Out-flow margin protection for a gas turbine engine

1. A cooled turbine exhaust case assembly located adjacent to a low pressure turbine section, the assembly comprising:

a plenum defined at least in part by a forward outer diameter flowpath ring and a turbine case, wherein the forward outer diameter flowpath ring is located aft of the low pressure turbine section;

a probe positioned at a probe opening formed in the forward outer diameter flowpath ring; and

an inlet opening in the turbine case for introducing cooling air to the plenum.

2. The assembly of claim 1 and further comprising:

one or more film cooling openings defined in the forward outer diameter flowpath ring for allowing cooling air to exit the plenum to a hot gas flowpath to provide film cooling to the forward outer diameter flowpath ring.

3. The assembly of claim 2 , wherein the film cooling openings defined in the forward outer diameter flowpath ring are located in a region that is upstream and spaced from the probe opening.

4. The assembly of claim 1 and further comprising:

a slider seal secured at the probe opening by tab structures to provide sealing between the probe and the forward outer diameter flowpath ring.

5. The assembly of claim 1 , wherein the probe comprises an exhaust gas temperature probe.

6. The assembly of claim 1 , wherein the inlet opening in the turbine case introduces cooling air to the plenum at a first angle relative to an adjacent surface of the turbine case, and wherein the first angle is about 15° to about 60°.

7. The assembly of claim 6 , wherein the first angle is defined in a generally circumferential direction with respect to the turbine case.

8. The assembly of claim 1 , wherein the inlet opening in the turbine case introduces cooling air to the plenum at an angle such that cooling air is not directly impinged upon the forward outer diameter flowpath ring.

9. The assembly of claim 1 and further comprising:

a cooling air delivery tube secured at the inlet opening in the turbine case, wherein the cooling air delivery tube is bent to deliver cooling air to the plenum at an angle relative to the turbine case.

10. The assembly of claim 9 , wherein the angle at which the cooling air delivery tube introduces cooling air to the plenum is such that cooling air is not directly impinged upon the forward outer diameter flowpath ring.

11. The assembly of claim 9 , wherein the cooling air delivery tube is bent to deliver cooling air to the plenum substantially tangential to an adjacent surface of the turbine case.

12. The assembly of claim 9 and further comprising:

a control orifice for throttling cooling air flow through the cooling air delivery tube to the plenum.

13. The assembly of claim 12 and further comprising:

a pin for securing the control orifice relative to the inlet opening.

14. The assembly of claim 1 , wherein the forward outer diameter flowpath ring has a divergent shape.

15. The assembly of claim 1 , wherein the turbine case comprises a low pressure turbine case.

16. A cooled turbine exhaust case assembly for a gas turbine engine, the assembly comprising:

a forward outer diameter flowpath ring;

a low pressure turbine case located generally radially outward of the forward outer diameter flowpath ring;

a plenum defined at least in part by the forward outer diameter flowpath ring and the low pressure turbine case;

an inlet opening in the low pressure turbine case for introducing cooling air to the plenum; and

one or more film cooling openings defined in an upstream region of the forward outer diameter flowpath ring for allowing cooling air to exit the plenum to a hot gas flowpath of the gas turbine engine to provide film cooling to the forward outer diameter flowpath ring.

17. The assembly of claim 16 , wherein the inlet opening in the low pressure turbine case introduces cooling air to the plenum at a first angle relative to an adjacent surface of the low pressure turbine case, and wherein the first angle is about 15° to about 60°.

18. The assembly of claim 16 , wherein the inlet opening in the low pressure turbine case introduces cooling air to the plenum at an angle such that cooling air is not directly impinged upon the forward outer diameter flowpath ring.

19. The assembly of claim 16 and further comprising:

a cooling air delivery tube secured to the low pressure turbine case at the inlet opening, wherein the cooling air delivery tube is bent to deliver cooling air to the plenum at an angle relative to the low pressure turbine case.

20. The assembly of claim 19 , wherein the angle at which the cooling air delivery tube introduces cooling air to the plenum is such that cooling air is not directly impinged upon the forward outer diameter flowpath ring.

21. The assembly of claim 19 , wherein the cooling air delivery tube is bent to deliver cooling air to the plenum substantially tangential to an adjacent surface of the low pressure turbine case.

22. The assembly of claim 19 and further comprising:

a control orifice for throttling cooling air flow through the cooling air delivery tube to the plenum.

23. The assembly of claim 16 and further comprising:

a probe positioned at a probe opening formed in the forward outer diameter flowpath ring.

24. A method for cooling a turbine exhaust case assembly for a gas turbine engine, the method comprising:

delivering cooling air to a plenum that is defined at least in part by a forward outer diameter flowpath ring and a turbine case, wherein the cooling air is delivered so as to substantially avoid directly impinging the forward outer diameter flowpath ring; and

exhausting the cooling air from the plenum to a hot gas flowpath of the gas turbine engine for providing film cooling.

25. The method of claim 24 , wherein the cooling air is delivered in a direction that is substantially tangential to an inner surface of the turbine case.

26. The method of claim 24 and further comprising:

sensing a parameter associated with the hot gas flowpath using a probe.