Turbomachinery casing

Abstract

The invention relates to a turbomachine housing (12) with axis (X), comprising an inner ring (2) and an outer ring (5) extending coaxially around the axis (X), and at least one structural arm (4) connecting the two rings (2, 5) to each other, with a radially internal end of the arm (4) connected to the inner ring (2) and a radially external end of the arm (4) connected to the outer ring (5), characterized in that the inner ring (2) comprises at least one blind cavity (8) formed as a recess from the outer surface of the inner ring (2), and the outer ring (5) comprises at least one opening (7) passing through it and positioned opposite the cavity (8) in a radial direction, said cavity (8) and said opening (7) being configured to receive a separating blade (3) intended to extend between the inner ring (2) and the outer ring (5) by being radially related to through the opening (7). Figure for the abbreviation: Fig. 2

Description

Title of the invention: Turbomachine housing

[0001] The invention relates generally to turbomachine housings, in particular intermediate housings located between high-pressure and low-pressure turbines.

[0002] More particularly, the invention relates to "multi-profile" housings comprising both radial arms having a structural support function and separating vanes which allow the housing to fulfill an aerodynamic distributor function. General technical field and prior art

[0003] A turbofan engine generally comprises, from upstream to downstream in the direction of gas flow, a fan, an annular primary flow channel, and an annular secondary flow channel. The air mass drawn in by the fan is thus divided into a primary flow, which circulates in the primary flow channel, and a secondary flow, which is concentric with the primary flow and circulates in the secondary flow channel.

[0004] The primary flow stream passes through a primary body comprising one or more compressor stages, for example a low-pressure compressor and a high-pressure compressor, a combustion chamber, one or more turbine stages, for example a high-pressure turbine and a low-pressure turbine, and a gas exhaust nozzle.

[0005] In a manner known per se, the turbomachine further comprises an interturbine casing whose hub is arranged between the high-pressure turbine casing and the low-pressure turbine casing. The interturbine hub comprises a fairing having an inner and an outer ferrule, which together define the flow path between the high-pressure turbine and the low-pressure turbine, as well as structural connecting arms (called "thick arms") which extend radially between the inner and outer ferrules.

[0006] In a so-called multi-profile configuration, the fairing includes, in addition to the arms, profiled separating vanes (or "splitters" in English) which allow the housing to perform a distributor function.

[0007] Usually, the separating vanes are either attached to the ferrules by their heads and feet, or come from the foundry with them.

[0008] Patent application FR3077329A proposes, for example, a configuration in which the ferrules have grooves configured to receive platforms formed at the base and tip of the blade. This configuration, however, complicates the structure of the blades and ferrules.

[0009] The manufacture of a block of the casing and the blades is not entirely satisfactory insofar as it requires milling and the proximity between the blades makes access for milling tools difficult.

[0010] Moreover, in all cases, the mechanical links between the ferrules and the blades are, due to thermal expansions, sources of stress on the blades and in particular at the base of these, due to the differences in thermal expansion behavior between the blades and the structural connecting arms. General presentation of the invention

[0011] One object of the invention is to remedy the aforementioned drawbacks.

[0012] In particular, according to one aspect, the invention proposes a turbomachine housing having an axis, comprising an inner shell and an outer shell which extend coaxially around the axis, and at least one structural arm which connects the two shells together with a radially inner end of the arm connected to the inner shell and a radially outer end of the arm connected to the outer shell, characterized in that the inner shell comprises at least one blind cavity formed in a hollow from the outer surface of the inner shell, and the outer shell comprises at least one opening which passes through it and which is placed opposite the cavity in a radial direction, said cavity and said opening being configured to receive a separating blade intended to extend between the inner shell and the outer shell by being brought through the opening.

[0013] Such a structure allows for a simple assembly of the blades, which simply need to be inserted into the openings of said part to constitute the casing.

