TUBOMACHINE ASSEMBLY WITH A ONE-PIECE SOCKET

Abstract

TITLE: TURBOMACHINE ASSEMBLY WITH A MONOBLOCK SHELL One aspect of the invention relates to a turbomachine assembly (10) comprising: an annular shell (20) with axis X, radially delimited by a lower surface (22) and an upper surface (24); at least one row of movable blades (40), each arranged opposite the lower surface of the shell and extending axially along its length (L1); at least one row of fixed blades (50); and a heat shield (600) opposite a row of movable blades and comprising: an insulating wall (610) extending from an upstream end (610A) to a downstream end (610B) on the upper surface of the shell, and radially delimited by an internal (612) and external (614) surface; and a recess (620) formed between the internal surface of the wall and a portion (24C) of the upper surface of the ferrule extending axially along at least the entire length of the moving blade. Figure to be published with the abbreviation: Figure 3

Description

Title of the invention: TUBOMACHINE ASSEMBLY WITH A ONE-PIECE SOCKET FLOOR TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of turbomachine shells such as an aircraft turbojet.

[0002] The present invention relates more particularly to a one-piece structure ferrule connected to a row of fixed blades. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Classically, a turbomachine shell is a circular part, of large diameter, mounted at the interface of many components of a turbine or turbomachine compressor and which must satisfy a large number of functions related to these components.

[0004] As shown in [Fig. 1], a turbine or turbomachine compressor assembly 10 according to the prior art comprises: • an annular ferrule 20 with axis X delimited along a radial axis R perpendicular to the axis X, by a lower surface 22 and an upper surface 24 and comprising: • a circular upstream part 210A comprising a plurality of 212A connection interfaces, each forming a flange (only one 212A connection interface is visible in Figure 1), • a downstream portion 210B axially opposed to the upstream portion 210A and comprising a plurality of connecting interfaces 212B, each forming a flange (only one connecting interface 212B is visible in Figure 1), and • a plurality of bolted connections 220, of the screw-bolt type, each connecting one of the connection interfaces 212A of the upstream part 210A with one of the connection interfaces 212B of the downstream part 210B of the annular ferrule 20 (only one bolted connection 220 is visible in figure 1), • at least one row of movable blades 40, each movable blade 40 being radially delimited by a lower end 42 and an upper end 44 opposite the lower surface 22 of the upstream part 210A of the annular ferrule 20 and radially spaced so as to define a radial clearance J between the upstream part 210A of the annular ferrule 20 and the movable blade 40, and • at least one row of fixed blades 50, each fixed blade 50 being radially delimited by a lower end 52 and an upper end 54 integral with the lower surface 22 of the downstream part 210B of the annular ferrule 20.

[0005] Such a turbomachine assembly 10 has a large number of parts which implies a relatively high mass and which complicates the correct positioning of the parts relative to each other, in particular the positioning of the upstream 210A and downstream 210B parts of the annular ferrule 20 relative to each other.

[0006] A turbomachine assembly 10, as shown in [Fig. 2], offers a solution to this problem by replacing the two-part annular ferrule 20 210A, 210B with a single-piece, monobloc annular ferrule 20. This modification of the geometry of the annular ferrule 20 eliminates the connecting interfaces 212A, 212B of the upstream 210A and downstream 210B parts of the annular ferrule 20, as well as the two bolted connections 220. This results in a reduction in the total number of parts in the turbomachine assembly 10, and therefore a significant weight saving and a simplification of the positioning of the parts relative to each other. Such a monobloc annular ferrule 20 is produced by an additive manufacturing process, also called 3D printing (3 dimensions), for example, by laser powder bed fusion.

[0007] However, it has been observed that the one-piece annular ferrule 20 has less rigidity which can cause a variation in the radial clearance J between the annular ferrule 20 and the moving blades 40 during the operation of the turbomachine which impacts its performance by reducing its efficiency.

