Patent Description:
As it is known, a gas turbine engine comprises a stator and a rotor, which is configured to rotate about a longitudinal axis inside the stator. The rotor comprises a shaft; and a plurality of blade sets distributed along the longitudinal axis and supported by the shaft that in some embodiment is made of a set of clamped discs. The stator comprises a casing; and a plurality of vane sets, each of which is interposed between two blade sets and is supported by the casing.

A hot gas stream under high pressure flows and expands through the vanes and the blades and determines the rotation of the rotor with respect to the stator.

The inner ends of the vanes of some sets of vanes engage a respective U-shaped sealing ring, which is located in a corresponding annular cavity of the shaft. The U-shaped sealing ring is made of a plurality of U-ring sectors joined one another and together with the vanes of the respective set defines a closed spaced called "plenum". An airstream flows inside the vanes, through the plenum and in the cavity through holes in order to avoid the ingestion of the hot gas stream into the cavity. For this reason, the airstream is called "sealing air".

Many solutions have been devised in order to properly direct flow of sealing air in the most efficient way such as in <CIT> or in <CIT>, the latter belonging to the same applicant. The solution proposed in the above-referenced patent application has proved to be rather efficient in preventing the ingestion of the hot gas stream. However, this solution is not always applicable in the existing gas turbine engine.

It is an aim of the present invention to provide a sealing assembly for engaging a vane of a gas turbine engine, which is efficient in mitigating the ingestion of hot gas stream into a cavity surrounding the easing assembly.

According to the present invention as defined by independent claim <NUM> there there is provided a sealing assembly for engaging a number of vanes of a gas turbine engine, the sealing assembly comprising:.

In this way, it is possible to change the geometry of the sealing assembly in order to vary the direction of the airstream also in existing gas turbine engine with a minimal modification of the design. In addition to that, the cover plate reduces the axial gap in a cavity designed to house the sealing assembly. Both effects mitigate the ingestion of hot gas.

Still according to independent claim <NUM>, the U-shaped sector is provided with said at least one through hole.

In this way, the airstream is channeled by the cover plate in the most convenient position for mitigating the ingestion of hot gases.

In particular, the U-shaped sector has a typical configuration comprising an upstream wall; and a downstream wall, which are provided with respective main faces and respective circumferential faces and conveniently the at least one cover plate is configured for being coupled to the upstream wall and/or to the downstream wall.

Conveniently, the cover plate is L-shaped and in contact with the U-ring sector along the main face and the circumferential face.

In particular, the cover plate comprises a main wall in contact with the main face and a circumferential wall facing the circumferential face.

In this way, the cover plate increases the thickness in axial direction of the U-shaped sector.

The cover plate further comprises a circumferential baffle that further reduces the axial gap. In particular, the circumferential baffle protrudes from the main wall in the opposite direction to the circumferential wall and is coplanar with the circumferential wall.

In particular, the cover plate comprises a radial baffle for directing the airstream. The radial baffle protrudes from the circumferential wall and is coplanar with the main wall.

In order to conveniently coupling the cover plate to the U-shaped sector, the U-shaped sector has at least one retaining groove and the cover plate has at least one retaining profile for engaging the retaining groove. In particular, the retaining groove and the retaining profile have matching shapes and preferably are L-shaped.

In particular, the cover plate comprises ad least one channel in fluidic communication with the through hole, preferably the channel is cut into the cover plate.

In this way, the cover plate can direct the airstream in a given direction.

In particular, the channel is open at one free end along the edge of the cover plate. This allows conveying the airstream in just one direction.

In alternative, the channel is open at the opposite ends of the channel along the edges of the cover plate so that the airstream can be directed in two directions.

In particular, the cover plate comprises at least one through opening in fluidic communication with said channel. This configuration allows flowing the airstream at any point along the channel.

In particular, the sealing assembly comprising a plurality of adjacent cover plates and shaped so as to be partially superimposed at their respective ends for the benefit of the tightness of the sealing assembly.

The present invention further concerns providing a gas turbine engine, which is free from the drawbacks of the prior art.

According to the present invention there is provided a gas turbine engine comprising a stator and a rotor, which is configured to rotate about a longitudinal axis; the stator comprising a plurality of vane sets distributed along the longitudinal axis and the rotor comprising a plurality of blade sets distributed along the longitudinal axis and alternated to the vane sets, wherein each vane set engage a respective sealing ring comprising a plurality of sealing assemblies as previously disclosed and joined one another.

