Turbomachine having an improved oil-recovery device

Abstract

Disclosed is a turbomachine (10) having an oil-recovery device comprising, between mutually rotatable first and second members (14, 16), a tubular tab (54) of the first member (14) surrounded by a tubular extension (56) of a shroud (42) of the second member which defines, with a shroud (44) of the first member (14), an interface zone, the tubular extension (56) comprising an outer groove (60) opposite the tab (54), characterised in that the extension (56) axially surrounds the tubular tab (54) beyond an axial half-length (l) of the tab (54), has an inner diameter (d72, d74, d76) equal to an inner diameter (d42) of the outer shroud (42) of the second member (16) and has an outer diameter (D72, D74, D76) smaller than or equal to an outer diameter (D42) of the outer shroud (42), and in that the annular groove thereof has a rectangular cross-section.

Description

[0001] DESCRIPTION

[0002] TITLE: TURBOMACHINE COMPRISING AN IMPROVED OIL RECOVERY DEVICE

[0003] Technical field of the invention

[0004] The invention relates to a turbomachine equipped with an oil recovery device with improved efficiency.

[0005] Technical background

[0006] It is known from the prior art, the documents WO 2014 / 199083 A1, EP 2 090 764 A1, EP 3 462 000 A1, FR 3 075 866 A1.

[0007] In a turbomachine of known type, a rear part of the low-pressure turbine shaft is generally mounted to rotate by at least one bearing mounted on a tubular wall of the inter-turbine casing. This bearing is placed in a first enclosure called a lubrication enclosure, which is delimited, on the one hand, by the inter-turbine casing and on the other hand, by a bearing support secured to the shaft of the low-pressure turbine shaft. The inter-turbine casing and the bearing support secured to the low-pressure shaft also separate this first enclosure from a second enclosure which is adjacent to it. The low-pressure shaft is also secured to a bearing support.

[0008] The lubrication chamber is connected to an oil circuit comprising an oil inlet pipe, through which the oil is pumped into the chamber. It comprises an oil recovery device comprising an oil return pipe, through which the oil returns to the oil circuit in order to be pumped again.

[0009] The inter-turbine casing being fixed and the bearing support secured to the low pressure shaft being rotating relative to it, the sealing of the enclosure vis-à-vis is ensured between these two members at the level of an interface zone which separates the two enclosures.

[0010] The bearing support in fact comprises an outer shell which is rotatably mounted inside an inner shell of the inter-turbine casing, and these two shells define the interface zone. This interface zone can receive a system for expelling the oil comprising at least one spiral and lunula device. This system can be supplemented by a dynamic sealing system, comprising a rear labyrinth seal and / or a brush seal.

[0011] Outside the lubrication enclosure, the second enclosure is pressurized. The pressurization allows a positive pressure to be applied across the interface zone to prevent oil from escaping from the lubrication enclosure. The pressurized enclosure further comprises an oil drainage device comprising a drainage conduit communicating with the outside of the turbomachine.

[0012] To ensure the return of lubricating oil from the bearing to the oil return duct, the oil must be guided from the bearing to a wall of the inter-turbine housing which communicates with an inlet of an oil return duct. To achieve this, the oil must bypass the interface area without penetrating it.

[0013] This is why the oil recovery device has a tubular tab, commonly called a "drip lance" which extends from the tubular wall supporting the bearing and which extends inside one end of the outer shell of the bearing support.

[0014] This tab is intended to guide the bearing during assembly to allow precise positioning of the low pressure shaft in order to avoid any contact between the shaft and the inter-turbine casing.

[0015] This tab is also configured to cause oil to be projected successively from the tab to the outer shell of the bearing support, then from the outer shell of the bearing support to the wall of the interturbine casing leading to the inlet of the oil return conduit.

[0016] To prevent oil from penetrating into the interface area, the outer shell of the bearing support is extended by a tubular extension which extends axially around the tubular tab beyond one end of the inner shell of the inter-turbine casing, and in which is formed an annular outer groove of circular section and concavity facing away from the tubular tab. This groove is intended to prevent oil from spreading along the tubular extension and then to the outer shell of the bearing support in the interface area. In operation, this configuration in principle allows oil to bypass the interface area without penetrating it.

[0017] However, it has been found that a problem arises when an aircraft equipped with such a turbomachine is parked on the ground and the turbomachine is shut down.

[0018] Indeed, in this case, the interface zone is no longer subjected to the pressurization pressure of the second enclosure, and the turbomachine is inclined a few degrees more towards the rear than during its normal operation. It has been observed that the oil tends to trickle by gravity along the drop-throttle tab, to bypass the end of the tubular extension then to insinuate itself by capillarity into the annular groove of circular section and to cross the interface zone, in particular by capillarity by crossing the interface zone, to finally penetrate into the second enclosure. Under certain conditions, oil can then be evacuated from this second enclosure by the oil drainage device and flow onto the tarmac on which the aircraft is parked.Oil can even reach a hotter enclosure of the turbomachine and cause smoke to be released, which would be detrimental to users' perception of the quality of the turbomachine.