[0008] Therefore, as shown in [Fig. 3], a turbomachine assembly 10 equipped with a one-piece annular shell 20 requires the addition of a raised portion 30 with a geometry that improves rigidity, such as ribs or triangular shapes, arranged on the upper surface 24 of the annular shell 20 to increase the stiffness of the annular shell 20. The increased stiffness of the shell minimizes the variation in radial clearance J between the one-piece annular shell 20 and the moving blade 40 during turbomachine operation. However, the addition of the raised portion 30 increases the mass of the one-piece annular shell 20, whereas the objective of using a one-piece annular shell is to reduce mass. Therefore, there is a need to optimize the ratio of the stiffness of the annular ferrule 20 to the mass of the annular ferrule 20. Summary of the invention

[0009] The invention offers a solution to the problems mentioned above, by modifying the geometry of the one-piece annular shell so as to increase the thermal response time of the one-piece annular shell while optimizing the reduction of the mass of the turbine or turbomachine compressor assembly and preserving the performance of the turbomachine.

[0010] A first aspect of the invention relates to a turbomachine assembly comprising: • a one-piece annular ferrule with axis X delimited along a radial axis R perpendicular to the X axis, by a lower surface and an upper surface, • at least one row of moving blades, each moving blade being radially delimited by a lower end and an upper end opposite the lower surface of the annular ferrule and radially spaced so as to define a radial clearance between the annular ferrule and the moving blade, and extending axially between an upstream leading edge and a downstream trailing edge, defining a length of the moving blade, and • at least one row of fixed blades, each fixed blade being radially delimited by a lower end and an upper end integral with the lower surface of the annular ferrule, and extending axially between an upstream leading edge and a downstream trailing edge defining a length of the fixed blade.

[0011] The turbomachine assembly includes a heat shield arranged opposite a row of movable blades and comprising: • an insulating wall extending from an upstream end located on the upper surface of the annular ferrule to a downstream end located on the upper surface of the annular ferrule, and radially delimited by an internal surface and an external surface, and • a recess formed between the inner surface of the insulating wall of the thermal shield and an intermediate part of the upper surface of the annular ferrule and extending axially along at least the entire length of the moving blade.

[0012] The one-piece annular shell of the turbomachine assembly according to the invention, thanks to the presence of a thermal shield, and more particularly the portion of the annular shell opposite the row of moving blades, has a thermal response time substantially equal to that of the moving blade, without adding mass.

[0013] Indeed, the removal of the bolted connections opposite the row of moving blades reduces the mass of the annular shell, which has an impact on its thermal behavior, and in particular on its thermal response time. The thermal response time of a part corresponds to the period during which the room temperature changes relative to the ambient air temperature in contact with at least one surface of the part. Its value depends primarily on the mass of the part and its thermal convection coefficient, expressed in W / m² / K (watts per square meter per Kelvin). More specifically, the change in a part's response time is proportional to the change in its mass and inversely proportional to its thermal convection coefficient. Consequently, the thermal response time of a single-piece annular shell, without bolted connections, is shorter than that of a two-part annular shell.During turbomachine operation, the thermal response time of the monobloc annular shell is therefore shorter than that of the moving blade, resulting in a faster expansion and contraction of the monobloc annular shell than of the moving blade. This difference between the thermal response times of the monobloc annular shell and the moving blade causes a variation in the radial clearance between these two parts during turbomachine operation, impacting its performance by reducing its efficiency. Adding a raised section, due to its mass, unintentionally increases the thermal response time of the monobloc annular shell but does not optimize the ratio of radial clearance variation to the mass of the fixed assembly.

[0014] The use of a thermal shield according to the invention has the effect of reducing the thermal response time of the portion of the shell opposite the thermal shield while minimizing the mass of the fixed assembly, which makes it possible to optimize the ratio of radial clearance variation to the mass of the fixed assembly.

[0015] In addition, creating a closed chamber in the heat shield makes it possible to significantly reduce the speed of the air flow present in the recess of the heat shield and therefore the heat transfer coefficient in the recess of the heat shield, which increases the thermal response time of the portion of the annular shell with respect to the row of moving blades, and therefore locally limits the variation of the radial clearance between the annular shell and the moving blade.

[0016] Advantageously, the annular ferrule, the heat shield and the rows of fixed blades form a fixed assembly.

[0017] Preferably, the upstream end and the downstream end of the insulating wall of the thermal shield each extend from the upper surface of the annular ferrule.

[0018] Advantageously, the recess in the heat shield is axially delimited between an upstream end and a downstream end, each corresponding to the intersection of the upper surface of the annular ferrule with the inner surface of the insulating wall of the thermal shield.

