GB2572191A

GB2572191A - A lockplate for a bladed rotor arrangement

Info

Publication number: GB2572191A
Application number: GB1804606.0A
Authority: GB
Inventors: Carter Neal; McNally Kevin
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2018-03-22
Filing date: 2018-03-22
Publication date: 2019-09-25
Also published as: GB201804606D0

Abstract

A cooling turbine arrangement for a gas turbine engine, turbine comprising an upstream stator and a downstream rotor. The stator comprises guide vanes 130 extending between inner 141 and outer platforms. The rotor comprises a disc of turbine blades attached via roots 144, the blades extending from a blade platform 140. A blade platform cavity 176 is formed radially inwards of the blade platform and a rim seal cavity 145 is defined between the stator and rotor. The rim seal cavity is in fluid connection with a main gas path of the engine via a gap separating the stator platform and the blade platform. The platform cavity and the rim seal cavity are partitioned by a weir 178, which may be integral with the blade platform or may be formed of a lock plate 148. The weir extends radially inwards from the blade platform and forms a pneumatic reservoir adjacent its radially inner surface. The weir allows fluid communication between the two cavities. When air enters the reservoir via the weir it is centrifugally pumped radially outwards as the rotor is rotated. Also claimed is a lock plate comprising an aperture to provide a flow path between two surfaces.

Description

(57) A cooling turbine arrangement for a gas turbine engine, turbine comprising an upstream stator and a downstream rotor. The stator comprises guide vanes 130 extending between inner 141 and outer platforms. The rotor comprises a disc of turbine blades attached via roots 144, the blades extending from a blade platform 140. A blade platform cavity 176 is formed radially inwards of the blade platform and a rim seal cavity 145 is defined between the stator and rotor. The rim seal cavity is in fluid connection with a main gas path of the engine via a gap separating the stator platform and the blade platform. The platform cavity and the rim seal cavity are partitioned by a weir 178, which may be integral with the blade platform or may be formed of a lock plate 148. The weir extends radially inwards from the blade platform and forms a pneumatic reservoir adjacent its radially inner surface. The weir allows fluid communication between the two cavities. When air enters the reservoir via the weir it is centrifugally pumped radially outwards as the rotor is rotated. Also claimed is a lock plate comprising an aperture to provide a flow path between two surfaces.

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A Lockplate for a Bladed Rotor Arrangement

Technical Field of Invention

The present invention relates to a turbine arrangement 110 and an associated lockplate. In particular, the invention relates to a turbine arrangement 110 of within a turbine stage of a gas turbine engine.

Background of Invention

Turbine arrangement 110s within gas turbine engines comprise a plurality of bladed rotors, each of which comprises a rotor disc and a plurality of rotor blades circumferentially mounted around the radial periphery of the rotor disc. Each rotor blade has an aerofoil, a platform, a shank and a root. The rotor comprises a plurality of circumferentially spaced axially extending slots defined by radially extending posts into which the root of each rotor blade is engaged. The roots of the rotor blades and rotor disc slots are generally fir tree or dovetail shaped such that the engagement of the blade roots in the rotor disc slots is sufficient to radially retain the blades when under centrifugal loading induced when the rotor is rotated in use.

As will be appreciated, the turbine section of a gas turbine engine, particularly the high pressure turbine, is an extremely hot section under normal operating conditions and there is a requirement to provide cooling air to various areas to prevent overheating and to prolong the working life of the engine. Cooled areas include the interior and exterior of the aerofoils, the platforms and the roots of the rotor blades and rotor disc posts which define the slots. To aid effective and efficient cooling, bladed rotors may comprise a plurality of lockplates arranged at either or both axial ends of the rotor blade roots which help restrict free fluidflow under the platforms and prevent axial movement of the rotor blades.

The present invention seeks to provide an improved cooling arrangement for a turbine blade arrangement.

Statements of Invention

The present invention provides a turbine arrangement 110, lockplate and gas turbine engine according to the appended claims.

