Patent Application
20180017260
The present disclosure is directed to a combustor anti-surge retention system. Specifically, an integral anti-surge lug on a vane support is utilized to provide anti-surge retention to combustor hardware in place of bolted joints.
Combustors, such as those used in gas turbine engines, typically include radially spaced inner and outer liners that define an annular combustion chamber in between. A bulkhead panel is provided at a forward end of the chamber to shield a forward section of the combustor from the relatively high temperatures in the chamber. A plurality of fuel nozzles extend into the combustor through the forward end and into the bulkhead panel to provide fuel to the combustor.
Combustor anti-surge retention systems are responsible for axially retaining combustor hardware during a surge event and are typically installed to the 1st stage vane support and outer diffuser case.
The radial design space associated with legacy anti-surge retention systems are significantly large and often require the use of a bolted configuration. The bolted legacy configurations use a combination of bolts, clinch nuts, and associated structural bosses to provide the means to assemble anti-surge tabs or blocks forward of a combustor catch-rail. During a surge event, the combustor deflects forward into the anti-surge tab and/or block and the mechanical load is transmitted through the bolts into the vane support, and out through the cases.
In accordance with the present disclosure, there is provided a combustor assembly for a gas turbine engine, comprising: a vane support ring; an annular combustor extending around a central axis and being located radially inwards of the vane support ring, the annular combustor including an aft end, a forward end with at least one opening through which at least one fuel nozzle is received, and an annular outer shell and an annular inner shell that define an annular combustion chamber there between, the annular outer shell including a radially-outwardly extending flange including at least one scallop cut; and a stop member integrally formed with the vane support ring.
In another and alternative embodiment, the radially-outwardly extending flange is located at the aft end.
In another and alternative embodiment, the radially-outwardly extending flange is annular.
In another and alternative embodiment, the at least one scallop cut and the stop member integrally formed with the vane support ring are configured for direct axial installation of the vane support ring over the combustor annular outer shell.
In another and alternative embodiment, the scallop cut in the radially-outwardly extending flange is sized to allow the stop member to pass through the radially-outwardly extending flange.
In another and alternative embodiment, the scallop cut in the radially-outwardly extending flange and the stop member are configured to assemble in a clocking bayonet style alignment.
In another and alternative embodiment, stop member includes a ring structure, a tab extending radially inwardly from the ring structure and a circumferential flange extending opposite the tab, the circumferential flange being integral to the vane support ring.
In another and alternative embodiment, the stop member is axially-forwardly spaced apart by a distance D from the radially-outwardly extending flange such that axial-forward movement of the annular combustor, with respect to directionality defined by the forward end and the aft end, is limited to an amount equal to the distance D.
In accordance with the present disclosure, there is provided a gas turbine engine comprising: a static structure; a compressor section; an annular combustor in fluid communication with the compressor section, the annular combustor extending around a central axis and being located radially inwards of the static structure, the annular combustor including an aft end, a forward end through which at least one fuel nozzle is received, and an annular outer shell and an annular inner shell that define an annular combustion chamber there between, the annular combustor being free of any rigid attachments directly between the static structure and the annular outer shell, the annular outer shell including a radially-outwardly extending flange having at least one scallop cut; a turbine section in fluid communication with the annular combustor; and at least one stop member integral with a vane support ring on the static structure and adjacent the radially-outwardly extending flange such that axial-forward movement of the annular combustor is limited, with respect to directionality defined by the forward end and the aft end.
In another and alternative embodiment, the stop member is axially-forwardly spaced apart by a distance D from the radially-outwardly extending flange such that movement of the annular combustor is limited to an amount equal to the distance D.
In another and alternative embodiment, the radially-outwardly extending flange is located at the aft end.
In another and alternative embodiment, the scallop cut is configured to allow the stop member to pass over the radially-outwardly extending flange.
In another and alternative embodiment, a quantity of the stop members are determined depending on the weight of the annular combustor and loads generated during operation.
In another and alternative embodiment, the at least one stop member is uniformly circumferentially integrated around the vane support ring.
In another and alternative embodiment, the scallop cut is configured such that the at least one stop member can pass over the radially-outwardly extending flange and then upon rotation of the at least one stop member relative to the radially-outwardly extending flange, the at least one stop member is configured in alignment to interfere with the radially-outwardly extending flange responsive to a surge event.
Other details of the combustor anti-surge retention system are set forth in the following detailed description and the accompanying drawing wherein like reference numerals depict like elements.