[0019] Preferably, the upper surface of the annular ferrule has an upstream portion extending axially from the upstream end of the insulating wall of the thermal shield to the upstream free end of the annular ferrule, and the upstream portion of the upper surface is aligned with the intermediate portion of the upper surface of the annular ferrule delimiting the recess.

[0020] Preferably, the annular ferrule includes a connecting portion arranged upstream of the upstream portion, at the upstream free end of the annular ferrule, the connecting portion being provided for the assembly of the annular ferrule to a surrounding element of the turbomachine assembly.

[0021] Preferably, the upstream portion of the annular ferrule extends axially from the upstream end of the heat shield to the connecting portion (for example a flange) of the ferrule.

[0022] Advantageously, the upper surface of the annular ferrule has a downstream portion extending axially from the downstream end of the insulating wall of the thermal shield to the downstream free end of the annular ferrule, and the downstream portion of the upper surface is aligned with the intermediate portion of the upper surface of the annular ferrule delimiting the recess.

[0023] Preferably, the insulating wall of the thermal shield has a regular cross-section, which allows the weight of the fixed assembly to be optimized.

[0024] Preferably, the insulating wall of the heat shield comprises a section whose thickness is less than that of the annular ferrule. The thickness of the insulating wall of the heat shield (measured between the inner surface of the insulating wall, defining the recess of the heat shield, and the outer surface of the insulating wall) is thus less than that of the annular ferrule (measured between the outer surface of the annular ferrule, defining the recess of the heat shield, and the inner surface of the annular ferrule). This characteristic makes it possible to optimize the weight of the fixed assembly while still providing the heat shield.

[0025] Preferably, the fixed assembly forms a single piece to minimize the total number of parts in the turbomachine assembly.

[0026] Advantageously, the annular ferrule, the heat shield and the fixed blade rows of the fixed assembly are formed from the same material.

[0027] Preferably, the insulating wall of the heat shield has a parabolic cross-section extending axially from the upstream end to the downstream end of the insulating wall of the heat shield, and whose concave side is oriented towards the upper surface of the annular ferrule. The parabolic shape of the The insulating wall of the thermal shield improves its aerodynamic properties while preserving good mechanical resistance of the insulating wall.

[0028] Advantageously, the external surface of the insulating wall of the heat shield is arranged on the upper surface of the annular shell at an angle α greater than or equal to 110°, preferably between 130° and 140°, measured outside the heat shield, at the upstream end of the insulating wall of the heat shield, between a tangent of the external surface of the insulating wall of the heat shield and the upper surface of the annular shell. This feature minimizes pressure losses due to friction of the air against the insulating wall of the heat shield during airflow in the turbine or compressor.

[0029] Preferably, the heat shield extends circumferentially around the entire periphery of the annular shell to thermally insulate the portion of the annular shell opposite the row of moving blades and limit the variation of the radial clearance between the annular shell and each of the moving blades of the row during the operation of the turbomachine.

[0030] Advantageously, the minimum axially measured distance between the upstream end of the heat shield recess and the leading edge of the moving blade is approximately equal to 10% of the moving blade length. This characteristic optimally limits the variation in radial clearance between the annular shell and the leading edge of the moving blade during turbomachine operation.

[0031] Preferably, the minimum axially measured distance between the downstream end of the recess and the trailing edge of the moving blade is approximately equal to 10% of the length of the moving blade. This characteristic optimally limits the variation in radial clearance between the annular shell and the trailing edge of the moving blade during turbomachine operation.

[0032] A second aspect of the invention relates to an aircraft turbomachine comprising a turbomachine assembly according to the invention.

[0033] A third aspect of the invention relates to a method of manufacturing the fixed assembly of the turbomachine assembly according to the invention, characterized in that it comprises an additive manufacturing step of the annular shell and the insulating wall of the heat shield by deposition and solidification of successive layers of a powder.

[0034] Advantageously, the additive manufacturing step of the manufacturing process also includes the manufacturing of the row of fixed blades so as to manufacture the fixed assembly in one and the same piece.

[0035] Preferably, the manufacturing process includes a step of emptying the powder present between the upper surface of the annular ferrule and the inner surface of the insulating wall of the thermal shield.

