Patent Description:
A rotary machine (such as a turbomachine) may include at least one stator vane. The stator vane may be utilised as part of a compressor stage or a turbine stage of a rotary machine. The stator vane may comprise a platform and an aerofoil.

If configured for use within a turbine stage of a rotary machine, the aerofoil is adapted to convert static pressure energy and/or heat energy of air passing through the turbine stage into kinetic energy. On the other hand, if configured for use within a compressor stage of a rotary machine, the aerofoil is adapted to convert kinetic energy and/or heat energy of air passing through the compressor stage into static pressure energy. The platform is configured to hold the aerofoil in place with respect to a frame of reference of the respective stage.

<CIT> discloses a turbomachine comprising a housing, and at least one turbine vane arranged within the housing. The at least one turbine vane includes a platform portion operatively connected to the airfoil portion. A cooling cavity is formed in the platform portion. The cooling cavity includes a first wall, a second wall arranged opposite the first wall, a third wall linking the first and second walls, and a fourth wall linking the first and second walls and positioned opposite the third wall. An impingement cooling plate extends into the cooling cavity and defines an inner cavity portion and an outer cavity portion. The impingement cooling plate includes at least one impingement cooling passage that is configured and disposed to guide an impingement cooling flow onto at least one of the first, second, third and fourth walls of the cooling cavity. The cooling cavity includes an opening closed by a cooling cavity cover.

<CIT> discloses a method for producing a turbine blade, and in particular a gas turbine blade comprising a head, a foot, and a blade section. The turbine blade also comprises an internal canalization system, including individual channels through which coolant gas can pass along a flow path within the turbine blade. The turbine blade also includes a plug with a throttle device which influences the passage of the coolant gas without impairing the flow of the coolant gas in the intake area. The throttle device is located in the rear section of the flow path and is positioned upstream of the exit openings.

<CIT> discloses a platform cooling arrangement for a turbine rotor blade having a platform and an interior cooling passage and, in operation, a high-pressure coolant region and a low-pressure coolant region. The platform includes a topside, which extends from the airfoil to a pressure side slashface, and an underside. The platform cooling arrangement may include: an airfoil manifold that resides near the junction of the pressure face of the airfoil and the platform; a slashface manifold that resides near the pressure side slashface; a high-pressure connector that connects the airfoil manifold to a high-pressure coolant region of the interior cooling passage; a low-pressure connector that connects the slashface manifold to a low-pressure coolant region of the interior cooling passage; cooling apertures that extend from a starting point along the pressure side slashface to a connection with the airfoil manifold, bisecting the slashface manifold therebetween; and a plurality of non-integral plugs.

<CIT> discloses a turbine blade or vane that includes a platform that is cooled by way of air and steam. The air cooling may form an open circuit, where the steam cooling may form a closed circuit. A platform steam cooling cavity is closed by a cover having an impingement-cooling insert.

<CIT> discloses a rotor blade for a turbomachine. The rotor blade includes an airfoil and a tip shroud coupled to the airfoil. The tip shroud includes a side surface. The airfoil and the tip shroud define a first cooling passage. The tip shroud further defines a second passage in fluid communication with the first cooling passage. The second cooling passage extends from the first cooling passage to a first outlet defined by the side surface. The first outlet is configured to direct a flow of coolant onto a tip shroud fillet of a first adjacent rotor blade.

<CIT> discloses a blade for a gas turbine engine, and particularly for the low-pressure turbine of a gas turbine with sequential combustion. The blade is produced in accordance with a casting process and has a blade airfoil which extends in the radial direction between an inner platform and an outer platform. The interior of the blade includes a cooling passage, bypassing the platforms, and through which flows a cooling medium, especially cooling air, for cooling the blade. In the outer and/or inner platform there are core outlet openings which arise from the use of a casting core, and which connect the cooling passage to the outside space and are sealed off by means of a sealing element. Optimum cooling is ensured by the sealing elements being formed and inserted into the core outlet openings so that they align with the wall surface of the cooling passage in a flush manner.

<CIT> discloses a blade having a blade, passage extending in a blade height direction (Dwh), a platform passage formed inside a platform, and a communication passage leading from an outer surface of a shaft-mounted part through the platform passage to the blade passage. An inner surface defining an inflow passage portion of the platform passage includes a shaft-side inner surface that faces a gas path side. The shaft-side inner surface spreads in a direction having more of a component of a blade thickness direction (Dwt) than a component of the blade height direction (Dwh). An inner surface defining the communication passage joins to the shaft-side inner surface.

<CIT> discloses an end plate of a blade having a gas path surface facing a combustion gas channel side, an end surface along an edge of the gas path surface, a plurality of channels, and a skirt hole. The plurality of channels extend along the direction of a partial end surface, which is a portion of the end surface, and are arranged in a perspective direction with respect to the partial end surface. The skirt hole opens at the partial end surface. The skirt hole communicates with an inside channel, which is the channel of the plurality of channels that is furthest from the partial end surface.

For better operation of a rotary machine, it is desirable to provide an improved stator vane for use therein, and in particular to provide an improved platform for a stator vane.

According to the present invention, there is provided a radially outer platform for a stator vane with the features of claim <NUM>.

The aperture may be formed as a result of casting of the platform body over a supporting structure. In addition, it may be that an upper portion of the plug is configured to extend away from the outer surface of the platform body whilst the plug is secured to the platform body to facilitate heat rejection to the fluid to which the radially outer surface of the platform body is exposed.

An effective thermal conductivity of the plug may be greater than an effective thermal conductivity of the platform body. It may be that the effective thermal conductivity of the plug is no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. Further, it may be that the effective thermal conductivity of the plug is no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. In addition, it may be that: the plug comprises a plug body; the plug body is coated with a thermal coating. An effective thermal conductivity of the thermal coating may be greater than an effective thermal conductivity of the plug body. It may be that the effective thermal conductivity of the thermal coating is no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. Further, it may be that the effective thermal conductivity of the thermal coating is no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. An effective thermal emissivity of the thermal coating may be greater than an effective thermal emissivity of the plug body. It may be that the effective thermal emissivity of the thermal coating is no less than <NUM>, and optionally no less than <NUM> or no less than <NUM>.

The plug may be configured to occupy no less than <NUM>% of the core aperture by volume whilst secured to the platform body to at least partially eliminate recirculation of the fluid conveyed by the internal fluid passageway within the core aperture. Further, the plug may be configured to occupy no less than <NUM>% of the core aperture by volume.

It may be that the plug is configured to be fixed to the platform body and to seal the core aperture. It may also be that the plug is configured to be fixed to the platform body by a welded joint or a brazed joint. Additionally, or alternatively, it may be that the plug is configured to be fixed to the platform body by an interference fit between interfering surfaces of the plug and the aperture. It may be that a sealant is disposed between the interfering surfaces of the plug and the platform body.

It may be that the platform includes a further plug, and the platform body defines: a further internal fluid passageway disposed between the radially outer surface and the radially inner surface, and a further core aperture extending from the radially outer surface to the further internal fluid passageway; the further plug is configured to be secured to the platform body and seal the further core aperture; and the further plug is configured to be partially disposed inside the further core aperture and partially disposed outside the further core aperture whilst secured to the platform body for improved heat transfer between a fluid conveyed by the further internal fluid passageway and the fluid to which the radially outer surface of the platform body is exposed.

It may be that the further plug is configured to be fixed to the platform body and to seal the further core aperture. It may also be that the further plug is configured to be fixed to the platform body by a welded joint or a brazed joint. Additionally, or alternatively, it may be that the further plug is configured to be fixed to the platform body by an interference fit between interfering surfaces of the further plug and the further core aperture. It may be that a sealant is disposed between the interfering surfaces of the further plug and the platform body. It may also be that the plug and the further plug are joined by a bridging portion to form a combined plug structure.

