GB2454014A

GB2454014A - Turbine transfer tube

Info

Publication number: GB2454014A
Application number: GB0721113A
Authority: GB
Inventors: Peter Richard Bates
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2007-10-27
Filing date: 2007-10-27
Publication date: 2009-04-29
Also published as: GB0721113D0

Abstract

A turbine assembly has a transfer tube arrangement 121 comprising a tube 124 extending from a first structure 122 to a second structure 125, the first structure 122 having a recess 123 to engage an inlet end 129 of the tube 124 and the second structure 125 having a chamfer 126 to engage an outlet end 118 of the tube 124, the tube 124 being configured to allow slide movement in the recess 123 relative to the chamfer 126. The chamfer 126 may be recessed into a hole 120 in the second structure 125, the tube 124 extending into the hole 120 to define a seal between side parts of the tube 124 and the hole 120. The inlet end 129 of the tube 124 may be curved and engage the recess 123 to allow pivoting. The first structure 122 may be a nozzle guide vane arrangement of a gas turbine engine.

Description

A TURBINE ROTOR ASSEMBLY

The present invention relates to turbine rotor assemblies and more particularly to transfer tube arrangements in turbine rotor assemblies utilised with regard to gas turbine engines in order to pass cooling air from a high pressure side to a low pressure side for distribution purposes.

Referring to Fig. 1, a gas turbine engine is generally indicated at 10 and comprises, in axial flow series, an air intake 11, a propulsive fan 12, an intermediate pressure compressor 13, a high pressure compressor 14, a combustor 15, a turbine arrangement comprising a high pressure turbine 16, an intermediate pressure turbine 17 and a low pressure turbine 18, and an exhaust nozzle 19.

The gas turbine engine 10 operates in a conventional manner so that air entering the intake 11 is accelerated by the fan 12 which produce two air flows: a first air flow into the intermediate pressure compressor 13 and a second air flow which provides propulsive thrust. The intermediate pressure compressor compresses the air flow directed into it before delivering that air to the high pressure compressor 14 where further compression takes place.

The compressed air exhausted from the high pressure compressor 14 is directed into the combustor 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive, the high, intermediate and low pressure turbines 16, 17 and 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low pressure turbines 16, 17 and 18 respectively drive the high and intermediate pressure compressors 14 and 13 and the fan 12 by suitable interconnecting shafts.

It will be appreciated in a number of circumstances it is desirable to provide for controlled distribution of air and other fluids between structures in an assembly. Figure 1 above illustrates an engine 10 as such an assembly in which fluid flow must be controlled and passed through the engine for efficiency. If these structures are thermally cycled there will be relative movements. It is necessary to ensure that distribution is consistent despite such relative movements. There will be relative movement between turbine rotor assemblies within a gas turbine engine in relation to distribution of coolant flows. In such circumstances a transfer tube is provided between a first structure and a second structure. The first structure includes a recess to accommodate the transfer tube and the second structure generally incorporates a chamfer surface to provide a seal. A fluid pressure is arranged to ensure that transfer tube is generally presented against the chamfer surface in order to avoid or reduce fluid leakage, that is to say coolant losses which may be detrimental to overall efficiency.

Figure 2 illustrates a typical prior transfer tube arrangement 101 in which a first structure 102 incorporates a recess 103 within which a transfer tube 104 is located. A second structure 105 incorporates a chamfer surface 106 against which the transfer tube 104 engages in order to form a seal. As will be noted the transfer tube 104 can slide generally in the recess 103 in a range defined by the chamfer 106 of the second structure 105 and an end wall 107 of the first structure 102 in the recess 103. In use generally there is an air pressure driven flow in the direction of arrowheads A. This flow A passes along the transfer tube 104 through the first structure 102 and into the second structure 105 and in particular a duct 108. It will also be appreciated that the air pressure created by the flow A engages flange portions 109 of the transfer tube 104 in order to force the engagement between the tube 104 and the chamfer 106 in order to create a seal. In operation the air pressure acts on the piston area defined by the flanges 109 of the tube 104 to push the tube 104 rearwards as indicated into engagement with the chamfer surface 106. In such circumstances rear parts of the tube 104 create a seal preventing leakage.

