Intermediate housing for a turbine

Abstract

The present invention relates to an intermediate casing (1) for a turbine, the intermediate casing comprising: ○ an inner wall (3) having an outer radial surface (30); ○ an outer wall (4) having an inner radial surface (40); and ○ a first arm (21), a second arm (22), a third arm (23) and a fourth arm (24), and - wherein: ○ the outer radial surface (30), the inner radial surface (40), the first arm (21) and the second arm (22) define a first space (6) between the outer radial surface, the inner radial surface, the first arm and the second arm, the first space having a first region (A1) in a first cross-sectional plane (P1), ○ the outer radial surface (30) and the inner radial surface (40) are separated by a radial distance (D1) of the first space in the first space (6) and in the first cross-sectional plane (P1), ○ the outer radial surface (30), the inner radial surface (40), the third arm (23) and the fourth arm (24) define a second space (7) between the outer radial surface, the inner radial surface, the third arm and the fourth arm, the second space having a second region (A2) in the first cross-sectional plane (P1), ○ the outer radial surface (30) and the inner radial surface (40) are separated by a radial distance (D2) of the second space in the second space (7) and in the first cross-sectional plane (P1), the intermediate casing (1) being characterized in that: - the first region (A1) and the second region (A2) are substantially the same, and - the radial distance (D1) of the first space and the radial distance (D2) of the second space are different.

Description

Technical field

[0001] The present invention relates to an intermediate casing for a gas turbine engine.

[0002] The present invention more particularly applies to the profile of the radial surface of the wall of an intermediate casing for a gas turbine engine, and to a method for manufacturing an intermediate casing for a gas turbine engine. Background art

[0003] With reference to Figures 1 to 3 , a known intermediate casing 1 according to the prior art is a structural component of a gas turbine engine that is inserted between two rotors (not shown) of the gas turbine engine, the rotors being configured to rotate at different speeds. Typically, the intermediate casing generally extends between the low-pressure compressor and the high-pressure compressor of a twin-spool, twin-flow, direct-drive gas turbine engine. In a triple-spool gas turbine engine or a geared gas turbine engine, the intermediate casing generally extends between the fan and the low-pressure compressor.

[0004] In any case, the intermediate casing 1 is capable of decelerating the air flow between the two rotors. To this end, as can be seen in Figure 1 and Figure 2 , the intermediate casing has a generally gooseneck (or gooseneck-shaped) structure, wherein the cross-section of the air flow passage at the inlet of the intermediate casing 1 is smaller than the cross-section of the air flow passage at the outlet of the intermediate casing.

[0005] Furthermore, the intermediate casing 1 includes a plurality of arms 2 that extend between the inner radial wall 4 and the outer radial wall of the intermediate casing 1 and have an aerodynamic profile. The arms 2 make it possible to transmit forces to the structural and stator parts of the gas turbine engine, typically transmitting forces from the bearings of the low-pressure shaft to the fan casing (not shown). In addition, the arms 2 form an aerodynamic fairing for utilities 5 (e.g., drain pipes, mechanical compressor drive shafts, rotational sensors) that extend between the inner radial part and the outer radial part of the gas turbine engine.

[0006] However, not all of the utilities 5 have the same volume. Thus, in particular, as can be seen in Figure 3 , the arms 2 of the intermediate casing 1 do not all have the same thickness. In addition, the position of the maximum thickness along the chord of the aerodynamic profile can also vary from one arm D2 to another. This position can also be determined during design to reduce the pressure losses caused by the arms 2 or to limit the deformations caused on one of the plurality of rotors.

[0007] Finally, over the entire intermediate casing 1, the shape of the inner radial wall 3 and the shape of the outer radial wall 4 are the same and symmetric. In fact, as can be seen in Figure 3As can be seen, the walls 3, 4 are generally designed to have a circular cross-section.

[0008] However, in terms of the maximum thickness and the position of this maximum thickness, the non-uniformity of the aerodynamic profile of the arm 2 results in non-uniformity of the cross-section of the channels for the air flow between the different arms 2 of the intermediate housing 1. Thus, in Figure 3 it, the first cross-section has a region A1, the second cross-section itself has a region A2, the region of the first cross-section is greater than the region of the second cross-section, and the region of the second cross-section is greater than the region A3 of the third cross-section. But this non-uniformity is harmful to the aerodynamic quality of the air flow passing through the intermediate housing 1, particularly in terms of pressure loss.

[0009] In this regard, the current design of the walls 3, 4 of the intermediate housing 1 is insufficient. In fact, the current design of the walls of the intermediate housing only enables the deceleration of the air flow to be controlled at the arms 2 where the maximum thickness is close to the average value of the maximum thickness. For this purpose, the current design of the walls of the intermediate housing proposes to uniformly form a hollow portion in the outer wall 4 of the intermediate housing 1 at an equal distance from the leading edge and the trailing edge of the arm 2 to avoid re-acceleration of the flow. The depth of this hollow portion systematically depends on the average value of the maximum thickness of the arm. Thus, the radius of the circular cross-section of the walls 3, 4 depends on the average maximum thickness of the arms 2 of the intermediate housing 1.

[0010] But this design does not take into account the arms 2 where the maximum thickness is far from the average value of the maximum thickness. Thus, the flow is not controlled throughout the intermediate housing 1.