As noted elsewhere herein, the present invention may relate to a gas turbine engine.

Arrangements of the present invention may be particularly, although not exclusively, beneficial for fans that are driven via a gearbox.

The gearbox may be a reduction gearbox (in that the output to the fan is a lower rotational rate than the input from the core shaft). Any type of gearbox may be used. For example, the gearbox may be a "planetary" or "star" gearbox, as described in more detail elsewhere herein.

Furthermore, except where mutually exclusive any feature described herein may be applied to any aspect and/or combined with any other feature described herein.

The engine core <NUM> comprises, in axial flow series, a low-pressure compressor <NUM>, a high-pressure compressor <NUM>, combustion equipment <NUM>, a high-pressure turbine <NUM>, a low-pressure turbine <NUM> and a core exhaust nozzle <NUM>. The fan <NUM> is attached to and driven by the low-pressure turbine <NUM> via a shaft <NUM> and an epicyclic gearbox <NUM>.

In use, the core airflow A is accelerated and compressed by the low-pressure compressor <NUM> and directed into the high-pressure compressor <NUM> where further compression takes place. The compressed air exhausted from the high-pressure compressor <NUM> is directed into the combustion equipment <NUM> where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low-pressure turbines <NUM>, <NUM> before being exhausted through the nozzle <NUM> to provide some propulsive thrust. The high-pressure turbine <NUM> drives the high-pressure compressor <NUM> by a suitable interconnecting shaft <NUM>.

The low-pressure turbine <NUM> (see <FIG>) drives the shaft <NUM>, which is coupled to a sun wheel, or sun gear, <NUM> of the epicyclic gear arrangement <NUM>. Radially outwardly of the planet gears <NUM> and intermeshing therewith is an annulus or ring gear <NUM> that is coupled, via linkages <NUM>, to a stationary supporting <NUM>.

Note that the terms "low pressure turbine" and "low pressure compressor" as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e., not including the fan <NUM>) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft <NUM> with the lowest rotational speed in the engine (i.e., not including the gearbox output shaft that drives the fan <NUM>).

It will be appreciated that the arrangement shown in <FIG> and <FIG> is by way of example only, and various alternatives are within the scope of the present invention. By way of further example, the connections (such as the linkages <NUM>, <NUM> in the <FIG> example) between the gearbox <NUM> and other parts of the engine <NUM> (such as the input shaft <NUM>, the output shaft and the fixed <NUM>) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the invention is not limited to the exemplary arrangement of <FIG>.

Accordingly, the present invention extends to a gas turbine engine having any arrangement of gearbox styles (for example star or planetary), support structures, input and output shaft arrangement, and bearing locations.

Optionally, the gearbox may drive additional and/or alternative components (e.g., the intermediate pressure compressor and/or a booster compressor).

Other gas turbine engines to which the present invention may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in <FIG> has a split flow nozzle <NUM>, <NUM> meaning that the flow through the bypass duct <NUM> has its own nozzle <NUM> that is separate to and radially outside the core engine nozzle <NUM>. However, this is not limiting, and any aspect of the present invention may also apply to engines in which the flow through the bypass duct <NUM> and the flow through the core <NUM> are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the invention may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine <NUM> may not comprise a gearbox <NUM>.

<FIG> shows the high-pressure turbine <NUM> of the gas turbine engine <NUM> in more detail. As mentioned above the high-pressure turbine <NUM> is arranged to drive the high-pressure compressor <NUM> via the shaft <NUM>. The high-pressure turbine <NUM> is arranged to extract power from the hot combustion products in order to drive the high-pressure compressor <NUM> via the shaft <NUM>. The high-pressure turbine <NUM> is arranged to produce a high-pressure ratio between the inlet and the outlet of the high pressure turbine <NUM> and thus the high pressure turbine <NUM> has a high ratio between the area of the outlet to the area of the inlet of the high pressure turbine <NUM>. The high-pressure turbine <NUM> comprises a turbine rotor <NUM> and a plurality of stages of axially spaced turbine rotor blades 52A, 52B, 52C and 52D mounted on the turbine rotor <NUM>. The turbine rotor <NUM> comprises a plurality of turbine discs <NUM> which have axially extending flanges which are secured together by bolted connections. The turbine rotor <NUM> and turbine rotor blades <NUM> are surrounded by a turbine casing <NUM>. The high-pressure turbine <NUM> has an inlet <NUM> defined at an upstream end of a first stage of turbine rotor blades 52A and an outlet <NUM> defined at a downstream end of a last stage of turbine rotor blades 52D.

Each turbine rotor blade <NUM> comprises a root <NUM>, a platform <NUM>, an aerofoil <NUM> and a shroud <NUM>. The root <NUM> extends in a first direction, radially inward direction, from the platform <NUM> and the aerofoil <NUM> extends a second opposite direction, radially outward direction, from the platform <NUM> and the shroud <NUM> is remote from the root <NUM> and platform <NUM>. The roots <NUM> of the turbine rotor blades <NUM> are located in slots in the rim of the corresponding turbine disc <NUM>. The inlet <NUM> is defined between the platforms <NUM> and the shrouds <NUM> of the first stage of turbine rotor blades 52A and the outlet <NUM> is defined between the platforms <NUM> and the shrouds <NUM> of the last stage of turbine rotor blades 52D. Thus, the inlet <NUM> is an annular inlet and is defined radially between the platforms <NUM> and the shrouds <NUM> of the first stage of turbine rotor blades 52A. Similarly, the outlet <NUM> is an annular outlet and is defined radially between the platforms <NUM> and the shrouds <NUM> of the last stage of turbine rotor blades 52D.

The aerofoils <NUM> of the turbine rotor blades <NUM> have leading edges <NUM> and trailing edges 57T and the inlet <NUM> is defined between the platforms <NUM> and the shrouds <NUM> of the first stage of turbine rotor blades 52A at the axial position where the leading edges <NUM> of the aerofoils <NUM> of the turbine rotor blades <NUM> intersect the platforms <NUM> and the shrouds <NUM> of the first stage of turbine rotor blades 52A and the outlet <NUM> is defined between the platforms <NUM> and the shrouds <NUM> of the last stage of turbine rotor blades 52D at the axial position where the trailing edges 57T of the aerofoils <NUM> of the turbine rotor blades <NUM> intersect the platforms <NUM> and the shrouds <NUM> of the last stage of turbine rotor blades 52D.

The radial direction, R, and the circumferential direction, θ, are also shown on <FIG>. The upstream ends of the platforms <NUM> of the first stage of turbine rotor blades 52A are arranged at a first radius R1, the downstream ends of the platforms <NUM> of the last stage of turbine rotor blades 52D are arranged at a second radius R2 and the second radius R2 is greater than the first radius R1. Each radius is measured in the radial direction R. However, in other arrangements the second radius R2 is equal to the first radius R1 or the second radius R2 is less than the first radius R1. The ratio of the first radius R1 to the second radius R2 may be greater than or equal to <NUM> and less than or equal to <NUM>. Also on <FIG>, a hub radius of the last stage of turbine rotor blades 52D is marked as Rhub, while a tip radius of the last stage of turbine rotor blades 52D is marked as Rtip.

