Dilution hole assembly

A dilution hole assembly is provided for a combustor. The dilution hole assembly includes a first wall and at least one outer vane. The first wall extends continuously about a centerline and defines a radially inward hole. The at least one outer vane projects radially inward from the first wall for swirling at least a portion of air flowing through the hole.

BACKGROUND

The present disclosure relates to a dilution hole assembly and, more particularly, to a dilution hole assembly for a combustor of a gas turbine engine.

Gas turbine engines, such as those that power modern commercial and military aircraft, include a fan section to propel the aircraft, a compressor section to pressurize a supply of air from the fan section, 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 thereby generate thrust.

The combustor section typically includes a wall assembly having an outer shell lined with heat shields that are often referred to as floatwall panels. Together, the panels define a combustion chamber. A plurality of dilution holes are generally spaced circumferentially about the wall assembly and flow dilution air from a cooling plenum and into the combustion chamber to improve emissions, and reduce and control the temperature profile of combustion gases at the combustor outlet to protect the turbine section from overheating.

The dilution holes are generally defined by a grommet that extends between the heat shield panel and supporting shell with a cooling cavity defined therebetween. Improvements to the functionality of dilution holes is desirable.

SUMMARY

A dilution hole assembly according to a, non-limiting, embodiment of the present disclosure includes a first wall extending continuously about a centerline and defining a radially inward hole; and at least one outer vane projecting radially inward from the first wall for swirling at least a portion of air flowing through the hole.

Additionally to the foregoing embodiment, the assembly includes a second wall extending continuously about the centerline and spaced radially inward from the first wall, wherein a first portion of the hole contains the at least one outer vane with each outer vane extending radially between and engaged to the first and second walls.

In the alternative or additionally thereto, in the foregoing embodiment, the assembly includes at least one inner vane projecting radially inward from the second wall, and spaced circumferentially about the centerline.

In the alternative or additionally thereto, in the foregoing embodiment, the at least one inner vane and the at least one outer vane are in counter swirling relationship to one-another.

In the alternative or additionally thereto, in the foregoing embodiment, the assembly includes a third wall extending continuously about the centerline and spaced radially inward from the second wall, wherein a second portion of the hole, radially inward of the first portion and radially inward of and bounded by the second wall contains the at least one inner vane with each inner vane extending radially between the second and third walls.

In the alternative or additionally thereto, in the foregoing embodiment, the hole includes a third portion radially inward of and bounded by the third wall and configured for flowing air generally parallel to the centerline.

In the alternative or additionally thereto, in the foregoing embodiment, the third wall is generally conical for impinging air that flows through the second portion against air that flows through the first portion.

In the alternative or additionally thereto, in the foregoing embodiment, a second portion of the hole is radially inward of and bounded by the second wall, and the second wall is generally conical for impinging air that flows through the first portion against air that flows through the second portion of the hole radially inward of the second wall.

In the alternative or additionally thereto, in the foregoing embodiment, a respective outer vane has an air jet passage having an inlet communicating through the first wall and an outlet communicating through the respective outer vane and in direct fluid communication with the hole for creating air turbulence.

In the alternative or additionally thereto, in the foregoing embodiment, the outlet is carried by a suction side of the respective outer vane.

A combustor according to another, non-limiting, embodiment includes a liner disposed about an axis and defining a combustion chamber; a shell radially outward of the liner, wherein a cooling cavity is defined the liner and the shell and an air plenum is radially outward of the shell; and a dilution hole assembly having an outer wall contacting the liner and the shell and defining a hole in fluid communication with the air plenum and the combustion chamber, and a second wall located in the hole, wherein an annular outer portion of the hole is defined by and between the outer and second walls and a second portion of the hole is defined at least in-part by and inward of the second wall.

Additionally to the foregoing embodiment, the outer wall isolates the cooling cavity from the hole.

In the alternative or additionally thereto, in the foregoing embodiment, the hole has a centerline and the second wall has an inner face defining at least in-part the inner portion and sloped radially outward with respect to the centerline and in the direction of air flow from the air plenum and into the combustion chamber.

In the alternative or additionally thereto, in the foregoing embodiment, the dilution hole assembly has a plurality of outer vanes in the annular outer portion and spaced circumferentially from one-another with respect to a centerline of the hole for swirling air flow through the annular outer portion.

In the alternative or additionally thereto, in the foregoing embodiment, the dilution hole assembly has a plurality of inner vanes in the inner portion and spaced circumferentially from one-another with respect to a centerline of the hole for swirling at least a portion of air flowing through the inner portion.