[0011] Therefore, it is necessary to mitigate at least one of the drawbacks of the prior art described above. Summary of the Invention

[0012] One of the objects of the present invention is to improve the aerodynamic behavior of the flow inside the intermediate housing.

[0013] Another object of the present invention is to increase the fuel consumption rate of a gas turbine engine.

[0014] Another object of the present invention is to improve the operability of the rotor arranged downstream of the intermediate housing.

[0015] To this end, the object of the present invention is to provide an intermediate housing for a gas turbine engine, the intermediate housing:

[0016] - having a longitudinal axis,

[0017] - comprising:

[0018] ○ an inner wall, the inner wall having an outer radial surface with respect to the longitudinal axis,

[0019] ○ The outer wall has an inner radial surface facing the outer radial surface with respect to the longitudinal axis, and

[0020] ○ The first arm, the second arm, the third arm, and the fourth arm extend radially from the outer radial surface to the inner radial surface, and

[0021] - wherein:

[0022] ○ The outer radial surface, the inner radial surface, the first arm, and the second arm define a first space therebetween, and the first space has a first region in a first cross-sectional plane of the intermediate housing perpendicular to the longitudinal axis,

[0023] ○ The outer radial surface and the inner radial surface are separated from each other with respect to the longitudinal axis by a radial distance of the first space in the first space and in the first cross-sectional plane,

[0024] ○ The outer radial surface, the inner radial surface, the third arm, and the fourth arm define a second space therebetween, and the second space has a second region in the first cross-sectional plane,

[0025] ○ The outer radial surface and the inner radial surface are separated from each other with respect to the longitudinal axis by a radial distance of the second space in the second space and in the first cross-sectional plane,

[0026] The intermediate housing is characterized in that the inner radial surface and / or the outer radial surface has a suitable profile in the first cross-sectional plane such that:

[0027] - The first region and the second region are substantially the same, and

[0028] - The radial distance of the first space and the radial distance of the second space are different.

[0029] In such an intermediate housing, the profile of each inter-arm surface is adapted to the thickness of the adjacent arm so that the flow decelerates uniformly throughout the intermediate housing. As a result, the uniformity of the aerodynamic behavior of the flow passing through the intermediate housing is improved, which improves the operability of the rotor arranged downstream of the intermediate housing and thus improves the fuel consumption rate of the gas turbine engine.

[0030] Advantageously but optionally, the intermediate housing according to the present invention may further include at least one of the following features, which may be employed individually or in combination:

[0031] * In such an intermediate housing:

[0032] - Each of the first arm, the second arm, the third arm, and the fourth arm:

[0033] ○ Has a plurality of thicknesses along the longitudinal axis, and

[0034] ○ has the maximum thickness among the multiple thicknesses,

[0035] - First cross-sectional plane:

[0036] ○ passes through the first arm and the second arm at their respective maximum thicknesses, and / or

[0037] ○ passes through the third arm and the fourth arm at their respective maximum thicknesses,

[0038] * In such an intermediate housing:

[0039] - The first space has a third region in a second cross-sectional plane of the intermediate housing that is perpendicular to the longitudinal axis and offset along the longitudinal axis relative to the first cross-sectional plane, the second cross-sectional plane of the intermediate housing,

[0040] - The second space has a fourth region in the second cross-sectional plane,

[0041] - The third region and the fourth region are substantially the same, and

[0042] - The inner radial surface and the outer radial surface have a circular profile in the second cross-sectional plane,

[0043] * In the first cross-sectional plane, the profile of the inner radial surface has additional recesses relative to the circular profile,

[0044] * In the first cross-sectional plane, the profile of the outer radial surface has additional recesses relative to the circular profile,

[0045] * The second arm and the third arm are the same.

[0046] It is also an object of the present invention to provide a gas turbine engine that includes a gas turbine engine housing as described previously.

[0047] Finally, it is an object of the present invention to provide a method for manufacturing an intermediate housing for a gas turbine engine, the intermediate housing:

[0048] - has a longitudinal axis,

[0049] - includes:

[0050] ○ an inner wall that has an outer radial surface relative to the longitudinal axis,

[0051] ○ an outer wall that has an inner radial surface facing the outer radial surface relative to the longitudinal axis, and

[0052] ○ The first arm, the second arm, the third arm, and the fourth arm, which extend radially from the outer radial surface to the inner radial surface, and

[0053] - wherein:

[0054] ○ The outer radial surface, the inner radial surface, the first arm, and the second arm define a first space therebetween, and the first space has a first region in a first cross-sectional plane of the intermediate housing that is perpendicular to the longitudinal axis,

[0055] ○ The outer radial surface and the inner radial surface are separated from each other by a radial distance of the first space with respect to the longitudinal axis in the first space and in the first cross-sectional plane,

[0056] ○ The outer radial surface, the inner radial surface, the third arm, and the fourth arm define a second space therebetween, and the second space has a second region in the first cross-sectional plane,

[0057] ○ The outer radial surface and the inner radial surface are separated from each other by a radial distance of the second space with respect to the longitudinal axis in the second space and in the first cross-sectional plane,

[0058] The manufacturing method is characterized in that the manufacturing method includes a step of profiling the inner radial surface and / or the outer radial surface such that in the first cross-sectional plane:

[0059] - The first region and the second region are substantially the same, and

[0060] - The radial distance of the first space and the radial distance of the second space are different.