The high-pressure turbine <NUM> also comprises a plurality of axially spaced stages of turbine stator vanes 60A, 60B, 60C and 60D and each turbine stator vane <NUM> comprises a radially outer platform <NUM>, an aerofoil <NUM> and a radially inner platform <NUM>. A first stage of turbine stator vanes 60A is arranged upstream of the first stage of turbine rotor blades 52A and a last stage of turbine stator vanes 60D is arranged upstream of the last stage of turbine rotor blades 52D. An intermediate stage of turbine stator vanes 60C is arranged downstream of the first stage of turbine stator vanes 60A and upstream of the last stage of turbine stator vanes 60D. The inner platforms <NUM> of the intermediate stage of turbine stator vanes 60C have a third radius R3 and the third radius R3 is greater than or equal to the first radius R1 and is greater than the second radius R2. The ratio of the third radius R3 to the first radius R1 is greater than or equal to <NUM> and less than or equal to <NUM>. The ratio of the second radius R2 to the third radius R3 is greater than or equal to <NUM> and less than or equal to <NUM>. The ratio of the third radius R3 to the first radius R1 is greater than or equal to <NUM> and less than or equal to <NUM> and the ratio of the second radius R2 to the third radius R3 is greater than or equal to <NUM> and less than <NUM>.

In this arrangement the third radius R3 is greater than the first radius R1, the third radius R3 is greater than the second radius R2 and the second radius R2 is greater than the first radius R1. However, in another arrangement the third radius R3 is greater than the first radius R1, the third radius R3 is greater than the second radius R2 and the second radius R2 is equal to the first radius R1. However, in a further arrangement the third radius R3 is equal to the first radius R1, the third radius R3 is greater than the second radius R2 and the second radius R2 is less than the first radius R1.

In this example there are four stages of turbine rotor blades 50A, 50B, 50C and 50D and four stages of turbine stator vanes 60A, 60B, 60C and 60D, the intermediate stage of turbine stator vanes 60C is the third stage of turbine stator vanes, but the intermediate stage of stator vanes may be the second stage of turbine stator vanes. However, in other arrangements there may be three stages of turbine rotor blades and three stages turbine stator vanes and the intermediate stage of turbine stator vanes is the second stage of turbine stator vanes or there may be five stages of turbine rotor blades and five stages of turbine stator vanes and the intermediate stage of turbine stator vanes is the second stage of turbine stator vanes, the third stage of turbine stator vanes or the fourth stage of turbine stator vanes. The high-pressure turbine <NUM> also comprises a stage of turbine outlet guide vanes 60E positioned axially downstream of the last stage of turbine rotor blades 52D.

The turbine rotor blades <NUM> and the turbine stator vanes <NUM> may comprise an intermetallic material. The turbine rotor blades <NUM> and the turbine stator vanes <NUM> may comprise titanium aluminide and in particular the turbine stator blades <NUM> and the turbine stator vanes <NUM> may comprise gamma titanium aluminide.

<FIG> shows one of the stator vanes <NUM> of the high-pressure turbine <NUM> shown by <FIG> in further detail, with like reference signs denoting common features. The aerofoil <NUM> extends between the radially outer platform <NUM> and the radially inner platform <NUM> along the radial direction R. The aerofoil <NUM> is fixed to the outer platform <NUM> at an outer end of the aerofoil <NUM> and to the inner platform <NUM> at an inner end of the aerofoil <NUM>. The aerofoil <NUM> may be fixed to the radially inner platform <NUM> and the radially outer platform <NUM> using any suitable fixing means, as will be apparent to those skilled in the art. Because the stator vane <NUM> is configured for use within the high-pressure turbine <NUM> shown by <FIG>, the aerofoil <NUM> is adapted to convert static pressure energy and/or heat energy of air passing through the high-pressure turbine <NUM> into kinetic energy. Each platform <NUM>, <NUM> is configured to hold the aerofoil <NUM> in place with respect to a frame of reference of the high-pressure turbine <NUM>.

It should be appreciated that the stator vane <NUM> and each of its constituent components are suitable for use in various types of rotary machines and is not limited to use in the context of a high-pressure turbine or a gas turbine engine. In particular, if the stator vane <NUM> is configured for use within a compressor stage of a rotary machine, the aerofoil <NUM> is adapted to convert kinetic energy and/or heat energy of air passing through the compressor stage into static pressure energy.

The radially outer platform <NUM> includes a platform body <NUM>. The platform body <NUM> defines an inner surface <NUM> and an outer surface <NUM>. The outer surface <NUM> is offset from the inner surface <NUM>, such that the inner surface is radially proximal to the rotational axis <NUM> when incorporated within a rotary machine, whereas the outer surface is radially distal from the rotational axis (e.g., is disposed radially outward of the inner surface). The platform body <NUM> also defines an internal fluid passageway <NUM> which is disposed between the outer surface <NUM> and the inner surface <NUM>. In addition, the platform body <NUM> defines a core aperture <NUM> which extends from the outer surface <NUM> to the internal fluid passageway <NUM>. During a manufacturing process of the platform <NUM>, the internal fluid passageway <NUM> is formed by casting the platform body <NUM> over a ceramic core. The geometry of the ceramic core corresponds to the geometry of the internal fluid passageway <NUM>. During the process of casting the platform body <NUM> over the ceramic core, the ceramic core is held in position by a supporting structure which extends through the platform body <NUM> from the outer surface <NUM> to the ceramic core. This may ensure more precise and accurate formation of the internal fluid passageway <NUM>. Both the ceramic core and the supporting structure are then removed by a leaching process in which the ceramic core and the supporting structure are dissolved using an appropriate solvent.

The existence of the ceramic core during the casting process and the subsequent removal of the ceramic core during the leaching process leads to the formation of the internal fluid passageway <NUM> within the platform body <NUM>. Similarly, the existence of the supporting structure during the casting process and the subsequent removal of the supporting structure during the leaching process leads to the formation of the core aperture <NUM> (also referred to as a core print or a core exit) within the platform body <NUM>. The core aperture <NUM> has a geometrical centreline <NUM> and an internal perimeter <NUM>.

In use, the inner surface <NUM> of the platform body <NUM> is exposed to a fluid (i.e. a gas) inside the high pressure turbine <NUM>. The fluid (i.e., the gas) flows over the inner surface <NUM> of the platform body <NUM> along a direction indicated by arrow <NUM>. The gas within the high-pressure turbine <NUM> comprises hot combustion products received from the combustion equipment <NUM> as discussed above. By virtue of containing the hot combustion products, the gas inside the high-pressure turbine <NUM> has a significantly higher temperature than the gas (e.g., the air) leaving the high-pressure compressor <NUM>. The inner surface <NUM> of the platform body <NUM> may therefore be referred to as a hotter gas washed side <NUM> of the platform body <NUM>.

The high temperature gas <NUM> inside the high-pressure turbine <NUM> heats the platform body <NUM> by convection at the inner surface <NUM>. The internal fluid passageway <NUM> is generally configured to convey a fluid therethrough along a direction indicated by arrows <NUM> and <NUM> for the purpose of heat exchange with the platform body <NUM>. The fluid conveyed by the internal fluid passageway <NUM> upstream of the aperture <NUM> is denoted by arrow <NUM>, whereas the fluid conveyed by the internal fluid passageway <NUM> downstream of the core aperture <NUM> is denoted by arrow <NUM>. The fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> is cooler than the high temperature gas inside the high-pressure turbine <NUM>, such that heat is received into the platform body <NUM> from the gas within the high-pressure turbine <NUM> at the inner surface <NUM> and subsequently received into the fluid conveyed by the internal fluid passageway <NUM>. Accordingly, the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> has a cooling effect on the platform body <NUM>.

