Combustor assembly with structural cowl and decoupled chamber

A combustor includes an outer liner, an inner liner, an annular cowl joining upstream ends of the outer and inner liners, and an annular deflector configured to shield the cowl from hot combustion gases in a combustion chamber defined between the outer liner, the inner liner and the deflector. The cowl has at least one opening for introduction of fuel and compressed air. The deflector includes at least one swirler. The cowl defines at least one axial cowl hole, and the deflector defines at least one corresponding axial deflector hole, wherein the corresponding deflector hole and cowl hole are configured to receive a fastener for fastening together the cowl and the deflector.

FIELD OF THE INVENTION

The present disclosure generally relates to gas turbine engines, and more specifically to combustors of such engines.

BACKGROUND OF THE INVENTION

In a gas turbine engine, pressurized air is provided from a compressor to a combustor, whereupon it is mixed with fuel and is burned in the combustion chamber. As shown inFIG. 1, an annular combustor1used in gas turbine engines typically includes outer and inner combustion liners2,3joined at their upstream ends to a dome assembly4or simply a “dome”. The dome assembly4usually includes an annular dome plate5and a plurality of circumferentially spaced fuel/air mixers6mounted therein for introducing the fuel/air mixture to the combustion chamber. A fuel injector stem (not shown) may extend into each mixer6for introducing fuel to the mixer. The amount of pressurized air which enters the mixers and correspondingly the inner and outer passages of the combustor, is typically regulated by outer and inner cowls7,8located upstream of the mixers6and the dome plate5. Each mixer6has a deflector9extending downstream therefrom for preventing excessive dispersion of the fuel/air mixture and shielding the dome plate5from the hot combustion gases of the combustion chamber.

Typically, the dome is the structural member that provides structural rigidity to the combustor, and is used to attach the cowls, deflectors, retainers, supports, and liners. For example, usually the outer cowl7and the outer combustor liner2are attached to the dome plate5by means of a first bolted joint, and the inner cowl8and the inner combustor liner3are attached to the dome plate5by means of a second bolted joint. Accordingly, both the outer and inner cowls7,8experience a slight change in pressure thereacross, as well as a vibratory load induced by the engine. While these environmental factors have a greater effect on the outer cowl, they nevertheless cause wear on both cowls and consequently limit the life thereof.

Therefore, it is desirable to provide a combustor to address at least one of the above-mentioned issues.

SUMMARY OF THE INVENTION

A combustor includes an outer liner, an inner liner, an annular cowl joining upstream ends of the outer and inner liners, and an annular deflector configured to shield the cowl from hot combustion gases in a combustion chamber defined between the outer liner, the inner liner and the deflector. The cowl has at least one opening for introduction of fuel and compressed air. The deflector includes at least one swirler. The cowl defines at least one axial cowl hole, and the deflector defines at least one corresponding axial deflector hole, wherein the corresponding deflector hole and cowl hole are configured to receive a fastener for fastening together the cowl and the deflector.

In some embodiments, the cowl comprises an annular cowl body and the at least one opening is formed in the annular cowl body.

In some embodiments, the cowl comprises at least one mounting rib extending downstream from the annular cowl body, and the at least one axial cowl hole is formed in the at least one mounting rib.

In some embodiments, the at least one opening comprises a plurality of circumferentially spaced openings formed in the annular cowl body, the at least one mounting rib comprises a plurality of mounting ribs extending downstream from positions circumferentially between adjacent openings, and the at least one axial cowl hole comprises a plurality of axial cowl holes formed in the plurality of mounting ribs, respectively.

In some embodiments, the cowl comprises at least one cowl arm extending upstream from the annular cowl body and attached to a casing surrounding the combustor.

In some embodiments, the cowl arm defines a mounting hole corresponding to a mounting hole formed in the casing, for receiving a fastener for attaching the cowl arm to the casing.

In some embodiments, the cowl arm comprises a split frame structure having split first and second legs extending from two circumferentially spaced positions of the cowl and joined at free ends thereof, as a common distal end.

In some embodiments, the cowl comprises an outer mounting flange and an inner mounting flange extending downstream from the annular cowl body, the outer and inner mounting flanges attached to the outer and inner liners, respectively.

In some embodiments, the cowl is a single-piece formed component.

In some embodiments, the deflector is disposed between the outer and inner liners, with an outer circumferential face thereof adjacent the outer liner, and an inner circumferential face thereof adjacent the inner liner.

In some embodiments, the deflector comprises an annular deflector body, and the at least one swirler extends upstream from the annular deflector body.

In some embodiments, the deflector comprises at least one deflector arm extending upstream from the annular deflector body, and the at least one axial deflector hole is defined in the at least one deflector arm.

In some embodiments, the deflector arm comprises a stand portion standing on and substantially perpendicular to the annular deflector body, and a pad portion extending near a distal end of the stand portion and substantially parallel to the annular deflector body, and wherein the axial deflector hole is defined in the pad portion of the deflector arm.