[0061] Advantageously but optionally, the manufacturing method according to the present invention may further include at least one of the following features that are employed alone or in combination:

[0062] * Each of the first arm, the second arm, the third arm, and the fourth arm of the intermediate housing:

[0063] ○ Has a plurality of thicknesses along the longitudinal axis, and

[0064] ○ Has a maximum thickness among the plurality of thicknesses,

[0065] The method further includes the following steps:

[0066] - Forming a first hollow portion in the outer wall and / or in the inner wall such that:

[0067] ○ The outer radial surface and the inner radial surface are separated from each other by a first radial distance of the first space in the first space and in the first cross-sectional plane with respect to the longitudinal axis, and the first radial distance of the first space extends from a point outside the first hollow portion of the outer radial surface and / or the inner radial surface, and

[0068] ○ The outer radial surface and the inner radial surface are separated from each other by a second radial distance of the first space in the first space and in the first cross-sectional plane with respect to the longitudinal axis, and the second radial distance of the first space extends from a point in the first hollow portion on the outer radial surface and / or the inner radial surface,

[0069] such that the difference between the first radial distance and the second radial distance of the first space is an increasing function of the difference between:

[0070] ○ the maximum thickness of the first arm and / or the second arm, and

[0071] ○ the average value of the respective maximum thicknesses of the first arm, the second arm, the third arm, and the fourth arm, and

[0072] - A second hollow portion is formed in the outer wall and / or in the inner wall such that:

[0073] ○ The outer radial surface and the inner radial surface are separated from each other by a first radial distance of the second space in the second space and in the first cross-sectional plane with respect to the longitudinal axis, and the first radial distance of the second space extends from a point outside the second hollow portion of the outer radial surface and / or the inner radial surface, and

[0074] ○ The outer radial surface and the inner radial surface are separated from each other by a second radial distance of the second space in the second space and in the first cross-sectional plane with respect to the longitudinal axis, and the second radial distance of the second space extends from a point on the outer radial surface and / or the inner radial surface and passes through the second hollow portion,

[0075] such that the difference between the first radial distance and the second radial distance of the second space is an increasing function of the difference between:

[0076] ○ the maximum thickness of the third arm and / or the fourth arm, and

[0077] ○ the average value of the respective maximum thicknesses of the first arm, the second arm, the third arm, and the fourth arm, and

[0078] * In this method:

[0079] - The first hollow portion is centered on a cross-sectional plane that passes through the first arm and the second arm at their respective maximum thicknesses, and

[0080] - The second hollow portion is centered on a cross-sectional plane that passes through the third arm and the fourth arm at their respective maximum thicknesses. Description of the Drawings

[0081] Other features, objects, and advantages of the present invention will become apparent from the following purely illustrative, non - limiting description that must be read with reference to the drawings, in which:

[0082] Already described Figure 1 is a perspective view of a known intermediate housing according to the prior art.

[0083] Figure 2 is in Figure 1 a longitudinal cross - sectional view of the intermediate housing shown in

[0084] Figure 3 is in Figure 1 another cross - sectional view of the intermediate housing shown in

[0085] Figure 4 is a view in a first cross - sectional plane perpendicular to the longitudinal axis of the intermediate housing of a first exemplary embodiment of a gas turbine engine intermediate housing according to the present invention.

[0086] Figure 5 is a circumferentially - expanded view of a second exemplary embodiment of a gas turbine engine intermediate housing according to the present invention.

[0087] Figure 6 is a view in a second cross - sectional plane perpendicular to the longitudinal axis of the intermediate housing of a third exemplary embodiment of a gas turbine engine intermediate housing according to the present invention.

[0088] Figure 7 is a flow chart detailing the steps of a first exemplary implementation of a manufacturing method according to the present invention.

[0089] Figure 8 is a view in the main cross - sectional plane of an intermediate housing manufactured by a second exemplary implementation of the manufacturing method according to the present invention.

[0090] In all the drawings, like elements are denoted by the same reference numerals. Detailed Description

[0091] Intermediate housing

[0092] Referring to Figures 4 to 6, the intermediate housing 1 is a structural gas turbine engine component that is inserted between two rotors (not shown) of a gas turbine engine, the rotors being configured to rotate at different speeds. For example, the intermediate housing 1 can extend between a low-pressure compressor and a high-pressure compressor of a twin-spool, dual-flow, direct-drive gas turbine engine. Alternatively, in a triple-spool gas turbine engine or a geared gas turbine engine, the intermediate housing 1 can extend between a fan and a low-pressure compressor.

[0093] As can be seen in Figures 4 to 6 , the intermediate housing 1 has a longitudinal axis X-X. The intermediate housing 1 further includes:

[0094] - an inner wall 3, the inner wall having an outer radial surface 30 relative to the longitudinal axis X-X,

[0095] - an outer wall 4, the outer wall having an inner radial surface 40 facing the outer radial surface 30 relative to the longitudinal axis X-X, and

[0096] - a first arm 21, a second arm 22, a third arm 23, and a fourth arm 24, the first arm, the second arm, the third arm, and the fourth arm extending radially from the outer radial surface 30 to the inner radial surface 40.