In use, the outer surface <NUM> of the platform body <NUM> is exposed to a fluid (i.e., a gas) outside the high-pressure turbine <NUM>. In some examples, the fluid (i.e., the gas) flows over the outer surface <NUM> of the platform body <NUM> along a direction indicated by arrow <NUM>. In other examples, the fluid (i.e., the gas) may be substantially stationary proximal to the outer surface <NUM> of the platform body <NUM>. The gas outside the high-pressure turbine <NUM> may typically be air which has not passed through the combustion equipment <NUM> a gas turbine engine in which the platform <NUM> is incorporated. Specifically, the gas outside the high-pressure turbine <NUM> may be air received from a compressor or a bypass duct of the gas turbine engine (e.g., the low-pressure compressor <NUM>, the high-pressure compressor <NUM> or the bypass duct <NUM> of the gas turbine engine <NUM> described above with reference to Figured <NUM>-<NUM>). Otherwise, the gas outside the high-pressure turbine <NUM> may simply be ambient air which is contained within a sealed chamber (e.g., turbine housing or casing) around the high-pressure turbine <NUM>. By virtue of not containing any hot combustion products, the gas outside the high-pressure turbine <NUM> has a significantly lower temperature than the gas inside the high-pressure turbine <NUM>. The outer surface <NUM> of the platform body <NUM> may therefore be referred to as a cooler-gas side <NUM> of the platform body <NUM>.

The low temperature gas outside the high-pressure turbine <NUM> may cool the platform body <NUM> by convection at the outer surface <NUM> (e.g. free convection if the gas is substantially stationary proximal to the outer surface <NUM> or forced convection if the gas flows over the outer surface <NUM>). The fluid to which the outer surface <NUM> is exposed is cooler than both the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> and the high temperature gas <NUM> inside the high-pressure turbine <NUM>, such that heat is received into the gas to which the outer surface <NUM> is exposed from the platform body <NUM> at the outer surface <NUM>. Accordingly, the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed has a further cooling effect on the platform body <NUM>.

The platform body <NUM> includes a radially outer platform boss <NUM> which extends in a direction which is generally away from the inner surface <NUM> (i.e., in a direction away from the rotational axis <NUM> when the stator vane <NUM> is mounted within a turbine stage of a rotary machine) to, for instance, facilitate mounting of the aerofoil <NUM> within a turbine stage of the high-pressure turbine <NUM> described above with reference to <FIG>. The core aperture <NUM> is sealed to ensure that the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> cannot exit the internal fluid passageway <NUM> through the core aperture <NUM>. Means for sealing the core aperture <NUM> are discussed in detail below with reference to <FIG> and <FIG>.

<FIG> shows a previously considered radially outer platform 61P in detail. The platform 61P is generally configured to perform a similar function as the outer platform <NUM> as described above with reference to <FIG>, with like reference signs denoting common or similar features. The platform 61P includes a platform body <NUM> and a cap 700P. The cap 700P is fixed to the platform body <NUM> and seals the aperture <NUM>. The sealing of the core aperture <NUM> provided by the cap 700P ensures that the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> cannot exit the internal fluid passageway <NUM> through the core aperture <NUM>. The cap 700P overlies the core aperture <NUM> and is fixed to the outer surface <NUM> of the platform body <NUM>. The cap 700P may be fixed to the outer surface of the platform body <NUM> by, for example, a welded joint or a brazed joint. The cap 700P is generally in the form of a plate and is wholly disposed outside of the core aperture <NUM>. Accordingly, a weight of the cap 700P (and therefore a weight of the platform 61P) may be minimised.

In contrast to the previously considered outer platform 61P, various example radially outer platforms <NUM> are now described with reference to <FIG>. <FIG> shows a detail view of a first example platform <NUM>, not falling within the scope of the claimed invention, <FIG> shows a detail view of a second example platform <NUM>, not falling within the scope of the claimed invention, <FIG> shows a detail view of a third example platform <NUM>, not falling within the scope of the claimed invention, whereas <FIG> shows a detail view of a fourth example platform <NUM>. <FIG> shows a detail sectional view of the fourth example platform <NUM> through section A-A (as marked on <FIG>). <FIG> shows a detail sectional view of the fourth example platform <NUM> through section B-B (as marked on <FIG>).

Each example platform <NUM> is generally configured to hold an aerofoil in place in a similar way to the radially outer platform <NUM> as described above with reference to <FIG>. Each example platform <NUM> may be incorporated within a stator vane <NUM> as shown in <FIG> and/or a high-pressure turbine <NUM> as shown in <FIG>, with like reference signs denoting common or similar features. In particular, each example platform <NUM> may have any of the features described above with respect to <FIG>. Otherwise, it will be appreciated that each example radially outer platform <NUM> may be incorporated within any suitable type of rotary machine, and/or within a stator vane for any suitable type of rotary machine, such as a turbomachine.

Each example platform <NUM> includes a platform body <NUM> and a plug <NUM>. Like the cap 700P described above with respect to <FIG>, the plug <NUM> is fixed to the platform body <NUM> and seals the core aperture <NUM> so as to prevent fluid <NUM>, <NUM> conveyed by the internal fluid passageway from exiting the internal fluid passageway <NUM> through the aperture <NUM>. Unlike the cap 700P described above with respect to <FIG>, the plug <NUM> is at least partially disposed within the aperture <NUM> in each example platform <NUM>. Consequently, in each example platform <NUM>, the plug <NUM> occupies at least a fraction of the aperture <NUM> by volume. The plug <NUM> has an inner surface <NUM> and an outer surface <NUM>. The inner surface <NUM> is defined as an external surface of the plug <NUM> which is relatively proximal to the internal fluid passageway <NUM> when the plug <NUM> is inserted into the aperture <NUM>, whereas the outer surface <NUM> is defined as an external surface of the plug <NUM> which is relatively distal to the internal fluid passageway <NUM> when the plug <NUM> is inserted into the aperture <NUM>. In use, the fluid <NUM>, <NUM> may exchange heat with the plug <NUM> in additional to exchanging heat with the platform body <NUM>.

Broadly, the plug <NUM> may be configured to be fixed to the platform body <NUM> by any suitable means. Advantageously, in any of the examples shown in <FIG>, the plug <NUM> may be fixed to the platform body <NUM> by welding or by brazing. As an example, a welded joint may be created between the internal perimeter <NUM> of the aperture <NUM> and an external perimeter <NUM> of the plug <NUM>. As another example, a brazed joint may be created between the perimeter <NUM> of the aperture <NUM> and the external perimeter <NUM> of the plug <NUM>. Each of these techniques may provide a strong fixing between the plug <NUM> and the platform body <NUM> and good sealing of the aperture <NUM>.

Otherwise, the plug <NUM> may be fixed to the platform body <NUM> by means of an interference fit between the plug <NUM> and the aperture <NUM>. As will be appreciated by those skill in the art, the external perimeter <NUM> of the plug <NUM> may be dimensioned so as to be slightly larger than the perimeter <NUM> of the core aperture <NUM> such that the external perimeter <NUM> of the plug <NUM> and the perimeter <NUM> come into contact with each other when the plug <NUM> is inserted into the core aperture <NUM> and thereby become interfering surfaces. This may provide simple and effective means for fixing the plug <NUM> to the platform body <NUM>, as well as enabling a wider range of materials to be used to form the platform body <NUM> and/or the plug <NUM>. In addition, a sealant may be adding during manufacturing such that the sealant is disposed between the interfering surfaces of the plug <NUM> and the platform body <NUM> when the plug <NUM> is inserted into the core aperture <NUM>. This may provide better sealing of the core aperture <NUM>.

Optionally, the perimeter <NUM> of the core aperture <NUM> is machined to prepare the core aperture <NUM> for insertion of the plug <NUM> during a further manufacturing step of the platform <NUM>. Machining of the core aperture <NUM> may enable better fixing of the plug <NUM> to the platform body and therefore aid sealing of the core aperture <NUM> by the fixing of the plug <NUM> to the platform bod <NUM>.