It will be understood that loss of fluid flow such as coolant flow through the arrangement depicted reduces efficiency. In such circumstances the flange portions 109 of the tube 104 create and effectively seal within the recess 103 whilst as indicated an end surface of the tube 104 creates a seal with the chamfer 106. Generally the front of the tube 104 including flanges 109 as well as the surface in engagement with the chamfer 106 are shaped to create effective seals which are operative despite relative radial, axial and circumferential movements between the first structure 102 and the second structure 105.

As will be appreciated problems occur with prior arrangement 101 in that if the tube 104 does not engage or fully engage with the chamfer surface 106 a seal will not be formed and fluid leakage will occur. In a gas turbine engine such leakage of coolant air will be detrimental to overall air cooling efficiency within the engine. It will also be appreciated that by the general nature of the front portion 109 of the tube 104 in the recess 103 rotation or tilt of the front is limited. In such circumstances when rotated, the edge of the front 109 of the tube 104 can chock or foul against the recess 103 preventing further rotation and again limiting the force of engagement with the surface 106 or preventing any engagement at all again resulting in leakage.

In accordance with aspects to the present invention there is provided a turbine rotor assembly having a transfer tube arrangement comprising a tube extending from a first structure to a second structure, the first structure having a recess to engage an inlet end of the tube and the second structure having a chamfer to engage an outJet end of the tube, the tube configured to allow slide movement in the recess relative to the chamfer, the assembly characteriseci in that the chamfer is recessed into a hole in the second structure and the tube extends into the hole to define a seal between side parts of the tube and the hole.

Typically, the side parts are curved to allow pivot and/or twist of the tube relative to the second structure.

Generally, the side parts are in a close tolerance fit to the hole to define the desired level of seal efficiency.

Generally, the hole is tapered towards the chamfer.

Possibly, the hole is smaller than the recess.

Also in accordance with aspects to the present invention there is provided a turbine rotor assembly tube transfer arrangement comprising a tube extending from a first structure to a second structure, the first structure having a recess to engage an inlet end of the tube and the second structure having a chamfer to engage an outlet end of the tube, the tube configured to allow slide movement in the recess relative to the chamfer, the arrangement characterised in that the tube at the inlet end engaging the recess is curved to allow pivot thereabout and maintains engagement of the inlet end with the recess.

Typically, the inlet end has spherical side portions.

Generally, the recess has a chamfer to engage the inlet end of the tube.

Typically, the first structure comprises a nozzle guide vane (NGV) housing in a gas turbine engine.

Typically, the second structure is a coolant path segment in a gas turbine engine.

Generally, the tube has a configuration to accommodate relative radial, axial and circumferential movements between the first structure and the second structure.

Typically, the configuration is to accommodate movements as a result of thermal cycling of the first structure and the second structure.

Typically, the first structure and the second structure are separate components with a gap between them.

Generally, in use the inlet end of the tube is subject to a fluid pressure to force slide of the tube towards the chamfer in the second structure.

Possibly, parts of the tube are arranged to expand or contract relative to the recess and/or hole in order to facilitate respective seals between the tube and the recess and/or hole.

Embodiments of aspects of the present invention will now be described by way of example with reference to the accompanying drawings in which: -Figure 3 is a schematic cross-section of a first embodiment of a transfer tube arrangement in a rotor turbine assembly in accordance with aspects to the present invention; and, Figure 4 is schematic cross- section of a second embodiment of a transfer arrangement in a rotor turbine assembly in accordance with aspects of the present invention.

Ps indicated above transfer tubes are utilised in turbine rotor assemblies in order to ensure good transfer of fluids such as coolant air flows in gas turbine engines.

The tubes effectively bridge two structures in order to provide a pathway for containment of the fluid flow despite relative movements between the structures. In operation the tube must be able to accommodate radial, axial and circumferential movements between the respective structures. If the tube can not accommodate such displacements then there is a likelihood of significant or increased leakage reducing overall efficiency.

A transfer tube arrangement used in a rotor turbine assembly in accordance with aspects of the present invention in particularly is used with regard to gas turbine engines. This assembly includes a nozzle guide vane (NGV) to steer and guide a gas flow through the engine and also an appropriate bleed to distribute fluid flows in the form of an air coolant. Typically, the coolant air may be taken from the low pressure compressor stages but for HP turbine the coolant air is normally from the HP compressor.