In the alternative or additionally thereto, in the foregoing embodiment, the dilution hole assembly has a plurality of outer vanes in the annular outer portion and spaced circumferentially from one-another with respect to a centerline of the hole for swirling air flowing through the annular outer portion, and a plurality of inner vanes in the inner portion and spaced circumferentially from one-another with respect to the centerline for swirling at least a portion of air flowing through the inner portion in a counter direction from the air flowing through the annular outer portion.

In the alternative or additionally thereto, in the foregoing embodiment, the dilution hole assembly has an inner wall located radially inward of the second wall with respect to the centerline and the inner portion is an annular inner portion.

In the alternative or additionally thereto, in the foregoing embodiment, the inner wall defines a jet stream portion of the hole located radially inward of the annular inner portion with respect to the centerline.

A dilution hole assembly for a combustor of a gas turbine engine according to another, non-limiting, embodiment includes a first wall defining a boundary of a first portion of a dilution hole for flowing a first airstream; and a second wall defining a boundary of a second portion of the dilution hole for flowing a second airstream.

Additionally to the foregoing embodiment, the second portion is annular and is bounded radially between the first and second walls and the first portion is radially inward of the second portion and the first wall.

DETAILED DESCRIPTION

FIG. 1schematically illustrates a gas turbine engine20disclosed as a two-spool turbo fan that generally incorporates a fan section22, a compressor section24, a combustor section26and a turbine section28. Alternative engines may include an augmentor section (not shown) among other systems or features. The fan section22drives air along a bypass flowpath while the compressor section24drives air along a core flowpath for compression and communication into the combustor section26then expansion through the turbine section28. Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engine architecture such as turbojets, turboshafts, and three-spool turbofans with an intermediate spool.

The engine20generally includes a low spool30and a high spool32mounted for rotation about an engine axis A via several bearing structures38and relative to a static engine case36. The low spool30generally includes an inner shaft40that interconnects a fan42of the fan section22, a low pressure compressor44(“LPC”) of the compressor section24and a low pressure turbine46(“LPT”) of the turbine section28. The inner shaft40drives the fan42directly or through a geared architecture48to drive the fan42at a lower speed than the low spool30. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system.

The high spool32includes an outer shaft50that interconnects a high pressure compressor52(“HPC”) of the compressor section24and a high pressure turbine54(“HPT”) of the turbine section28. A combustor56of the combustor section26is arranged between the HPC52and the HPT54. The inner shaft40and the outer shaft50are concentric and rotate about the engine axis A. Core airflow is compressed by the LPC44then the HPC52, mixed with the fuel and burned in the combustor56, then expanded over the HPT54and the LPT46. The LPT46and HPT54rotationally drive the respective low spool30and high spool32in response to the expansion.

In one non-limiting example, the gas turbine engine20is a high-bypass geared aircraft engine. In a further example, the gas turbine engine20bypass ratio is greater than about six (6:1). The geared architecture48can include an epicyclic gear train, such as a planetary gear system or other gear system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3:1, and in another example is greater than about 2.5:1. The geared turbofan enables operation of the low spool30at higher speeds that can increase the operational efficiency of the LPC44and LPT46and render increased pressure in a fewer number of stages.

A pressure ratio associated with the LPT46is pressure measured prior to the inlet of the LPT46as related to the pressure at the outlet of the LPT46prior to an exhaust nozzle of the gas turbine engine20. In one non-limiting example, the bypass ratio of the gas turbine engine20is greater than about ten (10:1); the fan diameter is significantly larger than the LPC44; and the LPT46has a pressure ratio that is greater than about five (5:1). It should be understood; however, that the above parameters are only exemplary of one example of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

In one non-limiting example, a significant amount of thrust is provided by the bypass flow path B due to the high bypass ratio. The fan section22of the gas turbine engine20is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet (10,668 meters). This flight condition, with the gas turbine engine20at its best fuel consumption, is also known as bucket cruise Thrust Specific Fuel consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust.

Fan Pressure Ratio is the pressure ratio across a blade of the fan section22without the use of a fan exit guide vane system. The low Fan Pressure Ratio according to one non-limiting example of the gas turbine engine20is less than 1.45:1. Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of (T/518.70.5), where “T” represents the ambient temperature in degrees Rankine. The Low Corrected Fan Tip Speed according to one non-limiting example of the gas turbine engine20is less than about 1,150 feet per second (351 meters per second).

