BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to gas turbine engines in general, and to the liners utilized within a gas turbine engine in particular.

2. Background Information

Liners are often employed in gas turbine engines to enclose high temperature, core gas paths. In many applications (e.g., exhaust nozzle, augmentor, etc.) the liners are configured to form an enclosed gas path that may be cylindrical or nearly cylindrical in shape.

In many instances, the liner includes an outer wall, an inner wall, and structural elements disposed between and attached to the inner and outer walls. The outer wall is disposed radially outside of the inner wall. The structural elements (typically referred to as “stiffeners”) disposed between the walls add structural rigidity to the liner. Each stiffener may be attached to the respective wall by a variety of techniques, but very often the stiffeners are attached by rivets. The walls and the stiffeners collectively form a stiff cylindrical structure that defines an interior passage through which core gas flows during operation of the engine. The stiffeners protect the liner from buckling or collapsing under differential pressure loads across the liner; e.g., a difference in pressure between the enclosed interior core gas passage region defined by the liner and the region disposed outside of the liner. For example, during a stall condition, the air pressure surrounding the outer wall of the liner (Pouter) is substantially higher than the air pressure within the interior liner region (Pinterior); (e.g., Pouter>Pinterior). If the difference in pressure across the liner is great enough, the liner could deform.

In many applications, the liner may be cooled to mitigate or prevent thermal issues. For example, both the inner and outer wall may include cooling apertures. A source of air (“cooling air”) at a higher pressure but lower temperature than the core gas flow passing through the enclosed liner interior passage may be disposed outside the liner. The higher pressure forces the cooling gas through the cooling apertures disposed in the outer wall and into the annular region defined between the inner and outer walls. The higher pressure also forces the cooling gas to exit the liner annular region through the cooling apertures disposed in the inner wall and into the core gas path.

During operation of the gas turbine engine, it is possible that a foreign object debris (“FOD”) may be ingested into and passed through the gas turbine engine. The foreign object, such as a bird, is often shredded into very small pieces as it passes through the gas turbine engine potentially causing damage to the gas turbine engine components. Under certain circumstances, some of the FOD can be displaced into the liner cooling apertures and/or into the annular region disposed between the inner and outer walls. The aforesaid debris can detrimentally affect the liner by clogging cooling apertures, etc. In addition, in some instances other undesirable debris can be displaced into the annular region disposed between the inner and outer walls.

What is needed is a method for determining the presence of debris within the annular region of the liner, one that permits testing of the cooling apertures to determine blockage, and one that permits debris to be removed from the annular region of the liner.

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, a liner for a gas turbine engine is provided that includes an outer wall, an inner wall, and a plurality of structural elements disposed between the inner wall and the outer wall. The outer wall is spaced apart from the inner wall and is disposed radially outside of the inner wall. The outer wall and inner wall form an annular structure having a circumference, and an annular region disposed between the first interior surface of the outer wall and the second interior surface of the inner wall. Each of the structural elements is attached to the outer wall and the inner wall. The outer wall includes at least one inspection port extending through the outer wall configured for access to the annular region disposed between the first interior surface of the outer wall and the second interior surface of the inner wall.

According to another aspect of the present disclosure, a gas turbine engine is provided that includes a fan section, a compressor section, a combustor section, a turbine section, and a liner disposed aft of the turbine section. The liner includes an outer wall, an inner wall, and a plurality of structural elements disposed between the inner wall and the outer wall. The outer wall is spaced apart from the inner wall and is disposed radially outside of the inner wall. The outer wall and inner wall form an annular structure having a circumference, and an annular region disposed between the first interior surface of the outer wall and the second interior surface of the inner wall. Each of the structural elements is attached to the outer wall and the inner wall. The outer wall includes at least one inspection port extending through the outer wall configured for access to the annular region disposed between the first interior surface of the outer wall and the second interior surface of the inner wall.