The internal fluid passageway <NUM> includes an internal fluid inlet 608A and an internal fluid outlet 608B. The fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> is received at the internal fluid inlet 608A and discharged from the internal fluid outlet <NUM>, such that the fluid generally flows from the internal fluid inlet 608A toward the internal fluid outlet 608B along the internal fluid passageway <NUM>. Optionally, the internal fluid inlet 608A is adapted to be fluidically connected to a compressor or a bypass duct of a gas turbine engine in which the platform <NUM> is incorporated (e.g., the low-pressure compressor <NUM>, the high pressure compressor <NUM> or the bypass duct <NUM> of the gas turbine engine <NUM> described above with reference to Figured <NUM>-<NUM>). If so, the internal fluid passageway <NUM> is configured to convey air received from the compressor <NUM>, <NUM> or the bypass duct <NUM> to the internal fluid outlet 608B in use. Further, the internal fluid outlet 608B may be adapted to be fluidically connected to a bypass duct <NUM> of the gas turbine engine, an exhaust nozzle <NUM> of the gas turbine engine <NUM> or to a location within a core <NUM> of the gas turbine engine <NUM> downstream of the platform <NUM>. Therefore, air received from the compressor <NUM>, <NUM> is utilised to cool the platform body <NUM>. However, this invention anticipates that the internal fluid inlet 608A may otherwise be adapted to be fluidically connected to a dedicated coolant reservoir, such that the internal fluid passageway <NUM> is configured to, in use, convey coolant received from the coolant reservoir to the internal fluid outlet 608B for subsequent discharge. The coolant may be, for instance, a lubricant oil.

The internal fluid passageway <NUM> may extend around at least one pillar <NUM> defined by the platform body <NUM>. The at least one pillar <NUM> may increase a structural strength of the platform body <NUM> and/or increase a surface area for heat transfer between the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> and the platform body <NUM>. In each of the examples of <FIG>, the internal fluid passageway <NUM> extends from the internal fluid inlet 608A, around the pillar <NUM> and to the internal fluid outlet 608B.

In the examples of <FIG>, the outer platform boss <NUM> is enlarged (compared to the example of <FIG>) such that the core aperture <NUM> extends through part of the outer platform boss <NUM>. This enables the core aperture <NUM> to be located closer to the internal fluid outlet 608B without adversely affecting the structural characteristics of the outer platform <NUM>. In particular, this enables the core aperture <NUM> to be located closer to the internal fluid outlet 608B without significantly increasing a difficulty of manufacturing the platform <NUM> during, for example, a process of shelling the geometry of the platform body <NUM> during a casting process. In turn, this may permit a greater range of possible design geometries for the platform <NUM>, which may aid the design of a more compact platform <NUM> (and therefore a more compact stator vane <NUM> and/or a more compact high-pressure turbine <NUM>). However, the core aperture <NUM> extending through part of the outer platform boss <NUM> in this manner means that the core aperture <NUM> has a greater height (as measured in a direction parallel to the radial direction R) compared to the previously considered platform 61P. If the core aperture <NUM> were sealed by means of a cap similar to the cap 700P described with respect to the previously considered platform 61P, the entire volume of the core aperture <NUM> would be exposed to the internal fluid passageway <NUM>. The exposure of the entire volume of the core aperture <NUM> to the internal fluid passageway <NUM> may lead to a significant amount recirculation of fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> within the core aperture <NUM>.

The plug <NUM> being at least partially disposed inside the core aperture <NUM>, as shown in each of the examples of <FIG>, reduces recirculation of fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> within the core aperture <NUM>. This may be associated with a reduced pressure drop between the internal fluid inlet 608A and the internal fluid outlet 608B, which may in turn be associated with better cooling of the platform <NUM> and an improved efficiency of a rotary machine (e.g., a gas turbine engine) in which the platform <NUM> is incorporated. However, the plug <NUM> being at least partially disposed within the core aperture <NUM> increases an installation mass of the platform <NUM>. Better cooling of the platform <NUM> (e.g., by increasing the cooling effect on the platform body <NUM> provided by the flow of fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM>) may increase a thermal operability range of the platform <NUM> and therefore a stator vane <NUM> of which it is a part. In particular, better cooling of the platform <NUM> may enable a bulk temperature of the fluid <NUM> inside the high-pressure turbine <NUM> to be relatively increased without risking thermal damage to the platform <NUM>, which may be associated with improved thermal efficiency of a gas turbine engine <NUM> in which the high-pressure turbine <NUM> is incorporated. In particular, if a material (e.g., metal) temperature is relatively high proximal to the internal fluid passageway <NUM> compared to nearby zones of the stator vane <NUM> (which may be referred to as a "hot spot") due to any applicable factors affecting the temperature, better cooling of the platform <NUM> due to reduced recirculation of fluid <NUM>, <NUM> within the core aperture <NUM> may be especially advantageous.

In each of the examples of <FIG>, the plug <NUM> occupies approximately <NUM>% of the core aperture <NUM> by volume so as to completely eliminate recirculation of fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> within the core aperture <NUM>. In other examples, the plug <NUM> may occupy no less than <NUM>% of the core aperture <NUM> by volume. In some examples, the plug <NUM> may occupy no less than <NUM>% of the core aperture <NUM> by volume. In further examples, the plug <NUM> may occupy no less than <NUM>% of the core aperture <NUM> by volume to at least partially eliminate recirculation of the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> within the core aperture <NUM> without necessarily significantly increasing the installation mass of the platform <NUM>.

In the first example platform <NUM> shown by <FIG>, not falling within the scope of the claimed invention, a internal protrusion <NUM> is formed within the core aperture <NUM>. The internal protrusion <NUM> generally extends in a direction away from the perimeter <NUM> of the core aperture <NUM> toward the geometrical centreline <NUM> of the core aperture <NUM>. The internal protrusion <NUM> may be formed during casting of the platform body <NUM> and/or during machining of the core aperture <NUM> as discussed above. An external shape of the plug <NUM> is shaped so as to correspond to an internal shape of the core aperture <NUM> (including the internal protrusion <NUM>). Accordingly, when the plug <NUM> is inserted into the core aperture <NUM>, the plug <NUM> abuts (e.g., comes into positive contact with) the internal protrusion <NUM>. The positive contact between the internal protrusion <NUM> and the plug <NUM> may aid in correct location of the plug <NUM> within the core aperture <NUM> during manufacturing of the first example platform <NUM> and may also enable better fixing of the plug <NUM> to the platform body <NUM>.

In the second example platform <NUM> shown by <FIG>, not falling within the scope of the claimed invention, and the third example platform <NUM> shown by <FIG>, not falling within the scope of the claimed invention, the platform body <NUM> defines a plurality of protrusions extending into the internal fluid passageway <NUM>. In <FIG> and <FIG>, the plurality of protrusions includes a first platform body protrusion <NUM> and a second platform body protrusion <NUM>. However, this disclosure anticipates there being a single protrusion <NUM> or more than two platform body protrusions. Each platform body protrusion <NUM>, <NUM> extends away from the inner surface <NUM> of the platform body <NUM> toward the outer surface <NUM> of the platform body <NUM> along a direction parallel to the radial direction R. In some examples, the platform body protrusions <NUM>, <NUM> may be shaped to take the form of pins or fins.

