Turbomachine blade that is cast with a local fattening of the section of the airfoil

1. A monocrystalline turbine blade for a turbomachine turbine rotor, said blade being cast and directionally solidified, comprising:

an airfoil with a leading edge, a pressure face, a suction face, a trailing edge, a skeleton and having a longitudinal axis, the faces having a neck line, respectively a pressure face neck and a suction face neck relative to the adjacent blade in the turbomachine rotor of which it forms an element, the airfoil having a theoretical profile;

an endpiece of the airfoil, having an airfoil end face on a stream side, forming an angle with the axis; and

a connection zone between the airfoil and said airfoil end face, said connection zone forming a fattening of the airfoil,

wherein said connection zone extends about the leading edge between a point P 1 situated on the suction face of the airfoil and on the end face of the endpiece upstream of the suction face neck with reference to the direction of flow of the fluid and a point P 3 situated on the pressure face of the airfoil and on the end face of the endpiece upstream of the pressure face neck,

wherein a line of points situated furthest upstream relative to a direction of flow of fluid in the connection zone P 2 is situated in line with the leading edge on the skeleton, and

wherein a surface of the connection zone has a profile C 1 between the line of the points P 2 and the point P 1 which is similar to the suction face surface of the theoretical profile of the airfoil, and a surface of the connection zone has a profile C 3 between the line of the points P 2 and the point P 3 which is similar to the pressure face surface of the theoretical profile of the airfoil.

2. The blade as claimed in claim 1 , wherein a section of said airfoil in the connection zone, measured perpendicularly to a leading edge of the theoretical profile, increases as it goes toward said endpiece, while remaining less than the section of the blade in its lower portion.

3. The blade as claimed in claim 1 , wherein the line of the points P 2 , excluding fillets for connection to the airfoil end face and to the leading edge of the blade, is rectilinear and forms with the airfoil end face an angle α at least equal to 75°.

4. The blade as claimed in claim 3 , wherein the angle α is less than 90°.

5. The blade as claimed in claim 1 , wherein a curvature of the connection zone, in at least one sectional plane perpendicular to a leading edge of the theoretical profile, at the corresponding point of the line of the points P 2 is a function of the curvature of the leading edge of the theoretical profile and of the distance separating, in said sectional plane, the point of the line of the points P 2 from the leading edge of the theoretical profile.

6. The blade as claimed in claim 5 , wherein the radius of curvature at said point of the line of the points P 2 is equal to a corresponding radius of curvature on the theoretical profile, plus a third of said distance.

7. The blade as claimed in claim 1 , wherein the surface of the zone of connection to the point P 1 is tangential along its end to the suction face of the blade.

8. The blade as claimed in claim 1 , wherein the surface of the connection zone at P 3 is tangential along its end to the pressure face of the blade.

9. The blade as claimed in claim 1 , wherein the profile C 1 is deduced, at least partially, from that of the suction face surface of the theoretical airfoil by a combination of geometric transformations of the translation, change of scale and/or affinity type.

10. The blade as claimed in claim 1 , wherein the profile C 3 is deduced, at least partially, from that of the pressure face surface FI of the theoretical airfoil by a combination of geometrical transformations of the translation, change of scale and/or affinity type.

11. The blade as claimed in claim 1 , wherein, in at least one sectional plane perpendicular to a leading edge of the theoretical profile, a center of gravity of the connection zone defined by a surface situated upstream of the points P 1 and P 3 relative to the direction of flow of the fluid is on the axis of smallest inertia of the surface of the theoretical profile.

12. A turbomachine module comprising at least one blade as claimed in claim 1 .

13. A turbomachine comprising at least one blade as claimed in claim 1 .

14. The blade as claimed in claim 3 , wherein an angle between the line of the points P 2 and the leading edge is based on the angle α.

15. The blade as claimed in claim 11 , wherein the center of gravity of the connection zone is as close as possible to a center of gravity of the theoretical profile.