IP and LP air will be used in the IP and possibly the LP turbine. This air coolant acts to force the transfer tube between a first structure in which the nozzle guide vanes are presented and a second structure is part of the engine assembly. As the housing for the nozzle guide vane and the other segments of the turbine rotor assembly must accommodate manufacturing and assembly tolerance stack up, as well as thermal cycling in the course of operation, it is necessary to provide a transfer tube to maintain good transfer of the fluid flow (coolant air) despite any relative displacements and mis-alignments.

In accordance with first aspects of the present invention an end, typically a rear or outlet end down stream of fluid flow direction is arranged to engage and be presented in a hole extending to a chamfer surface utilised to define a seal. As with prior arrangements the fluid flow pressure is utilised in order to cause slide engagement between the outlet end of the tube and the chamfer surface in order to maintain an adequate seal.

Figure 2 provides a schematic cross-section of a first embodiment of aspects of the present invention in respect of a transfer tube arrangement 121. In figure 3, a transfer tube 124 is located within a recess 123 of a first structure 122 as well as within a hole 120 of a second structure 125. As indicated previously, the first structure 122 may be a NGV housing and the second structure 125 may be a segment of the remainder of a turbine gas turbine engine. In such circumstances the tube 124 extends across a gap 119 between the structures 122, 125 in order to accommodate radial, axial and circumferential displacements between the structures 122, 125. As indicated above generally a fluid flow such as an air coolant forcefully passes in the direction of arrowheads B through the tube 124 between the structures 122, 125. The pressure created by the flow B engages an inlet part 129 at an inlet end of the tube 124 in order to generate an engagement pressure between an outlet part of the tube 118 and a chamfer 126 in order to inhibit leakage. Thus, most of the flow B will pass into a duct 128 of the second structure 125 for operational purposes.

In order to ensure a good seal and to prevent leakage in operation the tube 124 as indicated is generally forced rearwards with the flow B into contact with the chamfer 126. If this should not happen then it will be understood that a seal can not be created against the chamfer 126 and therefore leakage would occur. However, with regard to aspects to the present invention through appropriate shaping of the side parts of the end 118 of the tube 124 a back up or secondary seal is created. Leakage is limited due to the close contact between the side parts 118 and the hole 120. It will be appreciated the tube 124 in respect of the side parts will be closely shaped arid configured in order to provide a tight clearance fit with the hole 120 to minimise leakage. Nevertheless, it will also be understood in order to accommodate for radial, axial and circumferential displacement between the structures 122, that the parts 118 must also be able to slide and move within the hole 120. In such circumstances a perfect seal is not created.

The primary seal is still provided by engagement with the chamfer 126 under force created by the flow B. However, should this primary seal fail then in accordance with aspects to the present invention the secondary seal created by the side parts 118 relative to the hole 120 will still limit leakage.

It will be noted that the side parts 118 have a curved external shape as presented to the hole 120. Such curved or spherical shaping allows for pivot in terms of relative rotation between the structures 122, 125 in the direction of arrowheads C. In such circumstances should such relative rotation in the direction of arrowheads C between the structures 122, 125 occur portions of the part 118 will remain in engagement with the hole 120 and will still be able to provide for a secondary seal whilst also allowing lateral and circumferential displacements between the structures 122, 125.

It will also be appreciated due to the thickness profile of the curved configuration for the parts 118 and as a result of further expansion these parts 118 may expand radially to further improve the secondary seal created by association and juxtaposition relative to surfaces of the hole 120. Finally, the adjacent portions of the parts 118 as well as opposing juxtaposed parts of the hole 120 may be associated with a sealing compound or simply lubricant to further inhibit fluid leakage should the primary seal created by engagement with the chamfer 126 fully or partially fail.

In accordance with second aspects of the present invention a further chamfer 127 has been provided in the recess 123. This chamfer 127 is associated with further profiling and extension of an inlet end 129 of the tube 124. By such association and the end 29 having curved and typically spherical surfaces the rotational range in the direction of arrowheads C is less limited by an end wall 117 in comparison with prior arrangements 101 as depicted above with regard to Figure 2. In such circumstances under rotational extremes, if the tube 124 does not move sufficiently forward during operation, the tube 124 can still operate and rotate freely by pivot upon the further chamfer surface 127 with the curved surfaces of the end parts 129 still engaged with the recess 123 in order to create a seal. This seal is typically provided by surface portions of the end 129 in close tolerance engagement with the recess 123.

