STRESS RELIEVED RECTILINEAR DUCT

Abstract

A duct liner includes a corner flanked by a pair of keyhole slots. An exhaust duct assembly includes an impingement liner received within a duct and a duct liner received within the impingement liner, the duct liner with a multiple of corners, each of the corners flanked by a pair of keyhole slots.

Description

This application claims priority to U.S. Patent Appln. No. 61/765,208 filed Feb. 15, 2013.

BACKGROUND

The present disclosure relates to a duct and, more particularly, to a rectilinear duct with stress relief.

Gas turbine engines, such as those which power modern military aircraft, include a compressor section to pressurize a supply of air, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases and generate thrust. An augmentor section, or “afterburner”, may be located downstream of the turbine section to selectively increase thrust.

In some buried engine arrangements, an exhaust duct downstream of the augmentor may be at least partially rectilinear in cross-section A rectangular shaped duct exposed to hot gases may result in relatively high corner stresses.

SUMMARY

A duct liner according to one disclosed non-limiting embodiment of the present disclosure includes a corner flanked by a pair of keyhole slots.

A further embodiment of the present disclosure includes, wherein each of the pair of keyhole slots are displaced from the corner.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots extend parallel to the corner.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots extend through a flange

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots are linear.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots includes a circular end.

An exhaust duct assembly according to another disclosed non-limiting embodiment of the present disclosure includes an impingement liner received within the duct; and a duct liner received within the impingement liner, the duct liner with a multiple of corners, each of the corners flanked by a pair of keyhole slots.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots are displaced from the corner.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots extend parallel to the corner.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of the pair of keyhole slots extend through a duct liner flange of the duct liner.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the duct liner flange abuts an impingement liner flange of the impingement liner.

A further embodiment of any of the foregoing embodiments of the present disclosure includes a gasket between the duct liner flange and the impingement liner flange.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the duct liner flange abuts a bulkhead.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the bulkhead is defined by a gas turbine engine.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the bulkhead is defined by a Hot Acoustic Rig.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein each of said pair of keyhole slots includes a circular end.

A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein said circular end is displaced from each corner by 2.5 times a diameter of said circular end.

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation of the invention will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 is a general schematic view of an exemplary gas turbine engine with an exhaust duct section according to one disclosed non-limiting embodiment;

FIG. 2 is a general perspective view of the exhaust duct section according to one disclosed non-limiting embodiment;

FIG. 3 is a general schematic view of an exemplary Hot Acoustic Rig with an exhaust duct section according to another disclosed non-limiting embodiment;

FIG. 4 is an exploded perspective view of an exhaust duct assembly;

FIG. 5 is an expanded view of a duct liner corner; and

FIG. 6 is a schematic view of a duct liner corner illustrating only one keyhole slot.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gas turbine engine 20 is disclosed herein as a two-spool low-bypass augmented turbofan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26, a turbine section 28, an augmenter section 30, an exhaust duct section 32, and a nozzle system 34 along a central longitudinal engine axis A. Although depicted as an augmented low bypass turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are applicable to other gas turbine engines including non-augmented engines, geared architecture engines, direct drive turbofans, turbojet, turboshaft, multi-stream variable cycle and other engine architectures with a nozzle system.

The exhaust duct section 32 may be generally rectilinear in cross-section (also shown in FIG. 2). It should be appreciated that the exhaust duct section 32 may be mounted to the gas turbine engine 20 or be mounted to other systems such as a propane burner 50 operable as part of a Hot Acoustic Rig 52 (FIG. 3) to heat components for high temperature testing. That is, the exhaust duct section 32 may be utilized in numerous ways and be of various rectilinear shapes.

With reference to FIG. 4, the generally rectilinear exhaust duct section 32 includes an exhaust duct assembly 60. The exhaust duct assembly 60 generally includes a duct liner 62, a gasket 64, an impingement liner 66 and a duct 68. The impingement liner 66 is mounted within the duct 68 to interface with a multiple of bumpers 70 that provide resilient support. The duct liner 62 is mounted within the impingement liner 66 to interface with a multiple of bumpers 72. Fasteners 74 are mounted through a duct flange 76, and an impingement liner flange 78 such that a duct liner flange 80 is sandwiched between a bulkhead 82 (illustrated schematically) and the impingement liner flange 78 with the gasket 64 therebetween. The bulkhead 82 is representative of, for example, the engine 20, the rig 52 or other upstream system or systems.

With reference to FIG. 5, the duct liner 62 is generally rectilinear and includes a multiple of corners 84. A keyhole slot 86 flanks each corner 84. Each keyhole slot 86 generally includes a linear slot 88 with a distal end 90 that may be circular in shape. The pairs of keyhole slots 86 are parallel to and near each corner 84 to minimize the accumulation of thermal strain by allowing the duct liner flange 80 to deform as the duct liner flange 80 is cooler than the duct and resists the thermal expansion of the duct 68. Each keyhole slot 86 is approximately 1.15 inches (30 mm) in length and displaced from each corner 84 by approximately 2.5 time the diameter of the of distal ends 90 (FIG. 6). That is, for a distal end of 0.2 inches (5 mm) in diameter, each keyhole slot 86 is displaced approximately 0.5 inches (12.5 mm) from the corner 84.

The pairs of keyhole slots 86 minimize the accumulation of thermal strain through controlled deformation as the duct liner flange 80 cannot otherwise carry a bending load at the corners 84. That is, the pairs of keyhole slots 86 which flank each corner 84 permit controlled moment to minimize the accumulation of thermal strain.

It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.

Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations.

It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.

Claims

1. A duct liner comprising:

a corner flanked by a pair of keyhole slots.

2. The duct liner as recited in claim 1, wherein each of said pair of keyhole slots are displaced from said corner.

3. The duct liner as recited in claim 1, wherein each of said pair of keyhole slots extend parallel to said corner.

4. The duct liner as recited in claim 1, wherein each of said pair of keyhole slots extend through a flange.

5. The duct liner as recited in claim 1, wherein each of said pair of keyhole slots are linear.

6. The duct liner as recited in claim 5, wherein each of said pair of keyhole slots includes a circular end.

7. An exhaust duct assembly comprising:

a duct;

an impingement liner received within said duct; and

a duct liner received within said impingement liner, said duct liner with a multiple of corners, each of said corners flanked by a pair of keyhole slots.

8. The assembly as recited in claim 7, wherein each of said pair of keyhole slots are displaced from said corner.

9. The assembly as recited in claim 7, wherein each of said pair of keyhole slots extend parallel to said corner.

10. The assembly as recited in claim 7, wherein each of said pair of keyhole slots extend through a duct liner flange of said duct liner.

11. The assembly as recited in claim 10, wherein said duct liner flange abuts an impingement liner flange of said impingement liner.

12. The assembly as recited in claim 11, further comprising a gasket between said duct liner flange and said impingement liner flange.

13. The assembly as recited in claim 12, wherein said duct liner flange abuts a bulkhead.

14. The assembly as recited in claim 13, wherein said bulkhead is defined by a gas turbine engine.

15. The assembly as recited in claim 13, wherein said bulkhead is defined by a Hot Acoustic Rig.

16. The assembly as recited in claim 7, wherein each of said pair of keyhole slots includes a circular end.

17. The assembly as recited in claim 16, wherein said circular end is displaced from each corner by 2.5 times a diameter of said circular end.