[0036] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0037] Other advantages and features of the invention will become apparent from the following description, illustrated by the figures in which: • Fig. 1, already described, is a schematic longitudinal cross-sectional view of a state-of-the-art turbomachine assembly comprising a two-part annular shell; • The [Fig.2], already described, is a schematic view, in longitudinal section, of a turbomachine assembly according to the state of the art comprising a one-piece annular shell; • The [Fig.3], already described, is a schematic view, in longitudinal section, of a turbomachine assembly according to the state of the art comprising a one-piece annular shell and a raised part; • Fig. 4 is a schematic longitudinal section view of a turbomachine assembly comprising an annular shell according to the invention. DETAILED DESCRIPTION

[0038] An example of an embodiment of a turbomachine assembly according to the invention is described in detail below, with reference to the accompanying drawings. This example illustrates the features and advantages of the invention.

[0039] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0040] For the purposes of understanding the invention, the radial, tangential, and axial orientations will be adopted according to the RTA frame shown in the figures, whose tangent T and axial A axes extend in a horizontal plane along the orientation shown in the figures. The axial axis A is parallel to an X-axis of an annular shell of the turbomachine assembly. The upstream portion of the annular shell towards the downstream portion of the annular shell is oriented along the axial axis A of the RTA frame. The radial orientation extends radially with respect to the X-axis.

[0041] In the description, the terms "upstream" and "downstream" are defined with respect to the direction of air flow from the air inlet to the turbine or compressor to the air outlet. The terms "upper" and "lower" are defined according to radial orientation; the term "upper" designates the elements furthest radially from the X-axis, as opposed to the term "lower," which designates the elements closest radially to the X-axis.

[0042] Figure 4 represents a turbine or turbomachine compressor assembly 10 according to an embodiment of the invention comprising: • a one-piece annular ferrule 20 with axis X, radially delimited by a lower surface 22 and an upper surface 24 defining a thickness of the annular ferrule 20, • at least one row of 40 movable blades, • at least one row of fixed blades 50 extending from the lower surface 22 from the annular ferrule 20 towards the X-axis, and • a thermal shield 600 comprising an insulating wall 610 extending from an upstream end 610A located on the upper surface 24 of the annular ferrule 20 to a downstream end 610B located on the upper surface 24 of the annular ferrule 20, above a portion of the annular ferrule 20, opposite a row of movable blades 40.

[0043] According to certain embodiments of the annular ferrule 20 as shown in [Fig. 4], the annular ferrule 20 is axially delimited by: • an upstream portion 20A extending axially from the upstream end 610A of the insulating wall 610 of the thermal shield 600 towards the upstream free end of the annular ferrule 20, i.e. upstream of the leading edge 40A of the moving blade 40 of the fixed assembly 246, • a downstream portion 20B extending axially from the downstream end 610B of the insulating wall 610 of the thermal shield 600 towards the downstream end (not shown) of the annular ferrule 20, i.e. downstream of the trailing edge 40B of the moving blade 40 of the fixed assembly 246, • an intermediate portion 20C extending axially from the upstream portion 20A to the downstream portion 20B, i.e. from the upstream end 610A to the downstream end 610B of the insulating wall 610 of the thermal shield 600, and • a connecting portion 20D extending axially from the end of the upstream portion 20A, opposite its end connected to the intermediate portion 20C, the connecting portion 20D forming the upstream free end of the annular ferrule 20 in the form of a flange provided for the assembly of the annular ferrule 20 to a surrounding element of the turbomachine assembly 10.

[0044] The upstream portion 20A of the annular ferrule 20 comprises an upstream part 24A of the upper surface 24 of the annular ferrule 20. The upstream part 24A extends axially from the upstream end 610A of the insulating wall 610 of the thermal shield 600 towards the end of the upstream portion 20A, opposite its end connected to the intermediate portion 20C,

[0045] The downstream portion 20B of the annular ferrule 20 comprises a downstream part 24B of the upper surface 24 of the annular ferrule 20. The downstream part 24B extends axially to from the downstream end 610B of the insulating wall 610 of the thermal shield 600 towards the downstream end (not shown) of the annular ferrule 20.

[0046] The intermediate portion 20C of the annular ferrule 20 comprises an intermediate portion 24C of the upper surface 24 of the annular ferrule 20. The intermediate portion 24C extends axially from the upstream end 620A of the recess 620 to the downstream end 620B of the recess 620 of the heat shield 600. Therefore, the intermediate portion 24C of the upper surface 24 of the annular ferrule 20 delimits the recess 620 of the heat shield 600.