[0014] According to another aspect, a housing is also proposed comprising at least one separating blade extending radially between the two ferrules of the housing piece, said separating blade comprising a foot and a head, the foot and the head of the separating blade being received respectively in a cavity of the inner ferrule and in an opening opposite the outer ferrule, said foot being mechanically free in said blind cavity.

[0015] Such a housing is easy to assemble. The absence of a mechanical connection at the base of the blade avoids expansion stresses.

[0016] According to another aspect, the housing includes at least one sealing element between the blind cavity and the foot of the separating blade.

[0017] This sealing element may include an abradable seal interposed between the bottom of the blind cavity and the foot.

[0018] According to another aspect, the housing includes at least one slit extending from the foot of the separating blade or from the bottom of the blind cavity, the blind cavity or the foot of the separating blade then having at least one additional groove in which said slit is received.

[0019] According to another aspect, said blade extends from the foot of the separating blade or from the bottom of the blind cavity by being inclined with respect to a radial direction of the separating blade, of said foot or of said bottom, towards the side of the intrados of the blade along a transverse axis of the separating blade, that is to say along an axis perpendicular to the plane formed by the main axis of the motor and the radial axis of the separating blade.

[0020] According to another aspect, at least one separating blade is fitted flush with the outer ferrule, an assembly ensuring the seal between the outer surface of said ferrule and said separating blade.

[0021] According to yet another aspect, in which the casing comprises at least three separating vanes between each pair of successive arms.

[0022] The invention also relates, according to another aspect, to a method of assembling a structural housing of a turbomachine, in which a separating blade is radially brought through an opening in the outer shell of a structural housing part according to the invention.

[0023] Finally, the invention relates to a turbomachine comprising a turbomachine casing according to the invention, as well as an aircraft comprising such a turbomachine. Brief description of the drawings

[0024] Other features and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and should be read in conjunction with the accompanying figures in which:

[0025] [Fig.1] presents a turbomachine architecture, with the location of the low-pressure turbine casing highlighted.

[0026] [Fig.2] illustrates the structural housing of the turbomachine according to the invention.

[0027] [Fig.3a] details the placement of the separating blades in the casing.

[0028] [Fig.3b] illustrates a non-flush arrangement of a separating blade with respect to the external ferrule.

[0029] [Fig.4a] illustrates one embodiment of the junction between the foot of a blade separator and the inner ferrule.

[0030] [Fig.4b] illustrates another embodiment of the junction between the foot of a blade separator and the inner ferrule.

[0031] [Fig.4c] illustrates another embodiment of the junction between the foot of a blade separator and the inner ferrule.

[0032] Description of one or more implementation and realization methods

[0033] A turbine housing part 12 illustrated in [Fig.2] comprises an inner ferrule 2, an outer ferrule 5, and thick arms 4 extending radially between the inner ferrule 2 and the outer ferrule 5. The inner ferrule 2 and the outer ferrule 5 extend coaxially around a longitudinal axis X.

[0034] The outer ferrule 5 has a plurality of openings 7, each intended to receive the head 31 of a splitter blade 3. The inner ferrule has, for each opening 7 of the outer ferrule, a blind cavity 8 intended to receive the foot 32 of the corresponding blade 3. The splitter blades 3 may have the same profile, or may have different profiles, in which case the dimensions of each opening 7 can be adapted to the corresponding profile of the splitter blade 3 intended to be inserted therein.

[0035] More specifically, the blind cavities 8 are formed on the inner surface 21 of the inner ferrule 2, without passing completely through it. This prevents leakage between the flow between the inner ferrule 2 and the outer ferrule 5, on the one hand, and the flow along the outer surface 22 of the inner ferrule. The blind cavities 8 are adapted to receive the feet 32 ​​of the separator blades 3.

[0036] Each blind cavity 8 is located opposite the corresponding opening 7 in a radial direction relative to the motor, that is to say a direction perpendicular to the longitudinal axis X.

[0037] Thus, each separating blade 3 can be inserted through the opening 7 so that its foot 32 comes to rest in the blind cavity 8 opposite, and that its head is retained in the opening 7.