Providing a weir which extends radially inwards from the blade platform allows a pneumatic reservoir to be formed on the radially inner surface of the blade platform. As the rotor rotates, the pneumatic reservoir is centrifugally pumped to ensure that the pressure within the blade platform cavity is at a higher pressure than the main gas path. Hence, the weir helps provide a means of achieving positive pressure within the blade cavity to help reduce the ingestion of hot main gas path gas in the blade cavity.

The weir may be integrally formed with the platform. For example, the weir may be cast with the blade platform. Alternatively or additionally, the weir may be provided by a lockplate which engages with blade platform. The lockplate may include one or more apertures or form one or more apertures in conjunction with a wall portion of the platform.

Each of the blades may include a blade shank. Adjacent shanks may be separated by an inter-shank cavity. The one or more apertures may be circumferentially aligned with the inter-shank cavity.

The apertures may be formed within the lockplate. The apertures may be partially defined by the lockplate. The apertures may be partially defined by a wall which extends radially inwards from the blade platform. The lockplate may be located axially upstream of the blade root and disc post. The lockplate may cooperate with a plurality of similar lockplates to provide an annular wall upstream of the blade roots.

A second inlet may be provided by a flow path located between the lockplate and blade root or disc post.

The lockplate may have an upstream side and a downstream side in relation to the main gas path in use.

Within the scope of this application it is expressly envisaged that the various aspects, embodiments, examples and alternatives, and in particular the individual features thereof, set out in the preceding paragraphs, in the claims and/or in the following description and drawings, may be taken independently or in any combination. For example features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

In the description below, unless otherwise stated, the geometric references for axial and circumferential should be taken with reference to the principal axis of the gas turbine engine. The terms upstream and downstream should be taken with reference to the flow stream of the main gas path through the engine. Inward and outward facing surfaces should be taken with reference to the rotor surfaces.

Description of Drawings

Embodiments of the invention will now be described with the aid of the following drawings of which:

Figure 1 shows a schematic longitudinal section of a conventional gas turbine engine.

Figure 2 shows an isometric view of a high pressure turbine stage of a gas turbine engine, with a cut out to reveal a lockplate assembled in the rotor arrangement.

Figure 3 shows a detailed isometric view of a rotor arrangement including a lockplate.

Figure 4 shows a schematic circumferential section of the arrangement shown in Figure 3 together with an upstream nozzle guide vane.

Figure 5 shows a perspective downstream view of a rotor arrangement with lockplate having a plurality of fluid inlet apertures.

Figure 6 shows a circumferential section of the lockplate of the rotor arrangement of Figure 5.

Figure 7 shows an alternative turbine arrangement having a first and second inlet.

Detailed Description of Invention

A turbofan gas turbine engine 10, as shown in Figure 1, comprises in flow series an intake 11, a fan 12, an intermediate pressure compressor 13, a high pressure compressor 14, a combustion chamber 15, a high pressure turbine 16, an intermediate pressure turbine 17, a low pressure turbine 18 and an exhaust 19. The high pressure turbine 16 is arranged to drive the high pressure compressor 14 via a first shaft 20. The intermediate pressure turbine 17 is arranged to drive the intermediate pressure compressor 13 via a second shaft 21 and the low pressure turbine 18 is arranged to drive the fan 12 via a third shaft 22. In operation airflows into the intake 11 and is compressed by the fan 12. A first portion of the air flows through, and is compressed by, the intermediate pressure compressor 13 and the high pressure compressor 14 and is supplied to the combustion chamber 15. Fuel is injected into the combustion chamber 15 and is burnt in the air to produce hot exhaust gases which flow through, and drive, the high pressure turbine 16, the intermediate pressure turbine 17 and the low pressure turbine 18. The hot exhaust gases leaving the low pressure turbine 18 flow through the exhaust 19 to provide propulsive thrust. A second portion of the air bypasses the main engine and flows through a bypass duct 23 defined in part by a fan casing 24 and fan casing outlet 25. The second portion of air leaving the bypass duct 23 flows through a bypass, or fan, nozzle (not shown) to provide propulsive thrust.