[0047] Each moving blade 40 in the row is radially delimited by a lower end 42 and an upper end 44 opposite the lower surface 22 of the annular ferrule 20. The upper end 44 of the moving blade 40 is radially spaced from the lower surface 22 of the annular ferrule 20 so as to define a radial clearance J between the annular ferrule 20 and the moving blade 40. Each moving blade 40 extends axially between an upstream leading edge 40A and a downstream trailing edge 40B, defining a length L1 of the moving blade 40.

[0048] Each fixed blade 50 of the row is radially delimited by a lower end 52 and an upper end 54 integral with the lower surface 22 of the annular ferrule 20. Each fixed blade 50 extends axially between an upstream leading edge 50A and a downstream trailing edge 50B defining a length L2 of the fixed blade 50.

[0049] According to a preferred embodiment of the invention, the upstream portion 24A of the upper surface 24 of the annular ferrule 20 is aligned with the intermediate portion 24C of the upper surface 24 of the annular ferrule 20. Two aligned surfaces are surfaces that have the same tangent plane at their intersection. Consequently, no raised part or hollow is formed on the upstream portion 24A of the upper surface 24 of the annular ferrule 20, at the upstream end 610A of the insulating wall 610.

[0050] Advantageously, the downstream part 24B of the upper surface 24 of the annular ferrule 20 is also aligned with the intermediate part 24C of the upper surface 24 of the annular ferrule 20.

[0051] Not modifying the geometry of the upstream portion 20A or downstream portion 20B of the annular ferrule 20 makes it possible to avoid modifying the flow of outside air and to avoid suboptimally influencing the radial clearance J between the annular ferrule 20 and the moving blade 40. In addition, the lower surface 22 of the annular ferrule 20 may include an abradable coating layer arranged opposite the moving blade 40. The upstream portion 20A or downstream portion 20B of the annular ferrule 20 may have a diameter (internal or external) that varies constantly, for example in the shape of a cone.

[0052] The insulating wall 610 of the heat shield 600, extending from the upper surface 24 of the annular ferrule 20, comprises an inner surface 612 and an outer surface 614 radially opposed to each other. The insulating wall 610 of the heat shield 600 extends axially between an upstream end 610A and a downstream end 610B.

[0053] The heat shield 600 includes a recess 620 formed between the inner surface 612 of the insulating wall 610 of the heat shield 600 and the intermediate portion 24C of the upper surface 24 of the annular ferrule 20. The recess 620 therefore extends axially between an upstream end 620A and a downstream end 620B, surrounding a part of the intermediate portion 20C which surrounds at least the entire moving blade 40. The recess 610 of the heat shield 600 therefore has an axial length greater than or equal to the length L1 of the moving blade 40.

[0054] The introduction of the heat shield 600 onto the annular ferrule 20 at the radial clearance J to be controlled makes it possible to thermally isolate the intermediate portion 20C of the annular ferrule 20 from a first air flow 230 and to create a second air flow 630 in the recess 620 of the heat shield 600. The heat transfer from the second air flow 630 to the intermediate portion 20C of the annular ferrule 20 is therefore slowed down, making it possible to obtain an intermediate portion 20C having a temperature substantially close to the temperature of the moving blade 40.During turbomachine operation, under so-called "full throttle" conditions, the first air flow 230 outside the heat shield 600 has a first very high heat transfer coefficient H1, on the order of 1000 W / m2 / K, and the second air flow 630 in the recess 620 of the heat shield 600 has a second very low heat transfer coefficient H2, on the order of 10 W / m2 / K.

[0055] The thermal shield 600 extends circumferentially around the entire periphery of the annular ferrule 20.

[0056] According to one embodiment of the heat shield 600, the insulating wall 610 of the heat shield 600, such as that shown in [Fig. 4], has a parabolic cross-section extending axially from the upstream end 610A to the downstream end 610B of the insulating wall 610 of the heat shield 600. More particularly, the parabola formed by the insulating wall 610 of the heat shield 600 is a plane curve symmetrical with respect to an axis of symmetry S, approximately U-shaped, whose concave side is oriented towards the upper surface 24 of the annular ferrule 20. The internal surface 612 of the insulating wall 610 is therefore concave and the external surface 614 of the insulating wall 610 is therefore convex.