[0019] There is therefore a real need for a new configuration of the oil recovery device allowing the oil to bypass the interface zone under all circumstances.

[0020] More generally, there is a real need for a new configuration of an oil recovery device making it possible to optimize the flow of oil from a so-called "dropper" tab located near an interface zone between two members rotating relatively to each other. It will therefore be understood that the invention is therefore not limited to the configuration described in the present description.

[0021] Summary of the invention The present invention relates to a turbomachine equipped with an oil recovery device which overcomes the aforementioned drawback. These aims are achieved, in accordance with the invention, by proposing a modification of the external shell of the bearing support opposite the tubular tongue, with an extension of larger dimensions and having an external groove of rectangular and no longer circular section.

[0022] For this purpose, the invention proposes a turbomachine comprising first and second internal members movable in rotation relative to each other around an axis X, and at least one guide bearing mounted between first and second respective tubular walls of axis X of the first and second members, the first member further comprising a third wall substantially transverse to the axis X, the second member comprising a fourth wall substantially transverse to the axis X surrounded by said third wall, said third and fourth walls separating two enclosures, respectively a first bearing lubrication enclosure, and a second enclosure, the fourth wall being bordered by an outer shell of the second member and the third wall being bordered by an inner shell of the first member,the inner shell surrounding the outer shell and said inner and outer shells delimiting an interface zone between said enclosures, said turbomachine further comprising an oil recovery device comprising a tubular tongue which extends the first tubular wall of the first member and which extends axially inside one end of the outer shell of the second member, this tongue being configured to lead oil to be projected successively from the tongue to the outer shell of the second member, then from the outer shell of the second member to the third wall, said inner shell of the second member being extended by a tubular extension which surrounds the outside of the tubular tongue axially beyond one end of the inner shell of the first member, and in which is formed an outer groove of concavity facing away from the tubular tongue,characterized in that the extension surrounds the exterior of the tubular tongue axially beyond half an axial length of said tubular tongue, has an internal diameter equal to an internal diameter of the external ferrule of the second member and an external diameter less than or equal to an external diameter of the external ferrule, and in that its annular groove has a rectangular section.,

[0023] The tubular extension advantageously allows the oil dripping from the tubular tab to be displaced a significant axial distance from the interface zone and the rectangular shape of the groove of this extension prevents the oil from forming a capillary bridge and reaching the interface zone.

[0024] According to other characteristics of the turbomachine, the tubular extension comprises successively, from the outer shell of the second member:

[0025] - a first section, extending the outer shell of the second member, and with the same internal and external diameters as the internal and external diameters of said external shell in the interface zone,

[0026] - a second section, adjoining the first section, with an internal diameter equal to the internal diameter of the outer shell, and an external diameter less than the external diameter of the outer shell, and

[0027] - a third section, adjoining the second section, with an internal diameter equal to the internal diameter of the outer shell in the interface zone, and with a determined external diameter equal to the external diameter of the outer shell in the interface zone, the annular groove being delimited by an external wall of axis X of the second section and by transverse walls of the first and third sections at their junction with the second section, - the first lubrication enclosure of the bearing contains lubricating oil, the external wall of axis X of the second section determines a width L of the groove, the transverse wall of the third section determines a height H of the groove, and the groove is configured such that its height H is an affine function by intervals of its width L, according to a relation H = mx L + p of which coefficients m and p are associated with determined characteristics of said lubricating oil.

[0028] - the characteristics of the lubricating oil include a temperature of use below 120°C, a viscosity between 20 and 30 centistokes at 40°C and 4.9 to 5 centistokes at 100°C with a density between 0.9 and 1.05 Kg / L,

[0029] - advantageously the turbomachine is such that:

[0030] • for an interval of width L greater than or equal to 4 mm and less than 6 mm, m = -0.6 and p = 7,

[0031] • for a width interval L of 6 to 7mm, m = -0.2 and p =4.6,

[0032] • for a width L greater than 7mm, m = 0 and p = 3.2,

[0033] - the first and second sections on the one hand, and the second and third sections on the other hand, are connected at the bottom of the groove by a radius of curvature R less than or equal to 0.6 mm,

[0034] - the third section has an axial thickness greater than or equal to 1.2 mm,

[0035] - the first member is an inter-turbine casing, the second member is a bearing support secured to a low-pressure shaft, the first bearing lubrication enclosure communicates with an oil recovery conduit connected to an oil circuit of the turbomachine, and the second enclosure is a pressurized enclosure communicating with an oil drainage conduit connected to the outside of the turbomachine,