[0038] The thick arms 4, the two inner ferrules 2 and outer ferrule 5 can be formed from a single piece. This reduces the number of parts to be manufactured and the manufacturing and assembly time for these parts. Furthermore, manufacturing the ferrules 2, 5 and the arms 4 from a single piece allows for the production of more complex geometries than would be possible by assembling separate parts. Finally, this feature makes it possible to obtain a single structural part 12, in which the stresses are distributed, without any areas subjected to excessive stress.

[0039] A turbine housing 10 is assembled by attaching separator blades 3 to the housing piece 12.

[0040] The foot 32 of the separator blade 3 is mechanically free within the corresponding blind cavity 8 of the inner ferrule 2. Indeed, a consequence of the difference in profile between the thick arms 4 and the separator blades 3 is that their behavior in response to temperature changes in the engine during operation and at rest differs. The arms 4 and the separator blades 3 will therefore not exhibit the same thermal expansion behavior. The absence of a mechanical connection between the foot 32 of the separator blade 3 and the inner ferrule 2 prevents transient stresses from being transmitted to the inner ferrule 2, thus preserving its structural integrity.

[0041] In this case, a sealing element 9 with an abradable coating can be placed between the inner ferrule 2 and the feet 32 ​​of the separating blades 3, in the blind cavities 8. This can be a NIDA-type abradable seal and / or a high-temperature seal, so as to be able to withstand the high temperatures to which the turbine is subjected. When the engine is started, such an element 9 is compressed by the thermal expansion of the separator blade 3, so as to minimize aerodynamic leakage between the base 32 of the separator blade 3 and the inner shell 2. This ensures a seal between the lower surface 33 and the upper surface 34 of the separator blade, and thus improves the turbine's efficiency.

[0042] According to one embodiment, a complementary shape is provided for the foot 32 of the separating blade 3 and the blind cavity 8 of the internal ferrule. As shown in [Fig.4a], one or more blades 13 can be provided, extending from the bottom of the blind cavity 8. A groove 14 is then provided in the foot 32 of the separating blade 3, the groove being complementary in shape to the blade so as to ensure aerodynamic sealing between the foot 32 of the separating blade 3 and the blind cavity 8. Indeed, the blade opposes the aerodynamic flow which would tend to develop between the foot 32 of the blade 3 and the blind cavity 8 of the inner shell due to the pressure difference between the air flowing over the intrados 33 and the extrados 34 of the blade 3, which reduces energy losses in the turbine.

[0043] As shown in [Fig.4b], a lick 13' can also be provided on the foot 32 of the separating blade, the corresponding groove 14' then being made in the blind cavity 8.

[0044] It may be advantageous for the blades to be inclined with respect to a radial direction of the blade 3 so as to extend towards the side of the lower surface of the blade 3, thereby effectively opposing the aerodynamic flow. Alternatively, the blades may extend in the radial direction of the blade 3, as shown in [Fig. 4c].

[0045] During the assembly of a turbine housing 10, each separator blade 3 is put in place by being engaged through an opening 7 in the outer shell 5. In order to avoid aerodynamic losses due to the presence of a step 11 formed between the separator blade 3 and the outer shell 5, the separator blade 3 can be adjusted so that its head 31 is flush with the upper surface 51 of the outer shell 5.

[0046] Welds 91 can be arranged on the outer ferrule 5 at the point where it joins the head 31 of the blades 3. They allow the blades 3 to be welded to the outer ferrule 5, but also ensure a tight seal between the head 31 of the blades 3 and the outer ferrule 5.

[0047] A keying means may be provided at the openings 7 of the outer ferrule 5, in order to ensure that each blade is inserted into a suitable opening 7, particularly in the case of a multi-profile housing with blades having distinct profiles. The keying means may, for example, take the form of a tab. located on the head of at least one separating blade, engaging in a corresponding groove of the opening.