In some embodiments, the at least one swirler comprises a plurality of circumferentially spaced swirlers extending upstream from the annular deflector body, the at least one deflector arm comprises a plurality of circumferentially spaced deflector arm extending upstream from the annular deflector body, at positions circumferentially between adjacent swirlers.

In some embodiments, the deflector is a single-piece formed component.

A method of assembling a combustor having outer and inner liners, includes: joining upstream ends of the outer and inner liners via an annular cowl having at least one opening for introduction of fuel and compressed air; disposing an annular deflector including at least one swirler between the outer and inner liners and adjacent a downstream face of the cowl, to shield the cowl from a combustion chamber defined between the outer liner, the inner liner and the deflector; and fixedly attaching the deflector to the cowl via at least one fastener axially extending into the deflector and the cowl.

In some embodiments, the fastener extends into an axial cowl hole cowl defined in the cowl and an axial deflector hole defined in the deflector.

In some embodiments, the axial cowl hole is formed in a mounting rib extending downstream from an annular body of the cowl, and the axial deflector hole is defined in a deflector arm extending upstream from an annular body of the deflector.

In some embodiments, the annular deflector is disposed between the outer and inner liners with an outer circumferential face thereof adjacent the outer liner, and an inner circumferential face thereof adjacent the inner liner.

The method of claim16, further comprising attaching at least one cowl arm extending upstream from an annular body of the cowl, to a casing surrounding the combustor.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,FIGS. 2-7show a combustor10of a type suitable for use in a gas turbine engine.FIGS. 2 and 3are two cross-sectional schematic diagrams of the combustor10, taken from two different planes.FIGS. 4 and 5are two perspective views of a portion of the combustor10(a circumferential section of an annular cowl-and-deflector assembly of the combustor10), viewed from two different directions.FIG. 6is an exploded view of that portion.FIG. 7is a perspective view showing a whole annular cowl of the combustor10.FIGS. 4-7illustrate the structure of the combustor10in greater detail.

As shown, the combustor10includes a hollow body12defining a combustion chamber14therein. The hollow body12is generally annular in form and is defined by an outer liner16and an inner liner18. The upstream end of the hollow body12is substantially closed off by a cowl20attached to the outer liner16by a first row of fasteners22and to the inner liner18by a second row of fasteners24. At least one opening26is formed in the cowl20for the introduction of fuel and compressed air. The compressed air is introduced into the combustor10from a compressor (not shown) in a direction generally indicated by arrow “A”. The compressed air passes primarily through the opening26to support combustion and partially into the region surrounding the hollow body12where it is used to cool both the liners16and18and turbomachinery further downstream. An array of fuel injector stems28(only one is shown inFIG. 2) are mounted in a casing29which surrounds the combustor10. The fuel injector stem28extends through the opening26.

The cowl20is configured to regulate flow of the compressed air entering the opening26and the region surrounding the hollow body12, as well as to provide structural rigidity to the combustor assembly, as a structural cowl. In some embodiments, the cowl20includes a plurality of retaining arms30(also referred to as cowl arms, to distinguish from arms formed on other components) extending from an upstream face thereof. By attaching the retaining arms30to the casing29via fasteners31, the cowl20is fixed to the casing29.

An annular deflector32is disposed between the outer and inner liners16,18near a downstream face of the cowl20, with an outer circumferential face38thereof adjacent or in contact with the outer liner16, and an inner circumferential face39thereof adjacent or in contact with the inner liner18. The annular deflector32is configured and disposed such that the combustion chamber14is defined between the outer liner16, the inner liner18and the deflector32, and a plenum cavity34upstream the combustion chamber14, is defined between the deflector32the cowl20. In some embodiments, a tight fit is created between the liners16,18and the deflector32. In some embodiments, the plenum cavity34is sealed by the deflector32and the cowl20. The deflector32includes an annular deflector body36, at least one swirler40(shown inFIG. 2, also referred to as a mixer) and at least one retaining arm42(shown inFIG. 3, also referred to as a deflector arm), both extending upstream, towards the cowl20, from the deflector body36. The swirler40is configured to receive a distal end of a fuel injector stem28therein. The retaining arm42is configured to engage with the cowl20, in order to fix the deflector32to the cowl20. In some embodiments, the retaining arm42defines an axial hole44(axial deflector hole) extending substantially axially therein, and the cowl20defines a corresponding axial hole46(axial cowl hole) extending substantially axially therein. The axial holes44and46are configured to receive a fastener48such as a bolt, for fastening together the deflector32and the cowl20. As such, the deflector32can be axially attached to the cowl20, for example, via an axial bolted joint.