The implementation of a sealing ring made of the previously disclosed sealing assemblies mitigate the ingestion of hot gases and improves the performances of the gas turbine engine.

The present invention will now be described with reference to the accompanying drawings, which show a number of non-limitative embodiments thereof, in which:.

<FIG> is a section view, with part removed for clarity, of the sealing assembly of <FIG>.

In <FIG>, with numeral <NUM> is indicated a gas turbine engine comprising a stator <NUM> and a rotor <NUM> rotating about a longitudinal axis A1 with respect to the stator <NUM>. The rotor <NUM> comprises a shaft <NUM> made of a number of axially clamped discs not shown the Figures; and a plurality of blade sets <NUM> (just two of them are shown in <FIG>) distributed along the longitudinal axis A1 and supported by the shaft <NUM>. The stator <NUM> comprises a casing <NUM>; and a plurality of vane sets <NUM> (just one shown in <FIG>). Each vane set <NUM> is interposed between two blade sets <NUM> and is supported by the casing <NUM>. The inner ends of the vane <NUM> engage a respective U-shaped sealing ring <NUM>, which is located in a corresponding annular cavity <NUM> of the shaft <NUM>. The U-shaped sealing ring <NUM> together with the vanes <NUM> or the corresponding set defines a plenum <NUM>.

A dynamic seal <NUM> such as for example a labyrinth seal is arranged between the U-shaped sealing ring <NUM> and the shaft in the bottom of the cavity <NUM>.

In use, a hot gas stream under high-pressure flows in direction D1 through the vanes <NUM> and the blades <NUM> and determines the rotation of the rotor <NUM> with respect to the stator <NUM>. At the same time, an airstream flows inside the vanes <NUM> to the plenum <NUM> and from the plenum <NUM> through the cavity <NUM>.

With reference to <FIG>, the U-shaped sealing ring <NUM> comprises a plurality of sealing assembly <NUM>, which, in turn, comprises a U-shaped sector <NUM> and two adjacent cover plates <NUM> and is connected to a number of vanes <NUM> (just one them is shown in <FIG>).

Each U-shaped sector <NUM> comprises a bottom wall <NUM>; an upstream wall <NUM>; and a downstream wall <NUM> with reference to a direction D1 of the hot gases in the gas turbine engine <NUM> (<FIG>). The upstream and downstream walls <NUM> and <NUM> comprises respective outer main faces <NUM> and <NUM> and respective circumferential faces <NUM> and <NUM>.

Each U-shaped sector <NUM> is shaped so as to engage the bottom of the vanes <NUM> so that the U-shaped sector <NUM> and the vanes <NUM> enclose the plenum <NUM>.

Each vane <NUM> comprises an airfoil <NUM>, an outer shroud <NUM> and an inner shroud <NUM> coupled to the U-shaped sector <NUM>. The airfoil <NUM> is provided with a cooling air duct <NUM> fed by a dedicated opening on the outer shroud <NUM>. The inner shroud <NUM> comprises a platform <NUM>, a leading edge flange <NUM> and a trailing edge flange <NUM> extending radially inward from the platform <NUM>. The leading edge flange <NUM> is upstream the trailing edge flange <NUM> along the hot gas flow direction D1 and is coupled to the upstream wall <NUM> in a respective annular seat, while the trailing edge flange <NUM> is coupled to the downstream wall <NUM> in a respective annular seat.

The upstream wall <NUM> is provided with at least one through hole <NUM> for conveying an airstream outside the plenum and, preferably, with a plurality of through holes <NUM> circumferentially distributed.

Each cover plate <NUM> is configured for being coupled to the upstream wall <NUM> for channeling the airstream toward the platform <NUM>.

According to an embodiment not shown in the attached Figures also the downstream wall is provided with a plurality of through holes circumferentially distributed and an additional cover plate is configured for being coupled to the upstream wall for channeling the airstream toward the platform.

Each cover plate <NUM> is shaped as a sector and is arranged in contact with the main face <NUM> and the circumferential <NUM> face of the U-shaped sector <NUM>.

Each cover plate <NUM> comprises a main wall <NUM> facing the main face <NUM> and a circumferential wall <NUM> facing the circumferential face <NUM>.

As better shown in <FIG>, each cover plate <NUM> comprises a circumferential baffle <NUM> protruding from the main wall <NUM> of the opposite side of the circumferential wall <NUM>. In particular, the circumferential baffle <NUM> is coplanar with the circumferential wall <NUM>.