A portion of the high pressure turbine 16 of the turbofan gas turbine engine 10 is shown more clearly in Figure 2. The high pressure turbine 16 comprises a plurality of nozzle guide vanes 30 which guide hot gases from the combustion chamber 15 onto the turbine rotor blades 36 of a bladed turbine rotor arrangement 32. The bladed turbine rotor arrangement 32 comprises a turbine rotor 34, a plurality of turbine blades 36 and a plurality of lockplates 48 and 50, including fore 48 and aft 50 lockplates. The turbine blades 36 are mounted on the periphery of the turbine rotor 34 with each comprising an aerofoil 37, a platform 40, a shank 42 and a root 44.

The turbine rotor 34 comprises a plurality of circumferentially spaced axially extending slots 46 defined by disc posts 52. The root 44 of each turbine blade 36 is located in a respective one of the axially extending slots 46 so as to be radially retained by the engagement of the so-called fir tree shape of the root and the correspondingly shaped slot 46.

Lockplates 48, 50 are included at the axial extents of the disc posts 52 which define the root receiving axially extending slots. The lockplates 48, 50 provide a retaining function to prevent axial movement of the blades relative to the disc, and a sealing function to help reduce fluid flow under the blade platform and around the blade roots. Generally, an uncontrolled flow in this area would lead to excessive use of cooling air (which ultimately reduces efficiency) and deleterious levels of poorly distributed cooling air leading to overheating in some areas.

Figures 3 and 4 show respective perspective and section views of the rotor arrangement and cooling air flows as known in the art.

The turbine section is a high pressure turbine having a plurality of circumferentially arranged turbine blades 36 in flow series with a nozzle guide vane 30. Thus, there are shown the aerofoil 37, shank 42, a fore lockplate 48 and aft lockplate 50. The root 44 as shown in Figure 2 is obscured by the disc post 52 of the rotor disc 34. A blade platform 40 extends forward of the aerofoil 37 towards a vane platform 41 from which extends a vane root portion 43. A cavity 45 is defined between the blades 36 and vanes 30 below/radially inwards of the respective platforms. The cavity 45 may be referred to as the rim seal cavity 45.

The lockplates 48, 50 are plate-like members having a generally flat or planar body defined by a radially outer portion 54, a radially inner portion 56 and two circumferential edges 58, 60 which extend between the radially inner 56 and outer portions 54. The lockplates 48, 50 are arranged in a circumferentially distributed manner and abut one another to provide a full annulus shield around the disc posts and blade roots. The lockplates 48, 50 are located adjacent the blade roots 44 and disc posts 52 so as to have an inwardly facing axially upstream surface 62 and an outwardly facing axially downstream surface 64. The radially inner 56 and radially outer 54 portions of the lockplates 48, 50 include respective head and foot portions.

In relation to the aft or rear lockplate 50 it can be seen that the head portion is located in a groove provided be an inwardly extending flange 66 provided on the radially inner surface of the platform 40. The foot portion is located in the groove defined between the disc posts and a rear seal plate. The fore lockplate 48 includes a similar arrangement on the upstream side of the rotor. The fore lockplate may be spaced from the leading edge of the blade platform 40 such that it is downstream thereof.

The leading edge of the lockplate is proximate the trailing edge of the nozzle guide vane platform 141 and may extend axially forward of said trailing edge and be radially inwards thereof.

A fore seal plate 70 forms part of the rotor arrangement and may include one or more seals which help partition the flow between the static and rotating parts such that cooling air can be effectively channelled to the desired locations.

In the example shown in Figures 3 and 4, the seal plate 70 includes a sealing flange 72 which extends forwards towards the stator structure radially inwards of the nozzle guide vane 30.