[0097] The arms 21, 22, 23, 24 enable the transfer of forces to structural and stator parts of a gas turbine engine (not shown), the structural and stator parts of the gas turbine engine being connected to the inner wall 3 and the outer wall 4. In addition, the arms 21, 22, 23, 24 form an aerodynamic fairing for utilities (not shown) to pass through.

[0098] Furthermore, the intermediate housing 1 is capable of decelerating the air flow passing through the intermediate housing. To this end, the intermediate housing has a generally gooseneck (or gooseneck-shaped) structure, wherein the cross-section for the air flow to pass through at the inlet of the intermediate housing 1 is smaller than the channel cross-section of the air flow at the outlet of the intermediate housing 1. Additionally, channels for the air flow are arranged between the arms 21, 22, 23, 24. More precisely, the outer radial surface 30, the inner radial surface 40, the first arm 21, and the second arm 22 define a first space 6 between the outer radial surface, the inner radial surface, the first arm, and the second arm, and the outer radial surface 30, the inner radial surface 40, the third arm 23, and the fourth arm 24 define a second space 7 between the outer radial surface, the inner radial surface, the third arm, and the fourth arm.

[0099] In an advantageous embodiment, the second arm 22 and the third arm 23 are identical, such that the first space 6 and the second space 7 are circumferentially adjacent around the longitudinal axis X-X.

[0100] In a first cross-sectional plane P1 of the intermediate housing 1 perpendicular to the longitudinal axis X-X, the first space 6 has a first region A1 and the second space 7 has a second region A2. This is particularly evident in Figure 4 and is Figure 4 a view of the intermediate housing 1 in the first cross-sectional plane P1. Furthermore, the outer radial surface 30 and the inner radial surface 40 are separated by a radial distance D1 of the first space in the first space 6 and in the first cross-sectional plane P1, and the outer radial surface 30 and the inner radial surface 40 are separated by a radial distance D2 of the second space in the second space 7 and in the first cross-sectional plane P1. Herein, the concept of "radial" is defined with respect to the longitudinal axis X-X.

[0101] Furthermore, as can be seen in Figure 4 , the profile of the inner radial surface 30 and / or the outer radial surface 40 in the first cross-sectional plane P1 is configured such that:

[0102] - The first region A1 and the second region A2 are substantially the same, and

[0103] - The radial distance D1 of the first space and the radial distance D2 of the second space are different.

[0104] Thus, although the thicknesses of the arms 21, 22, 23, 24 are different, at least at the first cross-sectional plane P1, the channel cross-section of the flow within the intermediate housing is the same throughout the intermediate housing 1, which enables better control of the deceleration of the flow passing through the intermediate housing 1. Advantageously, only one of the two radial surfaces 30, 40 (for example, the inner radial surface 40 as can be seen in Figure 4 ) has a different profile between the arms around the longitudinal axis X-X, and the dimensions of this radial surface are designed such that the profile of this radial surface is adapted to the different geometries of the arms 21, 22, 23, 24. In fact, this radial surface is an element of the intermediate housing 1 that is easy to design and / or easy to profile during the manufacture and / or maintenance of the gas turbine engine. Furthermore, this radial surface simplifies the manufacture of the intermediate housing 1 while enabling the desired effect of making the flow uniform to be obtained.

[0105] In any case, as can be seen in Figure 4 , the thicker the arms 21, 22, 23, 24, the greater the radial distance D1 selected near this arm 21, 22, 23, 24, and vice versa. More precisely, the loss of circumferential space caused by the dimensions of the arms 21, 22, 23, 24 is compensated by the radial profiles of the radial surfaces 30, 40 of the walls 3, 4 that are sufficiently close to the arms 21, 22, 23, 24.

[0106] In Figure 4In the embodiment shown, the profile of the inner radial surface 40 (shown in solid lines) has additional recesses 401, 402, 403, 404 relative to the circular profile (shown in dashed lines) in the first cross-sectional plane P1. These recesses 401, 402, 403, 404 form a hollow portion, and the depth of the hollow portion depends on the thickness of the arms 21, 22, 23, 24 closest to the hollow portion. The greater the thickness of the arms 21, 22, 23, 24 compared to the average value of the thicknesses of the arms 21, 22, 23, 24, the deeper the recesses 401, 402, 403, 404. Conversely, if the thickness of the arms 21, 22, 23, 24 is smaller compared to the average value of the thicknesses of the arms 21, 22, 23, 24, the recesses 401, 402, 403, 404 are opposite to the circular recesses, as can be seen in Figure 4 Advantageously, the profile of the outer wall 40 includes a plurality of additional recesses 401, 402, 403, 404 relative to the circular profile, for example, including recesses 401, 402 having the same orientation and deeper than the circular profile, and recesses 403, 404 having an orientation opposite to the circular profile. However, this is not restrictive, because in another embodiment, alternatively or in combination, in the first cross-sectional plane, the profile of the outer radial wall 30 has additional recesses 401, 402, 403, 404 relative to the circular profile.

