  214   i ,  214   ii  and a respective side surface  224 ,  240  of the shear web panel  212 , setting the angle of inclination X, Y between the base  220  of each mounting flange  214   i ,  214   ii  and the shear web panel  212 . 
     The upstand  222  of each mounting flange  214   i ,  214   ii  is adhesively bonded to a respective side surface  224 ,  240  of the shear web panel  212 . Adhesive  228  (not shown in  FIG. 6  for clarity) may be applied between the upstand  222  of a mounting flange  214   i ,  214   ii  and a respective side surface  224 ,  240  of the panel  212  either before arranging the one or more spacers  230 , or after the arrangement of spacers  230 . Preferably adhesive  228  is applied before the one or more spacers  230  are arranged. Conducting the manufacturing stages in this order can aid in a more thorough adhesion between the mounting flange  214   i ,  214   ii  and web panel  212  as the adhesive  228  is squeezed into any openings throughout the bond gap  226 ,  242  when arranging the one or more spacers  230 . 
     In the example depicted in  FIG. 6 , a compression joint is formed to hold each mounting flange  214   i ,  214   ii  and the shear web panel  212  in fixed relation during manufacture of the shear web  210  prior to any adhesive  228  being cured. In this example, a nut and bolt configuration  244  is arranged through the mounting flange upstands  222  and shear web panel  212  in a substantially chordwise direction (C). Use of wedge shaped or tapering washers  246  ensures the compressive force is enacted on a surface perpendicular to the direction of the force and aids in the accurate alignment of shear web components. 
     It is anticipated that other means for holding a mounting flange  214  and shear web panel  212  in fixed relation during manufacture may be implemented in other examples, and the invention is not limited in this respect. For example, a U or G shaped clamp may be arranged below the mounting flange  214 , with fixed and movable jaws of the clamp extending around the base  220  of the mounting flange  214  to interface with the flange upstand  222  and a side surface  224 ,  240  of the shear web panel  212 . In such an example using a U or G shaped clamp, holes in the shear web components through which bolts may be arranged would not be required. 
     In some examples, the adhesive  228  (shown in  FIG. 3 ) in the bond gaps  226 ,  242  is completely cured during the manufacture of the shear web  210 . In other examples, the adhesive  228  may be part-cured during assembly of the shear web  210  before the shear web  210  is arranged with a wind turbine blade shell. In such an example, the adhesive  228  in the bond gap  226 ,  242  may be fully cured concurrently with the curing of the adhesive  238  (shown in  FIG. 5 ) which bonds the shear web  210  to a surface  236  of the wind turbine blade shell. 
       FIG. 7 a    is a schematic perspective view showing a spanwise portion  248  of a wind turbine blade  250  comprising a spanwise portion  252  of a shear web  210 . The wind turbine blade  250  comprises a blade shell  254  having a twisted profile designed to effectively capture energy from wind incident on the blade  250 . Transverse cross sections  256 ,  258  in first and second spanwise sections  260 ,  262  of the shear web  210  are shown on  FIG. 7 a   . A comparison of the cross sections  256  and  258  shows the varying airfoil profile throughout the spanwise portion  248  of the blade  250 . 
       FIGS. 7 b  and 7 c    respectively show detailed views of the regions on  FIG. 7 a    marked v and vi. Accordingly,  FIG. 7 b    shows a schematic view of the shear web  210  in a transverse cross section in a first spanwise section  260  of the shear web  210 , and  FIG. 7 c    shows a schematic view of the shear web  210  in a transverse cross section in a second spanwise section  262  of the shear web  210 . 
     In this example, each of the mounting flanges  214  comprise first and second spanwise flange sections  214   a ,  214   b  which are bonded respectively to first and second spanwise sections  212   a ,  212   b  of the shear web panel  212 . The first and second spanwise flange sections  214   a ,  214   b  are substantially identical in transverse cross section as shown in  FIGS. 7 b  and 7 c   . A shear web  210  as shown in this example therefore does not require unique flange sections having different transverse cross-sections in comparison to the prior art example of  FIGS. 2 a    to  2   c.    
