Improved interface between combustion chamber and gas turbine distributor

Abstract

Improved interface between combustion chamber and gas turbine distributor. Gas turbine (1) comprising a central shaft (X) and an annular combustion chamber (4) about the central shaft (X) and having an inner wall (41) and an outer wall (42), a high-pressure turbine distributor (50) arranged at a downstream end of the combustion chamber (4) in a direction of gas flow exiting the combustion chamber (4), and having a plurality of blades (53) extending between an inner shell (51) and an outer shell (52) each comprising an upstream extension (512, 522) forming an annular sleeve (54) extending upstream, the inner and outer walls (41, 42) being partially inserted into the annular sleeve (54) such that, in operation, the inner and outer walls (41, 42) are respectively in contact with the upstream extension (512, 522) of the internal and external ferrules (51,52) in a stacking direction (P) transverse to the central axis (X). Figure for the abbreviation: Fig. 3.,

Description

Title of the invention: Improved interface between combustion chamber and gas turbine distributor. Technical field

[0001] The present description relates to a gas turbine, particularly for aircraft, and specifically to the interface between the combustion chamber and the high-pressure distributor of such a gas turbine. The present description also relates to a method for assembling such a gas turbine. Previous technique

[0002] In a gas turbine, particularly in an aircraft turbomachine, the combustion chamber is generally annular around a central axis which is also the axis of rotation of the gas turbine. Furthermore, a high-pressure distributor (HPD) is generally located at the outlet of the combustion chamber and guides the hot gases from combustion to the high-pressure and then low-pressure turbines. To achieve this, the high-pressure distributor comprises a plurality of fixed blades arranged circumferentially around an axis concentric with the central axis.

[0003] In a known manner, each blade comprises at least one vane extending between an inner platform and an outer platform. These outer platforms form ring sectors which, when the blades are assembled and placed side by side, respectively form an inner and an outer ring. The inner faces of these inner and outer rings define a flow channel for the hot gas streams from the combustion chamber.

[0004] Furthermore, the inner and outer shells are generally connected to an inner and outer wall, respectively, of the combustion chamber, for example by means of annular flanges and sealing strips. In other words, the contact interface between the combustion chamber and the high-pressure distributor lies in a plane perpendicular to the central axis.

[0005] Although this arrangement is generally satisfactory in some cases, drawbacks, particularly related to differential expansion, may arise under certain conditions. This is especially true when the materials used for the combustion chamber and the high-pressure distributor are different, for example, metal for the combustion chamber and a ceramic matrix composite (CMC) for the high-pressure distributor. Indeed, since the expansion of ceramic is much lower than that of metal, the seal at the interface between the combustion chamber and the high-pressure distributor may be affected. This can also be the case when the Thermal gradients are significant between the combustion chamber and the DHP, even when both are made of metal.

[0006] Furthermore, differential expansion can also cause a step between the combustion chamber and the DHP platforms. This step creates a discontinuity and can lead to recirculation or flame arrest, depending on the direction and orientation of the step. In both cases, the consequences can be negative for the durability of the components (local heating) and for the performance of the gas turbine (pressure losses). These differential expansion issues are all the more important due to the improvement in engine performance, which requires the use of new materials and higher operating temperatures.

[0007] There is therefore a need for a solution to limit sealing losses at the interface between the combustion chamber and the high-pressure distributor, and to improve the durability of the parts and the performance of the gas turbine. Description of the invention

[0008] The present description relates to a gas turbine comprising a central shaft and: - an annular combustion chamber around the central shaft and having an inner wall and an outer wall, - a high-pressure turbine distributor arranged at a downstream end of the combustion chamber in a direction of gas flow exiting the combustion chamber, and having a plurality of blades extending between an inner and an outer ferrule, the inner and outer shells each comprising an upstream extension forming an annular sleeve extending upstream, the inner and outer walls of the combustion chamber being partly inserted into the annular sleeve so that in operation, the inner and outer walls are respectively in contact with the upstream extension of the inner and outer shells in a stacking direction transverse to the central axis.

[0009] In the present description, an axial direction is considered along the central axis of the gas turbine, which is the axis of rotation of the rotating parts of the turbine, and which is also the central axis of the annular combustion chamber and the distributor. In other words, the annular combustion chamber and the distributor are axisymmetric about the central axis. Furthermore, the terms "upstream" and "downstream" are considered according to a normal direction of gas flow in the turbine along the central axis, specifically from the combustion chamber to the high-pressure turbine, passing through the high-pressure distributor.

[0010] Furthermore, the terms "internal" and "external" are considered in a radial direction perpendicular to the central axis. Thus, the external wall of the combustion chamber, for example, is further from the central axis than its internal wall in the radial direction.