[0036] - the interface zone is a receiving zone of a system for expelling oil comprising a front spiral and front lunules and a rear spiral and rear lunules interposed between the inner and outer shells,

[0037] - the interface zone receives behind said system to expel the oil a dynamic sealing system comprising at least one dynamic seal. Brief description of the figures

[0038] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0039] [Fig. 1] Figure 1 is an axial sectional view of a rear part of a turbomachine according to the state of the art,

[0040] [Fig. 2] Figure 2 is an axial sectional view of an extension of an outer shell of a bearing support of the turbomachine of Figure 1,

[0041] [Fig. 3] Figure 3 is a sectional view of the rear part of the turbomachine according to the state of the art illustrating the path of the lubricating oil,

[0042] [Fig. 4] Figure 4 is an axial sectional view of an extension of an outer shell of a bearing support of a turbomachine according to the invention,

[0043] [Fig. 5] Figure 5 is a sectional view of the rear part of the turbomachine according to the invention illustrating the path of the lubricating oil;

[0044] [Fig. 6] Figure 6 is a perspective view of the end of the outer shell of the bearing bracket and its extension.

[0045] Detailed description of the invention

[0046] Figure 1 shows a rear part 12 of a turbomachine 10 produced in accordance with the state of the art. In a known manner, the turbomachine comprises first and second respective internal members 14, 16 movable in rotation relative to each other around an axis X and at least one guide bearing 20 mounted between the first and second members.

[0047] In the present case, the invention relates in particular to the case of an inter-turbine casing 14 internally receiving in rotation a low pressure shaft 15 via a bearing support 16 secured to this low pressure shaft 15. The low pressure shaft also comprises a rear end carrying a journal 19 of a low pressure turbine 18. It will be understood that this arrangement which is the subject of the present description is not limiting of the invention and that the invention can be applied to other members mounted in rotation in a relative manner with respect to each other, such as for example bearing supports secured to journals of low pressure turbines and high pressure turbines.

[0048] A segmented radial seal 22 is also mounted between the interturbine casing 14 and the low pressure shaft 15.

[0049] The inter-turbine casing 14, which here forms the first member, is a substantially annular casing which is crossed by a primary gas stream 24 of the turbomachine. Turbine disks 26, integral with the low-pressure turbine journal 16, are also placed in the gas stream 24 and their blades 28 are arranged alternately with rectifier blades 30.

[0050] The inter-turbine casing 14 comprises a first tubular wall 32 of axis X and the bearing support 16 comprises a second tubular wall 33, the bearing 20 being mounted between these walls 32, 33.

[0051] The inter-turbine casing 14 further comprises a third wall 36, substantially transverse to the axis X.

[0052] The bearing support 16, which here forms the second member, comprises a fourth wall 34, substantially transverse to the axis X, which is surrounded by the third wall 36 of the inter-turbine casing 14. The fourth wall 34 therefore rotates inside the third wall 36, which is fixed.

[0053] The inter-turbine casing 14, the low-pressure shaft 15 and the bearing support 16 delimit a first bearing lubrication enclosure 38 comprising lubricating oil inside the rear part 12 of the turbomachine 10. Furthermore, these fourth and third walls 34, 36 separate the first bearing lubrication enclosure 38 from a second enclosure 40, external to the first enclosure 38.

[0054] The fourth wall 34 is bordered by an outer shell 42, thus also forming part of the bearing support 16, and the third wall 36 is bordered by an inner shell 44, thus forming part of the inter-turbine casing 14. The two shells 42, 44 are arranged opposite one another, the inner shell 44 surrounding the outer shell 42. As a result, the two outer shells 42 and inner shells 44 delimit an interface zone 46 between the two enclosures 38, 40.

[0055] Conventionally, the second enclosure 40 is a pressurized enclosure supplied with pressurized air taken from a tapping made on one of the compressors of the turbomachine. This enclosure 40 is pressurized so as to exert a positive pressure on the interface zone 46 in which can be housed, in a non-limiting manner of the invention, a system for expelling the oil comprising at least one spiral and lunules, which can be supplemented in or outside the interface zone 46 by a dynamic sealing system such as a labyrinth or brush seal ensuring the seal between the lubrication enclosure 38 and the second enclosure 40.

[0056] Since none of these systems are limiting of the invention, it will be considered in the remainder of this description that the interface zone 46 only comprises a system for expelling the oil.

[0057] The purpose of pressurizing the enclosure 40 is to confine the lubricating oil of the bearing 20 inside the lubrication enclosure 38. In addition, this second enclosure 40 comprises an oil drainage conduit 41, which communicates with the exterior of the turbomachine.