[0107] Referring to Figure 5 , Figure 5 is a developed view of the intermediate housing 1 taken around the longitudinal axis X-X in a circumferential three-dimensional surface having a circular cross-section. Each of the arms 21, 22, 23, 24 has a plurality of thicknesses e1, e2, e3, e4 along the longitudinal axis X-X. More precisely, each arm 21, 22, 23, 24 has a chord C1, C2, C3, C4, and the chord joins the leading edges 210, 220, 230, 240 of the aerodynamic profiles of the arms 21, 22, 23, 24 to the trailing edges 212, 222, 232, 242 in a plane substantially parallel to the average flow within the intermediate housing 1. Thus, each thickness e1, e2, e3, e4 is selected perpendicular to the chord C1, C2, C3, C4 along the longitudinal axis X-X between the pressure sides 211, 221, 231, 241 and the suction sides 213, 223, 233, 243 of the aerodynamic profiles of the arms 21, 22, 23, 24. Among the plurality of thicknesses e1, e2, e3, e4, there are maximum thicknesses em1, em2, em3, em4, and the positions of the maximum thicknesses along the chords C1, C2, C3, C4 can be different from one arm 21, 22, 23, 24 to another, as can be seen in Figure 5As can be seen. However, in an advantageous embodiment of the intermediate housing, at the respective maximum thicknesses em1, em2, em3, em4 of the arms 21, 22, 23, 24, the profiles of the walls 30, 40 as described previously are produced in the inter-arm space. In other words, the first cross-sectional plane P1 described previously:

[0108] - passes through the first arm 21 and the second arm 22 at the respective maximum thicknesses em1, em2 of the first arm 21 and the second arm 22, and / or

[0109] - passes through the third arm 23 and the fourth arm 24 at the respective maximum thicknesses em3, em4 of the third arm 23 and the fourth arm 24.

[0110] In fact, at the maximum thicknesses em1, em2, em3, em4 of the arms 21, 22, 23, 24, the reduction in the cross-sectional area of the flow passage is greatest. Therefore, it is most advantageous to profile the radial surfaces 30, 40 of the walls 3, 4 by changing the radial distances D1, D2 separating the walls from each other to ensure that the regions A1, A2 of the first channel 6 and the second channel 7 are the same.

[0111] Referring to Figure 5 and Figure 6 , in a second cross-sectional plane P2 of the intermediate housing 1 that is perpendicular to the longitudinal axis X-X and offset relative to the first cross-sectional plane P1 along the longitudinal axis X-X, the first space 6 has a third region A3 and the second space 7 has a fourth region A4. In one embodiment, the third region A3 and the fourth region A4 are substantially the same, and the inner radial surface 30 and the outer radial surface 40 have a circular profile in the second cross-sectional plane P2. In fact, as can be seen in Figure 5 , it is not necessary to change the profiles of the radial surfaces 30, 40 of the walls 3, 4 along the entire length of the arms 21, 22, 23, 24 along the longitudinal axis X-X. In fact, the aerodynamic profiles of the arms 21, 22, 23, 24 are substantially the same at positions far enough from the respective maximum thicknesses em1, em2, em3, em4 of the arms 21, 22, 23, 24 along the longitudinal axis X-X. Therefore, the flow is uniform and consistent when passing through the second cross-sectional plane P2 without the need to change the profiles of the radial surfaces 30, 40 of the walls 3, 4.

[0112] Manufacturing method

[0113] Referring to Figure 7 and Figure 8 , a manufacturing method E for the intermediate housing 1 of a gas turbine engine will now be described.

[0114] The intermediate housing 1 has a longitudinal axis X-X and further includes:

[0115] - An inner wall 3, the inner wall having an outer radial surface 30 relative to the longitudinal axis X-X,

[0116] - An outer wall 4, the outer wall having an inner radial surface 40 relative to the longitudinal axis X-X facing the outer radial surface 30, and

[0117] - A first arm 21, a second arm 22, a third arm 23, and a fourth arm 24, the first arm, the second arm, the third arm, and the fourth arm radially extending from the outer radial surface 30 to the inner radial surface 40.

[0118] In addition, the outer radial surface 30, the inner radial surface 40, the first arm 21, and the second arm 22 define a first space 6 between the outer radial surface, the inner radial surface, the first arm, and the second arm, and the outer radial surface 30, the inner radial surface 40, the third arm 23, and the fourth arm 24 define a second space 7 between the outer radial surface, the inner radial surface, the third arm, and the fourth arm. And in a first cross-sectional plane P1 of the intermediate housing 1 perpendicular to the longitudinal axis X-X, the first space 6 has a first region A1 and the second space 7 has a second region A2. Further, the outer radial surface 30 and the inner radial surface 40 are separated by a radial distance D1 of the first space in the first space 6 and in the first cross-sectional plane P1, and the outer radial surface 30 and the inner radial surface 40 are separated by a radial distance D2 of the second space in the second space 7 and in the first cross-sectional plane P1. In addition, each of the arms 21, 22, 23, 24 has a plurality of thicknesses along the longitudinal axis X-X. More precisely, each of the arms 21, 22, 23, 24 has a chord that joins the leading edge of the aerodynamic profile of the arm 21, 22, 23, 24 to the trailing edge in a plane substantially parallel to the mean flow within the intermediate housing 1. Thus, each thickness is selected perpendicular to the chord along the longitudinal axis X-X between the pressure side and the suction side of the aerodynamic profile of the arms 21, 22, 23, 24. Among the plurality of thicknesses, there are maximum thicknesses em1, em2, em3, em4, and the positions of the maximum thicknesses along the chord can be different from one arm 21, 22, 23, 24 to another.