[0057] The geometry of the insulating wall 610 of the thermal shield 600 is defined by the following parameters: • a height h of the recess 620 of the thermal shield 600 corresponding to the greatest distance, measured radially, between the intermediate part 24C of the upper surface 24 of the annular ferrule 20 and the internal surface 612 of the insulating wall 610 of the thermal shield 600, the air volume of the recess 620 of the thermal shield 600 depending directly on the height h and the axial length of the recess 620 measured between the upstream end 620A and the downstream end 620B of the recess 620, • a thickness e corresponding to the minimum distance between the internal surface 612 and the external surface 614 of the insulating wall 610 of the thermal shield 600, • a distance d corresponding to the minimum distance, measured axially, between the upstream end 620A of the recess 620 of the heat shield 610 and the leading edge 40A of the moving blade 40, • a distance corresponding to the minimum distance, measured axially, between the upstream end 620B of the recess 620 of the heat shield 600 and the trailing edge 40B of the movable blade 40, and • an angle a, measured outside the heat shield 610, at the upstream end 610A of the insulating wall 610 of the heat shield 600, between a tangent T of the external surface 614 of the insulating wall 610 of the heat shield 600 and the upstream part 24A of the upper surface 24 of the annular ferrule 20.

[0058] The second heat transfer coefficient H2, expressed in W / m2 / K, measured in the recess 620 of the heat shield 610 is inversely proportional to the height h of the recess 620 of the heat shield 610. The height h of the recess 620 of the heat shield 600 must therefore be relatively large in order to obtain a large volume of air in the recess 620 of the heat shield 600 and therefore a very low second heat transfer coefficient H2. Furthermore, increasing the value of the height h causes an increase in the total mass of the fixed assembly 246. The maximum value of the height h of the recess 620 of the thermal shield 600 depends on the manufacturing constraints related to the manufacturing method of the insulating wall 610 of the thermal shield 600. Preferably, the height h of the recess 220 of the thermal shield 600 is between 10mm and 50mm.

[0059] The thickness e of the insulating wall 610 of the thermal shield 600 influences the mechanical strength of the insulating wall 610, the bending of the annular ferrule 20, and the total mass of the fixed assembly 246. The variation in the thickness e of the insulating wall 610 is proportional to the variation in the total mass of the fixed assembly 246 and inversely proportional to the variation in the mechanical resistance of the insulating wall. Advantageously, the thickness e of the insulating wall 610 of the thermal shield 600 is constant between the upstream end 610A and the downstream end 610B of the insulating wall 610 and is between 1mm and 5mm.

[0060] Since the intermediate portion 20C of the annular ferrule 20 is a piloting zone for the radial clearance J between the annular ferrule 20 and the moving blade 40, the thermal insulation of the intermediate portion 20C of the annular ferrule 20, by the thermal shield 600, must be ensured from the leading edge 40A to the trailing edge 40B of the moving blade 40 and the values ​​of the distances d and d' must be strictly greater than zero.

[0061] More specifically, the radial clearance J between the annular ferrule 20 and the upper end 44 of the moving blade 40, at the leading edge 40A of the moving blade 40, has a direct impact on the performance of the turbomachine. The thermal insulation of the first airflow 230 by the heat shield 600 on the annular ferrule 20 at the leading edge 40A of the moving blade 40 makes it possible to optimally limit the variation of the radial clearance J between the annular ferrule 20 and the upper end 44 of the moving blade 40, at the leading edge 40A of the moving blade 40, and thus to increase the performance of the turbomachine. Advantageously, the distance d is substantially equal to 10% of the length L1 of the moving blade 40 in order to improve the effectiveness of the heat shield 600 on the annular ferrule 20 at the leading edge 40A of the moving blade 40.