The platform body protrusions <NUM>, <NUM> are generally configured to promote heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the platform body <NUM>. The platform body protrusions <NUM>, <NUM> may be referred to as pedestals. In particular, the platform body protrusions <NUM>, <NUM> increase a surface area for convective heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the platform body <NUM>. Further, the platform body protrusions <NUM>, <NUM> may incite mixing (e.g., turbulent mixing) of the fluid <NUM> conveyed by the internal fluid passageway <NUM> in a region surrounding the platform body protrusions <NUM>, <NUM> by increasing a tortuosity of a path taken by the fluid <NUM> through the internal fluid passageway <NUM>. Mixing of the fluid <NUM> conveyed by the internal fluid passageway <NUM> in the region surrounding the platform body protrusions <NUM>, <NUM> may be associated with an increased rate of heat transfer from the platform body <NUM> to the fluid <NUM> conveyed by the internal fluid passageway <NUM>. The platform body protrusions <NUM>, <NUM> may also locally increase a velocity of the fluid <NUM> conveyed by the internal fluid passageway <NUM>.

In both of <FIG> and <FIG>, the plug <NUM> is disposed within the core aperture <NUM> such that the plug abuts (e.g. is in contact with) the plurality of platform body protrusions <NUM>, <NUM>. The contact between the plurality of platform body protrusions <NUM>, <NUM> ensures that the fluid <NUM> conveyed by the internal fluid passageway <NUM> is prevented from passing over the plurality of platform body protrusions <NUM>, <NUM> and therefore the fluid <NUM> must flow around each of the platform body protrusions <NUM>, <NUM> when being conveyed by the internal fluid passageway <NUM> from the internal fluid inlet 608A to the internal fluid outlet 608B. This may be associated with increased mixing of the fluid <NUM> conveyed by the internal fluid passageway <NUM> in the region surrounding the platform body protrusions <NUM>, <NUM>, which may in turn be associated with an increased rate of heat transfer between the platform body <NUM> and the fluid <NUM> conveyed by the internal fluid passageway <NUM>.

In the third example platform <NUM> of <FIG>, the plug <NUM> includes a plurality of protrusions extending away from the lower surface <NUM> of the plug <NUM> and into the internal fluid passageway <NUM>. In <FIG>, the plurality of protrusions includes a first plug protrusion <NUM> and a second plug protrusion <NUM>. However, this disclosure anticipates there being greater than two plug body protrusions or there being only a single plug protrusion <NUM>. The plug protrusions <NUM>, <NUM> increase a surface area for convective heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the plug <NUM> and therefore promote heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the plug <NUM>. Improved heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the plug <NUM> may reduce a temperature of the fluid <NUM>, which may result in improved heat transfer between the fluid <NUM> and the platform body <NUM> and therefore increase the cooling effect on the platform body <NUM> provided by the fluid <NUM> conveyed by the internal fluid passageway <NUM>.

Further, in the third example platform <NUM> of <FIG>, each of the plurality of plug protrusions <NUM>, <NUM> overlie and abut a corresponding platform body protrusion <NUM>, <NUM>. This increases surface area for convective heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the plug <NUM> as well as inciting mixing (e.g., turbulent mixing) of the fluid <NUM> conveyed by the internal fluid passageway <NUM> in a region surrounding the plug protrusions <NUM>, <NUM>. Consequently, each of the plug protrusions <NUM>, <NUM> abutting a corresponding platform body protrusion <NUM>, <NUM> may further promote heat transfer between the fluid <NUM> conveyed by the internal fluid passageway <NUM> and the plug <NUM>. In examples in which there is only a single plug protrusion <NUM>, the plug protrusion <NUM> overlies and abuts the platform body protrusion <NUM>.

In the fourth example platform <NUM> shown by <FIG>, the plug <NUM> extends outside of the core aperture <NUM>. In particular, a lower portion <NUM> of the plug <NUM> extends into the internal fluid passageway <NUM> and an upper portion <NUM> of the plug <NUM> extends away from the outer surface <NUM> of the platform body <NUM>. When the outer platform <NUM> is incorporated within a rotary machine, the lower portion <NUM> of the plug is relatively proximal to the rotational axis <NUM>, whereas the upper portion <NUM> of the plug <NUM> is relatively distal to the rotational axis <NUM>.

The plug <NUM> extending outside of the core aperture <NUM> generally results in improved heat transfer between the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> and the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed. As a result, the cooling effect on the platform body <NUM> provided by the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> may be increased, with various associated advantages as discussed above. In the example of <FIG> and <FIG>, the both the lower portion <NUM> of the plug <NUM> extends into the internal fluid passageway <NUM> and the upper portion <NUM> of the plug <NUM> extends away from the outer surface <NUM> of the platform body <NUM>.

The lower portion <NUM> of the plug <NUM> extending into the internal fluid passageway <NUM> may facilitate heat reception from the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> into the plug <NUM> by providing an increased surface area for the heat transfer therebetween. In turn, this may promote heat rejection from the plug <NUM> into the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed due to an increased temperature of the plug <NUM>, which may result in increased convective heat transfer between the plug <NUM> and the fluid to which the outer surface <NUM> is exposed. However, the lower portion <NUM> of the plug <NUM> being disposed within (e.g., extend into) the internal fluid passageway <NUM> may increase a resistance to flow of the fluid <NUM>, <NUM> within the internal fluid passageway <NUM>, which may result in a larger pressure drop across the internal fluid inlet 608A and the internal fluid outlet 608B and therefore useful energy losses through the internal fluid passageway <NUM>.

Nevertheless, the larger pressure drop across the internal fluid inlet 608A and the internal fluid outlet 608B may be associated with some advantages. For instance, the larger pressure drop across the internal fluid inlet 608A and the internal fluid outlet 608B may reduce a Mach number of the fluid <NUM> being discharged from the internal fluid outlet 608B. If the fluid being discharged from the internal fluid outlet 608B has a high Mach number, the fluid <NUM> being discharged from the internal fluid outlet 608B may become choked or a shock wave may develop within the fluid <NUM> inside the internal fluid passageway <NUM>. Both of these phenomena have the effect of limiting mass-flow through the internal fluid outlet 608B and therefore reducing a flow rate of the fluid <NUM> through the internal fluid passageway <NUM>, which in turn limits the cooling effect provided by the fluid <NUM> conveyed by the internal fluid passageway <NUM> to the platform body <NUM>. In addition, it may be that the internal fluid outlet 608B is configured to discharge the fluid <NUM> conveyed by the internal fluid passageway <NUM> into a turbine stage of a rotary machine (e.g., a gas turbine engine). The larger pressure drop across the internal fluid inlet 608A and the internal fluid outlet 608B reduces the pressure of fluid <NUM> discharged from the internal fluid outlet 608B, which reduce losses within the turbine stage of the gas turbine engine. In particular, it may be that the internal fluid outlet 608B is configured to discharge the fluid <NUM> conveyed by the internal fluid passageway <NUM> into the turbine stage of a rotary machine for the purpose of film cooling. A reduced pressure of the fluid <NUM> discharged from the internal fluid outlet 608B may reduce a probability of flow detachment from a surface to which the fluid <NUM> discharged from the internal fluid outlet 608B is configured to provide film cooling.

In addition, a mass of the plug <NUM> (and therefore a mass of the platform <NUM>) is relatively increased by the lower portion <NUM> of the plug <NUM> being disposed within the internal fluid passageway <NUM>. Nevertheless, the benefits associated with improved heat transfer between the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> and the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed may generally outweigh any drawbacks associated with the larger pressure drop across the internal fluid inlet 608A and the internal fluid outlet 608B as well as the increased installation mass of the platform <NUM>.

In the particular example of <FIG> and <FIG>, the lower portion <NUM> of the plug extends into the internal fluid passageway <NUM> such that the inner surface <NUM> of the plug <NUM> abuts an opposing surface of the internal fluid passageway <NUM>. This ensures that all of the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> must flow around the lower portion <NUM> of the plug <NUM>, which may provide increased heat transfer therebetween at the cost of increased resistance to flow of the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM>. However, in other examples, the lower portion <NUM> of the plug may only partially extend into the internal fluid passageway <NUM> such that the inner surface of the plug <NUM> is offset from the opposing surface of the internal fluid passageway <NUM>. This may be associated with lower resistance to flow of the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> while providing an increased surface area for heat transfer.

