Modular wind turbine blades

Abstract

A modular wind turbine blade is described. The modular wind turbine blade comprises first and second blade modules having spar caps embedded within their outer shells. The spar caps taper in thickness resulting in tapered recesses being defined in the outer shells. The tapered recesses in the first and second blade modules are aligned when the modules are placed end-to-end to form a continuous double-tapered channel. A connecting member having a double-tapered structure is bonded in the channel to connect the modules together. The invention also provides a mould for making the blade modules in which the mould surface includes a protruding elongate feature having a tapered portion configured to form the recesses in the outer shells. During layup and moulding of the outer shells, spar caps are supported on top of the tapered portion of the elongate feature.

1 . A modular wind turbine blade comprising first and second blade modules connected together by an elongate connecting member, each blade module comprising:
 an outer shell having a laminate structure, the outer shell defining an outer surface of the blade module, and a connecting region of the outer shell defining an interface end of the blade module;   a longitudinal spar structure embedded in the laminate structure of the outer shell, the spar structure having a tapered portion in the connecting region of the outer shell, the thickness of the tapered portion decreasing progressively moving towards the interface end of the blade module, such that a tapered recess is defined in the outer surface of the blade module in the connecting region, the tapered recess accordingly having a depth relative to the outer surface of the blade module that increases progressively moving towards the interface end of the blade module,   wherein the first and second blade modules are arranged end-to-end with their respective interface ends in abutment and their respective tapered recesses aligned to define a continuous double-tapered channel spanning the connecting regions of the first and second blade modules,   wherein the elongate connecting member has a double-tapered structure comprising first and second tapered ends, the double-tapered structure being complementary in shape to the double-tapered channel,   and wherein the elongate connecting member is bonded in the double-tapered channel and bridges the longitudinal spar structures of the first and second blade modules thereby connecting the blade modules together.   
     
     
         2 . The modular wind turbine blade of  claim 1 , wherein the connecting member comprises a pre-cured stack of pultrusions. 
     
     
         3 . The modular wind turbine blade of  claim 1 , wherein the tapered recess of each blade module has a flat portion of substantially constant depth adjacent to the interface end of the blade module. 
     
     
         4 . The modular wind turbine blade of  claim 1 , further comprising first and second bulkheads located inside the blade and bonded together at the interface between the first and second blade modules. 
     
     
         5 . The modular wind turbine blade of  claim 1 , further comprising a pre-cured cap bonded over the connecting member. 
     
     
         6 . A mould assembly for making a modular wind turbine blade, the mould assembly comprising:
 a mould surface shaped to form at least part of an outer shell of a first blade module of the modular wind turbine blade; and   an elongate feature protruding from the mould surface, the elongate feature having a tapered end region defining an inclined upper surface for supporting a portion of a spar structure to be embedded in the outer shell of the first blade module,   wherein a first end portion of the elongate structure tapers in height relative to the mould surface.   
     
     
         7 . The mould assembly of  claim 6 , wherein the mould surface has a first portion shaped to form at least part of the outer shell of the first blade module, and a second portion shaped to form at least part of the outer shell of a second blade module, and wherein the first and second portions are located in adjacent spanwise sections of the mould. 
     
     
         8 . The mould assembly of  claim 7 , wherein the mould includes a common elongate protruding feature spanning the first and second portions of the mould surface. 
     
     
         9 . The mould assembly of  claim 8 , wherein the common elongate protruding feature has a double-tapered structure comprising a tapered first end protruding from the first portion of the mould surface and a tapered second end protruding from the second portion of the mould surface. 
     
     
         10 . The mould assembly of  claim 9 , wherein the common elongate feature includes an intermediate section of substantially constant height between the first and second ends. 
     
     
         11 . The mould assembly of  claim 8 , wherein the common elongate feature is removable from the mould and configured for subsequent use to connect the first blade module to a second blade module. 
     
     
         12 . The mould assembly of  claim 8 , wherein the common elongate feature comprises a pre-cured stack of pultrusions. 
     
     
         13 . The mould assembly of  claim 6 , wherein the protruding elongate feature has a substantially flat portion of substantially constant height adjacent the tapered end portion, and the spar structure is arranged in the mould such that it terminates substantially at a boundary between the tapered end portion and the flat portion of the elongate feature.