[0119] As can be seen in Figure 7 the method E includes a step E1 of profiling the inner radial surface 30 and / or the outer radial surface 40 such that in the first cross-sectional plane P1:

[0120] - The first region A1 and the second region A2 are substantially the same, and

[0121] - The radial distance D1 of the first space and the radial distance D2 of the second space are different.

[0122] This profile machining provides the intermediate housing 1 with the same advantages as the previously described intermediate housing. In fact, the air flow passing through the intermediate housing 1 manufactured by this manufacturing method E has a limited number of Mach number non-uniformities around the longitudinal axis X-X. In fact, the intermediate housing 1 no longer has cross-sectional dimension differences from one flow path to another. Therefore, the Mach number decreases uniformly along the longitudinal axis X-X at the inner wall 3 and / or the outer wall 4, regardless of the inter-arm flow path under consideration.

[0123] As also visible in Figure 6 In one embodiment, the manufacturing method E further includes the steps of forming a first hollow portion 401, E2, and a second hollow portion 402, E3, in the inner wall 3 and / or the outer wall 4 of the intermediate housing 1. More precisely, therefore, the first hollow portion 401 is formed such that:

[0124] - The outer radial surface 30 and the inner radial surface 40 are separated from each other in the first space 6 and in the first cross-sectional plane P1 by a first radial distance D11 of the first space with respect to the longitudinal axis X-X, and the first radial distance D11 of the first space extends from a point outside the first hollow portion 401 of the outer radial surface 30 and / or the inner radial surface 40, and

[0125] - The outer radial surface and the inner radial surface are separated from each other in the first space and in the first cross-sectional plane by a second radial distance D12 of the first space with respect to the longitudinal axis X-X, and the second radial distance D12 of the first space extends from a point in the first hollow portion 401 of the outer radial surface 30 and / or the inner radial surface 40.

[0126] Furthermore, these radial distances D11, D12 are formed such that the difference between the first radial distance D11 and the second radial distance D12 of the first space is an increasing function of the difference between:

[0127] - The thicknesses em1, em2 of the first arm 21 and / or the second arm 22, and

[0128] - The average value of the respective maximum thicknesses em1, em2, em3, em4 of the first arm 21, the second arm 22, the third arm 23, and the fourth arm 24.

[0129] In the same way, the second hollow portion 402 is formed such that:

[0130] - The outer radial surface 30 and the inner radial surface 40 are separated from each other in the second space 7 and in the first cross-sectional plane P1 by a first radial distance D21 of the second space with respect to the longitudinal axis X-X, and the first radial distance D21 of the second space extends from a point outside the second hollow portion 402 of the outer radial surface 30 and / or the inner radial surface 40, and

[0131] - The outer radial surface and the inner radial surface are separated from each other by a second radial distance D22 of the second space in the second space and in the first cross-sectional plane with respect to the longitudinal axis X-X, and the second radial distance D22 of the second space extends from a point of the outer radial surface 30 and / or the inner radial surface 40 and passes through the second hollow portion 402.

[0132] In addition, these radial distances D21, D22 are manufactured such that the difference between the first radial distance D21 and the second radial distance D22 of the second space is an increasing function of the difference between:

[0133] - the maximum thicknesses em3, em4 of the third arm 23 and / or the fourth arm 24, and

[0134] - the average value of the respective maximum thicknesses em1, em2, em3, em4 of the first arm 21, the second arm 22, the third arm 23, and the fourth arm 24.

[0135] Due to these steps E2, E3 for forming the hollow portions, it is possible to obtain as in Figure 4 or Figure 8The intermediate housing 1 shown in [figures]. In these figures, the dashed line shows the circular profile of the inner radial surface 40 in the first cross-sectional plane P1. The radius R of this profile depends on the average value of the maximum thicknesses em1, em2, em3, em4 of the arms 21, 22, 23, 24 of the intermediate housing 1. More precisely, the radius R is determined such that if the arms 21, 22, 23, 24 all have the same maximum thickness em1, em2, em3, em4 equal to the average value of the maximum thicknesses em1, em2, em3, em4, then this circular profile of the inner radial surface will ensure that the Mach number decreases uniformly along the longitudinal axis X-X at the inner wall and / or outer wall 4, and this is independent of the inter-arm passages considered. The solid line itself shows the profile of the radial inner wall 40 obtained after the steps E2, E3 of forming the hollow portions described previously. As can be seen in these figures, the smaller the difference between the maximum thicknesses em1, em2, em3, em4 of the arms 21, 22, 23, 24 and the average value of the maximum thicknesses em1, em2, em3, em4, even negative (in the case where the maximum thicknesses em1, em2, em3, em4 of the arms are less than the average value of the maximum thicknesses em1, em2, em3, em4), the smaller the radial distances D1, D2 of the space. Conversely, the greater the difference between the maximum thicknesses em1, em2, em3, em4 of the arms and the average value of the maximum thicknesses em1, em2, em3, em4, the greater the radial distances D1, D2 of the space. Thus, the profile of the obtained inner radial surface 40 is asymmetric and has a plurality of additional recesses 401, 402, 403, 404 with respect to the circular profile. It should be noted that the profile of the outer radial wall 30 can be changed using the same design logic and has the same effect. However, the fact should be taken into account that the air flow velocity is different near the inner radial surface 40 and near the outer radial surface 30. In addition, due particularly to the gooseneck shape, the aerodynamic friction can be specific. Therefore, the depth of the hollow portion in the outer radial surface 30 is adjusted.