In a preferred arrangement both the part 129 and the part 118 have curved surfaces to allow respective articulation and pivot about their respective engagement portions with the recess 123 and hole 120. In such circumstances by such pivoting articulation it will be appreciated that easier accommodation of relative displacement between the structures 122, 125 can be achieved.

A further typical advantage with regard to provision of a curved surface to the part 129 is that during assembly it is possible that the structures 122, 125 will not be as arranged in operation. For example with regard to a gas turbine engine whereas the engine will normally operate in a horizontal configuration as depicted in Figure 2 in assembly the engine may be assembled in a vertical configuration. In such circumstances the air transfer tube 124 may need to accommodate for misalignment between the structures 122, 125. By provision of the curved shaping to the parts 129, 118, and in particular through the angular association between the further chamfer 127 and the curved surface of part 129, relative rotation by the tube 124 can be achieved in order to accommodate mismatch between the structures 122, 125 which may disappear or become more tolerable when the arrangement 121 is re-aligned to its horizontal configuration as depicted.

It will be noted that typically the size or diameter of the recess 123 and therefore the part 129 will be greater than the hole 120 and therefore side parts 118.

Such differences in size may be utilised in order to provide force concentration of the pressure created by the flow B engaging the effective seal between the parts 129 and the recess 123 in sliding the tube 124 towards the chamfer 126.

Generally, the tube 124 will be formed from an appropriate material to resist probable temperature differentials of and between the structures 122, 125 in operation. Thus, the tube 124 will typically be formed from a metal and a similar material to the structures 122, 125.

It is advantageous if the tube 124 is formed from the same material but it will also be appreciated that parts or all of the tube 124 may be formed from different materials in order to minimise wear and achieve better slide and/or seal associations to prevent leakage.

By aspects to the present invention and through the hole 120 it will be appreciated that the potential for fluid or air leakage as a result of disengagement between the end 118 and the chamfer 126 is reduced by the provision of secondary sealing of side parts of the end 118 within the hole 120. It will also be appreciated through use of a chamfer and shaping of the inlet part and in particular normally the front part of the tube 124 there are advantages with regard to creating an arrangement in which there is potential for increased rotational freedom and therefore capability to accommodate greater relative movements between the first structure 122 and the second structure 125. Relative rotation about the tube 124 in the recess 123 and hole 120 will also aid assembly particularly with regard to gas turbine engines where there will be variations in the orientation between assembly and use.

As indicated above it is generally mis-alignment between the structures across which the transfer tube extends which causes blocking and chocking limiting slight movement of the tube and therefore primary sealing engagement to prevent leakage. Figure 4 provides a schematic cross-section of a second embodiment of a transfer tube arrangement in accordance to aspects of the present invention. A general configuration of the arrangement of 131 is similar to that depicted in Figure 3 except a taper 142 is provided in the recess 133 of the first structure 132 in order to increase the radial range of misalignment between the structures 132 and 135 and increase articulation and tilt in the direction of arrowheads H. It will also be noted that an end wall of the first structure 132 again incorporates a chamfer 137 to allow such rotation even when the end 139 is engaged with the chamfer 137 to accommodate for relative articulation in the direction of arrowheads E. With regard to the embodiment depicted in Figure 3 it will be noted that the size of the rear side parts 148 have been increased to allow greater rotation in the direction of arrowheads E and therefore articulation in association with curved shaping of the end 139 in engagement with the recess 133. By such modifications as indicated the potential for relative movement between the structures 132, without chocking and lockup limiting slide movement for seal engagement between the part 118 or side parts of 148 and the chamfer 136 is increased.

In operation the embodiment as depicted in Figure 4 will again operate through a fluid flow, typically air coolant, passing in the direction of arrowhead D through the tube 134. This flow D will create pressure driving slide movement of the tube 134 such that there is engagement with the chamfer 136 in order to create a seal.