Referring toFIG. 2, the combustor section26generally includes an annular combustor56with an outer combustor wall assembly60, an inner combustor wall assembly62, and a diffuser case module64that surrounds assemblies60,62. The outer and inner combustor wall assemblies60,62are generally cylindrical and radially spaced apart such that an annular combustion chamber66is defined therebetween. The outer combustor wall assembly60is spaced radially inward from an outer diffuser case68of the diffuser case module64to define an outer annular plenum70. The inner wall assembly62is spaced radially outward from an inner diffuser case72of the diffuser case module64to define, in-part, an inner annular plenum74. Although a particular combustor is illustrated, it should be understood that other combustor types with various combustor liner arrangements will also benefit. It is further understood that the disclosed cooling flow paths are but an illustrated embodiment and should not be so limited.

The combustion chamber66contains the combustion products that flow axially toward the turbine section28. Each combustor wall assembly60,62generally includes a respective support shell76,78that supports one or more heat shields or liners80,82. Each of the liners80,82may be formed of a plurality of floating panels that are generally rectilinear and manufactured of, for example, a nickel based super alloy that may be coated with a ceramic or other temperature resistant material, and are arranged to form a liner configuration mounted to the respective shells76,78.

The combustor56further includes a forward assembly84that receives compressed airflow from the compressor section24located immediately upstream. The forward assembly84generally includes an annular hood86, a bulkhead assembly88, and a plurality of swirlers90(one shown). Each of the swirlers90are circumferentially aligned with one of a plurality of fuel nozzles92(one shown) and a respective hood port94to project through the bulkhead assembly88. The bulkhead assembly88includes a bulkhead support shell96secured to the combustor wall assemblies60,62and a plurality of circumferentially distributed bulkhead heat shields or panels98secured to the bulkhead support shell96around each respective swirler90opening. The bulkhead support shell96is generally annular and the plurality of circumferentially distributed bulkhead panels98are segmented, typically one to each fuel nozzle92and swirler90.

The annular hood86extends radially between, and is secured to, the forwardmost ends of the combustor wall assemblies60,62. Each one of the plurality of circumferentially distributed hood ports94receives a respective on the plurality of fuel nozzles92, and facilitates the direction of compressed air into the forward end of the combustion chamber66through a swirler opening100. Each fuel nozzle92may be secured to the diffuser case module64and projects through one of the hood ports94into the respective swirler90.

The forward assembly84introduces core combustion air into the forward section of the combustion chamber66while the remainder of compressor air enters the outer annular plenum70and the inner annular plenum74. The plurality of fuel nozzles92and adjacent structure generate a blended fuel-air mixture that supports stable combustion in the combustion chamber66.

Referring toFIG. 3, the heat resistant panel80of wall assembly60(which may include an array of panels) includes a hot side102that generally defines in-part a boundary of the combustion chamber66and an opposite cold side104. The shell76includes an outer side106that faces and defines in-part a boundary of the cooling plenum70and an opposite inner side108that faces and is spaced from the cold side104of the heat shield80. An annular cooling cavity110is located between and defined by the cold side104of the heat shield80and the inner side108of the shell76.

A dilution hole assembly112is illustrated and described in relation to the outer wall assembly60for simplicity of explanation; however, it is understood that the same dilution hole assembly may be applied to the inner wall assembly62of the combustor56. The dilution hole assembly112generally functions to flow dilution air (see arrow114) from the cooling plenum70, through the wall assembly60, via the dilution hole assembly112, and into the combustion chamber66. This dilution air may generally enter the combustion chamber66as a jet stream with a turbulent flowing periphery to improve combustion efficiency throughout the chamber and further serves to cool and/or control the temperature profile of combustion gases at the exit of the combustor56.

The dilution hole assembly112may include a centerline116, an outer wall118extending continuously about the centerline116, a dilution hole120located inward of and defined by the outer wall118, a second wall122located in the dilution hole120and spaced radially inward of the outer wall118, an annular outer portion124of the dilution hole120defined by and between the outer and second walls118,122, a third or inner wall126spaced radially inward of the second wall122, an annular second or mid portion128of the dilution hole120defined by and located between the second and third walls122,126, and a jet stream portion130of the dilution hole120defined by and located radially inward of the third wall126. The flow of dilution air114is generally divided into three portions or airstreams with each airstream flowing through the respective annular outer portion124, the annular mid portion128and the jet stream portion130. The direction of air flow may be different for each airstream of air114(see arrows132,134and136) and orientated so that at least the outer airstream132and the mid airstream134generally impinge upon one-another or otherwise create turbulence for enhanced mixing with combustion gases. The third or inner airstream136may behave as a jet stream for maximum penetration into the core region of the combustion chamber66.