The sealing flange 72 includes radially inner and outer labyrinth seals having teeth which engage with respective stator components.

The seal plate 70 partitions the area axially forward of the blade roots 44 into two separate chambers having different operating pressures. The air chambers may be fed from a common source such as the high pressure compressor, typically the final stage of the high pressure compressor. The different pressures are provided by the seals for the seal plate 70 and/or metering features which restrict the flow of the cooling air to a required pressure.

The first chamber is the rim seal cavity 45 located between the blade 36 and nozzle guide vane 30 and radially inwards of the respective platforms 40, 41. The rim seal cavity 45 may be defined by the forward lockplate 48, a portion of either or both of the nozzle guide vane platform 41 and blade platform 40. The upstream stator may comprise one or more walls which define the rim seal cavity in part. The rim seal cavity 45 is open to the main gas path and held at a positive pressure in relation to the main gas path, or fed with a flow of fluid, to prevent ingestion of hot gas into the rim seal cavity. Hence, there is a general flow of cooling air D to keep the rim seal between the blade and nozzle guide vane platforms 40, 41 vented.

The second chamber 74 is located radially inwards of the seal plate and inner edge of the lockplate 48. This chamber is in fluid communication with the blade root 44 and shank 42 to provide cooling thereto. Thus, there is a cooling flow path which extends from the second chamber 74 and past the blade root 44 and/or blade shank 42. The cooling flow path may be defined in part by the inner surface of the lockplate as shown by arrow A, and/or may be passed axially rewards into one or more passages which exist between the blade root 44 and blade shank 42.

A space below the blade platform 40 and inside the lockplates 48 is defined as a blade platform cavity 76. This receives cooling air from the second chamber 74 and provides cooling to the underside of the blade platforms 40. Gaps exist between the circumferential edges of the platforms 40 through which the cooling air leaks. The leakage of this air may be controlled by one or more sealing features, many of which are described in the art. As with the rim seal cavity and rim seal gap between the platforms, it is beneficial to provide positive pressure, relative to the main gas path, within the blade platform cavity 76 to prevent ingestion of hot air onto the blade shank 42 and root 44 area.

Additional flows may extend from the blade root 44, shank 42, blade platform cavity 76 or second chamber 72 into internal cooling passages within the blade 36.

Thus, as depicted in Figure 4, there is a rim seal cavity flow D which extends from the rims seal cavity inlet to the rim seal gap between the leading edge of the blade platform 40 and the trailing edge of the nozzle guide vane platform 41. A second flow path A is provided from the blade platform cavity inlet at the root of the blade to the blade platform cavity 76. The blade platform cavity exhausts to the main gas path via flow paths B and C between adjacent blade platforms.

Figures 5 and 6 show a perspective and sectional view respectively of a turbine arrangement 110 of a gas turbine engine similar to the one represented in Figure 1. The turbine arrangement 110 comprises: an upstream stator including nozzle guide vane 130 and a downstream bladed rotor 134 comprising a disc which incorporates a plurality of circumferentially distributed turbine blades 136. Each blade 136 has an aerofoil 137 extending from a blade platform 140 and a root portion 144 securing the blade 137 to the disc via an interlock provided by disc posts 135. A blade platform cavity 176 is located radially inwards of the blade platform 140 and a rim seal cavity 145 is located between the stator 130 and rotor 134. The rim seal cavity 145 is in fluid connection with a main gas path of the gas turbine engine by the rim seal gap which separates the stator and rotor platforms 141,140 in the gas path wall.

A weir 178 in the form of a wall extends radially inwards from the blade platform 140 to partially partition the rim seal cavity 145 and blade platform cavity 176. The weir 178 forms a reservoir 180 adjacent the blade platform 140 such that air can collect there in use. The blade platform cavity 176 and rim seal cavity 145 are in fluid communication via the weir 178 such that air can enter the reservoir 180 from the rim seal cavity 145.