As indicated previously this seal will prevent leakage of the flow. However, should the tube 134 inadequately slide or lock a secondary seal is provided through the side portions of the end 148 engaging opposed parts of the hole 140 to limit leakage in use.

By aspects of the present invention as indicated a transfer tube arrangement is provided which can accommodate for displacement between structures such as an NGV housing and segments of a gas turbine engine. Problems with regard to lockup of the transfer tube resulting in unacceptable leakage of fluid flow such as coolants is inhibited through provision of a curvature to an end of the transfer tube along with positioning in a hole to define a secondary seal to limit leakage.

Although described principally with respect to a turbine rotor assembly of a gas turbine engine, it will be appreciated that aspects of the present invention may also be applied to assethblies of structures which may become mis-aligned although fluid transfer must be maintained by a transfer tube especially where the structures become hot and are thermally cycled with the potential for relative displacement.

Modifications and alterations to aspects of the present invention will be appreciated by those skilled in the art. Thus as indicated above the transfer tube may be formed from a material and be specifically shaped to achieve better secondary sealing in use. The hole and recess may themselves taper slightly towards their respective chamfers to again improve the quality of the secondary seal although the slide function to accommodate displacement between the structures must still be maintained.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. A turbine rotor assembly having a transfer tube arrangement (101, 121, 131) comprising a tube (104, 124, 134) extending from a first structure (102, 122, 132) to a second structure (105, 115, 125), the first structure having a recess (103, 123, 133) to engage an inlet end (109, 129, 139) of the tube and the second structure having a chamfer (106, 126, 136) to engage an outlet end (118, 148) of the tube, the tube configured to allow slide movement in the recess relative to the chamfer, the assembly characterised in that the chamfer is recessed into a hole (120, 140) in the second structure and the tube extends into the hole to define a seal between side parts (118, 148) of the tube and the hole.
2. An assembly as claimed in claim 1 wherein the side parts are curved to allow pivot and/or twist of the tube relative to the second structure.
3. An assembly as claimed in claim 1 or claim 2 wherein the side parts are in a close tolerance fit to the hole to define the desired level of seal efficiency.
4. An assembly as claimed in any of claims 1, 2 or 3 wherein the hole is tapered towards the chamfer.
5. An assembly as claimed in any preceding claim wherein the hole is smaller than the recess.
6. A turbine rotor assembly tube transfer arrangement (101, 121, 131) comprising a tube (104, 124, 134) extending from a first structure (102, 122, 132) to a second structure (105, 115, 125) , the first structure having a recess (103, 123, 133) to engage an inlet end (109, 129, 139) of the tube and the second structure having a chamfer (106, 126, 136) to engage an outlet end (118, 148) of the tube, the tube configured to allow slide movement in the recess relative to the chamfer, the assembly characterised in that the tube at the inlet end (129, 139) engaging the recess is curved to allow pivot thereabout and maintains engagement of the inlet end with the recess.
7. An assembly as claimed in claim 6 wherein the inlet end has spherical side portions.
8. An assembly as claimed in claim 6 or claim 7 wherein the recess has a chamfer (127, 137) to engage the inlet end of the tube.
9. An assembly as claimed any preceding claim wherein the first structure comprises a nozzle guide vane (NGV) housing in a gas turbine engine.
10. An assembly as claimed in any preceding claim wherein the second structure is a coolant path segment in a gas turbine engine.
11. An assembly as claimed in any preceding claim wherein the tube has a configuration to accommodate relative radial, axial and circumferential movements between the first structure and the second structure.
12. An assembly as claimed in claim 11 wherein the configuration is to accommodate movements as a result of thermal cycling of the first structure and the second structure.
13. An assembly as claimed in any preceding claim wherein the first structure and the second structure are separate components with a gap (119, 149) between them.
14. An assembly as claimed in any preceding claim wherein in use the inlet end of the tube is subject to a fluid pressure to force slide of the tube towards the chamfer in the second structure.
15. An assembly as claimed in any preceding claim wherein parts of the tube are arranged to expand or contract relative to the recess and/or hole in order to facilitate respective seals between the tube and the recess and/or the hole.
16. A turbine rotor assembly substantially as herein before described with reference to the accompanying drawings.
17. A gas turbine engine incorporating a turbine rotor assembly as claimed in any preceding claim
18. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.