[0048] The thick arms 4 can accommodate servitudes. The servitudes take the form of hollow channels made inside the crankcase arms, thus connecting the internal vein to the external vein and allowing the radial passage - that is to say through the airflow of the turbine - of air, oil, oiled air or pipes or electrical cables.

[0049] According to one embodiment, the turbine casing 10 comprises at least three separator blades 3 between each pair of successive arms 4. Thus, the entire casing comprises more separator blades 3 than arms 4. This results in a mechanically resistant casing, while maximizing the number of blades exposed to the flow, and therefore the power generated by the turbine.

[0050] The assembly can be carried out as follows: the process consists of providing a turbine housing part 12, comprising an inner ferrule 2, an outer ferrule 5, and thick arms 4 ensuring the mechanical connection between the two ferrules. Blind cavities 8 are then formed in the inner ferrule 2 and corresponding openings 7 in the outer ferrule 5, the openings 7 being located above the corresponding blind cavities 8 along radial axes perpendicular to the direction of the engine. A separator blade 3 is then inserted into each opening 7, and the base 32 of the blade 3 is then positioned by sliding it into the corresponding blind cavity 8.

[0051] Finally, the invention relates to a turbomachine comprising a casing 10 according to the invention, as well as an aircraft, in particular an airplane, equipped with such a turbomachine.

Claims

Demands

1. Turbomachine housing (10) with axis (X), comprising an inner shell (2) and an outer shell (5) extending coaxially around the axis (X), and at least one structural arm (4) connecting the two shells (2, 5) to each other, with a radially inner end of the arm (4) connected to the inner shell (2) and a radially outer end of the arm (4) connected to the outer shell (5), characterized in that the inner shell (2) comprises several blind cavities (8) formed as a recess from the outer surface of the inner shell (2), and the outer shell (5) comprises several openings (7) that pass through the outer shell (5), each opening (7) being positioned opposite a respective cavity (8) in a radial direction, each cavity (8) and each opening (7) being configured to receive a separating blade (3) intended to extend between the inner shell (2) and the external ferrule (5) being brought through the opening (7).in which the housing comprises several separating vanes (3) having different profiles, each separating vane comprising, at its two opposite radial ends, a foot (32) and a head (31), the foot (32) and the head (31) of the separating vane (3) being received respectively in the cavity (8) of the inner ferrule (2) and in the opening (7) opposite the outer ferrule (5), said foot (32) being mechanically free in said cavity (8), in which each opening (7) comprises a groove and in which the head (31) of each separating vane (3) comprises a tab adapted to form a means of misalignment with the groove of the opening (7) in which said separating vane (3) is received.

2. Turbomachine housing (10) according to claim 1, comprising at least one sealing element arranged radially between one of the cavities (8) and the foot (32) of one of the separator blades (3).

3. Turbomachine housing (10) according to claim 2, wherein the sealing element comprises an abradable element (9) mounted between the bottom of the cavity (8) and the foot (32).

4. Turbomachine housing (10) according to claim 1, comprising at least one blade (13, 13') extending radially in projection from the base (32) of one of the separating blades (3) or from the bottom of one of the cavities (8), said cavity (8) or said base (32) of the blade separator (3) having at least one additional groove (14, 14') in which said lick is received.

5. Turbomachine housing (10) according to claim 4, wherein said blade (13, 13') extends from the foot (32) of the separator blade (3) or from the bottom of the cavity (8) being inclined with respect to a radial direction of the separator blade (3), of said foot or of said bottom, towards the side of the intrados of the blade (3) along a transverse axis of the separator blade.

6. Turbomachine housing (10) according to any one of claims 1 to 5, wherein at least one separator blade (3) is mounted so as to be flush with the external surface of the outer shell (5), and wherein a leak-proof assembly is made between the external surface of said outer shell (5) and said separator blade (3).

7. Turbomachine housing (10) according to any one of claims 1 to 6, wherein the housing comprises at least three separating blades (3) between each pair of circumferentially successive arms (4).

8. Turbomachine, characterized in that it comprises a turbomachine housing (10) according to any one of claims 1 to 7.

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