[0011] Furthermore, the terms "interior," "exterior," and their derivatives refer to the orientation of a wall face relative to a given enclosure. For example, the combustion chamber comprises an annular enclosure formed between the inner and outer walls of the combustion chamber. The inner face of the outer and inner walls is the face directed toward the interior of said enclosure, this face being in contact with the hot gases produced by combustion. Conversely, the outer face of the outer and inner walls is the face directed toward the exterior of said enclosure, this face potentially being in contact with an airflow external to the combustion chamber, for example, cooling air.

[0012] It is understood that, according to the present description, the upstream extensions of the inner and outer shells form an upstream protrusion of the distributor, compared to the usual shape of high-pressure distributors. Thus, the annular sleeve formed by these upstream extensions extends further upstream than a downstream end of the inner and outer walls of the combustion chamber. This allows a portion of the combustion chamber, more precisely a downstream portion of the inner and outer walls, to be inserted into the annular sleeve of the distributor. It is therefore understood that a downstream portion of the combustion chamber is fitted into the annular sleeve, in the manner of cylindrical tubes fitted one inside the other.

[0013] By "in operation" or "hot," it is understood that the engine is running and the moving parts of the gas turbine, particularly the rotors, are rotating. Combustion therefore takes place in the combustion chamber, resulting in an increase in temperature within it, with the hot gases being ejected to the turbine via the high-pressure distributor. Consequently, during operation, the inner and outer walls of the combustion chamber undergo expansion. In this configuration, the inner and outer walls of the combustion chamber are respectively in contact with the upstream extension of the inner and outer shells.

[0014] It should be noted in this regard that when the engine is stopped, in a "cold" configuration when the combustion chamber is not operating, the inner and outer walls of the combustion chamber may also be in contact with the upstream extension of the inner and outer shells, or be slightly separated from it, for example by a distance of less than 1 mm. In the first case, contact is ensured even when cold, and the contact pressure between the combustion chamber and the distributor increases further when hot, due to the expansion of the combustion chamber walls. The seal is therefore all the more effective. In the second case, the The hot expansion of the combustion chamber walls brings them into contact with the annular sleeve, thus filling the initial gap between these surfaces. The small gap (less than 1 mm) present when cold ensures sufficient sealing at the moment of relighting, just before the walls expand.

[0015] In the present description, the inner and outer walls of the combustion chamber are in contact with the inner and outer shells of the combustion chamber respectively by being stacked one on top of the other in a bearing direction, defining the stacking direction. This stacking direction, perpendicular to the contact plane (or interface) between the different surfaces, is transverse to the central axis, unlike the usual prior art configuration, in which the inner and outer shells are fixed to the combustion chamber by means of annular flanges, implying a stacking direction parallel to the central axis.

[0016] In this configuration, in the event of differential expansions when the walls of the combustion chamber expand more than the distributor, the internal and external walls of the combustion chamber will come to press against the ferrules of the distributor, in particular the annular sleeve.

[0017] Thus, this solution makes it possible to limit, or even eliminate, the risk of stepping due to differential expansion, thereby limiting performance loss and improving the lifespan of the parts, while ensuring sealing despite significant differential expansion. This solution is particularly advantageous in the case of parts made of different materials (metal for the combustion chamber and CMC for the distributor, for example), but is also advantageous in the case of significant temperature differences, even when all the parts are made of metal.

[0018] In certain embodiments, the inner shell and the outer shell each comprise a main portion between which the blades extend and of which an inner face delimits a flow channel for the gases exiting the combustion chamber, the upstream extension extending the continuity of the main portion.

[0019] It is understood that the main portion has the usual shape and dimensions of distributor shells according to the prior art, the upstream extension constituting an outgrowth in relation to this main portion. It is further understood that the main portion and the upstream extension are continuous with one another and form a single piece, that is to say, the inner (or outer) shell. The upstream extensions allow the insertion of the inner and outer walls of the combustion chamber, while ensuring continuity of walls between the combustion chamber and the high-pressure distributor. This makes it possible to limit the presence of discontinuities and thus limit flame arrests or the presence of recirculations in the hot gas flow, and thereby improve the performance of the gas turbine.

[0020] In certain embodiments, the distributor and the combustion chamber are arranged such that, in operation, a downstream portion of the internal and external walls which is in contact with an inner face of the upstream extensions of the internal and external shells respectively and which extends to a downstream end of the internal and external walls, is tangent to said inner face.