During operation, pressurised air is provided to the rim seal cavity 145 from a suitable compressor stage and exits via the rim seal gap which separates the stator and rotor platforms 140,141. Pressurised air also flows downstream over the weir 178 and into the reservoir 180 located under the blade platform 140. Air within the reservoir 180 will be rotated due to rotation of the turbine rotor 134 in use and centrifugally loaded so as to be pumped radially outwards towards the platform and out of the inter platform gaps between adjacent blade platforms.

It will be appreciated that the turbine rotor 134 will be rotating at this point to provide the pressurised air. Hence, the air flows over the weir 178 on the radially inner surface of the weir 178 due to the direction of flow in the rim seal cavity 145 and centrifugal load imparted by the rotation of the rotor 134. It will be appreciated that the term 'over' used in relation to the flow of air is relative and does not mean vertically over, or above. Rather it denotes the general flow of air which is moving radially outwards into the reservoir 180 as limited by the weir 178.

The weir 178 may be any suitable structure which appends from the blade platform 140 and provides the reservoir 180 under the blade platform 140. Hence the reservoir 180 may be provided by a formation which is integral with blade platform 140 so as to be homogeneously formed with the blade. Such a feature may be provided either by casting, welding or machining for example. Hence, the weir 178 may be provided in part or in full by a wall in the form of a flange. The flange may extend from a proximal end attached to the radially inner side of platform 140 to a distal free end over which the air flows from the Alternatively or additionally, as shown in Figures 5 and 6, the weir 178 may be provided in part by one or more lockplate 148.

The weir 178 may be provided by apertures which are bounded by a peripheral wall. The peripheral wall may be provided by the lockplate body 182, or by the lockplate body 182 together with a portion of the blade platform 140. One or more of the peripheral walls may provide the weir 178.

In the case where the lockplate 148 provides the weir 178, the lockplate 148 may comprise: a plate body 182 having at least one flow path A' through the lockplate 140 from an upstream side to a downstream side on the radially inner side of the blade platform 140. The flow path A' may be provided by one or more apertures 184 in the lockplate 148. The one or more apertures 184 may be provided by a hole which is cast or machined into the lockplate 148, or by an open notch in the radially outer edge of the plate body which combines with a portion of the blade to provide a closed aperture. The portion of the blade 134 may be provided by any suitable structure such as a flange extending from the platform to provide the closed flow passage and weir. Thus, the weir 178 may be provided individually by a portion of the blade 134 and a portion of the lockplate 148.

The fore lockplate 148 may be a plate-like member having a generally flat or planar body defined by a radially outer portion 154, a radially inner portion 156 and two circumferential edges 158,160 which extend between the radially inner 156 and outer portions 154. The lockplate 148 is one of a plurality of similar lockplates arranged in a circumferential array around the annular distribution of blades. Neighbouring lockplates may abut one another to provide a full annulus shield around the disc posts 135 and blade roots 144. The fore lockplates 148 are located adjacent the blade roots 144 and disc posts 152 so as to have an inwardly facing surface 162 and an outwardly facing surface 164.

The fore lockplate 148 includes a head portion which may be located in a suitable groove or other feature provided by the radially inner surface of the blade platform 140. The foot portion may be retained in a groove or other feature. As shown in Figure 6, this may be provided by a seal plate 170 or similar structure which is part of or attached to the rotor disc.

The rim seal cavity 145 may be in the form of an annular chamber extending around the circumference of the engine between the stator 130 and rotor 134. The rim seal cavity 145 is in fluid communication with the main gas path and is pressurised with air so as to remain at a positive pressure in relation to the main gas path to ensure that there is a continuous flow of cooling air into the main gas path from the rim seal cavity to help maintain a seal and prevent ingestion of the high temperature air into the rim seal cavity 145 and unprotected parts of the turbine.