     Each of the flange sections  214   a ,  214   b  comprises a base  220  and an upstand  222  extending transversely to the base  220 . An angle A defined between the base  220  and the upstand  222  of the mounting flange  214 , or base  220  and upstand  222  of each flange section  214   a ,  214   b , is substantially constant throughout the spanwise portion  252  of the shear web  210 . For example, as seen in a comparison of  FIGS. 7 b  and 7 c   , the angle A between the base  220  and upstand  222  is substantially 90° for the first and second spanwise flange sections  214   a ,  214   b.    
     Conversely, the angle of inclination X between the panel  212  and the base  220  of the mounting flange  214  varies throughout the spanwise portion  252  of the shear web  210  in order to accommodate the twisted profile of the blade shell  254 . The base  220  of the first flange section  214   a , in the first spanwise section  260  of the shear web  210 , is inclined at a first angle X 1  with respect to the shear web panel  212 . The base  220  of the second flange section  214   b , located in the second spanwise section  262  of the shear web  210 , is inclined at a second angle X 2  with respect to the shear web panel  212 . The second angle of inclination X 2  is different to the first angle X 1  when comparing the orientation of a first spanwise flange section  214   a  to the orientation of a corresponding second spanwise flange section  214   b.    
     Referring still to  FIGS. 7 b  and 7 c   , the shear web  210  comprises a first spacer  230   a  arranged in the bond gap  226   a  between the first flange section  214   a  and the panel  212  in the first spanwise section  260  of the shear web  210 . Similarly, in the second spanwise section  262  of the shear web  210 , the shear web  210  comprises a second spacer  230   b  arranged in the bond gap  226   b  between the second flange section  214   b  and the panel  212 . As shown in  FIGS. 7 b  and 7 c   , the respective first spacer  230   a  has a different size and/or shape to the corresponding second spacer  230   b  located in the second spanwise section  262  of the shear web  210 . 
     The thickness H of the adhesive bondline  238  between the shear web  210  and the blade shell surface  236  is substantially uniform along the length of the shear web  210 . A comparison of the adhesive bondlines  238   a ,  238   b  in  FIGS. 7 b  and 7 c    shows the consistency in bondline thickness H between the first spanwise section  260  of the shear web  210 , in  FIG. 7 b   , and the second spanwise section  262  of the shear web  210  in  FIG. 7 c   . A bondline  238  of consistent thickness H along the length of the shear web  210  improves structural properties of the wind turbine blade  250  and enables more accurate structural modelling in designing the blade  250 . Further, adhesive usage is reduced with a consistent bondline thickness in comparison to the prior art example of  FIGS. 1 a  to 1 c   , resulting in a reduction in the weight of the wind turbine blade  250 . 
     A shear web  210  in accordance with this example therefore comprises the advantages of each of the prior art shear webs described with reference to  FIGS. 1 a  to 2 c   . Namely, the shear web  210  in this example enables a substantially uniform bondline thickness H between the shear web  210  and the blade shell surface  236  along the length of the shear web  210 , without the requirement of multiple unique flange sections which each have different transverse cross-sections. A substantially uniform bondline thickness H may therefore be achieved whilst reducing the number of unique parts required for the shear web  210 . 
     In a further example, the shear web  210  comprises a mounting flange  214  having a sufficient torsional flexibility that the flange  214  may twist along its spanwise length where spacers  230  of different shapes and/or sizes are located in the bond gap  226 . A single flange section  214   a ,  214   b  may therefore twist along its spanwise length, defining a plurality of angles X between the shear web panel  212  and the base  220  of the mounting flange section  214   a ,  214   b  along the length of the section. 
     In other spanwise portions of the blade  250  (not shown), the angle A between the base  220  and the upstand  222  of spanwise adjacent flange sections  214   a ,  214   b  may be different, the flange sections being dissimilar in transverse cross section. The angle A between the base  220  and upstand  222  of a first flange section  214   a  may therefore be different to the angle A between the base  220  and upstand  222  of a second flange section  214   b.    
       FIG. 8  shows a schematic view of a further portion  264  of a shear web  210  of a wind turbine blade  250  in a transverse cross section. In some spanwise portions of the wind turbine blade  250  it is anticipated that the upstand  222  of each mounting flange  214   i ,  214   ii  may be arranged substantially parallel to a respective side surface  224 ,  240  of the shear web panel  212  and that one or more spacers  230  are therefore not required in a bond gap  226 ,  242  to set an angle of inclination X of the mounting flange base  220 . As shown in  FIG. 8 , in such spanwise portions  264 , the bond gaps  226 ,  242  are a substantially uniform width W 3  throughout, and the upstand  222  of a mounting flange  214  is not inclined relative to the shear web panel  212 . In such a spanwise portion  264 , the shear web  210  may simply comprise an elongate panel  212  and one or more mounting flanges  214  extending along a longitudinal edge  216  of the panel  212 . 