[0021] It is understood that the internal and external walls of the combustion chamber are configured to conform to the shape of the inner face of the upstream extensions of the internal and external ferrules of the distributor, particularly during operation. The fact that the downstream portion of the internal and external walls is tangent to an inner face of the internal and external ferrules further limits the presence of step during the transition from the combustion chamber to the high-pressure distributor, thus reducing pressure losses and the risk of flame arrest.

[0022] In certain embodiments, in operation, the downstream portion of the internal and external walls of the combustion chamber has a shape complementary to the annular sleeve.

[0023] It is understood that the downstream portion is the portion of the inner and outer walls that is inserted into the annular sleeve and extends to the downstream end of the inner and outer walls. The complementary shape, particularly during operation, improves the continuity of contact between the combustion chamber walls and the annular sleeve, thus improving the seal between the combustion chamber and the high-pressure distributor.

[0024] In some embodiments, the contact between the inner and outer walls of the combustion chamber and the annular sleeve is a sliding contact, configured to allow relative axial sliding between the combustion chamber and the distributor.

[0025] It is understood that a degree of freedom exists between the combustion chamber and the distributor in the axial direction. This allows the axial positioning of the combustion chamber relative to the annular sleeve to be adjusted so that, when cold, the walls of the combustion chamber are in contact with the annular sleeve while exerting a low pressure on it (unlike a firm contact where the contact pressure is higher, in the case of expansion of the combustion chamber for example), or slightly spaced from it.

[0026] This cold adjustment allows, when the engine is running, for a desired and predetermined contact force to be obtained between these different walls due to differential expansion. The contact force is predetermined so that, during operation, the contact between the different walls is sufficiently strong to ensure the sealing of the assembly, without risking excessive stresses that could compromise the integrity of the parts.

[0027] In some embodiments, at least the outer wall comprises a plurality of disturbers projecting from an outer face of said outer wall, the outer wall being in contact with the upstream extension of the outer shell in the stacking direction via the disturbers, the latter being arranged to form between them guide channels configured to guide a flow of cooling air towards a downstream end of the outer wall.

[0028] Unlike a configuration in which the contact interface between the combustion chamber and the annular sleeve is flat, curved, and continuous, the presence of the disruptors implies a discontinuous contact interface. The main surface of the outer wall (or outer face of the outer wall) is thus spaced from the upstream extension of the outer shell by a distance corresponding to the thickness of the disruptors in the radial direction. Two adjacent disruptors further form a channel. In other words, an axially elongated space is formed between two adjacent disruptors, the main surface of the outer face of the outer wall, and the inner face of the upstream extension of the outer shell. These guiding channels allow a flow of cooling air to be directed, thereby creating a protective film along the walls of the combustion chamber and the shells.

[0029] In some embodiments, the gas turbine comprises a fixed casing carrying the combustion chamber and the distributor, the combustion chamber being mounted in a movable manner in axial translation relative to the fixed casing, so that the internal and external walls of the combustion chamber are configured to move axially along the central axis inside the annular sleeve.

[0030] It is thus possible to adjust the axial position of the combustion chamber according to the operating conditions and / or the engine temperature. The gas turbine may, for example, include a calculation unit configured to axially move the combustion chamber according to these parameters, in order to ensure contact between the surfaces of the combustion chamber and the distributor, while limiting the contact forces between them.

[0031] In some embodiments, the combustion chamber is made of metal, and the high-pressure turbine distributor is made of composite matrix ceramic.

[0032] The arrangement of the combustion chamber, inserted in the annular sleeve of the distributor according to the present description, makes it possible to limit the disadvantages related to the significant differential expansions implied by the difference in material between the combustion chamber and the high-pressure distributor.

[0033] The present description also relates to a turbomachine comprising a gas turbine according to any one of the preceding embodiments.

[0034] The present description also relates to a method for assembling a gas turbine comprising a central shaft, the method comprising: - the supply of an annular combustion chamber around the central axis and having an internal wall and an external wall, - the supply of a high-pressure turbine distributor having a plurality of blades extending between an inner and an outer shell, the inner and outer shells each comprising an upstream extension forming an annular sleeve extending upstream, - the assembly of the distributor and the combustion chamber so as to arrange the distributor at a downstream end of the combustion chamber according to a direction of flow of the gases exiting the combustion chamber, by partially inserting the internal and external walls of the combustion chamber into the annular sleeve so that in operation, the internal and external walls are respectively in contact with the upstream extension of the internal and external shells in a stacking direction transverse to the central axis.

[0035] Unlike the usual prior art configuration, in which the inner and outer shells are fixed to the combustion chamber by means of annular flanges and fastening means such as screws and nuts, the combustion chamber, in the method described herein, is assembled to the distributor by insertion into the annular sleeve of said distributor. In addition to the aforementioned advantages related to this arrangement and to differential expansion, this assembly method is simple and time-efficient.

