Seals for gas turbine engines
A turbine shroud for use in a gas turbine engine that includes a metallic carrier, a blade track, and a seal is disclosed. The seal is engaged with surfaces of the metallic carrier and the blade track to block ingress of hot gasses at the interface of the blade track and the metallic carrier.
1. A turbine shroud for use in a gas turbine engine that extends around a central axis, the turbine shroud comprising
an annular metallic carrier adapted to be coupled to a gas turbine engine case and formed to include a cooling channel that opens inwardly in a radial direction,
an annular blade track nested in the annular metallic carrier and arranged radially inward of the cooling channel, and
a metallic seal engaged with surfaces of the annular metallic carrier and a radially-outer surface of the annular blade track to block ingress of hot gases into the cooling channel at the interface of the annular blade track and the annular metallic carrier,
wherein the seal includes a first split ring having a W-shaped cross section that opens outwardly in the radial direction so that pressurized cooling air provided to the cooling channel encourages the first split ring to change size axially such that the first split ring engages the surfaces of the annular metallic carrier during use of the turbine shroud.
2. The turbine shroud of claim 1 , wherein the annular blade track comprises a ceramic-containing blade track.
3. The turbine shroud of claim 1 , wherein the first split ring includes a circumferential break that allows the first split ring to be expanded and contracted.
4. The turbine shroud of claim 3 , wherein the circumferential break in the first split ring provides a gap between first and second portions of the first split ring when the first split ring is assembled into the turbine shroud, and wherein the seal includes a gap filler that extends across the gap between the first and second portions of the first split ring.
5. The turbine shroud of claim 3 , wherein first and second portions of the first split ring adjacent to the circumferential break overlap one another when the first split ring is assembled into the turbine shroud.
6. The turbine shroud of claim 1 , wherein the seal includes a second split ring having a W-shaped cross section that opens outwardly in the radial direction so that pressurized cooling air provided to the cooling channel encourages the second split ring to change size axially during use of the turbine shroud.
7. The turbine shroud of claim 6 , wherein the first split ring and the second split ring each include a circumferential break that allows the first split ring and the second split ring to be expanded and contracted.
8. The turbine shroud of claim 7 , wherein the circumferential break of the first split ring is spaced about 180 degrees from the circumferential break of the second split ring.
9. The turbine shroud of claim 8 , wherein the second split ring is nested inside the first split ring so that at least a portion of the second split ring is arranged radially inward of the first split ring.
10. The turbine shroud of claim 8 , wherein about half of the second split ring is nested inside the first split ring.
11. The turbine shroud of claim 8 , wherein substantially all of the second split ring is nested inside the first split ring.
12. The turbine shroud of claim 1 , wherein the seal includes a plurality of biasing members arranged to bias the first split ring toward engagement with the annular blade track.
13. The turbine shroud of claim 12 , wherein the biasing members include a first spring ring that extends around the first split ring and engages a first radially-outwardly opening trough formed by the W-shaped cross section of the first split ring and a second spring ring that extends around the first split ring and engages a second radially-outwardly opening trough formed by the W-shaped cross section of the first split ring.
14. A turbine shroud for use in a gas turbine engine that extends around a central axis, the turbine shroud comprising
a carrier adapted to be coupled to a gas turbine engine case and formed to include a cooling channel that opens inwardly in a radial direction,
a blade track nested in the carrier and arranged radially inward of the cooling channel, and
a seal engaged with surfaces of the carrier defining the cooling channel and a radially-outer surface of the blade track, the seal including a first split ring having a W-shaped cross section that opens outwardly in the radial direction.
15. The turbine shroud of claim 14 , wherein the blade track comprises a ceramic-containing blade track.
16. The turbine shroud of claim 14 , wherein the seal includes a second split ring having a W-shaped cross section that opens outwardly in the radial direction and at least a portion of the second split ring is nested inside the first split ring.
17. The turbine shroud of claim 16 , wherein the first split ring and the second split ring each include a circumferential break that allows the first split ring and the second split ring to be expanded and contracted and the circumferential break of the first split ring is spaced about 180 degrees from the circumferential break of the second split ring.
18. The turbine shroud of claim 14 , wherein the seal includes a plurality of biasing members arranged to bias the first split ring toward engagement with the annular ceramic-containing blade track.
19. A method of assembling a turbine shroud comprising
creating a seal by nesting a first split ring having a W-shaped cross section and a second split ring having a W-shaped cross section so that circumferential breaks in the first and the second split rings are offset from one another by about 180 degrees, and
positioning the seal radially between a carrier and a blade track so that the seal engages surfaces defining a radially-inwardly opening cooling channel formed by the carrier and a radially-outer surface of the blade track.