The outer wall118has a first face138that generally faces radially outward and a substantially opposite face140that defines in-part the annular outer portion124of the hole120. The outward face138is generally in contact with the shell76and the liner80and a portion thereof may define, in-part, the cooling cavity110such that the outer wall118substantially segregates the cavity110from the dilution hole120. Contact of the outward face138with the liner80may be an ‘engagement’ such that the liner and the outer wall118are one unitary part. The contact of the outward face138(or a face extending therefrom) may be a sealing contact with the shell76. A first end portion142of the outer wall118may be substantially flush with the hot side102of the liner80and an opposite end portion144of the outer wall118may project beyond the shell76and into the plenum70. To promote impingement and/or mixing of airstreams132,134, the inward face140may be sloped radially inward as the face spans axially in a downstream direction with respect to the centerline116(i.e. direction of airstream136).

The second or mid wall122has a first face146that generally faces radially outward and a substantially opposite face148that defines in-part the annular mid portion128of the dilution hole120. To promote impingement and/or mixing of airstreams132,134, the outward face146may be sloped radially inward as the face146spans axially in a downstream direction. Similarly, and to promote impingement, the inward face148may be sloped radially outward as the face148spans axially in the downstream direction. With both faces146,148sloped, the mid wall122may have a triangular shaped cross section and/or when viewing the faces individually, they are each cone or frustum-like in appearance. The mid wall122may be generally hollowed-out to reduce weight.

The inner wall126has a first face150that generally faces radially outward and may have a substantially opposite face152that defines the inner portion130of the dilution hole120. To promote impingement and/or mixing of airstreams132,134, the outward face150may be sloped radially outward as the face150spans axially in a downstream direction. The inward face152may be substantially cylindrical or otherwise sloped to adjust for the needed penetration of the airstream136into the core region of the combustion chamber66. The inner wall126or outward face150may be cone or frustum-like in appearance.

To further enhance impingement and/or mixing of airstreams132,134the dilution hole assembly112may include a plurality of outer vanes154in the annular outer portion124and a plurality of inner vanes156in the annular inner portion128of the dilution hole120. The plurality of vanes154,156create a circumferential swirling action of the respective airstreams132,134and in counter circumferential directions. Each vane of the plurality of outer vanes154are spaced circumferentially from the next adjacent vane and extend radially between and may be engaged to the inward face140of the outer wall118and the outward face146of the mid wall122. Similarly, each vane of the plurality of inner vanes156are spaced circumferentially from the next adjacent vane and extend radially between and may be engaged to the inward face148of the mid wall122and the outward face150of the inner wall126.

Each vane of the plurality of outer vanes154may further include an air jet passage158having an inlet160communicating through the end portion144of the outer wall118and an outlet162that may communicate through a suction side164of the vane154. Air may thus flow from the plenum70, through the passage158and into the outer portion124of the dilution hole120for creating turbulence within the airstream132for enhanced mixing of dilution air114with combustion gases. Although not illustrated, it is further contemplated and understood that similar air jet passages may be in the inner vanes156.

It is understood that various combinations and/or omissions of the above described features may be incorporated. For instance, one or all of the walls118,122,126may not be sloped and the vanes154,156may be used solely for mixing of dilution air. Alternatively, there may be no vanes, and the sloping of walls118,122,126may be used solely to mix or create turbulence within and about the dilution air streams. Yet further, the mid wall122and the vanes156may be omitted altogether such that the dilution air114has only two streams, or more walls may be added to further divide the dilution air.

Because applications of the dilution hole assembly112(e.g. combustor dilution holes) may be relatively small, manufacturing of the structure may be accomplished through additive manufacturing. Through additive manufacturing, the structure116may be formed as one unitary part. Individual features may be as small as about 0.010 inches (0.254 millimeters) in thickness or diameter while being generally non-porous, and various holes may be generally as small as 0.012 inches (0.305 millimeters) in diameter and/or as dictated by the filtering of any undesired particulate within surrounding airstreams. It is further understood and contemplated that minimal dimensions may be reduced with continued improvements in additive manufacturing processes.

It is understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude and should not be considered otherwise limiting. It is also understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will also benefit. Although particular step sequences may be shown, described, and claimed, it is 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 described. Various non-limiting embodiments are disclosed; 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 understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For this reason, the appended claims should be studied to determine true scope and content.