[0036] In certain embodiments, the shape and position of the internal and external walls of the combustion chamber and of the upstream extension of the internal and external shells are determined so that, in operation, said internal and external walls have a shape complementary to the annular sleeve.

[0037] In particular, the shape and position of the various walls can be determined by taking into account the coefficients of expansion of the different parts and the envisaged operating temperatures. These parameters are determined in such a way that, during operation, i.e., when hot and the various walls expand, the outer wall (or the inner wall) of the combustion chamber conforms to the shape of the upstream extension of the outer (or inner) shell, being in contact with it.

[0038] In some embodiments, an axial position of the combustion chamber relative to the distributor is determined according to the operating regime of the gas turbine.

[0039] The gas turbine may, for example, include a computing unit configured to axially displace the combustion chamber according to the operating speed and / or the engine temperature, in order to ensure contact between the combustion chamber and the distributor, while limiting the contact forces between These factors, for example, can be shifted axially upstream when the chamber is very hot to allow for greater expansion. Conversely, for colder operating points, the chamber can be shifted axially downstream and towards the distributor. Brief description of the drawings

[0040] The invention and its advantages will be better understood upon reading the following detailed description of various embodiments of the invention, given by way of non-limiting examples. This description refers to the accompanying figure pages, on which:

[0041] [Fig. 1] Fig. 1 represents a schematic longitudinal cross-sectional view of a turbomachine,

[0042] [Fig.2] Fig.2 is a partial axial cross-sectional view of a combustion chamber and distributor of a gas turbine according to the prior art,

[0043] [Fig.3] Fig.3 is a partial axial cross-sectional view of a combustion chamber and distributor of a gas turbine according to an embodiment of the invention,

[0044] [Fig.4] Fig.4 is a partial perspective view of a downstream end of a wall of the combustion chamber of Fig.3, according to a first modified example of the embodiment,

[0045] [Fig. 5A-5B] Figures 5A-5B are axial and partial cross-sectional views of a combustion chamber and distributor of a gas turbine according to a second modified example of the embodiment. Description of the implementation methods

[0046] One embodiment of the present exposition will be presented with reference to figures 1 to 5B.

[0047] The terms "upstream" and "downstream" are subsequently defined with respect to the direction of gas flow through a turbomachine, indicated by arrow G in [Fig. 1], or by arrow F in Figures 2 and 3, which represent the flow of hot gases in the combustion chamber 4. Furthermore, the terms "internal" and "external" are considered in a radial direction perpendicular to the central axis X. Thus, the external wall 42 of the combustion chamber, for example, is farther from the central axis X than its internal wall 41 in the radial direction. In addition, the terms "internal," "external," and their derivatives denote the orientation of the face of a wall with respect to the internal enclosure E of the combustion chamber 4 described below.

[0048] Figure 1 illustrates a double-flow turbomachine 100 comprising, in a known manner from upstream to downstream successively, at least one fan S, a gas turbine engine part 1 comprising successively at least one compressor stage low pressure 2, high pressure compressor 3, a combustion chamber 4, at least one stage of high pressure turbine 5 and low pressure turbine 6. The rotors of the compressors 2, 3, the turbines 5, 6 and the blower S rotate around the central axis X of the turbomachine 100, and can be coupled together by different transmission and gear systems.

[0049] In a manner known per se, the combustion chamber (hereinafter referred to more simply as "chamber 4") is coupled to the high-pressure turbine 5 via a high-pressure distributor (hereinafter referred to more simply as "distributor 50").

[0050] Figure 2 shows a simplified axial half-section of a portion of a gas turbine 1' according to the prior art. Document EP 1 607 682 A1 describes in more detail an example of coupling between a chamber and a distributor.

[0051] The chamber 4, and in particular its inner enclosure E, is delimited by an annular inner wall 41 and an annular outer wall 42, more precisely by the inner faces 41a, 42a of the latter, both axisymmetric about the central axis X. Injectors (not shown) arranged at an upstream end of the chamber 4 allow the injection of fuel and oxidizer into the chamber 4, the burnt gases then flowing downstream into the inner enclosure E in the direction of arrow F. A downstream end 411, 421 of the inner and outer walls 41, 42 respectively, is fixed to the distributor 50.