     In an example, the mounting flanges  214  may extend along the entire length of the shear web  210 , or may alternatively extend in discrete spanwise (S) lengths  214   a ,  214   b . For example, such mounting flange sections  214   a ,  214   b  may extend in 1 m lengths and may be spaced along the length of the shear web  210  at regular or irregular spanwise intervals. 
     The mounting flange(s)  214  are adhesively bonded to side surfaces  224 ,  240  of the shear web panel  212 . In this example, the shear web  210  comprises a mounting flange  214  bonded to each side surface  224 ,  240  of the shear web panel  212 . It is also anticipated that in some spanwise portions of the blade  250 , the shear web  210  may only comprise a mounting flange  214  adhesively bonded to one of the side surfaces  224  or  240  of the panel  212 . 
     A spanwise portion  264  of the blade  250  as shown in  FIG. 8 , wherein the upstand  222  of a mounting flange  214  is substantially parallel to the shear web panel  212 , may be considered a datum point in the blade  250 . A deviation in the relative angle Z between the blade shell surface  236  and the shear web panel  212  from such a datum point along the length of the shear web  210  could require the use of a spacer  230  as described throughout in order to set the angle X of the mounting flange base  220  with respect to the web panel  212  for a given spanwise portion to match the inclination angle Z of the blade shell surface  236  with respect to the web panel  212 . 
       FIG. 9  is a schematic view of a further example shown in a transverse cross section. In this example, the shear web  310  comprises a mounting flange  314  having an upstand  322   i  a further upstand  322   ii , hereafter referred to as a second upstand, which extends transversely to the base  320 . The mounting flange  314  is therefore substantially pi-shaped (π) in transverse cross section and the longitudinal edge  316  of the shear web panel  312  is received between the upstands  322 . A bond gap  326  is defined between the upstand  322   i  and side surface  324 , and a further, second, bond gap  342  is defined between the second upstand  322   ii  and opposite side surface  340  of the panel  312 . 
     In a similar manner to the example described with reference to  FIG. 5 , each of the bond gaps  326 ,  342  are substantially triangular when viewed in a transverse cross section and taper in chordwise width W 4 , W 5 . The bond gaps  326 ,  342  taper in an opposite sense to one another as a result of the inclination X of the mounting flange base  320  in relation to the shear web panel  312 . 
     The bond gaps  326 ,  342  are at least partially filled with adhesive (not shown) which bonds each upstand  322   i ,  322   ii  to a respective side surface  324 ,  340  of the shear web panel  312 . One or more spacers  330 , as previously described, are located in each of the bond gaps  326 ,  342  to set an angle of inclination X between the shear web panel  312  and the base  320  of the mounting flange  314 . As described with reference to  FIGS. 7 a  to 7 c   , spacers  330  arranged in different spanwise sections of the shear web  310  may have a different size and/or shape such that the angle X between the web panel  312  and the mounting flange base  320  varies along the length of the shear web  310  to match the twisted profile of a wind turbine blade shell. 
     Further, as described with reference to the L-shaped mounting flanges  214  in  FIGS. 7 a  to 7 c   , the pi-shaped mounting flange  314  of this example may comprise first and second spanwise flange sections which are bonded respectively to first and second spanwise sections of the shear web panel  312 . The angle of inclination X between the base  320  of a first mounting flange section and the shear web panel  312  may be different to the angle of inclination X between the base  320  of a second mounting flange section and the shear web panel  312 . 
     In a similar manner to the example shown in  FIG. 8 , in some spanwise portions of the blade, a spacer  320  may not be required in the bond gaps  326 ,  342  between the upstands  322   i ,  322   ii  of a pi-shaped mounting flange  314  and the shear web panel  312 . In such a spanwise portion, the upstands  322   i ,  322   ii  of the pi-shaped flange  314  are arranged substantially parallel to the respective side surfaces  324 ,  340  of the shear web panel  312  to which they are adhesively bonded. 
