Thermally compliant forward outer-diameter ring for a gas turbine engine
A forward outer diameter ring includes a flowpath ring extending circumferentially about a central axis and extending axially from a first end to a second end relative to the central axis. The second end of the flowpath ring is axially aft of the first end. A hoop stiffener is connected to the second end of the flowpath ring and extends circumferentially around the second end of the flowpath ring. The hoop stiffener includes a first stiffener end connected to the second end of the flowpath ring and a second stiffener end axially aft of the first stiffener end. The hoop stiffener further includes tabs formed in the second stiffener end. The tabs are circumferentially spaced apart from one another and connect the case segments to the second stiffener end. The case segments are circumferentially arranged about the central axis relative one another.
1. A forward outer diameter ring comprising:
a flowpath ring extending circumferentially about a central axis and extending axially from a first end to a second end relative to the central axis, wherein the second end is axially aft of the first end;
a hoop stiffener connected to the second end of the flowpath ring and extending circumferentially around the second end of the flowpath ring, and wherein the hoop stiffener comprises:
a first stiffener end connected to the second end of the flowpath ring;
a second stiffener end axially aft of the first stiffener end; and
tabs formed in the second stiffener end, and wherein the tabs are circumferentially spaced apart from one another;
case segments connected to the second stiffener end by the tabs, and wherein the case segments are circumferentially arranged about the central axis relative one another; and
a slot between a first case segment and a second case segment of the case segments.
2. The forward outer diameter ring of claim 1 further comprising:
a finger seal extending radially outward and axially aft from the first end of the flowpath ring, wherein the finger seal is connected to the flowpath ring at the first end of the flowpath ring.
3. The forward outer diameter ring of claim 1 further comprising:
a second hoop stiffener connected to a radially outer side of the flowpath ring between the first end and the second end of the flowpath ring, wherein the second hoop stiffener extends circumferentially around the flowpath ring.
4. The forward outer diameter ring of claim 1 , wherein the hoop stiffener further comprises:
a full hoop formed on the first stiffener end and extending circumferentially about the second end of the flowpath ring and extending completely around the second end of the flowpath ring.
5. The forward outer diameter ring of claim 4 , wherein the hoop stiffener further comprises a midsection between the first stiffener end and the second stiffener end of the hoop stiffener curves radially outward from both the first stiffener end and the second stiffener end.
6. The forward outer diameter ring of claim 5 , wherein the hoop stiffener further comprises:
an axial cross-section of the hoop stiffener from the first stiffener end to the second stiffener end is bell-shaped.
7. The forward outer diameter ring of claim 4 , wherein the hoop stiffener further comprises:
circumferential cuts on the second stiffener end, wherein each of the circumferential cuts extends between two of the tabs, and wherein each circumferential cut extends overa seam between two of the case segments.
8. The forward outer diameter ring of claim 7 , wherein each of the circumferential cuts tapers axially toward the second stiffener end as each of the circumferential cuts extends aft.
9. The forward outer diameter ring of claim 1 further comprising:
a seal extending axially along the slot, wherein the seal is connected to the first case segment and the second case segment.
10. The forward outer diameter ring of claim 9 , wherein the seal is a feather seal, the feather seal comprising:
a first recess formed in a first edge of the first case segment, wherein the first recess extends axially along the first edge and extends circumferentially into the first edge of the first case segment;
a second recess formed in a second edge of the second case segment, wherein the second recess extends axially along the second edge and extends circumferentially into the second edge of the second case segment, and wherein the second edge of the second case segment faces the first edge of the first case segment; and
a plate in the first and second recesses and extending in the slot between the first case segment and the second case segment.
11. The forward outer diameter ring of claim 9 , wherein the seal is a sealing rail comprising: a plate wherein the plate projects radially outward to a midpoint of the plate; and a cross-sectional profile that is bell-shaped.
12. The forward outer diameter ring of claim 9 , wherein the seal comprises:
a plate curving from the first case segment to the second case segment and over the slot, wherein the plate comprises:
one or more holes extending through the plate over the first case segment; and
one or more slots extending through the plate over the second case segment, wherein each of the one or more slots is elongated in a circumferential direction relative to the central axis;
one or more fasteners extending through the one or more holes and connecting the plate to the first case segment; and
one or more pins extending radially from the second case segment and into the one or more slots to form a sliding connection between the plate and the second case segment.
13. The forward outer diameter ring of claim 1 , wherein:
the first case segment comprising a first edge extending axially along a length of the first case segment relative the central axis; and the second case segment comprising a second edge
extending axially along a length of the second case segment relative to the central axis, and
wherein the first edge and the second edge overlap.
14. The forward outer diameter ring of claim 13 , wherein the first edge of the first case segment shiplaps with the second edge of the second case segment.
15. The forward outer diameter ring of claim 13 , wherein the first edge of the first case segment is angled and narrows in a radial direction relative to the central axis as the first edge extends circumferentially relative to the central axis, wherein the second edge of the second case segment is angled and narrows in the radial direction as the second edge extends circumferentially relative to the central axis, and wherein the first edge and the second edge comprise matching slopes.
16. The forward outer diameter ring of claim 1 , further comprising a ship-lap seal axially between the flowpath ring and one or more of the case segments, the ship-lap seal comprising a tab extending radially outward from each case segment and extending forward from each case segment to extend over the second end of the flowpath ring and overlap with the second end of the flowpath ring, and wherein the ship-lap seal extends circumferentially around the second end of the flowpath ring.
17. The forward outer diameter ring of claim 1 , further comprising:
support hooks connected to a radially outer surface of one or more of the case segments at an aft end of the one or more of the case segments and configured to project into a support hook slot formed in a turbine exhaust case strut.
18. The forward outer diameter ring of claim 1 further comprising:
a support flange extending circumferentially around the central axis, the support flange connected to a radially outer portion on a fore side of a turbine exhaust case strut, and wherein the support flange is configured to radially support a radially inner portion of an aft end of one or more of the case segments.
19. A cooled turbine exhaust case assembly for a gas turbine engine, the assembly comprising:
a forward outer diameter ring, the forward outer diameter ring comprising:
a flowpath ring extending circumferentially about a central axis and extending axially from a first end to a second end relative to the central axis, wherein the second end is axially aft of the first end;
a hoop stiffener connected to the second end of the flowpath ring and extending circumferentially around the second end of the flowpath ring, and wherein the hoop stiffener comprises:
a first stiffener end connected to the second end of the flowpath ring;
a second stiffener end axially aft of the first stiffener end; and
tabs formed in the second stiffener end, and wherein the tabs are circumferentially spaced apart from one another;
case segments connected to the second stiffener end by the tabs, and wherein the case segments are circumferentially spaced about the central axis from one another;
a slot between each pair of the case segments; and
a seal extending axially along the slot, wherein the seal is connected to two of the case segments;
a turbine case located radially outward of the forward outer diameter ring;
a turbine exhaust case axially aft the turbine case and connected to the turbine case via a forward outer turbine exhaust case;
a plenum defined by the forward outer diameter ring, the turbine case, the turbine exhaust case, and the forward outer turbine exhaust case;
an inlet opening in the turbine case for introducing cooling air to the plenum; and
one or more film cooling openings in a fore region of the forward outer diameter ring configured to allow cooling air to exit the plenum to a hot gas path of the gas turbine engine to provide film cooling to the forward outer diameter ring.