[0052] The distributor 50 constitutes the inlet stage of the high-pressure turbine 5 (not shown in [Fig. 2]). The distributor 50 is an axisymmetric component about the central axis X and comprises a plurality of fixed blades distributed angularly about the central axis X. As is known, each blade comprises at least one vane 53 extending between an inner platform and an outer platform. These outer platforms form ring sectors which, when the blades are assembled and placed side by side, respectively form an inner shell 51 and an outer shell 52. The inner faces 51a, 52a of these inner 51 and outer 52 shells define a flow channel for the hot gas streams from the chamber 4.

[0053] The inner 51 and outer 52 ferrules are fixed respectively to the inner 41 and outer 42 walls of the chamber 4, by means of annular flanges 45 and screw-nut systems 46, for example. Sealing strips (not shown) are generally arranged at the contact interface I between the chamber 4 and the distributor 50. Thus, the contact interface I constitutes a bearing surface between the chamber 4 and the distributor 50, lying in a plane perpendicular to the central axis X. Consequently, a stacking direction P between the chamber 4 and the distributor 50 is parallel to the central axis X.

[0054] In this context, differential expansion can cause a step M, or accentuate the latter, between chamber 4 and ferrules 51, 52 of distributor 50, which can cause discontinuity and lead to recirculation or flame catching.

[0055] Figure 3 shows a simplified axial half-section of a portion of a gas turbine 1 according to an embodiment of the present description. Elements with the same numerical references as the prior art example described with reference to Figure 2 are identical to the latter and will not be repeated. It should be noted that in this example, the chamber 4 is made of metal and the distributor 50 is made of CMC. This example is not, however, limiting, as the invention also applies to a chamber 4 and a distributor 50 both made of metal.

[0056] The gas turbine 1 according to this embodiment differs from the prior art, firstly, in that the downstream ends 411, 421 of the inner 41 and outer 42 walls of the chamber 4 are free ends and do not include an annular flange. Secondly, the inner 51 and outer 52 shells of the distributor 50 comprise a main portion 511, 521, and an upstream extension 512, 522.

[0057] The main portions 511, 521 are substantially equivalent to the inner 51 and outer 52 ferrules according to the prior art. In particular, their inner face 511a, 521a delimits the flow path of the hot gases exiting the chamber 4, and the blades 53 extend radially between said inner faces 511a, 521a. The upstream extensions 512, 522 are outgrowths of the ferrules 51, 52 extending upstream from the main portions 511, 521.

[0058] More specifically, a first upstream extension 512 extends upstream from the main portion 511 of the inner ferrule 51, and a second upstream extension 522 extends upstream from the main portion 521 of the outer ferrule 52. The upstream extensions 512, 522 together form an annular sheath 54, preferably axisymmetric around the central axis X.

[0059] A portion of the internal wall 41 and external wall 42, including the downstream ends 411, 421 of the chamber 4, is inserted into the annular sleeve 54 formed by the upstream extensions 512, 522. It is understood in this regard that the space formed between the upstream extensions 512, 522 is larger, even slightly, than the distance between the internal wall 41 and external wall 42, at least at the downstream ends 411, 421, in order for such an insertion to be possible.

[0060] In other words, the chamber 4 and the distributor 50 are arranged so that, in a state in which the chamber 4 is inserted into the annular sleeve 54, an outer face 41b of the inner wall 41 is opposite an inner face 512a of the first upstream extension 512, and an outer face 42b of the outer wall 42 is opposite an inner face 522a of the second upstream extension 522.

[0061] It will be understood that, in order to increase the quality of the coupling between chamber 4 and distributor 50, the part of chamber 4 inserted into the annular sleeve 54 has a form complementary to the latter. In other words, in this example, since the inner wall 41 of chamber 4 is substantially straight and parallel to the central axis X in its downstream end region, the inner face 512a of the first upstream extension 512 is also substantially straight and parallel to the central axis X. A contact or support interface I is therefore substantially parallel to the central axis X and cylindrical. It should be noted that this interface I is axisymmetric about the central axis X.

[0062] Similarly, since the outer wall 42 of chamber 4 is inclined inwards in its downstream end region, the inner face 522a of the second upstream extension 522 is also inclined with respect to the central axis X, such that a contact or support interface I is inclined and has a substantially frustoconical shape about the central axis X.

[0063] It should be noted that in the example shown in [Fig. 3] and in the following figures, the inner wall 41 and the first upstream extension 512 on the one hand, and the outer wall 42 and the second upstream extension 522 on the other hand, are intentionally shown spaced apart to facilitate visualization and description, and in particular to highlight their complementary shapes. Nevertheless, during hot operation, contact does exist between these different walls, at least in the vicinity of the downstream end 411, 421.