[0136] In one embodiment, as can be seen in Figure 5 the previously described hollow portions 401, 402 can be formed such that:

[0137] - The first hollow portion 401 is centered on the cross-sectional plane P1, which passes through the first arm 21 and the second arm 22 at the respective maximum thicknesses em1, em2 of the first arm 21 and the second arm 22, and

[0138] - The second hollow portion 402 is centered on the cross-sectional plane P1, which passes through the third arm 23 and the fourth arm 24 at the respective maximum thicknesses em3, em4 of the third arm 23 and the fourth arm 24.

[0139] Thus, it is possible to obtain as shown in Figure 5The intermediate housing 1 shown in. As can be seen in this figure, the hollow portions 401, 402 are formed on both sides of the line joining the positions of the maximum thicknesses em1, em2, em3, em4 of the arms 21, 22, 23, 24 along the longitudinal axis X-X. Advantageously, the hollow portions 401, 402 are formed in a substantially rectangular region of the inner radial surface 30 and / or the outer radial surface 40, as can be seen in Figure 5 . Even more advantageously, the width of this rectangular region corresponds to approximately 10% of the chords C1, C2, C3, C4 of the adjacent arms 21, 22, 23, 24, and the chords of the adjacent arms are selected in a plane substantially parallel to the average flow within the intermediate housing 1. Thus, the manufacturing method E involves limited modification of the walls 3, 4 of the intermediate housing 1. In addition, the positions of the hollow portions 401, 402 are optimized according to the positions of the maximum thicknesses em1, em2, em3, em4 along the longitudinal axis X-X.

Claims

1. An intermediate casing (1) for a gas turbine engine, the intermediate casing (1): - having a longitudinal axis (X-X), - comprising: an inner wall (3) having an outer radial surface (30) relative to the longitudinal axis (X-X), an outer wall (4) having an inner radial surface (40) facing the outer radial surface (30) relative to the longitudinal axis (X-X), and a first arm (21), a second arm (22), a third arm (23) and a fourth arm (24) which extend radially from the outer radial surface (30) to the inner radial surface (40), and - wherein: the outer radial surface (30), the inner radial surface (40), the first arm (21) and the second arm (22) define a first space (6) between the outer radial surface, the inner radial surface, the first arm and the second arm, the first space having a first region (A1) in a first cross-sectional plane (P1) of the intermediate casing (1) perpendicular to the longitudinal axis (X-X), the outer radial surface (30) and the inner radial surface (40) are separated from each other in the first space (6) and in the first cross-sectional plane (P1) by a radial distance (D1) of the first space relative to the longitudinal axis (X-X), the outer radial surface (30), the inner radial surface (40), the third arm (23) and the fourth arm (24) define a second space (7) between the outer radial surface, the inner radial surface, the third arm and the fourth arm, the second space having a second region (A2) in the first cross-sectional plane (P1), the outer radial surface (30) and the inner radial surface (40) are separated from each other in the second space (7) and in the first cross-sectional plane (P1) by a radial distance (D2) of the second space relative to the longitudinal axis (X-X), the intermediate casing (1) is characterized in that the profile of the inner radial surface (40) and / or the outer radial surface (30) in the first cross-sectional plane (P1) is configured such that: - the first region (A1) and the second region (A2) are substantially the same, and - the radial distance (D1) of the first space and the radial distance (D2) of the second space are different.

2. The intermediate casing (1) according to claim 1, wherein - each of the first arm (21), the second arm (22), the third arm (23) and the fourth arm (24): has a plurality of thicknesses (e1, e2, e3, e4) along the longitudinal axis (X-X), and has a maximum thickness (em1, em2, em3, em4) among the plurality of thicknesses (e1, e2, e3, e4), - the first cross-sectional plane (P1): Through the first arm (21) and the second arm (22) at their respective maximum thicknesses (em1, em2), and / or Through the third arm (23) and the fourth arm (24) at their respective maximum thicknesses (em3, em4).

3. The intermediate housing (1) according to claim 1 or 2, wherein - the first space (6) has a third region (A3) in a second cross-sectional plane (P2) of the intermediate housing (1) that is perpendicular to the longitudinal axis (X-X) and offset from the first cross-sectional plane (P1) along the longitudinal axis (X-X), - the second space (7) has a fourth region (A4) in the second cross-sectional plane (P2), - the third region (A3) and the fourth region (A4) are substantially the same, and - the inner radial surface (40) and the outer radial surface (30) have a circular profile in the second cross-sectional plane (P2).

4. The intermediate housing (1) according to claim 1 or 2, wherein, In the first cross-sectional plane (P1), the profile of the inner radial surface (40) has additional recesses (401, 402, 403, 404) relative to the circular profile.

5. The intermediate housing (1) according to claim 1 or 2, wherein, In the first cross-sectional plane (P1), the profile of the outer radial surface (30) has additional recesses (401, 402, 403, 404) relative to the circular profile.

