The application relates generally to gas turbine engines and, more particularly, to integrated strut and vane arrangements in such engines.
Gas turbine engine ducts may have struts in the gas flow path, as well as vanes for guiding a gas flow through the duct. An integrated strut and turbine vane nozzle (ISV) forms a portion of a turbine engine gas path. The ISV usually includes an outer and an inner ring connected together with struts which are airfoil shaped to protect supporting structures and/or service lines in the interturbine duct (ITD) portion, and airfoils/vanes in the turbine vane nozzle portion. The integration is achieved by combining the airfoil shaped strut with the airfoil shape of a corresponding one of the vanes. The ISV can be made from one integral piece or from the assembly of multiple pieces. It is more difficult to adjust the flow of the vane nozzle airfoil if the ISV is a single integral piece. A multiple-piece approach with segments of turbine vane nozzles allows the possibility of mixing different classes of segments in the ISV to achieve proper engine flow. However, a significant challenge in a multiple-piece arrangement of an ISV, is to minimize the interface mismatch between the parts to reduce engine performance losses. Conventionally, complex manufacturing techniques are used to minimize this mismatch between the parts of the integrated strut and vane. In addition, mechanical joints, such as bolts, are conventionally used, but are not preferred because of potential bolt seizing in the hot environment of the ISV.
In one aspect, there is provided a strut and turbine vane nozzle (ISV) arrangement in a gas turbine engine, comprising: an interturbine duct (ITD) retained with a vane ring, the ITD including inner and outer annular duct walls defining an annular flow passage having an axis, an array of circumferentially spaced-apart struts extending radially across the flow passage, the vane ring including an ray of circumferentially spaced-apart vanes extending between inner and outer rings, each of the struts being angularly aligned in the circumferential direction with an associated one of the vanes, the ITD having at least one first angular positioning element including a first positioning surface and the vane ring having at least one second angular positioning element including a second positioning surface, the first and second positioning surfaces facing each other and both being perpendicular to a tangential direction with respect to the axis, and the first and second positioning surfaces being in contact.
In another aspect, there is provided a strut and turbine vane nozzle (ISV) arrangement in a gas turbine engine comprising: an interturbine duct (ITD) supported within an annular outer casing and coupled at a downstream end thereof with a segmented vane ring which includes a plurality of circumferential segments, the ITD including inner and outer annular duct walls arranged concentrically about an axis and defining a first annular flow passage therebetween, an array of circumferentially spaced-apart struts extending radially across the flow passage, the segmented vane ring including segmented inner and outer rings arranged concentrically about said axis and defining a second annular flow passage therebetween, the second flow passage being positioned downstream of and substantially aligning with the first flow passage, an array of circumferentially spaced-apart vanes extending radially across the second flow passage, each of the struts being angularly aligned with an associated one of the vanes and forming therewith an integrated strut-vane airfoil, each of the segments of the vane ring having said one of the vanes which is in the formation of the integrated strut-vane airfoil, a lug and slot arrangement provided between the ITD and the respective segments of the vane ring to angularly align the struts of the ITD with the respective associated vanes in order to limit mismatch at the integration of the strut-vane airfoils, the ITD and the segments of the vane ring being configured to allow the lug and slot arrangement to be engaged when the ITD and the segmented vane ring are axially moved towards each other during engine assembly.
In a further aspect, there is provided a strut and turbine vane nozzle arrangement in a gas turbine engine comprising: an interturbine duct (ITD) supported within an annular outer casing and coupled to a segmented vane ring which includes a plurality of circumferential segments, the ITD including inner and outer annular duct walls defining an annular first flow passage having an axis, an array of circumferentially spaced-apart struts extending radially across the first flow passage, the segmented vane ring including segmented inner and outer rings arranged concentrically about said axis and defining a second annular flow passage therebetween, the second flow passage being positioned downstream of and substantially aligning with the first flow passage, an array of circumferentially spaced-apart vanes extending radially across the second flow passage, each of the struts being angularly aligned with an associated one of the vanes and forming therewith an integrated strut-vane airfoil, an interface between the strut and the associated vane in each integrated strut-vane airfoil defining a tag-groove configuration wherein the strut at a downstream end thereof includes a first radially extending tag having circumferentially opposed sides and the vane at an upstream end thereof includes a second radially extending tag having circumferentially opposed sides, the first tag and the second tag being forced under aero-dynamic forces during engine operation into contact on one side with the other side free of contact to angularly align the strut and the vane in each integrated strut-vane airfoil.
Reference is now made to the accompanying figures in which:
The gas turbine engine 10 includes a first casing 20 which encloses the turbo machinery of the engine, and a second, outer casing 22 extending outwardly of the first casing 20 such as to define an annular bypass passage 24 therebetween. The air propelled by the fan 12 is split into a first portion which flows around the first casing 20 within the bypass passage 24, and a second portion which flows through a core flow path 26 which is defined within the first casing 20 and allows the flow to circulate through the multistage compressor 14, combustor 16 and turbine section 18 as described above.
Throughout this description, the axial, radial and circumferential directions are defined respectively with respect to a central axis 27, and to the radius and circumference of the gas turbine engine 10.