[0064] These different walls can also be in contact when cold, with the engine stopped, or slightly spaced apart as illustrated in [Fig. 3]. However, in this second case, when the engine is hot and running, the temperature increase causes the internal wall 41 and external wall 42 to expand and press against the walls of the annular sleeve 54.

[0065] According to this embodiment of the invention, when the turbine 1 is operating, the inner wall 41 of the chamber 4 is in contact with the first upstream extension 512, the contact between these two surfaces occurring in a stacking direction P substantially perpendicular to the contact interface I between these two surfaces. Unlike the prior art, this stacking direction P is not parallel to the central axis X but transverse to it. In the case of the inner wall 41 of this example, the stacking direction P is substantially perpendicular to the central axis X.

[0066] Similarly, when the turbine 1 is in operation, the outer wall 42 of the chamber 4 is in contact with the second upstream extension 522, the contact between these two surfaces being in a stacking direction P substantially perpendicular to the interface I of contact between these two surfaces, and transverse to the central axis X.

[0067] In a first modified example of this embodiment, the gas turbine 1 may include disturbances 48. These disturbances 48 are highlighted on the [Fig.4], representing a partial perspective view of the outer face 42b of the outer wall 42 of chamber 4 in the vicinity of its axial end 421.

[0068] It should be noted that this example is not limiting, the disturbers 48 being able to be arranged on the outer face 41b of the inner wall 41, in addition to or instead of the outer wall 42, or on the inner face 512a of the first upstream extension 512 and / or on the inner face 522a of the second upstream extension 522. In this second case, the outer faces 41b, 42b would then be smooth.

[0069] The perturbators 48 have the form of walls projecting radially outwards from the outer face 42b of the outer wall 42. These walls extend mainly longitudinally, preferably parallel to the central axis X, and preferably to the downstream end 421. Each perturbator 48 includes a flat top 48a, intended to come into contact with the inner face 522a of the second upstream extension 522.

[0070] It is therefore understood that, in the presence of the agitators 48, the outer face 42b of the outer wall 42 is not directly in contact with the inner face 522a of the second upstream extension 522 via a planar, curved, and continuous contact interface, but the outer wall 42 is in contact with said inner face 522a through the agitators 48. The shaded portions of the vertices 48a of the agitators 48 in [Fig. 4] symbolize the areas intended to come into contact with the inner face 522a. Consequently, in this case, the contact interface is curved but discontinuous.

[0071] The perturbators 48 can be distributed angularly around the central axis X, preferably at regular intervals, such that two adjacent perturbators 48 form a guide channel 49. In particular, a guide channel 49 is delimited by the lateral walls of the adjacent perturbators 48, by a portion of the outer face 42b of the outer wall 42, and by a portion of the inner face 522a of the upstream extension 522 (not visible in [Fig. 4]) with which the perturbators 48 are in contact. The space formed between the outer face 42b and the inner face 522a is thus equal to the thickness of the perturbators 48.

[0072] These guide channels 49 allow the flow of a fluid external to the chamber 4, for example cooling air, creating an air film which cools both the ferrules 51, 52 of the distributor 50 and the walls 41, 42 of the chamber 4. The dashed arrows on [Fig.4] represent the flow of cooling air in the different guide channels 49.

[0073] It should be noted that the thickness of the perturbators 48 may not be constant in the axial direction. As shown in [Fig. 4], the thickness of the perturbators 48 may decrease as it approaches the downstream end 421, and be zero at the downstream end 421. This allows the outer wall 42 to be in direct contact with the upstream extension 522 at the downstream end 421, thus improving the seal. Cooling air can be exhausted via openings in the upstream extension 522.

[0074] Alternatively, the disruptors 48 may not be axial by extending parallel to the central axis X, but be slightly beveled at least at the downstream end 421 in the direction of the blades 53, taking into account their angle of incidence, in order to initiate a gyration of the cooling flow.

[0075] In a second modified example of this embodiment, shown in Figures 5A-5B, the combustion chamber 4 is mounted in a movable manner in axial translation relative to a fixed housing 70 which also carries the distributor 50. To achieve this, the chamber 4 can be attached to an axial positioning device 80, itself movably mounted on the fixed housing 70. For example, a base 81 of the device 80 can be fixed to an upstream end of the outer wall 42 and connected by means of a mast 82 to an arm 83 movable in translation along the central axis X. The chamber 4 is thus fixed to the arm 83, and an axial displacement of the latter therefore causes the chamber 4 to move closer to or further away from the distributor 50.

[0076] The arm 83 can be actuated by a computing unit (not shown), which can move the arm 83 upstream or downstream depending on certain parameters such as the temperature or the operating speed of the engine.