       FIG. 10  schematically shows an arrangement of pi-shaped (π) mounting flanges  314  with a shear web panel  312  in a transverse cross-sectional view. In the assembly of a shear web  310  comprising pi-shaped mounting flanges  314 , the process may be simplified in comparison to the method for manufacturing a shear web  210  comprising L-shaped mounting flanges  214  as described with reference to  FIG. 6 . 
     When assembling a shear web  310  comprising a mounting flange  314  having two upstands  322 , there is a reduced requirement for fixtures or compression joints to correctly align components. Adhesive (not shown in  FIG. 10 ) is applied and one or more spacers  330  are arranged in each bond gap  326 ,  342  between the upstands  322  and the web panel  312 , the adhesive at least partially filling the bond gaps  326 ,  342 . The geometry of the spacers  330  and their arrangement with upstands  322  of the mounting flanges  314  serve to self-locate each mounting flange  314  in the desired orientation with respect to the shear web panel  312  through the application of a force in a direction substantially parallel to the shear web panel  312 , indicated by arrows F on  FIG. 10 . The required angle X between the mounting flange base  320  and the shear web panel  312  can therefore be achieved in a simple manufacturing process. As with the example described with reference to  FIG. 6 , adhesive in the bond gaps  326 ,  342  may be cured during the manufacture of the shear web  310 . Alternatively, the adhesive may be part-cured prior to being completely cured concurrently with the curing of adhesive bonding the shear web  310  to wind turbine blade surface  336 . 
     The examples described above provide a shear web for a wind turbine blade having a number of advantages over shear webs of the prior art. A shear web as described above may comprise fewer unique components, for example by implementing flange sections having a substantially identical transverse cross section, thereby increasing part commonality and reducing the cost of producing a wind turbine blade. Further, with shear webs as described in the examples above, a substantially uniform adhesive bondline thickness between the shear web and a surface of the wind turbine blade shell may be achieved without requiring a large number of unique flange sections. 
     The angle of inclination of the base of each mounting flange with respect to the shear web panel is more accurately matched to the angle of inclination of the blade shell surface with respect to the shear web panel throughout the shear web than with shear webs of the prior art. The load bearing capacity of the blade is thereby increased, and the substantially uniform bondline thickness enables more accurate structural modelling of the blade in the design phase. Further, adhesive usage, and thereby also weight of a blade comprising a shear web as described above, is reduced as a result of the substantially uniform bondline thickness along the length of the shear web despite the twisted profile of the blade. 
     The methods for manufacturing shear webs as described above also present advantages over prior art methods of manufacturing shear webs. In the methods described above, a shear web may be produced in a simpler manufacturing method than those of the prior art. In prior art methods for producing wind turbine blade shear webs, such as lamination or Vacuum Assisted Resin Transfer Moulding (VARTM), complex and often expensive tooling may be required to accurately manufacture a shear web to the design specification. No such tooling is required in manufacturing a shear web accordance with the examples provided above. Further, ancillary equipment such as vacuum pumps or infusion systems are not required in the present method. 
     Flexibility in the orientation of the shear web panel in the manufacture of a shear web according to the above described methods provides a benefit over prior art manufacturing methods. A vertically oriented shear web panel has a smaller footprint than a horizontally oriented panel, enabling more efficient use of floor space in a manufacturing facility. The methods may be used for a variety of different shear web designs for use in different wind turbine blade models, and separate tooling is not required to produce different shear web designs; further increasing efficiency of floor space usage. Shear webs for many different blade designs may therefore be produced in a single manufacturing facility. 
     Many modifications may be made to the examples described above without departing from the scope of the present invention as defined in the accompanying claims. 
     For example, although mounting flanges having an upstand extending substantially perpendicular to their base are depicted throughout the figures in relating to the examples described above, it is also anticipated that mounting flanges having angles other than 90° between the base and upstand may be adhesively bonded to a side surface of the panel. Such mounting flanges or flange sections may be implemented in spanwise portions where a spacer is required to set the angle of inclination of the base, and also in spanwise portions without a spacer in the bond gap. Similarly, mounting flanges, or mounting flange sections, having a range of different angles between their respective bases and upstands may be implemented along the shear web.