Cooled dual wall liner closeout

An example exhaust duct assembly includes a front liner, an intermediate liner and a rear liner. Each of the front, intermediate and rear liners include an inner liner exposed to combustion gases and an outer liner spaced radially apart from the inner liner. An air passage defined between the inner liner and the outer liner provides cooling air utilized for insulating an inner surface of the exhaust duct assembly. A closeout member is provided between the inner and outer liner and defines a portion of an air passage between the closeout member and the inner liner. Air flowing through the air passage is injected into a joint to provide cooling. The closeout member includes a horizontal leg that is bendable in a radial direction to accommodate relative movement between the inner liner and the outer liner.

BACKGROUND OF THE INVENTION

This invention relates generally to a dual wall exhaust liner for a gas turbine engine. More particularly, this invention relates to a dual wall exhaust nozzle and/or duct closeout.

A gas turbine engine typically includes a plurality of turbine blades that transform energy from a mainstream of combustion gasses into mechanical energy that rotates and drives a compressor. The combustion gases exit the gas turbine engine through an exhaust nozzle. The exhaust nozzle assembly typically includes a hot side liner exposed to hot combustion gases and a cold side liner spaced radially apart from the hot side liner. The space between the hot side liner and the cold side liner defines a passage for cooling air. The cooling air is provided along the hot side liner to protect against the extreme heat generated by the combustion gases.

The hot side liner will often include a plurality of openings for communicating cooling air along an interior surface of the exhaust nozzle. The cooling air forms an insulating layer along the interior surface of the exhaust nozzle that protects the hot side liner. The hot side liner operates at a temperature much greater than that of the cold side liner. Accordingly, the cold side liner and hot side liner expand and contract differently in response to thermal conditions. The relative thermal expansions and contractions can generate stresses and strains in the hot side and cold side liner.

Further, it is known to provide for both stationary and articulating exhaust nozzle and ducts. Articulating exhaust nozzles and ducts allow for selectively directing combustion gases. The articulated exhaust nozzle and ducts includes several segments movable relative to each other. The interface between each segment requires that the air passage defined between the hot side and cold side liners be closed off. Further, it is desirable that the interface is cooled and sealed to contain combustion gases within the exhaust nozzle. Closing off the air passage at each interface joint complicates localized cooling between movable segments. The dynamic nature of the interface between movable segments creates a challenge to cooling of the hot side liner.

Accordingly, it is desirable to develop a dual wall exhaust liner closeout that accommodates differing thermal expansions and provides cooling airflow at an interface between movable segments of an exhaust nozzle and or duct assembly.

SUMMARY OF THE INVENTION

An example embodiment of this invention is an exhaust duct assembly including a dual wall exhaust liner having a closeout member that accommodates thermal expansion and provides for cooling a closeout and an interface between movable segments.

An example exhaust duct assembly includes a front liner, an intermediate liner assembly and a rear liner assembly. The front liner assembly is rotatable about a fixed mount point. The intermediate liner assembly is rotatable relative to the front liner assembly, and the rear liner assembly is rotatable relative to the intermediate liner. Each of the front, intermediate and rear liner assemblies, include an inner liner exposed to combustion gases and an outer liner spaced radially apart from the inner liner. An air passage is defined between the inner liner and the outer liner for cooling air utilized to insulate and cool the inner liner.

A closeout member is provided between the inner and outer liner and is riveted to the outer liner and welded or brazed to the inner liner. The closeout defines a portion of an air passage between the closeout member and the inner liner. Cooling air is injected into the interface between segments through the air passage defined by the closeout. The closeout member includes two bent portions disposed between a horizontal leg and an outer leg segment. The horizontal leg is bendable in a radial direction to accommodate relative movement between the inner liner and the outer liner. Although, the closeout is bendable, it also has a stiffness desired to maintain the structure and a spatial relationship between the inner and outer liner.

Accordingly, the exhaust liner of this invention includes a closeout that accommodates differing thermal expansions and provides cooling air flow to an interface between moveable segments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIG. 1, an exhaust duct assembly10includes a forward duct12and an aft duct14. Exhaust gases enter the exhaust duct assembly through the forward duct12and move through and are exhausted out the aft duct14. The example exhaust duct assembly10includes a front liner16, an intermediate liner18and a rear liner20. The front liner16is rotatable about the axis26at the joint28. The intermediate liner18rotates relative to the front liner16, and the rear liner20rotates relative to the intermediate liner18.

A first joint32is disposed along a first bearing plane22between the intermediate liner18and the rear liner20. A second joint30is disposed along a second bearing plane24. The first joint32and the second joint30are disposed at an angle relative to a plane perpendicular to an inner surface25of the exhaust duct assembly10. Rotation of the front liner16, intermediate liner18and rear liner20relative to each other provides for direction of combustion gases exiting the exhaust duct assembly10.