The upstream wall <NUM> has a retaining groove <NUM> extending from the main face <NUM> for housing a retaining profile <NUM> extending from the main wall <NUM> of the cover plate <NUM>. The retaining groove <NUM> and the retaining profile <NUM> have a matching shape and preferably are L-shaped.

With reference to <FIG>, each cover plate <NUM> comprises channels <NUM>, which are configured to be, in use, in fluidic communication with the through holes <NUM>. Each channel <NUM> extends along the main face <NUM> and the circumferential face <NUM> and is cut into the main wall <NUM> and circumferential wall <NUM> of the cover plate <NUM>. In particular, each channel <NUM> comprises a blind groove cut into the main wall <NUM> and by an open groove, which is cut into the circumferential wall <NUM> and is in communication with the blind groove. In other words, the channel is open just at the end along the circumferential wall <NUM>.

According to a variation shown in <FIG>, each channel <NUM> is open at both ends.

With reference to the embodiment disclosed in <FIG> reference numeral <NUM> indicates a sealing assembly, which comprises a U-shaped sector <NUM> and a cover plate <NUM>. The U-shaped sector <NUM> differentiates from the U-shaped sector <NUM> for the fact that hole <NUM> (<FIG>) are replaced by through holes <NUM>. For this reason, the other parts of the U-shaped sector <NUM> will be indicated with the same reference numerals for indicating corresponding parts of the U-shaped sector <NUM> (<FIG>).

The through holes <NUM> end in proximity of the bottom wall <NUM> and, for this reason, the cover plate <NUM> covers a greater portion of the main face <NUM>. The cover plate <NUM> differentiates from the cover plate <NUM> for the fact that is provided with a main wall <NUM> larger than the main wall <NUM> shown in <FIG>. The other parts of cover wall <NUM> are indicated with the same reference numerals indicating the corresponding parts of cover plate <NUM> (<FIG>).

According to the variation of <FIG>, the cover plate <NUM> comprises through openings <NUM> in fluidic communication with respective channels <NUM> (<FIG>). The through openings <NUM> are located along the main wall <NUM> and/or the circumferential wall <NUM>.

According to the further variation of <FIG>, cover plate <NUM> comprises a radial baffle <NUM> protruding from the circumferential wall <NUM>. The radial baffle <NUM> is substantially coplanar with the main wall <NUM>.

With reference to the embodiment disclosed in <FIG> with reference numeral <NUM> is indicated a sealing assembly, which comprises a U-shaped sector <NUM> and a cover plate <NUM>. The U-shaped sector <NUM> differentiates from the U-shaped sector <NUM> (<FIG>) for the fact that it comprises one additional retaining groove <NUM> parallel to retaining groove <NUM>.

Similarly, the cover plate <NUM> differentiates from the cover plate <NUM> for the fact that it comprises an additional retaining profile <NUM> parallel to retaining profile <NUM>.

According to the embodiment of <FIG>, the sealing assembly differentiates from the previous embodiments in the through holes <NUM> made in the leading flange <NUM>. Through holes <NUM> made in the leading flange <NUM> could be either in addition to the through holes in the U-shaped sector or just the sole through holes for evacuating the air from plenum <NUM>. According to the second option, the cover plate <NUM> has the function of guiding, in particular deflecting, the airstream flowing from plenum <NUM>.

According to a further variation not shown in the attached Figures, the through holes are made in the trailing flange.

With reference to <FIG>, cover plates <NUM> and shaped so as to be partially superimposed at their respective ends.

Claim 1:
A sealing assembly for engaging a number of vanes of a gas turbine engine, the sealing assembly comprising a U-shaped sector (<NUM>; <NUM>; <NUM>), which is configured for engaging at least one vane (<NUM>) so that the U-shaped sector (<NUM>; <NUM>; <NUM>) and the vane (<NUM>) enclose a plenum (<NUM>), which communicates to the outside trough at least one through hole (<NUM>; <NUM>; <NUM>) for conveying an airstream outside the plenum (<NUM>); wherein the sealing assembly further comprises at least one cover plate (<NUM>; <NUM>; <NUM>; <NUM>) configured for being coupled to the U-shaped sector (<NUM>; <NUM>; <NUM>) for guiding said airstream in a given direction, the sealing assembly being characterised in that the U-shaped sector (<NUM>; <NUM>; <NUM>) is provided with said at least one through hole (<NUM>; <NUM>).