[0077] For example, when chamber 4 is very hot, the calculation unit axially shifts arm 83, and consequently chamber 4, upstream to allow for greater expansion. This configuration is shown in Figure 5A, and the upstream direction of movement of arm 83 and chamber 4 is symbolized by the left-pointing dashed arrow. In this case, the downstream end 411, 421 of the inner wall 41 and outer wall 42 is moved upstream into the annular sleeve 54, a distance C being an axial length between the downstream end 411 of the inner wall 41 and the upstream end 512c of the first extension 512.

[0078] Given the frustoconical shape of the annular sleeve 54, narrowing downstream, this "rear position" of the chamber 4 in the sleeve 54, where its section is larger and more open, allows a greater expansion of the internal 41 and external 42 walls of the chamber 4. This is preferable in high-temperature operating regimes involving significant expansions, in order to limit overstress at the contact interface between the different walls.

[0079] Conversely, for colder operating points involving lower expansions, the calculation unit axially shifts arm 83 downstream, and consequently chamber 4. This configuration is shown in Figure 5B, and the downstream direction of movement of arm 83 and chamber 4 is symbolized by the dashed arrow pointing to the right. In this case, the downstream end 411, 421 of the inner wall 41 and outer wall 42 is advanced downstream in the annular sleeve 54, a distance C' being an axial length between the downstream end 411 of the internal wall 41 and the upstream end 512c of the first extension 512, C' being greater than C.

[0080] Given the frustoconical shape of the annular sleeve 54, which narrows downstream, this "forward" position of the chamber 4 within the sleeve 54, where its cross-section is smaller and more enclosed, allows the inner wall 41 and outer wall 42 to come into contact with the walls of the sleeve 54, even though the temperatures and therefore the expansions are lower. This is preferable in operating regimes at lower temperatures involving lower expansions, in order to improve the seal at the contact interface between the different walls. Such a seal would indeed be degraded if the chamber 4 had remained in the "recessed" position described above.

[0081] It should be noted that this second example of the embodiment can also be implemented in combination with the first example, involving the presence of disruptors 48 as previously described.

[0082] A method for assembling a gas turbine 1 includes, in particular, providing a combustion chamber 4 and a high-pressure distributor 10 as described above. The shape and dimensions of the chamber 4 and the distributor 10 are determined to be complementary, especially when the engine is running. For example, chamber 4 and distributor 10 can be dimensioned so that, when hot, a radial distance between the outer face 41b, 42b of the inner wall 41 and outer wall 42, in the vicinity of the downstream end 411, 422, is substantially equal to a radial distance, on the same section, between the inner face 512a, 522a of the upstream extensions 512, 522. In addition, the downstream end 421 of the outer wall 42 having a plunging shape, the upstream extension 522 is therefore formed to have a complementary shape by widening upstream.These shapes and dimensions are determined in particular according to the respective coefficients of expansion of the different parts, and their conditions of use.

[0083] In an assembly step, the distributor 10 is arranged at the downstream end 411, 421 of the chamber 4, by partially inserting the internal wall 41 and external wall 42 of the chamber 4 into the annular sleeve 54.

[0084] During this assembly, the axial position of the chamber 4 in the annular sleeve 54 is adjusted so that in operation, the internal wall 41 and external wall 42 are respectively in contact with the upstream extension 512, 522 of the internal 51 and external 52 ferrules in the stacking direction P transverse to the central axis X.

[0085] For example, the chamber 4 can be positioned axially so that when cold, with the engine stopped, the downstream ends 411, 421 of the internal wall 41 and external wall 42 simply come into contact with the internal faces 512a, 522a of the upstream extensions 512, 522, without forcing, so as to have a contact pressure of zero or almost zero. This allows, when walls 41 and 42 expand when hot, with the engine running, for an increase in the contact pressure between these different walls. Thus, having zero or near-zero contact pressure when cold allows a certain degree of expansion of walls 41 and 42, increasing the seal between the walls while limiting overstress.

[0086] Alternatively, the chamber 4 can be positioned axially such that, when cold and the engine is stopped, the downstream ends 411, 421 of the inner wall 41 and outer wall 42 do not come into contact with the inner faces 512a, 522a of the upstream extensions 512, 522, but approach them, for example, to a distance of less than 1 mm. This space when cold is filled when hot as the inner wall 41 and outer wall 42 of the chamber 4 expand.

[0087] It should be noted that this axial adjustment can be carried out by the aforementioned axial positioning device 80, also allowing the axial position of the chamber 4 to be optimized according to the operating regime.