The ISV arrangement 28 generally comprises a radially annular outer duct wall 30 and a radially annular inner duct wall 32 concentrically disposed about the engine axis 27 (
Referring concurrently to
The ISV arrangement 28 further includes a guide vane nozzle section (which is referred to as a vane ring (not numbered) hereinafter). The vane ring may be formed as a single piece part or as a segmented vane ring according to this embodiment. The vane ring may include a radially outer ring 38 and a radially inner ring 40 disposed concentrically about the engine axis 27 and thereby defining an annular flow passage 42 therebetween. The annular flow passage 42 may be positioned downstream, substantially aligning with the annular flow passage 33. An array of circumferentially spaced-apart vanes 44 may extend radially across the annular flow passage 42, each having an airfoil shape with opposed pressure and suction sides for directing the gas flow to an aft rotor (not shown). Each of the struts 34 may be angularly aligned in the circumferentially direction with an associated one of the vanes 44. For convenience of description, the associated one of the vanes is indicated as 44′ (see
In this embodiment, the segmented vane ring includes a plurality of segments, each segment including a circumferential section of the outer and inner rings 38, 40 and a number of the vanes 44 at least one of which is a vane 44′ associated with one of the struts 34. A lug and slot arrangement 46 may be provided between the ITD and respective vane ring segments, in order to limit mismatch at the integration of the strut-vane airfoils. For example, a lug 48 may be attached to the outside of the outer ring 38 of the vane ring, the lug having circumferentially opposed sides 47, 49 (See
Alternatively, the lug 48 may be loosely received in the slot 50 and may be forced into contact with only one of the opposed sides of the slot 50, by aerodynamic forces during engine operation. One side 47 or 49 of the lug 48 and a corresponding one side of the slot 50 in contact during engine operation, define respective angular positioning surfaces.
In the ISV arrangement 28 according to this embodiment, the ITD may include annular outer and inner shoulders 52 and 54 on the respective outer and inner duct walls 30, 32. Each of the annular shoulders 52, 54 may be axially located in a downstream section of the respective outer and inner duct walls 30, 32. Such downstream sections are defined downstream of the struts 34. For example, the inner annular shoulder 54 may be defined at the downstream end of the inner duct wall 32 and the annular outer shoulder 52 may be defined within the annular outer duct wall 30 axially between a main section of the outer duct wall 30 and a downstream extension which extends axially over and therefore surrounds the outer ring 38 of the vane ring. The annular shoulders 52, 54 are each defined with annular axial and radial surfaces (not numbered). The annular axial surfaces of the outer and inner shoulders 52, 54 face each other to radially position the vane ring when an upstream end of the vane ring is received between the two annular shoulders 52, 54.
An annular groove (not numbered) may be defined in respective axial surfaces of the annular shoulders 52, 54 to receive, for example an annular ceramic rope seal 62 therein in order to reduce gas leakage between the first and second flow passages 32, 42.
The ISV arrangement 28 in this embodiment may further include an outer casing 56 which may be a part of the first casing 20 (shown in
The annular slot of the lug and slot engagement 58 may be configured to be disassemble-able in order to allow the annular lug/flange to be axially placed in position. The lug and slot engagement 58 may be located at the downstream extension of the annular outer duct wall 30. The vane ring may be axially restrained between the annular shoulders 52, 54 of the ITD and a low pressure turbine seal structure 60. In operation, the aerodynamic load will push the ITD against the low pressure turbine seal structure 60. The vane segments will be pushed against the low pressure turbine seal 60 and an inner support ring 64.
The inner support ring 64 may be bolted a fixed inner stator structure to supports the vane ring segments during the assembly procedure in order to form the vane ring around the inner support ring 64 such that the vane ring is substantially aligned with the ITD for engine assembly before the upstream end of the vane ring is received between the annular shoulders 52, 54. An annular shield 66 may be provided around the segmented vane ring while the individual segments of the vane ring are placed on the inner support ring 64 to retain the segments during formation of the vane ring on the inner support ring 64, thereby facilitating engine assembly procedures.
Regular lugs and slots may be used in the embodiments described above with reference to
Referring to
Tag 69 is axially located at a downstream end of the strut 34 and the downstream end forms an interface between the strut 34 and the associated vane 44″ when the strut 34 is integrated with the associate vane 44″. The tag 69 extends radially substantially along a radial length of the strut 34 such that the downstream end of the strut 34 defines an axial step in a circumferential cross-section of the strut 34, as shown in
Tag 70 is axially located at an upstream end of the associated vane 44″, and the upstream end forms an interface between the associated vane 44″ and the strut 34. The tag 70 extends radially substantially along a radial length of the vane 44″ such that the upstream end of the associated vane 44″ defines an axial step in a circumferential cross-section of the vane 44″ to mate with the axial step formed at the downstream end of the strut 34, as illustrated in
In the ISV arrangement 28 according to this embodiment, two bayonet mount arrangements 76, one on the inner duct wall and one on the outer duct wall may be provided between the ITD and the respective vane ring segments. The first bayonet mount 76 may include an annular groove 78 defined in a downstream end of the inner duct wall 32 (see
An anti-rotational device 82 (see
Referring to
As shown in
The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the described subject matter. It is also understood that various combinations of the features described above are contemplated. For instance, the particular angular positioning arrangements described in the various embodiments may be combined with various ITD and vane ring structures in radial or axial retaining systems, which may be new or known to people skilled in the art. Still other modifications which fall within the scope of the described subject matter will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.
This application is a divisional of U.S. patent application Ser. No. 13/961,136 filed Aug. 7, 2013, the content of which is hereby incorporated by reference.
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Number | Date | Country | |
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Parent | 13961136 | Aug 2013 | US |
Child | 15797242 | US |