Turbomachine inner casing fitted with a heat shield
View Patent ↗The present invention relates to an improvement in the clearances 12 between a casing and the moving blades 11 of a rotor 1 of a turbomachine, in particular a casing provided for this purpose, and also to a turbomachine fitted with such a casing. The invention applies in particular to aircraft turbojet engines. It relates more particularly to a turbomachine inner casing 21 comprising a plurality of annular shrouds 23 that are provided with flanges 24 for joining two adjacent shrouds 23 together. According to the invention, this inner casing 21 further includes: at least one circumferential heat shield 5 covering the flanges 24 in contact with two adjacent shrouds 23 ; and a cavity 6 filled with a first thermal insulation 8 , said cavity being located between a concave internal surface 51 a , 52 a of the heat shield 5 and the flanges 24. The heat shield 5 is formed by a plurality of sectors 50 joined end to end.
1. A turbomachine inner casing comprising:
a plurality of annular shrouds that are provided with flanges for joining two adjacent shrouds together, which further includes:
at least one circumferential heat shield covering the flanges in contact with two adjacent shrouds; and
a cavity filled with a first thermal insulation, said cavity being located between a concave internal surface of the heat shield and the flanges,
wherein an outermost surface of the heat shield sandwiching the cavity between the heat shield and the flanges is free of holes, and
the outermost surface of the heat shield directly faces the flanges in a radial direction.
2. The turbomachine inner casing as claimed in claim 1 , wherein the heat shield includes, on its concave internal surface, at least one projecting circumferential sealing rib directed toward the facing flange and coming into contact with said flange.
3. The turbomachine inner casing as claimed in claim 1 , wherein the heat shield includes, on its concave internal surface, at least one transverse sealing rib that matches the shape of the facing flanges.
4. The turbomachine inner casing as claimed in claim 1 , wherein the heat shield is formed by a plurality of sectors joined end to end.
5. The turbomachine inner casing as claimed in claim 4 , wherein the sectors are identical.
6. The turbomachine inner casing as claimed in claim 4 , wherein each sector includes a plurality of circular holes configured to fasten the sector to the flanges by bolts.
7. The turbomachine inner casing as claimed in claim 6 , wherein each sector includes, on its concave internal surface, radially aligned with each circular hole, a bearing surface that projects toward the surface of the flange facing it.
8. The turbomachine inner casing as claimed in claim 6 , wherein each sector includes, on its convex external surface, radially aligned with each circular hole, a counterbore for receiving one end of a bolt.
9. The turbomachine inner casing as claimed in claim 1 , wherein the heat shield has a cross section in the form of a U provided with a base and with two arms.
10. The turbomachine inner casing as claimed in claim 9 , wherein the cavity is formed by pockets between the arms of the U and the flanges facing said arms of the U.
11. The turbomachine inner casing as claimed in claim 9 , wherein the cavity is formed by a circumferential housing between the base of the U and the flanges facing said base of the U.
12. The turbomachine inner casing as claimed in claim 1 , wherein the first thermal insulation is chosen from inert air, glass fiber and silica wool felt.
13. The turbomachine inner casing as claimed in claim 1 , wherein the heat shield is formed by an envelope filled with a second thermal insulation.
14. The turbomachine inner casing as claimed in claim 13 , wherein the second thermal insulation includes at least one of glass fiber or silica wool felt.
15. The turbomachine inner casing as claimed in claim 13 , wherein the envelope consists of a flexible metal sheet.
16. The turbomachine inner casing as claimed in claim 13 , wherein the first thermal insulation is inert air.
17. A turbomachine fitted with an inner casing as claimed in claim 1 .
18. A turbomachine inner casing comprising:
a plurality of annular shrouds that are provided with flanges for joining two adjacent shrouds together, which further includes:
at least one circumferential heat shield covering the flanges in contact with two adjacent shrouds, and
a cavity filled with a first thermal insulation, said cavity being located between a concave internal surface of the heat shield and the flanges,
wherein said heat shield is formed by a plurality of sectors joined end to end; and
each sector has a first end and a second end, the second end having a cross section larger in size than the cross section of the first end, the second end of a second sector overlapping the first end of a first sector adjacent the second sector.
19. The turbomachine inner casing as claimed in claim 18 , wherein, in the overlap region between two adjacent sectors, the concave internal surface of the second sector matches the convex external surface of the first sector.
20. The turbomachine inner casing as claimed in claim 18 , wherein the sectors are placed end to end around the flanges, the first end of each sector being located downstream of a circumferential airflow and the second end of each sector being located upstream thereof, the circumferential flow of air flowing around the inner casing.