6. The intermediate housing (1) according to claim 1 or 2, wherein, The second arm (22) and the third arm (23) are identical.

7. A gas turbine engine, the gas turbine engine comprising the intermediate housing (1) according to any one of claims 1 to 6.

8. A method (E) for manufacturing an intermediate housing (1) of a gas turbine engine, the intermediate housing (1): - having a longitudinal axis (X-X), - comprising: an inner wall (3), the inner wall having an outer radial surface (30) relative to the longitudinal axis (X-X), an outer wall (4), the outer wall having an inner radial surface (40) facing the outer radial surface (30) relative to the longitudinal axis (X-X), and a first arm (21), a second arm (22), a third arm (23), and a fourth arm (24), the first arm, the second arm, the third arm, and the fourth arm extending radially from the outer radial surface (30) to the inner radial surface (40), and - wherein: the outer radial surface (30), the inner radial surface (40), the first arm (21), and the second arm (22) define a first space (6) between the outer radial surface, the inner radial surface, the first arm, and the second arm, the first space having a first region (A1) in a first cross-sectional plane (P1) of the intermediate housing (1) that is perpendicular to the longitudinal axis (X-X), the outer radial surface (30) and the inner radial surface (40) are separated by a radial distance (D1) of the first space relative to the longitudinal axis (X-X) in the first space (6) and in the first cross-sectional plane (P1), The outer radial surface (30), the inner radial surface (40), the third arm (23), and the fourth arm (24) define a second space (7) between the outer radial surface, the inner radial surface, the third arm, and the fourth arm, and the second space has a second region (A2) in the first cross-sectional plane (P1). The outer radial surface (30) and the inner radial surface (40) are separated from each other by a radial distance (D2) of the second space in the second space (7) and in the first cross-sectional plane (P1) with respect to the longitudinal axis (X-X). The method (E) is characterized in that the method includes a step (E1) of profiling the inner radial surface (40) and / or the outer radial surface (30) such that in the first cross-sectional plane (P1): - The first region (A1) and the second region (A2) are substantially the same, and - The radial distance (D1) of the first space and the radial distance (D2) of the second space are different.

9. The method (E) for manufacturing an intermediate case (1) of a gas turbine engine according to claim 8, wherein, The first arm (21), the second arm (22), the third arm (23), and the fourth arm (24) of the intermediate housing (1) each:[[]] Have a plurality of thicknesses (e1, e2, e3, e4) along the longitudinal axis (X-X), and Have a maximum thickness (em1, em2, em3, em4) among the plurality of thicknesses (e1, e2, e3, e4). The method (E) further includes the following steps:[[]] - Forming (E2) a first hollow portion in the outer wall (4) and / or in the inner wall (3) such that:[[]] The outer radial surface (30) and the inner radial surface (40) are separated from each other by a first radial distance (D11) of the first space in the first space (6) and in the first cross-sectional plane (P1) with respect to the longitudinal axis (X-X), and the first radial distance (D11) of the first space extends from a point outside the first hollow portion of the outer radial surface (30) and / or the inner radial surface (40), and The outer radial surface and the inner radial surface are separated from each other by a second radial distance (D12) of the first space in the first space and in the first cross-sectional plane with respect to the longitudinal axis (X-X), and the second radial distance (D12) of the first space extends from a point in the first hollow portion of the outer radial surface (30) and / or the inner radial surface (40). Such that the difference between the first radial distance (D11) and the second radial distance (D12) of the first space is an increasing function of the difference between:[[]] The maximum thickness (em1, em2) of the first arm (21) and / or the second arm (22), and The average value of the corresponding maximum thicknesses (em1, em2, em3, em4) of the first arm (21), the second arm (22), the third arm (23), and the fourth arm (24); and - A second hollow portion is formed (E3) in the outer wall (4) and / or in the inner wall (3) such that: The outer radial surface (30) and the inner radial surface (40) are separated from each other in the second space (7) and in the first cross-sectional plane (P1) by a first radial distance (D21) of the second space with respect to the longitudinal axis (X-X), the first radial distance (D21) of the second space extending from a point outside the second hollow portion of the outer radial surface (30) and / or the inner radial surface (40), and The outer radial surface and the inner radial surface are separated from each other in the second space and in the first cross-sectional plane by a second radial distance (D22) of the second space with respect to the longitudinal axis (X-X), the second radial distance (D22) of the second space extending from a point of the outer radial surface (30) and / or the inner radial surface (40) and passing through the second hollow portion, such that the difference between the first radial distance (D21) and the second radial distance (D22) of the second space is an increasing function of the difference between: the maximum thicknesses (em3, em4) of the third arm (23) and / or the fourth arm (24), and the average value of the respective maximum thicknesses (em1, em2, em3, em4) of the first arm (21), the second arm (22), the third arm (23), and the fourth arm (24).

10. The method (E) for manufacturing an intermediate casing (1) of a gas turbine engine according to claim 9, wherein: - The first hollow portion is centered on a cross-sectional plane (P1) that passes through the first arm (21) and the second arm (22) at their respective maximum thicknesses (em1, em2), and - The second hollow portion is centered on a cross-sectional plane (P1) that passes through the third arm (23) and the fourth arm (24) at their respective maximum thicknesses (em3, em4).

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