The rim seal cavity 145 is defined by opposing static and rotating parts. Thus, on the upstream side the cavity 145 is defined by a stator 130, and on the downstream side by a rotor 134. The interface between the stator 130 and rotor 134 is defined by a rim seal gap in the gas path wall between the respective stator and rotor platforms 141,140. Within the engine, the stator 130 and rotor 134 are separated by a seal 172. The seal 172 may be provided by a two-part seal in which one part is rotating and the other static. The seal may be any suitable type including a labyrinth seal as shown in Figure 6. The labyrinth seal includes a plurality of annular seal fins which extend from the rotor to opposing seal plates on the stator. Seals suitable for gas turbine engines and the application described herein are well known in the art.

An amount of air will leak through the seal to provide an inlet for and pressurisation of the rim seal cavity 145. An additional fluid pathway may be provided to ensure the flow requirement of the rim seal cavity 145 is met.

The seal may form part of a so-called seal plate which appends from the rotor as shown in Figure 6. The seal plate may be a disc-like structure which fits around the rotor shaft and attaches to the rotor disc 134. The labyrinth seal may be provided in part by a flange which extends from the rotor, the flange being part of a seal plate.

A second cavity, a blade platform cavity 176, is defined radially inwards of the blade platform 140 and aft of the fore lockplate 148. The blade platform cavity 176 may include and may be fully or partially circumferentially partitioned by the blade shanks 142. The rear side of the blade platform cavity 176 may be provided by one or more aft lockplates 150 or equivalent structures. Where circumstances permit the aft portion of the blade platform cavity 176 may be left open.

The blade platform cavity 176 may include the space immediately radially inwards of the blade platform 140 and extend radially inwards to include the blade shank 142, blade root 144 and disc posts 135 which provide the retention slots for the blade roots 144. Alternatively, the blade platform cavity 176 may terminate at the blade roots and/or disc posts/slots.

The fore lockplate 148 may include one or more flow path openings. The flow path openings may be in the form of one or more apertures 184. The one or more apertures 184 may extend from the fore side 164 to the aft side 162 to provide a fluid pathway through the lockplate 148. The one or more apertures 184 is located adjacent the blade platform cavity 176 such that the perforation provides a flow path from the rim seal cavity 145 to the blade platform cavity 176.

The apertures 184 are radially inwards and removed from the radial extreme of the blade platform cavity 176 such that there is a portion of the blade platform cavity 176 which is radially outwards of the aperture 184. This radially outer portion of the blade platform cavity 176 provides the blade platform reservoir 180 in which a head of air can be stored and centrifugally pumped in use. The centrifugal pumping is provided when the rotor rotates and the mass of the air is forced outwards thereby increasing the static pressure in the reservoir 180.

The increase in pressure due to the centrifugal pumping ensures that the pressure within the blade platform cavity 176 is higher than the rim seal cavity. Hence, during use, air within the blade platform cavity 176 remains at a positive pressure relative to the pressure on the gas path facing surface of the platform 140.

It will be appreciated that the size and position of the apertures 184, and weir 178, will be dependent on the required flow and pressures needed which will be engine specific. There may be a single or a plurality of apertures 184 in the fore Iockplatel48. The apertures 184 may be located within a mid-region of the lockplate 140 and may terminate at or radially outwards of the blade root and disc posts. The apertures may cover up to 80% of the radial extent of the lockplate. Preferably, the apertures will cover 60% of the lockplate. The apertures may be located circumferentially between the blade shanks 142 and/or roots 144 of the blades so as to be aligned with the inter-shank cavity which spans between the shanks 142. However, the apertures may circumferentially overlap with the blade shanks 142, where desired. There may be one or more apertures 184 per inter-shank cavity. Thus, as can be seen in Figure 5, there are two apertures feeding into a portion of the blade platform cavity 176 which is defined between two of the blade shanks 142.