The upper portion <NUM> of the plug <NUM> extending away from the outer surface <NUM> facilitates heat rejection from the plug <NUM> to the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed by providing an increased surface area for the heat transfer therebetween. In a similar way to the lower portion <NUM> discussed above, the upper portion <NUM> of the plug <NUM> extending away from the outer surface <NUM> of the platform body <NUM> increases a resistance to any flow of the fluid to which the outer surface <NUM> is exposed. In addition, a mass of the plug <NUM> (and therefore a mass of the platform <NUM>) is relatively increased. Nevertheless, the benefits associated with improved heat transfer between the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> and the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed may generally outweigh the drawbacks associated with the increased resistance to flow of the fluid <NUM> flowing over the outer surface <NUM> as well as the increased installation mass of the platform <NUM>.

The fluid <NUM>, <NUM> within the internal fluid passageway <NUM> is subject to convective heating between the internal fluid inlet 608A and the internal fluid outlet 608B due to the relatively hot fluid <NUM> flowing over the inner surface <NUM> of the platform body <NUM>. Such convective heating results in a bulk temperature of the fluid <NUM>, <NUM> increasing as the fluid is conveyed from the internal fluid inlet 6087A to the internal fluid outlet 608B. Consequently, during operation, the bulk temperature of the fluid <NUM> upstream of the core aperture <NUM> is typically significantly lower than the bulk temperature of the fluid <NUM> downstream of the core aperture <NUM>. It follows that a temperature of the lower portion <NUM> of the plug <NUM> proximal to the internal fluid inlet 608A is lower than a temperature of the lower portion <NUM> of the plug <NUM> relatively proximal to the internal fluid outlet 608B during operation.

The plug <NUM> is characterised by an effective thermal conductivity. The effective thermal conductivity of the plug <NUM> is related to the structural arrangement and the material composition of the plug <NUM>. In general, the effective thermal conductivity of the plug <NUM> may be relatively high. In particular, the effective thermal conductivity of the plug <NUM> may be greater than an effective thermal conductivity of the platform body <NUM>. A high effective thermal conductivity of the plug <NUM> promotes thermal conduction throughout the plug <NUM>. Accordingly, a difference in the temperature of the lower portion <NUM> of the plug <NUM> proximal to the internal fluid inlet 608A and the temperature of the lower portion <NUM> of the plug <NUM> proximal to the internal fluid outlet 608A may be decreased. That is to say that the temperature of the lower portion <NUM> of the plug <NUM> proximal to the internal fluid outlet 608B is relatively decreased whereas the temperature of the lower portion <NUM> of the plug <NUM> proximal to the internal fluid inlet 608A is relatively increased. In other words, a uniformity of the temperature of the plug <NUM> around the lower portion <NUM> of the plug <NUM> may be increased.

An increased temperature uniformity throughout the lower portion <NUM> of the plug <NUM> may lead to an increased average difference between the temperature of the plug <NUM> and the temperature of the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> over the surface area of the plug <NUM> which is exposed to the fluid <NUM>, <NUM> within the internal fluid passageway <NUM>. This increased average temperature difference may result in better convective heat transfer between the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> and the plug <NUM>, which may in turn enhance the cooling effect provided to the platform body <NUM> by the internal fluid passageway <NUM>. This may also result in especially improved heat reception into the plug <NUM> from the fluid <NUM>, <NUM> in the lower portion <NUM> of the plug <NUM> relatively proximal to the internal fluid outlet 608B.

In addition, a relatively high effective thermal conductivity of the plug <NUM> may result in an increased temperature uniformity throughout the plug <NUM>, including within the upper portion <NUM> as applicable. This may promote heat exchange between the plug <NUM> and the fluid to which the outer surface <NUM> of the platform body <NUM> is exposed due to an increased average temperature difference therebetween, which further enhances the cooling effect provided to the platform body <NUM> by the internal fluid passageway <NUM>. To promote thermal conduction throughout the plug <NUM>, the effective thermal conductivity of the plug <NUM> may be no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. Optionally, the effective thermal conductivity of the plug <NUM> may be no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure or no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure.

The plug <NUM> may comprise a plug body <NUM> which is coated with a thermal coating <NUM>, as shown in the examples of <FIG> and <FIG>. An effective thermal conductivity of the thermal coating <NUM> is greater than an effective thermal conductivity of the plug body <NUM>. Therefore, the provision of the thermal coating <NUM> to the plug <NUM> may increase thermal conduction around a periphery of the plug <NUM>. In a similar way to as described above, this results in a uniformity of the temperature of the plug <NUM> around a periphery of the plug <NUM> being relatively increased. Further, use of a specially selected thermal coating <NUM> for the purpose of increasing the uniformity of the temperature of the plug <NUM> around the periphery of the plug <NUM> allows a material for the plug body <NUM> to be selected according to other design criteria, which may result in a reduced installation mass of the platform <NUM>, for example.

To promote thermal conduction around the periphery of the plug <NUM>, the effective thermal conductivity of the thermal coating <NUM> may be no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. Optionally, the effective thermal conductivity of the thermal coating <NUM> may be no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure or no less than <NUM> W m-<NUM> K-<NUM> at <NUM> and at atmospheric pressure. More generally, the effective thermal conductivity of the thermal coating <NUM> may be at least <NUM> W m-<NUM> K-<NUM> greater than the effective thermal conductivity of the plug body <NUM> at <NUM> and at atmospheric pressure.

In addition, or instead, an effective thermal emissivity of the thermal coating <NUM> may be greater than an effective thermal emissivity of the plug body <NUM>. Therefore, the provision of the thermal coating <NUM> to the plug <NUM> may increase thermal radiation from the periphery of the plug <NUM> into the fluid <NUM> to which the outer surface <NUM> of the platform body <NUM> is exposed and/or to any other nearby components of a rotary machine in which the platform <NUM> is incorporated. To promote thermal radiation from the periphery of the plug <NUM>, the effective thermal emissivity of the thermal coating <NUM> may be no less than <NUM>, and optionally no less than <NUM> or no less than <NUM>.

The platform body <NUM> of any of the example platforms <NUM> in accordance with the present invention may define a plurality of internal fluid passageways <NUM> and a corresponding plurality of core apertures <NUM>, each core aperture extending from the outer surface <NUM> of the platform body <NUM> to a respective internal fluid passageway <NUM>. Each core aperture <NUM> may be sealed by a respective plug <NUM>. Each internal fluid passageway <NUM>, core aperture <NUM> and respective plug <NUM> may have any of the features described herein as appropriate and applicable. The platform body <NUM> defining a plurality of internal fluid passageways <NUM> may increase a total cooling effect which may be provided to the platform body <NUM> in use.

