Fan casing for an aircraft turbomachine
A fan casing for an aircraft turbomachine includes an annular body extending around an axis and equipped with an annular attachment flange at each of its axial ends. The casing further includes an annular coating made from abradable material, wherein the body is made from a composite material, and further includes an annular stiffener that is arranged inside the body and that carries the coating. The stiffener includes an annular ring, a radially outer face of which is separated radially from the body and a radially inner face of which receives the coating. The stiffener further includes annular attachment tabs configured to the wall to the body.
1. A fan casing for an aircraft turbomachine, comprising an annular body extending about an axis (A) and equipped with an annular fastening flange at each of its axial ends, and an annular coating made from abradable material, wherein said annular body is made from a composite material and further comprises an annular stiffener configured to reinforce and increase the stiffness of the structure of the fan casing, the fan casing being configured to surround a plurality of blades, the annular stiffener is arranged radially inside said annular body and carries said coating, said stiffener comprising an annular wall, a radially outer face of which is separated radially from the annular body and a radially inner face of which receives said coating,
wherein the fan casing comprises an empty annular space between the annular wall of the stiffener and the annular body of the fan casing, the empty annular space having a fixed shape and a fixed volume,
wherein the annular stiffener comprises annular tabs configured to fasten said wall to said annular body,
wherein the annular stiffener has a constant omega-shaped cross-section in capital form providing mechanical strength, retention capacity and keeping the form of the annular space, and
wherein the annular wall and the annular tabs of the annular stiffener are integrally formed,
wherein the annular stiffener comprising carbon folds increasing its stiffness,
wherein each of said tabs is L-shaped in cross-section and comprises a first annular leg configured to fasten to the annular body, and a second annular leg configured to connect the wall to said first annular leg.
2. The fan casing according to claim 1 , wherein said annular body is made from a preform of woven fibres and densified by a polymeric resin.
3. The fan casing according to claim 1 , wherein said stiffener has a constant thickness (e).
4. The fan casing according to claim 3 , wherein the stiffener has a constant thickness of 5 mm.
5. The fan casing according to claim 1 , wherein said wall has a diameter which varies along said axis (A).
6. A method for producing a fan casing according to claim 1 , the method comprising:
a) producing the annular body in composite material,
b) producing the stiffener,
c) placing and fastening the stiffener inside the body, and
d) placing and fastening the abradable coating on the radially inner face of the stiffener.
7. The method according to claim 6 , wherein the stiffener is produced in carbon folds.
8. The method according to claim 6 , wherein the stiffener is glued to the fan body.
9. An aircraft turbomachine, comprising a fan casing according to claim 1 .
10. The fan casing according to claim 1 , wherein said stiffener is located in a central portion of the body and is configured to extend opposite top of blades of a fan wheel.
11. The fan casing according to claim 1 , wherein the stiffener has an axial length or dimension, along the axis of rotation, of between 40 and 60% of the length of the fan casing.
12. The fan casing according to claim 1 , wherein the stiffener is made from carbon folds.
13. The fan casing according to claim 1 , wherein the annular wall and the annular tabs are produced in carbon folds.
14. The fan casing according to claim 1 , wherein the stiffener has an axial dimension of about 400 mm and a height of 30 mm.
15. The fan casing according to claim 1 , wherein the first annular leg and the second annular leg are perpendicular to the wall or inclined with regard to the wall of the stiffener.
16. A fan casing for an aircraft turbomachine, comprising an annular body extending about an axis (A) and equipped with an annular fastening flange at each of its axial ends, and an annular coating made from abradable material, wherein said body is made from a composite material and further comprises an annular stiffener that is made of composite material and arranged inside said body, the stiffener carrying said coating, said stiffener comprising an annular wall, a radially outer face of which is separated radially from the body and a radially inner face of which receives said coating,
wherein an empty annular space having a fixed shape and a fixed volume is provided between the body and the annular wall,
wherein the stiffener comprises annular tabs glued to said body,
wherein the stiffener comprising carbon folds increasing its stiffness.
17. The fan casing according to claim 16 , wherein the annular wall and the annular tabs of the stiffener are integrally formed.
18. The fan casing according to claim 16 , wherein each of said tabs is L-shaped in cross-section and comprises a first annular leg configured to fasten to the annular body, and a second annular leg configured to connect the wall to said first annular leg.
19. The fan casing according to claim 18 , wherein said second annular leg is perpendicular to at least one of said wall and said first annular leg.
20. The fan casing according to claim 18 , wherein said second annular leg is inclined with respect to at least one of said wall and said first annular leg.
21. The fan casing according to claim 18 , wherein the second annular legs of the tabs have at least one of different heights (h1, h2) and different radial dimensions with respect to said axis (A).