Fiber preform for a hollow turbine engine vane

Abstract

A fiber preform for a hollow turbine engine vane, and a method of fabricating such a hollow vane are provided. The preform includes a first fiber structure including a main longitudinal portion for forming a pressure side wall of an airfoil; a second fiber structure including a main longitudinal portion for forming a suction side wall of the airfoil; each of the first and second fiber structures includes a first interlinking zone extending along the front edge of its main longitudinal portion, which first zones are integral with each other and form a first interlinking portion, and a second interlinking zone extending along the rear edge of its main longitudinal portion, the second zones being integral with each other and forming a second interlinking portion. The main longitudinal portions of the first and second fiber structures are dissociated so as to leave a gap between the main longitudinal portions forming an airfoil hollow.

1 . A fiber preform for a hollow turbine engine vane, the preform comprising:
 a first fiber structure obtained by three-dimensional weaving and comprising at least one main longitudinal portion suitable essentially for forming a pressure side wall of an airfoil;   a second fiber structure obtained by three-dimensional weaving and comprising at least one main longitudinal portion suitable essentially for forming a suction side wall of the airfoil;   wherein each of the first and second fiber structures further includes a first interlinking zone extending along the front edge of its main longitudinal portion, which first zones are integral with each other and form a first interlinking portion of the preform, and a second interlinking zone extending along the rear edge of its main longitudinal portion, the second zones being integral with each other and forming a second interlinking portion of the preform; and   wherein the main longitudinal portions of the first and second fiber structures are dissociated so as to leave a gap between said main longitudinal portions suitable for forming an airfoil hollow;   wherein the first interlinking zones of the first and second fiber structures are woven jointly in interlinked manner and/or the second interlinking zones of the first and second fiber structures are woven jointly in interlinked manner;   wherein the main longitudinal portions of the first and second fiber structures are woven jointly in non-interlinked manner;   wherein at least one of the fiber structures further includes at least one radial portion extending from the bottom or top edge of its main longitudinal portion and suitable for forming a platform or a fastener flange; and   wherein at least one of the fiber structures includes an overlap portion that, when the fiber structure is flat, lies in front of at least a portion of the first interlinking zone of said fiber structure or behind at least a portion of the second interlinking zone of said fiber structure, a gap being left between said overlap portion and the interlinking zone in question.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . A fiber preform according to  claim 1 , wherein the first and/or second interlinking portion possesses smaller width at its base and/or at its tip than in its middle. 
     
     
         5 . A hollow vane, in particular of the TRV type, wherein it is made as a single piece of composite material from a fiber preform according to  claim 1 , said preform being shaped in a mold and embedded in a matrix. 
     
     
         6 . A hollow vane according to  claim 5 , wherein the fiber preform is made with fibers of ceramic oxide type, preferably of alumina, mullite, silica, or zirconia. 
     
     
         7 . A hollow vane according to  claim 5 , wherein the matrix is of ceramic oxide type, preferably of alumina, mullite, silica, or zirconia. 
     
     
         8 . A turbine engine, comprising a hollow vane according to  claim 5 . 
     
     
         9 . A method of fabricating a hollow vane, comprising the following steps:
 weaving and cutting out a fiber preform according to  claim 1 ;   folding and shaping the fiber preform in a mold possessing the shape of the desired unfinished blank;   placing an insert in the gap between the two main longitudinal portions;   injecting and solidifying the matrix around the fiber preform in order to obtain the unfinished blank;   removing the insert; and   machining the interlinking parts of the unfinished flank corresponding to the interlinking portions of the fiber preform so as to obtain the leading and trailing edges of the final part.   
     
     
         10 . A method according to  claim 9 , wherein, during the shaping step, the second fiber structure is curved so as to present, between its second and first interlinking zones, at least a first concave curve suitable for forming the downstream portion of the pressure side of the vane, followed by a convex curve suitable for forming the upstream portion of the pressure side of the vane, itself followed by a second concave curve serving to join with the first fiber structure in the first interlinking zone, a distal portion of the first interlinking zone then extending on the suction side of the chord plane defined by the leading and trailing edges of the desired final part. 
     
     
         11 . A method according to  claim 10 , wherein the step of machining the first interlinking part of the unfinished blank, corresponding to the first interlinking portion of the fiber preform, includes cutting away from the distal portion of the first interlinking part and smoothing the leading edge and the suction side wall. 
     
     
         12 . A method according to  claim 9 , wherein the step of machining the second interlinking part of the unfinished blank, corresponding to the second interlinking portion of the fiber preform, essentially comprises thinning down said second interlinking part in order to obtain the trailing edge.