In any of the aspects or embodiments described above and herein, the outer wall includes first cooling apertures, and wherein the at least one inspection port disposed in the outer wall has an area that is greater than the area of any of the first cooling apertures.

In any of the aspects or embodiments described above and herein, the at least one inspection port is configured to be uncovered during operation of the gas turbine engine.

In any of the aspects or embodiments described above and herein, further including at least one an inspection port cover attached to the outer wall to cover at least a portion of a respective one of the at least one inspection port.

In any of the aspects or embodiments described above and herein, the plurality of structural elements may extend around the circumference of the annular structure, and define a plurality of independent annular sub-regions, and at least one of the independent annular sub-regions includes the at least one inspection port disposed in a portion of the outer wall of the respective annular sub-region.

In any of the aspects or embodiments described above and herein, the at least one inspection port is no more than four inspection ports.

In any of the aspects or embodiments described above and herein, each of the plurality of independent annular sub-regions includes at least one said inspection port disposed in the portion of the outer wall of the respective annular sub-region.

In any of the aspects or embodiments described above and herein, the at least one inspection port in a respective one of the independent annular sub-regions is a single said inspection port and has a first area, and the respective one of the independent annular sub-regions includes an outer wall portion and a plurality of first cooling apertures disposed in the outer wall portion, and wherein the first cooling apertures disposed within the outer wall portion have a collective second area, and the first area is less than about ten percent (10%).

In any of the aspects or embodiments described above and herein, the first area may be less than about six percent (6%) of the second area.

In any of the aspects or embodiments described above and herein, the first area may be greater than about two percent (2%) of the second area.

In any of the aspects or embodiments described above and herein, the first area may be greater than about four percent (4%) of the second area.

In any of the aspects or embodiments described above and herein, the first area may be in a range of about two percent (2%) to about ten percent (10%) of the second area.

In any of the aspects or embodiments described above and herein, an inspection port may be configured to be uncovered during operation of the gas turbine engine.

In any of the aspects or embodiments described above and herein, the at least one inspection port in a respective one of the independent annular sub-regions may be a plurality of said inspection ports, each said inspection port having a first area, and the collective first areas is a second area. The respective one of the independent annular sub-regions includes an outer wall portion and a plurality of first cooling apertures disposed in the outer wall portion, and the first cooling apertures disposed within the outer wall portion have a collective third area, and the second area is less than about ten percent (10%) of the third area.

In any of the aspects or embodiments described above and herein, the first area may be less than about six percent (6%) of the second area.

In any of the aspects or embodiments described above and herein, the second area may be greater than about two percent (2%) of the third area.

In any of the aspects or embodiments described above and herein, the second area may be greater than about four percent (4%) of the third area.

In any of the aspects or embodiments described above and herein, the second area may be in a range of about two percent (2%) to about ten percent (10%) of the third area.

In any of the aspects or embodiments described above and herein, an inspection port cover may be provided, wherein the at least one inspection port in a respective one of the independent annular sub-regions is a single said inspection port and has a first area, and the respective one of the independent annular sub-regions includes an outer wall portion and a plurality of first cooling apertures disposed in the outer wall portion, and wherein the first cooling apertures disposed within the outer wall portion have a collective second area, and the first area is greater than about ten percent (10%) of the second area, and wherein the inspection port cover is attached to the outer wall and covers at least a portion of the inspection port.

In any of the aspects or embodiments described above and herein, a plurality of inspection port covers may be provided, wherein the at least one inspection port in a respective one of the independent annular sub-regions is a plurality of said inspection ports, each said inspection port having a first area, and the collective first areas is a second area, and the respective one of the independent annular sub-regions includes an outer wall portion and a plurality of first cooling apertures disposed in the outer wall portion, and wherein the first cooling apertures disposed within the outer wall portion have a collective third area, and the second area is greater than about ten percent (10%) of the third area, and wherein each of the plurality of inspection port covers is attached to the outer wall and covers at least a portion of a respective one of the inspection ports.