The gas turbine engine 20 generally includes a low spool 30 and a high spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided.
The low spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a geared architecture 48 to drive the fan 42 at a lower speed than the low spool 30. The high spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and high pressure turbine 54. It is to be understood that “low pressure” and “high pressure” as used herein are relative terms indicating that the high pressure is greater than the low pressure. An annular combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate via bearing systems 38 about the engine central longitudinal axis A which is collinear with their longitudinal axes.
The core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the annular combustor 56, then expanded over the high pressure turbine 54 and low pressure turbine 46. The turbines 46 and 54 rotationally drive the respective low spool 30 and high spool 32 in response to the expansion.
The annular outer shell 60 free of any rigid attachments directly between the static structure 72 and the annular outer shell 60. In this regard, the annular combustor 56 is “free floating” within the gas turbine engine 20 such that the flanges 62a provide the exclusive rigid support. The term “rigid” and variations thereof as used herein refer to a support that resists deformation under the weight of the annular combustor 56 and under the loads generated in operation of the gas turbine engine 20. Rigid supports, such as the flanges 62a, thus support the weight of the annular combustor 56 under the loads generated in operation, while a flexible or non-rigid support could not bear the weight of the annular combustor 56 under such loads.
Certain events in the operation of the gas turbine engine 20 can cause the annular combustor 56 to move axially forward. As an example, a surge event in the gas turbine engine 20 can cause a back pressure that tends to urge the annular combustor 56 forward in a pivot motion about the flanges 62a. At least a component of the pivot motion is in an axially forward direction. If the axially-forward component of the motion is substantial, the outer shell 60 and bulkhead 68 may be subject to plastic deformation. A plurality of integral vane support anti-surge lugs, or simply, stop members 76 are therefore used in combination with a radially-outwardly extending flange 60a of the annular outer shell 60 to limit axial-forward motion of the annular combustor 56. Because the stop members 76 are used to limit movement, the annular combustor 56 does not need to be made more structurally robust, such as with thicker walls, to resist movement.
As an example, the distance D between the radially-outwardly extending flange 60a and the stop member 76 is selected such that the distance D is less than a gap distance, represented as distance G in
Referring also to
The clearance scallop cuts 82 on the adjacent combustor outer burner liner flange 60a allows direct axial assembly of the integral vane support anti-surge lug stop members 76. A bayonet assembly method allows direct axial installation of vane support ring 80 over the combustor annular outer shell 60, with a final circumferential clocking into position. Anti-surge contact locations 84 are then placed at a location circumferentially away from the outer burner liner flange scallop cuts 82. The flange scallop cuts 82 can be spaced equally or unequally along the circumference of the flange 60a. The flange scallop cuts 82 can reduce weight.
In an alternative exemplary embodiment,
The stop member 176 includes a vane support structure 177 from which the tabs 176a extend. The vane support structure 177 extends around the engine central axis A and includes a circumferential flange 179 that extends radially in a direction opposite of the tabs 176a. The circumferential flange 179 is secured between a first flange 172a and a second flange 172b of the outer static structure 172. The circumferential flange 179, first flange 172a and second flange 172b include openings 181 that align to receive a fastener 183 (
The clearance slots i.e., scallop cuts 182 in the flange 160a are designed to allow for ease of insertion of the tabs 176 past the flange 160a. The cuts 182 allow for direct axial assembly of the anti-surge hardware. A similar clocking bayonet style positioning can be utilized to align the tabs 176 into place.
The disclosed design utilizes existing combustor outer burner liner as a surge-retention feature.
The disclosed design places anti-surge tabs integrally onto the vane support, thus simplifying assembly and reducing part count.
The disclosed design has a minimal structural impact while introducing a new retention system.
The bolted legacy designs are limited in design space due to required gapping for clinch nut flaring tools, bolt shank size, and associated boss min wall thicknesses. Reduced radial required design space allows for advanced vane support concepts to reduce heat transfer into life-limited outer cases.
The disclosed anti-surge design could alternatively be used in any application where aft axial assembly for forward-loadbearing tabs is required by the means of clearance scallops on adjacent hardware.
An advantage of the disclosure is that it reduces anti-surge component counts, cost, and weight. Significant radial vane support design space is gained by eliminating the legacy anti-surge bolted joint configuration. Integral anti-surge lugs on the vane support transmit surge load directly to the cases without the use of a bolted joint.
There has been provided a combustor anti-surge retention system. While the combustor anti-surge retention system has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.