More details of the liners16,18, the cowl20, deflector32, and connections of them will be described hereinafter in conjunction withFIGS. 4-7. As shown inFIGS. 4-7, the annular cowl20includes an annular cowl body50, an outer mounting flange52and an inner mounting flange54extending downstream from the annular cowl body50near an outer and inner circumferential surface of the body50, respectively. The outer mounting flange52defines radial mounting holes53corresponding to radial mounting holes17formed in the outer liner16, for receiving the fasteners22. The inner mounting flange54defines radial mounting holes55corresponding to radial mounting holes19formed in the inner liner18, for receiving the fasteners24. There is an array of circumferentially spaced openings26(only two are shown) formed in the annular cowl body50. One opening26is provided for a fuel injector stem28. In some embodiments, the openings26are located around the radial middle portion of the annular cowl body50. An array of circumferentially spaced retaining arms30extend upstream from the annular cowl body50, for example, from positions adjacent the outer mounting flange52and circumferentially between adjacent openings26. Each retaining arm30defines at least one radial mounting hole corresponding to at least one radial mounting hole formed in the casing29for receiving the fastener31(shown inFIGS. 2 and 3).

As best seen inFIGS. 6 and 7, the retaining arm30of the cowl20FIG. 7is a split retaining arm provided with a split frame support structure that can effectively absorbs vibrations. In some embodiments, the split frame support structure may have an inverted ‘V’ shape, and include split first and second legs301,303extending from two circumferentially spaced positions of an annular body50of the cowl20, and joined at free ends thereof, as a common distal end305. There are two radial mounting holes307,309defined in the distal end305of the split retaining arm30. Such a split frame support structure can increase the capability of absorbing vibrations and reduce rotor imbalance due to undesired motion and imbalance such as rocking, bobbing, swaying, of the fan, the compressor, and/or the turbine blades during operation, and thereby can provide stable supports and increase durability.

The annular cowl20further includes mounting ribs58extending downstream from the cowl body50, for example, from positions circumferentially between adjacent openings26. The mounting rib58may radially terminate at the same length as the cowl body50and interconnect the outer and inner mounting flanges52,54. The axial hole46is formed in the mounting rib58. In some embodiments, the axial hole46is a though hole defined through an axial thickness of the mounting rib58. In some embodiments, each of the mounting ribs58is formed with at least one such an axial hole46.

In some embodiments, the whole cowl20is a single-piece formed component, and the cowl parts including the cowl body50, the outer and inner mounting flanges52,54, the retaining arms30, and the mounting ribs58are formed integratedly via additive manufacturing or conventional manufacturing techniques such as casting followed by machining.

The annular deflector body36may be an annular plate tightly fitted between the outer liner16and the inner liner18. An array of circumferentially spaced swirlers40extend upstream from the annular deflector body36, at positions corresponding to the array of circumferentially spaced cowl openings26for the array of fuel injector stems28to pass through, respectively. Each swirler40receives a distal end of a fuel injector stem28(shown inFIG. 2) therein. As best seen inFIG. 6, the swirler40is an annular component with generally cylindrical structure, and it includes a radial array of angularly directed swirl vanes41. The swirl vanes41are angled with respect to the axial centerline of the swirler40so as to impart a swirling motion to air flow entering the swirler40. There is an array of retaining arms42extending upstream from the annular deflector body36, at positions circumferentially between adjacent swirlers40. In the exemplary embodiment as shown inFIG. 6, the retaining arm42includes a stand portion62standing on the annular deflector body36and a pad portion64extending from a distal end of the stand portion62. The stand portion62may extend along an axial direction and substantially be perpendicular to the annular deflector body36. The pad portion64may extend substantially parallel to the annular deflector body36, for example, along a radial direction. The axial deflector holes44are defined in the pad portions64of the retaining arms42. In assembly, as shown inFIG. 4, the fastener such as bolt48is inserted into the axial deflector holes44and the axial cowl hole46, and thereby fasten the deflector32and the cowl20.

In some embodiments, the whole deflector32is a single-piece formed component, and the deflector parts including the deflector body36, the swirlers40, and the retaining arms42, are formed integratedly via additive manufacturing or conventional manufacturing techniques such as casting followed by machining.

Returning toFIGS. 2 and 3, via the deflector32, the cowl20is shielded from hot combustion gases in the combustion chamber14. As the deflector32is attached axially to the cowl20, there may be no longer needs for using radial fasteners to attach the deflector32to the cowl20or the liner16or18. As such, the deflector32is prevented from suffering high stress due to the rotation during operation of the engine. Thus, the high stress parts/regions, such as the cowl20, and the plenum cavity34sealed by the deflector32and the cowl20, are segregated from the high temperature parts/regions, such as the deflector32, and the combustion chamber14defined between the deflector32and the liners16,18.

It should be noted that, althoughFIGS. 2 and 3illustrate a single annular combustor, the present disclosure is also applicable to other types of combustors, such as multi-annular combustors. It should be also noted that the present disclosure is applicable to other types of swirlers or retaining arms as well.

In the combustor design as described herein, the use of the structural cowl eliminates the need for a traditional dome that is separately used to provide structural rigidity and attach such as swirler assemblies. The design also decouples the high stress and high temperature regions, and reduces rotor imbalance. Thus, the design may achieve at least some of the following advantages, for example, durability increase, part count reduction, assembly complexity reduction, and cost reduction.