Thus, as depicted in Figure 6, there is a rim seal cavity inlet flow A which extends from the rim seal cavity inlet to the rim seal gap between the leading edge of the blade platform 40 and the trailing edge of the nozzle guide vane platform 41 with a first flow path A. The flow path within the rim seal cavity bifurcates to provide a second flow path A' into the reservoir over the weir. The blade platform cavity exhausts to the main gas path via flow paths B and C between adjacent blade platforms.

Figure 7 shows a further example in which the structure corresponds largely to the example shown in Figures 5 and 6. A marked difference with the example of Figure 7, is the presence of a further flow path, or second infeed, into the blade platform cavity 176. The second infeed is provided by a fluid flow path that extends from a cooling chamber 174 which supplies cooling air to the blade root 144 and, alternatively or additionally, to the internal cooling passages of the blade indicated by the dashed line. The second infeed cooling air chamber is fluidicaIly separated from the rim seal cavity 145 by one or more seals.

The second infeed to the blade platform cavity 176 may be provided radially inwards of the lockplate 148. The fluid pathway may extend between the lockplate 148 and blade root 144 and disc post 142, and/or through the blade root 144 to provide cooling thereto. Additionally or alternatively, one or more internal blade cooling passageways may be fed from the blade platform cavity 176 via one or more blade cooling passageway inlets (not shown). Such passageways and inlets are well known in the art and may be provided in the axial or radially inner faces of the blade root 144.

The seal plate 170 described above in relation to Figure 6, includes a sealing flange 172 which extends forwards towards the static structure 143 which sits radially inwards of the nozzle guide vane 130. The sealing flange 172 includes radially inner and outer labyrinth seals having teeth which engage with respective stator components.

The seal plate 170 partitions the area fore of the blade roots 144 into two separate chambers having different operating pressures. The air chambers may be fed from a common source such as the high pressure compressor, typically the final stage of the high pressure compressor, or different compressor stages. The flow path that exists between the respective compressor and air chamber may include one or more pressure and flow regulating features. Thus, the different pressures in the first and second chambers may be provided by the seals of the seal plate 170 and/or metering features which restrict the flow of the cooling air to a required pressure.

The second chamber 174 is located radially inwards of the lockplate 148. This chamber is in fluid communication with the blade root 144 and shank 142 to provide cooling thereto. Thus, there is a cooling flow path D which extends from the rim seal cavity 145 to the blade platform cavity 176 via the weir, which in the example shown, is provided by the aperture 184 in the lockplate 148. Air from the blade platform cavity 176 bleeds B, C, through the inter-platform gap which separates adjacent platforms of circumferentially adjacent rotor blades 136. The second infeed flow path A extends from the second infeed cooling chamber 174, past the blade root 144 and/or blade shank 142. The second infeed cooling flow path A may be defined in part by the inner surface of the lockplate 148 as shown, and/or may be passed axially rewards into one or more passages which exist between the blade root and blade shank.

Hence, the fluid flow path through the lockplate is a first fluid flow path and a second fluid flow path is provided radially inwards of the lockplate and the first and second fluid flow paths are fluidically isolated from one another upstream of the lockplate.

It will be understood that the invention is not limited to the described examples and embodiments and various modifications and improvements can be made without departing from the concepts described herein and the scope of the claims. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more described features.

Claims

Claims:

1. A turbine arrangement (110) of a gas turbine engine, the turbine arrangement (110) comprising:

an upstream stator including a plurality of nozzle guide vanes (130), each of the plurality of nozzle guide vanes having inner (141) and outer platforms with a vane aerofoil extending therebetween;

a downstream rotor (134) comprising a disc which incorporates a plurality of circumferentially distributed turbine blades (136), each blade having an aerofoil (137) extending from a blade platform (140) and a root portion (144) securing the turbine blade to the disc, a blade platform cavity (176) radially inwards of the blade platform;

a rim seal cavity (145) between the stator and rotor, the rim seal cavity in fluid connection with a main gas path of the gas turbine engine via an inter-stage gap which separates the nozzle guide vane inner platform and blade platform, wherein the blade platform cavity and rim seal cavity are partitioned by a weir (178) which extends radially inwards from the blade platform and forms a pneumatic reservoir (180) adjacent a radially inner surface of the blade platform, the blade platform cavity and rim seal cavity being in fluid communication via a fluid flow path which extends over the weir such that air entering reservoir via the weir is centrifugally pumped radially outwards when the rotor is rotated during normal use.