In the fourth example platform <NUM>, as seen in <FIG>, the platform body <NUM> defines a plurality of internal fluid passageways and plurality of core apertures. The plurality of internal fluid passageways includes the internal fluid passageway <NUM> and a further internal fluid passageway <NUM>', while the plurality of core apertures includes the core aperture <NUM> and a further core aperture <NUM>'. Like the internal fluid passageway <NUM>, the further internal fluid passageway <NUM>' is disposed between the inner surface <NUM> and the outer surface <NUM> and is generally configured to convey a further fluid <NUM>', <NUM>' therethrough for the purpose of heat exchange with the platform body <NUM> and/or the further plug <NUM>'. The internal fluid passageway <NUM> may be separated from the further internal fluid passageway <NUM>' by a septum wall <NUM> defined by the platform body <NUM>, such that the fluid <NUM>, <NUM> conveyed by the internal fluid passageway <NUM> does not mix with the further fluid <NUM>', <NUM>' conveyed by the internal fluid passageways <NUM>' along the length of each internal fluid passageway. The further core aperture <NUM>' extends from the outer surface <NUM> to the further internal fluid passageway <NUM>'. The platform <NUM> includes a further plug <NUM>'. In a similar way to the plug <NUM>, the further plug <NUM>' is fixed to the platform body <NUM> and seals the further core aperture <NUM>'. More generally, the further plug <NUM>' may have any of the features of the plug <NUM> described above with reference to <FIG>.

The further plug <NUM>' is generally similar to the plug <NUM>, with like reference signs differentiated by the prime (') symbol denoting similar or common features. However, the plug <NUM> and the further plug <NUM>' may have some dissimilar features, as in the example of <FIG>. Otherwise, this disclosure envisages that the plug <NUM> and the further plug <NUM>' have substantially identical features. Further, although both of the plug <NUM> and the further plug <NUM>' are partially disposed outside the respective core apertures <NUM>, <NUM>' in the example of <FIG>, this need not necessarily be the case. For instance, it may be that neither only one of the plug <NUM> and the further plug <NUM>' are partially disposed outside of the respective core aperture <NUM>, <NUM>'.

In the specific example of <FIG>, according to the invention, the further plug <NUM>' differs from the plug <NUM> in that the lower portion <NUM>' of the plug defines a plurality of heat exchange channels <NUM>'-<NUM>'. <FIG> shows a cross section of the further plug <NUM>' through section B-B as marked on <FIG>. In the example of <FIG>, the lower portion <NUM>' of the plug defines five heat exchange channels, including a first heat exchange channel <NUM>', a second heat exchange channel <NUM>', a third heat exchange channel <NUM>', a fourth heat exchange channel <NUM>' and a fifth heat exchange channel <NUM>'. However, the lower portion <NUM>' of the further plug <NUM>' may have any suitable number of heat exchange channels <NUM>'-<NUM>'. Each heat exchange channel <NUM>'-<NUM>' is defined by at least one fin <NUM>'-<NUM>' and <NUM>'-<NUM>', with each heat exchange channel <NUM>'-<NUM>' being separated by an internal fin <NUM>'-<NUM>'. In this example, the first heat exchange channel <NUM>' is defined by a first external fin <NUM>' and a first internal fin <NUM>' while the fifth heat exchange channel <NUM>' is defined by a second external fin <NUM>' and the fourth internal fin <NUM>'. In other examples, the external fins <NUM>'-<NUM>' may not be present, such that the first heat exchange channel <NUM>' is only defined by the first internal fin <NUM>' and the fifth heat exchange channel <NUM>' is only defined by the fourth external fin <NUM>'.

As best seen in <FIG>, each heat exchange channel <NUM>'-<NUM>' has a respective inlet 741A'-745A' configured to receive fluid <NUM>' from the internal fluid inlet 608A and a respective outlet 741B'-745B' configured to discharge fluid <NUM>' to the internal fluid outlet 608B. Each heat exchange channel <NUM>'-<NUM>' is configured to convey fluid received from the respective inlet 741A'-745A' to the respective outlet 741A'-745A' for heat exchange with the further plug <NUM>' therein. In the example of <FIG>, each internal fin <NUM>'-<NUM>' has a non-linear shape (e.g., a zig-zag shape) which increases a surface area for heat transfer between fluid conveyed through the respective heat exchange channel <NUM>'-<NUM>' and the further plug <NUM>'. However, in other examples, each internal fin may have another shape (e.g., a linear shape).

The lower portion <NUM>' defining the plurality of heat exchange channels <NUM>'-<NUM>' generally promotes and improves heat exchange between the fluid <NUM>', <NUM>' conveyed by the further internal fluid passageway <NUM>' and the further plug <NUM>'. Therefore, the cooling effect on the platform body <NUM> provided by the fluid <NUM>', <NUM>' conveyed by the further internal fluid passageway <NUM>' may be increased as a result of better heat transfer between the fluid <NUM>', <NUM>' conveyed by the further internal fluid passageway <NUM>' and the fluid to which the outer surface <NUM> is exposed.

It should be appreciated that the plug <NUM> (as described with reference to <FIG>) may have any of the features described above in respect of the further plug <NUM>' with reference to <FIG> and <FIG>. For instance, the lower portion <NUM> of the plug <NUM> may similarly define a plurality of heat exchange channels in a similar way to the lower portion <NUM>' of the plug <NUM>'. In addition, the further plug <NUM>' and the plug <NUM> may be joined by a suitable bridging portion to form a combined plug structure. This may reduce a complexity of assembly of the platform <NUM> during manufacture and/or further promote heat transfer between the plug <NUM> (and the further plug <NUM>') and the gas to which the outer surface <NUM> is exposed.

Although the plug <NUM> has been described as being fixed to the platform body <NUM> and sealing the core aperture <NUM>, this need not necessarily be the case. For example, it may be that the platform body <NUM> comprises a cap like the cap 700P described above with reference to <FIG>. If so, the cap may be fixed to the platform body <NUM>, seal the core aperture <NUM>, and retain the plug <NUM> within the core aperture <NUM> such that the plug <NUM> is secured to the platform body <NUM> (by the cap). The cap may be fixed to the platform body <NUM> by a welded joint or a brazed joint. If so, the plug <NUM> may not seal the core aperture <NUM> (with the sealing provided by the cap being relied upon instead).

<FIG> shows a highly schematic top view of an aircraft <NUM> comprising a gas turbine engine <NUM>. The gas turbine engine <NUM> comprises a platform <NUM> in accordance with the platform <NUM> described above with reference to <FIG>. The platform <NUM> may be included in a stator vane <NUM> as described above with reference to <FIG>, and the platform <NUM> (and the stator vane <NUM>, if applicable) may be included within a turbine stage <NUM> in accordance with that described above in reference to <FIG>. Otherwise, the gas turbine <NUM> may generally be in accordance with the gas turbine engine <NUM> described above with reference to <FIG>.

It will be understood that the invention is not limited to the embodiments above described and various modifications and improvements can be made without departing from the concepts described herein. 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 features described herein. The scope of protection is defined in the appended claims.

Claim 1:
A radially outer platform (<NUM>) for a stator vane (<NUM>), the platform including a platform body (<NUM>) and a plug (<NUM>), and
wherein the platform body defines:
a radially inner surface (<NUM>),
a radially outer surface (<NUM>) offset from the radially inner surface,
an internal fluid passageway (<NUM>) disposed between the radially outer surface and the radially inner surface, and
a core aperture (<NUM>) extending from the radially outer surface to the internal fluid passageway;
wherein the plug is configured to be secured to the platform body; and
wherein the plug is configured to be partially disposed inside the core aperture and extend outside of the core aperture whilst secured to the platform body for improved heat transfer between a fluid (<NUM>, <NUM>) conveyed by the internal fluid passageway and a fluid (<NUM>) to which the radially outer surface is exposed;
wherein a lower portion (<NUM>') of the plug (<NUM>) is configured to extend into the internal fluid passageway whilst secured to the platform body to facilitate heat reception from the fluid (<NUM>, <NUM>) conveyed by the internal fluid passageway;
characterised in that the lower portion (<NUM>') of the plug (<NUM>) defines a plurality of heat exchange channels (<NUM>'-<NUM>') for improved heat exchange between the fluid (<NUM>, <NUM>) conveyed by the internal fluid passageway (<NUM>') and the plug.