[0062] More particularly, the radial clearance J between the annular ferrule 20 and the upper end 44 of the moving blade 40, at the trailing edge 40B of the moving blade 40, has a secondary impact on the performance of the turbomachine, the thermal insulation of the first air flow 230 by the heat shield 600 on the annular ferrule 20 at the trailing edge 40B of the moving blade 40 makes it possible to optimally limit the variation of the radial clearance J between the annular ferrule 20 and the upper end 44 of the moving blade 40, at the trailing edge 40B of the moving blade 40, and thus to increase the performance of the turbomachine. Advantageously, the distance is approximately equal to 10% of the length L1 of the moving blade 40 in order to improve the effectiveness of the heat shield 600 on the ferrule at the trailing edge 40B of the moving blade 40.

[0063] The angle α formed upstream of the insulating wall 610 of the thermal shield 600 must be as large as possible to minimize pressure losses due to friction of the air against the insulating wall 610 of the thermal shield 600 during the flow of outside air. The maximum value of the angle α depends on the manufacturing constraints related to the manufacturing method of the insulating wall 610 of the thermal shield 600. Advantageously, the angle α is greater than or equal to 110°, preferably between 130° and 140°.

[0064] The annular ferrule 20, the thermal shield 600 and the fixed blade rows 50 form a fixed assembly 246.

[0065] According to certain embodiments of the fixed assembly 246 shown in [Fig.4], the fixed assembly 246 is monobloc so as to form a single piece to minimize the total number of parts of the turbomachine assembly 10. Advantageously, the annular shell 20, the heat shield 600 and the fixed blade rows 50 of the fixed assembly 246 are formed in the same material.

[0066] The manufacturing process of the fixed assembly 246 according to an embodiment of the invention includes an additive manufacturing step of the annular ferrule 20 and the insulating wall 610 of the thermal shield 600 by deposition and solidification of successive layers of a powder.

[0067] The additive manufacturing process uses, for example, laser powder bed fusion technology. This technology consists of forming successive layers of fused metal powder particles using a laser.

[0068] The additive manufacturing step of the manufacturing process for the fixed assembly 246 comprises the following substeps: • construction of the annular ferrule 20, and • construction of the insulating wall 610 of the thermal shield 600 from the upper surface 24 of the previously constructed annular ferrule 20.

[0069] Advantageously, the succession of powder layers in the construction sub-step of the annular shell 20 is carried out in the radial direction R, from the lower surface 22 to the upper surface 24 of the annular shell 20 to form the thickness of the annular shell 20. The succession of powder layers in the construction sub-step of the insulating wall 610 of the heat shield 600 is, for example, carried out in the radial direction R, from the upstream ends 610A and downstream ends 610B towards the apex of the parabola of the insulating wall 610.

[0070] According to certain embodiments of the fixed assembly 246, the additive manufacturing step also includes a substep for building the row of fixed blades 50 from the lower surface 22 of the previously constructed annular ferrule 20. The succession of powder layers in the substep for building the row of fixed blades 50 is, for example, carried out in the radial direction R, from the upper end 54 to the lower end 52 of the fixed blade 50.

[0071] Preferably, the manufacturing process may include an additional step of emptying the powder present between the intermediate part 24C of the upper surface 24 of the annular ferrule 20 and the internal surface 612 of the insulating wall 610 of the heat shield 600, the emptying step being carried out after the additive manufacturing step.

[0072] The turbomachine assembly 10 according to the invention, equipped with a heat shield 600, has a significantly reduced mass compared to that of turbomachine turbine assemblies equipped with bolted connections 220 or a raised part 30 which is designed to stiffen the annular shell 20. In addition, the presence of a heat shield 600 makes it possible to provide thermal insulation both by separating the intermediate portion 20C of the annular shell 20 from the first air flow 230 and by presenting a second very low heat transfer coefficient H2 in the recess 620 of the heat shield 600.This double thermal insulation increases the thermal response time of the intermediate portion 20C of the annular shell 20, relative to the moving blade 40, to a thermal response time corresponding to an expansion equivalent to that of the moving blade 40. This significantly limits the variation in radial clearance J between the intermediate portion 20C of the annular shell 20 and the moving blade 40. The presence of a thermal shield 600 thus increases the turbomachine's efficiency through optimized control of the radial clearance J between the annular shell 20 and the moving blade 40. Furthermore, the thermal shield 600, due to its aerodynamic geometry, is less intrusive than a raised section 30 designed to stiffen the annular shell 20, such as a triangular rib, thereby minimizing pressure losses.In addition, the fixed assembly 246 of the turbomachine assembly 10 has a simplified geometry allowing its manufacture by an additive manufacturing process.