2. A gas turbine arrangement as claimed in claim 1, wherein the weir is provided by a wall having one or more apertures (184) therein, the apertures providing the fluid communication between the blade platform cavity and rim seal cavity.

3. A gas turbine arrangement as claimed in claim 2, wherein the one or more aperture is located adjacent a blade shank (142) of the turbine blade.

[Each of the blades may include a blade shank. Adjacent shanks may be separated by an inter-shank cavity. The one or more apertures may be circumferentially aligned with the inter-shank cavity.]

4. A gas turbine arrangement as claimed in claim 3, wherein the one or more apertures are provided by a lockplate (148).

[The apertures may be formed within the lockplate. The apertures may be partially defined by the lockplate. The apertures may be partially defined by a wall which extends radially inwards from the blade platform. The lockplate may be located axially upstream of the blade root and disc post. The lockplate may cooperate with a plurality of similar lockplates to provide an annular wall upstream of the blade roots.]

5. A turbine arrangement as claimed in any preceding claim, wherein the fluid flow path through the lockplate is a first fluid flow path and a second fluid flow path is provided radially inwards of the lockplate, the first and second fluid flow paths being fluidically isolated from one another upstream of the lockplate.

6. A turbine arrangement as claimed in claim 5, wherein the second fluid flow path provides cooling air to an internal cooling passage of the blade aerofoil.

7. A turbine arrangement as claimed in claim 6, wherein the first and second fluid paths are provided in fluid communication with a common compressor stage.

8. A turbine arrangement as claimed in any of claims 2 to 7, further comprising an annular array of lockplates, wherein at least one lockplate includes a plurality of the one or more apertures.

9. A turbine arrangement as claimed in any preceding claim wherein the lockplate has a radial depth and the aperture is contained within the outer 60% of the radial depth.

10. A turbine arrangement as claimed in any preceding claim, wherein the lockplates extend circumferentially across at least two blades roots.

11. A turbine arrangement as claimed in any preceding claim, wherein the blade platform cavity includes a first inlet via the weir and a second inlet which is fluidically separated from the rim seal cavity upstream of the lockplate.

12. A turbine arrangement as claimed claim 11, wherein the second inlet is provided radially inwards and axially rearwards of the lockplate.

13. A lockplate for covering the root of a turbine blade in a gas turbine engine, comprising: a plate body having at least one aperture to provide a fluid flow path through the lockplate from a first surface to a second surface.

14. A gas turbine engine comprising the turbine arrangement of any of claims 1 to 13.

Intellectual Property Office

Application No: GB1804606.0

Examiner:

Ms Megan Parker

Claims searched:

1-12 and 14 in part

Date of search: 19 September 2018

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-12 and 14 WO 2007/063128 Al (SIEMANS) See abstract, figures 1-5, whole description especially paragraphs [0022]-[0033], noting stator 1, rotor 2 with blade platform 10, blade platform cavity 16, weir 17 X 1-3, 10-12 and 14 US 2009/0175732 Al (GLASSPOOL) See abstract, figures 1-4, whole description, especially paragraphs [0015]-[0022], noting stator 20, rotor 30, platform 34, blade platform cavity 58, rim seal cavity 69, weir 62 X 1, 10-12 and 14 EP 3043024 Al (SIEMANS) See abstract, figures 1-5, whole description especially paragraphs [0037]-[0044], noting stator 6, rotor disc 15, platform 24, weir 65

Categories:

X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention. same category. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.

Field of Search:

Search of GB, EP, WO & US patent documents classified in the following areas of the UKCX :