Method of fabricating a composite material blade having internal channels, and a composite material turbine engine blade

1. A method of fabricating a turbine engine blade out of composite material comprising fiber reinforcement densified by a matrix, the method comprising:

making a fiber blank by weaving a first plurality of warp yarns with a second plurality of weft yarns, the warp yarns of the first plurality being arranged in successive layers and extending in a longitudinal direction of the fiber blank corresponding to a longitudinal direction of the blade to be made, one layer of warp yarns in the first plurality of warp yarns being woven with the second plurality of weft yarns and including one or more yarns fully consisting of sacrificial material;

shaping the fiber blank to obtain a preform of the blade to be made;

densifying the preform by impregnating the preform with a liquid composition including a precursor for the material of the matrix to obtain a blade having fiber reinforcement constituted by the preform and densified by the matrix; and

after the preform has been densified, completely eliminating the one or more yarns fully consisting of sacrificial material to form an internal channel in the blade,

wherein the internal channel extends in the longitudinal direction of the blade and includes a first end at a bottom surface of a root of the blade and a second end at a tip of an airfoil of the blade, and

wherein the one layer of warp yarns including the one or more yarns fully consisting of sacrificial material is an internal layer of warp yarns situated between two surface layers forming a skin of the blade.

2. The method according to claim 1 , wherein the sacrificial material is selected from at least one of the following materials:

a hot-melt material; and

a material that can be dissolved by a solvent.

3. The method according to claim 2 , wherein the one or more yarns of sacrificial material are eliminated by heat treatment or by applying a solvent.

4. The method according to claim 1 , wherein the fiber blank is made by three-dimensionally weaving at least yarns of the second plurality of weft yarns linking together yarns of the first plurality of warp yarns over a plurality of layers.

5. The method according to claim 4 , wherein the three-dimensional weaving is multi-layer weaving with a weave of a type selected from at least one of the following weaves: satin, multi-satin, multi-plain, and interlock.

6. The method according to claim 1 , wherein the yarns of the first plurality of warp yarns other than the one or more yarns made of sacrificial material, and the yarns of the second plurality of weft yarns, are made of ceramic or carbon material.

7. The method according to claim 1 , wherein weights of the yarns of sacrificial material is determined as a function of sizes of the internal channels formed in the blade.