Each of the front, intermediate and rear liner assemblies16,18, and20include an inner liner36exposed to the combustion gases and an outer liner38spaced radially apart from the inner liner36. An air passage42defined between the inner liner36and the outer liner38provides cooling air utilized for insulating the inner surface25. The configuration of the example articulating exhaust duct assembly10includes the first joint32and second joint30. The liners16,18,20rotate relative to each other along the bearing planes22,24. The air passage42between the inner liner36and outer liner38is closed off at each joint30,32. A closeout member is provided between the inner and outer liner36,38on either side of the joint interface22,24.

Referring toFIG. 2, the joint30includes a Z-shaped closeout member40within the intermediate liner18and a C-shaped closeout58within the rear liner20. The Z-shaped closeout member40is riveted to the outer liner38and welded and/or brazed to the inner liner36. Although, the illustrated example utilizes rivets70and a welded or braze attachment means, other fastening methods as are known are within the contemplation of this invention. The Z-shaped closeout40defines a portion of an end air passage41between the closeout member40and the inner liner36. Air flowing through the end air passage41is injected into the joint30to provide cooling.

The inner liner36is exposed to combustion gases at elevated temperatures and expands and contracts differently than that of the outer liner38. The closeout member40provides for relative movement between the inner liner36and the outer liner38. The Z-shaped closeout member40includes two bent portions45disposed between a horizontal leg44and an outer leg segment48. The bend portions45provide for bending of the horizontal leg44in a radial direction to accommodate relative movement between inner liner36and the outer liner38. The horizontal leg44is disposed at an angle31relative to the inner liner36. The angle31in the illustrated example is approximately 2 degrees. The angle31provides compliance in the horizontal leg44and improves manufacturability.

The C-shaped closeout member58disposed within the rear liner20at the first joint30includes a horizontal leg62that bends radially to accommodate differences in thermal expansion between the inner liner36and the outer liner38. The horizontal leg62is disposed at an angle37relative to the inner liner38. The C-shaped closeout member58also includes an outer leg segment60that is attached to the outer liner38and an inner leg segment64that is attached to the inner liner38. The inner leg segment64includes tabs68that space the C-shaped closeout member58from the inner liner36to define the end air passage41. The C-shaped closeout member58includes only a single bend65for accommodating bending of the horizontal leg62. The C-shaped closeout member58is also used in the Z-shaped closeouts at the end of the aft liner. The use of only a single bend65accommodates a decrease in space between the inner liner36and outer liner38.

The Z-shaped closeout member40and the C-shaped closeout member58close off ends of the intermediate liner18and the rear liner20at the first joint30. The intermediate liner18is spaced apart from the rear liner20such that a gap between the two is formed to provide for relative motion.

The intermediate liner18and the rear liner include ends72and74that are angled radially outwardly from the inner surface25. The outward angle of the ends72and74are not necessary for all applications and a worker versed in the art would understand how to advantageously configure the ends for a specific application. The outward angle of the ends72provides a non-stepped inner flow surface no matter what the relative position between the intermediate liner18and the rear liner20. The rear liner20includes a corresponding oval shape that when rotated relative to the intermediate liner18results in a mismatched inner surface25. The angled ends72,74prevent a flat surface from jutting out into the main stream of combustion gases. As appreciated, the interface between the intermediate liner18and the front liner16includes a similar configuration.

Referring toFIG. 3, cooling air indicated at78flows within the air passage42defined between the inner liner36and outer liner38. A worker versed in the art with the benefit of this disclosure would understand that many different means of providing cooling air78to the passage42are within the scope of this invention. The cooling air flows from the passage42to the end air passage41and out into the joint30. The cooling air78also exits through a plurality of openings35in the inner liner36disposed adjacent the inner leg segment46. Cooling air78that flows through the openings35forms an insulating layer for protecting the inner liner36from the extreme temperature of combustion gasses. The specific size and orientation of the openings35are determined to provide the desired magnitude and shape of cooling air flow along the inner surface25.

Referring toFIG. 4, a partial cut away is shown of the interface between the closeout member40and the inner liner36. The inner leg segment46of the closeout member40is cutaway to illustrate the tabs68that space the closeout member from the inner liner36and the plurality of openings35that inject air along the inner surface25to generate the desired cooling and insulating layer.

Although the example exhaust duct assembly10illustrated and described provides for articulation along several bearing planes, a worker with the benefit of this disclosure would recognize the applicability to exhaust duct assemblies of various designs and configuration.