[0088] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0089] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. A gas turbine (1) comprising a central shaft (X) and: - an annular combustion chamber (4) about the central shaft (X) and having an inner wall (41) and an outer wall (42), - a high-pressure turbine distributor (50) arranged at a downstream end of the combustion chamber (4) in the direction of gas flow exiting the combustion chamber (4), and having a plurality of blades (53) extending between an inner shell (51) and an outer shell (52), the inner and outer shells each comprising an upstream extension (512, 522) forming an annular sleeve (54) extending upstream, the inner and outer walls (41, 42) of the combustion chamber (4) being partially inserted into the annular sleeve (54) such that, in operation, the inner and outer walls (41, 42) are respectively in contact with the upstream extension (512, 522) of the internal and external ferrules (51,52) in a stacking direction (P) transverse to the central axis (X), the gas turbine (1) further comprising a fixed casing (70) carrying the combustion chamber (4) and the distributor (50), the combustion chamber (4) being mounted in a movable manner in axial translation relative to the fixed casing (70), such that the internal and external walls (41, 42) of the combustion chamber (4) are configured to move axially along the central axis (X) inside the annular sleeve (54).

2. Gas turbine (1) according to claim 1, wherein the inner shell (51) and the outer shell (52) each comprise a main portion (511, 521) between which the blades (53) extend and of which an inner face (511a, 521a) delimits a flow channel of the gases exiting the combustion chamber (4), the upstream extension (512, 522) extending the continuity of the main portion (511, 521).

3. Gas turbine (1) according to claim 1 or 2, wherein the distributor (50) and the combustion chamber (4) are arranged such that, in operation, a downstream portion of the inner and outer walls (41, 42) which is in contact with an inner face (512a, 522a) of the upstream extensions (512, 522) of the inner and outer shells respectively and which extends to a downstream end (411, 421) of the internal and external walls (41, 42), is tangent to said internal face (512a, 522a).

4. Gas turbine (1) according to any one of claims 1 to 3, wherein, in operation, a downstream portion of the internal and external walls (41, 42) of the combustion chamber (4) have a shape complementary to the annular sleeve (54).

5. Gas turbine (1) according to any one of claims 1 to 4, wherein the contact between the inner and outer walls (41, 42) of the combustion chamber (4) and the annular sleeve (54) is a sliding contact, configured to permit relative axial sliding between the combustion chamber (4) and the distributor (50).

6. Gas turbine (1) according to any one of claims 1 to 5, wherein at least the outer wall (42) comprises a plurality of disruptors (48) projecting from an outer face (42b) of said outer wall (42), the outer wall (42) being in contact with the upstream extension (522) of the outer shell (52) in the stacking direction (P) via the disruptors (48), the latter being arranged to form between them guide channels (49) configured to guide a flow of cooling air towards a downstream end (421) of the outer wall (42).

7. Gas turbine (1) according to any one of claims 1 to 6, wherein the combustion chamber (4) is made of metal, and the distributor (50) is made of composite matrix ceramic.

8. Turbomachine (100) comprising a gas turbine (1) according to any one of the preceding claims.

9. A method for assembling a gas turbine (1) comprising a central shaft (X), the method comprising: - providing an annular combustion chamber (4) about the central shaft (X) and having an inner wall (41) and an outer wall (42), - providing a high-pressure turbine distributor (50) having a plurality of blades (53) extending between an inner shell (51) and an outer shell (52), the inner and outer shells each comprising an upstream extension (512, 522) forming an annular sleeve (54) extending upstream, the distributor (50) and the combustion chamber (4) being supported by a fixed housing (70), the combustion chamber (4) being movably mounted in axial translation relative to the fixed housing (70), - the assembly of the distributor (50) and the combustion chamber (4) so ​​as to arrange the distributor (50) at a downstream end of the combustion chamber (4) according to a direction of flow of the gases exiting the combustion chamber (4), by partially inserting the internal and external walls (41, 42) of the combustion chamber (4) into the annular sleeve (54) so ​​that in operation, the internal and external walls (41, 42) are respectively in contact with the upstream extension (512, 522) of the internal and external ferrules (41, 42) in a stacking direction (P) transverse to the central axis (X), - the displacement of the internal and external walls (41, 42) of the combustion chamber (4) axially along the central axis (X) inside the annular sleeve (54).

10. A method according to claim 9, wherein the shape and position of the inner and outer walls (41, 42) of the combustion chamber (4) and of the upstream extension (512, 522) of the inner and outer shells (41, 42) are determined so that, in operation, said inner and outer walls (41, 42) have a shape complementary to the annular sleeve (54).

11. Method according to claim 9 or 10, wherein an axial position of the combustion chamber (4) relative to the distributor (50) is determined as a function of the operating regime of the gas turbine (1).

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