Claims

1. Demands Turbomachine assembly (10) comprising: - a one-piece annular ferrule (20) with axis X delimited along a radial axis R perpendicular to the axis X, by a lower surface (22) and an upper surface (24), - at least one row of movable blades (40), each movable blade (40) being radially delimited by a lower end (42) and an upper end (44) opposite the lower surface (22) of the annular ferrule (20) and radially spaced so as to define a radial clearance (J) between the annular ferrule (20) and the movable blade (40), and extending axially between an upstream leading edge (40A) and a downstream trailing edge (40B), defining a length (Ll) of the movable blade (40), and - at least one row of fixed blades (50), each fixed blade (50) being radially delimited by a lower end (52) and an upper end (54) integral with the lower surface (22) of the annular ferrule (20), and extending axially between an upstream leading edge (50A) and a downstream trailing edge (50B) defining a length (L2) of the fixed blade (50); - characterized by: - in that it comprises a thermal shield (600) arranged opposite a row of movable blades (40) and comprising: • an insulating wall (610) extending from an upstream end (610A) located on the upper surface (24) of the annular ferrule (20) to a downstream end (610B) located on the upper surface (24) of the annular ferrule (20), radially delimited by an internal surface (612) and an external surface (614), and • a recess (620) formed between the inner surface (612) of the insulating wall (610) of the thermal shield (600) and an intermediate portion (24C) of the upper surface (24) of the annular ferrule (20) and extending axially along at least all the length (Ll) of the movable blade (40) arranged opposite the thermal shield (600), - and in that the insulating wall (610) of the thermal shield (600) has a parabolic cross-section extending axially from the upstream end (610A) to the downstream end (610B) of the insulating wall (610) of the thermal shield (610) and whose concave side of the parabola is oriented towards the upper surface (24) of the annular ferrule (20).

2. Turbomachine assembly (10) according to claim 1, characterized: - in that the upper surface (24) of the annular shell (20) has an upstream part (24A) extending axially from the upstream end (610A) of the insulating wall (610) of the heat shield (600) towards the upstream free end of the annular shell (20), - and in that the upstream part (24A) of the upper surface (24) of the upstream portion (20A) of the annular shell (20) is aligned with the intermediate part (24C) of the upper surface (24) of the annular shell (20) delimiting the recess.

3. Turbomachine assembly (10) according to any one of the preceding claims, characterized in that the annular shell (20), the heat shield (600) and the fixed blade rows (50) form a fixed assembly (246) in one single piece.

4. Turbomachine assembly (10) according to any one of the preceding claims, characterized in that the external surface (614) of the insulating wall (610) of the heat shield (600) is arranged on the upper surface (24) of the annular shell (20) by forming an angle α greater than or equal to 110°, measured outside the heat shield (610), at the upstream end (610A) of the insulating wall (610) of the heat shield (600), between a tangent (T) of the external surface (614) of the insulating wall (610) of the heat shield (600) and the upper surface (24) of the annular shell (20).

5. Turbomachine assembly (10) according to any one of the preceding claims, characterized in that the shield thermal (600) extends circumferentially around the entire periphery of the annular ferrule (20).

6. Turbomachine assembly (10) according to any one of the preceding claims, characterized in that the minimum axially measured distance (d) between the upstream end (620A) of the recess (620) of the heat shield (600) and the leading edge (40A) of the moving blade (40) is substantially equal to 10% of the length (Ll) of the moving blade (40).

7. Turbomachine assembly (10) according to any one of the preceding claims, characterized in that the minimum axially measured distance (d') between the downstream end (610B) of the insulating wall (610) of the heat shield (610) and the trailing edge (40B) of the moving blade (40) is substantially equal to 10% of the length (Ll) of the moving blade (40).

8. Aircraft turbomachine, characterized in that it comprises a turbomachine assembly (10) according to any one of the preceding claims.

9. Method of manufacturing a turbomachine assembly (10) according to any one of claims 1 to 7, characterized in that it comprises an additive manufacturing step of the annular shell (20) and the insulating wall (610) of the heat shield (600) by deposition and solidification of successive layers of a powder.

10. Manufacturing method according to claim 9, characterized in that the additive manufacturing step also includes the manufacturing of the row of fixed blades (50).

Images