Turbine frame assembly and method of designing turbine frame assembly

Patent metadata

Field	Value
Publication number	US-9982564-B2
Application number	US-201314654953-A
Country	US
Kind code	B2
Filing date	Dec 11, 2013
Priority date	Dec 29, 2012
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A structural case assembly comprises a frame, fairing and heat shield. The frame is fabricated from a material having a temperature limit below an operating point of a gas turbine engine, and comprises an outer ring, an inner ring and a plurality of struts extending therebetween to define a flow path. The fairing is fabricated from a material having a temperature limit above the operating point of the gas turbine engine, and comprises a ring-strut-ring structure that lines the flow path. The heat shield is disposed between the frame and the fairing to inhibit radiant heat transfer therebetween. The heat shield may block all line-of-sight between the fairing and the frame. The frame may be produced from CA-6NM alloy. A method for designing a turbine case structure includes selecting a frame material having a temperature limit below the operating point of an engine.

First claim

The invention claimed is:

1. A turbine exhaust case comprising:
a frame fabricated from a material having material properties that enable the frame to support at least a portion of a gas turbine engine below an operating temperature of the gas turbine engine but not at or above the operating temperature of the gas turbine, the frame comprising:
an outer ring;
an inner ring; and
a plurality of struts joining the outer ring and the inner ring;

a fairing fabricated from a material having material properties enabling the fairing to operate above the operating temperature of the gas turbine engine, the fairing comprising a ring-strut-ring structure that lines the flow path; and
a heat shield disposed between the frame and the fairing to inhibit radiant heat transfer between the frame and the fairing, wherein the heat shield comprises:
a first inner heat shield positioned between the fairing and the inner ring, wherein the inner heat shield is attached to the inner ring of the frame; and
a second inner heat shield positioned between the fairing and the inner ring, wherein the second inner heat shield is attached to the fairing to restrain the second inner heat shield, wherein the first and second inner heat shields are spaced from each other.

2. The turbine exhaust case of claim 1 wherein the heat shield blocks all line-of-sight between the fairing and the frame.

3. The turbine exhaust case of claim 1 wherein the heat shield is fabricated from a material having material properties enabling the heat shield to operate within the gas turbine engine at a higher temperature than that of the frame.

4. The turbine exhaust case of claim 1 wherein the frame is fabricated from CA-6NM alloy.

5. The turbine exhaust case of claim 1 wherein the heat shield is fabricated from Inconel 625 alloy.

6. The turbine exhaust case of claim 1 wherein the fairing is fabricated from Inconel 625 alloy.

7. The turbine exhaust case of claim 1 , wherein:
the heat shield further comprises:
a forward heat shield extending radially from the inner heat shield to partially enclose one of the plurality of struts;
an outer heat shield positioned between the fairing and the outer ring of the frame; and
an aft heat shield extending from the second inner heat shield to the outer heat shield, wherein the aft heat shield is joined to the second inner heat shield and the outer heat shield.

8. The turbine exhaust case of claim 7 , wherein the second inner heat shield extends towards the first inner heat shield from a fixed joint to a sliding joint, and wherein the fixed joined restrains the second inner heat shield relative to the fairing and the sliding joint permits the second inner heat shield to move in at least one direction relative to the fairing.

9. The turbine exhaust case of claim 7 wherein the heat shield forms a ring-strut-ring structure.

10. A turbine structural case comprising:
a frame produced from CA-6NM alloy, the frame comprising:
an outer ring;
an inner ring; and
a plurality of struts joining the outer ring and the inner ring to define a load path between the outer ring and the inner ring;

a fairing comprising a ring-strut-ring structure that defines a flow path within the load path; and
a heat shield disposed between the frame and the fairing to inhibit heat transfer between the frame and the fairing, wherein the heat shield comprises:
a first segment attached to the inner ring; and
a second segment attached to the fairing, wherein the first and second segments are spaced from each other, and wherein the first and second segments are positioned between the fairing and the inner ring.

11. The turbine structural case of claim 10 wherein the heat shield and the fairing are fabricated from materials having material properties that enable use of the heat shield and fairing within the gas turbine engine at a higher temperature than CA-6NM alloy.

12. The turbine structural case of claim 10 wherein the heat shield blocks all line-of-sight between the fairing and the frame.

13. The turbine structural case of claim 10 wherein the heat shield forms a barrier to all radiant heat capable of emanating from the fairing toward the frame.

14. A method for designing a case structure including a heat shield that is disposed between a frame and a fairing, the method comprising:
determining a temperature of an engine operating point for a gas turbine engine;
selecting a frame material capable of supporting at least a portion of the gas turbine engine below the temperature but not at or above the temperature;
selecting a fairing material capable of operating within the gas turbine engine above the temperature;
determining a temperature gradient between the fairing and the frame at the engine operating point;
selecting a heat shield material capable of operating within the gas turbine engine when exposed to the temperature gradient;
building a case structure comprising:
a frame constructed from the frame material;
a fairing constructed from the fairing material; and
a heat shield constructed from the heat shield material; and

joining a first segment of the heat shield to an inner ring of the frame; and
joining a second segment of the heat shield to the fairing such that the second segment is spaced from the first segment of the heat shield, wherein the first and second segments are positioned between the fairing and the inner ring.

15. The method of claim 14 wherein the frame material is selected for being less expensive than a material capable of withstanding the temperature.

16. The method of claim 15 wherein repair costs of the frame over a service life of the frame are less expensive than initial cost of a frame produced from a material capable of withstanding the temperature.

17. The method of claim 14 wherein the frame material is CA-6NM alloy.

18. The method of claim 14 wherein the temperature is a function of maximum operating temperature of the gas turbine engine and time.

19. The method of claim 14 and further comprising:
developing a heat shield that blocks all line-of-sight between the frame and the fairing.

20. The method of claim 14 wherein the heat shield forms a barrier to all radiant heat that emanates from the fairing toward the frame.

Assignees

• United Technologies Corp

Inventors

• Yeager William
• Scott Jonathan Ariel

Classifications

• F05D2230/00

  Manufacture · CPC title

• F05D2300/175

  Superalloys · CPC title

• F05D2260/231

  Preventing heat transfer · CPC title

• F05D2300/171

  Steel alloys · CPC title

• F05D2220/32

  in gas turbines · CPC title