[0058] The lubricating oil is pumped under pressure into the lubrication enclosure 38 through an oil inlet conduit 48 and is recovered by an oil recovery device which allows the oil to be evacuated from the lubrication enclosure through a conduit 50, so that it is recovered and then pumped back into this enclosure 38. To reach the conduit 50, as shown by the arrows in FIG. 1, the lubricating oil from the bearing 20 must first reach an internal face 52 of the third wall 36 of the inter-turbine casing 14 from where it is conveyed to the inlet of the conduit 50.

[0059] It will be noted that in the plan of figure 1, the conduit 50 has been represented in dotted lines.

[0060] For this purpose, as illustrated in more detail in Figure 3, the oil recovery device also comprises a tubular tab 54 which extends the first tubular wall 32 of the inter-turbine casing 14 and which extends axially towards the outer shell 42 of the bearing support 16, and more particularly inside one end 43 thereof.

[0061] This tab 54 is intended to guide the bearing 20 during its assembly to allow precise positioning of the low pressure shaft.

[0062] 15 in order to avoid any contact between the shaft 15 and the inter-turbine casing 14.

[0063] In a known manner, when the turbomachine is in operation, oil is sprayed successively from the tab 54 to the outer shell 42 of the bearing support 16, then from the outer shell 42 of the bearing support

[0064] 16 to the inner surface 52.

[0065] In known manner, the end 43 of the inner shell 42 of the bearing support 16 is extended by a tubular extension 56 which extends axially and partially around the tubular tongue 54. This extension 56 extends beyond one end 58 of the inner shell 44 of the inter-turbine casing 14, and is therefore not arranged in the interface zone 46, but is placed outside of it. In this extension 56 is formed an outer groove 60 whose concavity is turned away from the tubular tongue 54.

[0066] An extension 56 of this type in accordance with the state of the art has been shown in Figure 2. As can be seen, the extension 56 has substantially the same internal and external diameters as the outer shell 42 of the bearing support 16 and its groove 60 has a determined width L and depth P. The groove 60 has a circular section.

[0067] However, in such a configuration, it has been found that, when the turbomachine is stopped, for certain angles of inclination, corresponding for example to an inclination of the turbomachine of approximately 4°, which is typically an inclination of a turbomachine under the wing in the parking position of the aircraft, the oil coming from the tubular tongue 54 drips onto the internal wall 62 of the extension 56 then, flowing onto its end face 64, is not limited to dripping from the end face 64 but also tends to penetrate by capillarity into the groove 60 to form a lubricant bridge from where it spreads against an external wall 66 of the internal shell 42 of the support 16 until it reaches the interface zone 46.When the interface zone 46 is equipped with a system for expelling the oil such as a double system comprising a front auger 67 and front lunules 69 and a rear auger 68 and rear lunules 68, the oil can pass through this system then enter the second enclosure 40 from where it can be evacuated by the drainage conduit 41.

[0068] The invention proposes a modification of the extension 56 making it possible to remedy this problem.

[0069] For this purpose, as illustrated in Figures 2 and 5, the extension 56 first extends beyond half an axial length I of the tubular tongue 54.

[0070] Furthermore, as illustrated in Figure 5, the extension 56 surrounds the outside of the tubular tongue 54 axially beyond half an axial length I of the tubular tongue 54. It has an inside diameter equal to an inside diameter of the outer ferrule 42 of the second member 16 and an outside diameter less than or equal to an outside diameter of the outer ferrule, and its annular groove 60 has a rectangular section.

[0071] The free end of the extension 56 thus forms a return which, combined with the rectangular shape of the section of the outer annular groove 60, prevents the oil from forming a bridge by capillarity through this annular groove 60 to reach the interface zone 46. Indeed, unlike a groove of circular section, a groove of rectangular section makes it possible to break the continuity of the oil film and to prevent its propagation through the annular groove 60.

[0072] More particularly, as illustrated in FIG. 5, the tubular extension 56 successively comprises, from the outer ferrule 42 of the support 16, a first section 72, a second section 74 and a third section 76.

[0073] The first section 72 extends the outer ferrule 42 of the support 16, and has the same internal diameters d?2 and external diameters D72 as the internal diameters d42 and external diameters D42 of the outer ferrule 42 in the interface zone 46.

[0074] Then the tubular extension comprises a second section 74, joined to the first section 72. The second section 74 has an internal diameter d?4 equal to the internal diameter d42 of the outer shell 42 in the interface zone 46, and an external diameter D74 less than the external diameter D42 of the outer shell 42 in the interface zone 46. Finally, the third section 76, joined to the second section 74, has an internal diameter d?4 equal to the internal diameter d42 of the outer shell 42, and an external diameter D?6 determined equal to the external diameter D42 of the outer shell 42.

[0075] It will therefore be understood that the second and third sections 74, 76 thus form a step which extends axially outside the tubular tongue 54 beyond the axial half-length I of this tubular tongue 54. The axial dimensions of the first to third sections 72, 74, 76 therefore determine the coverage of the tubular extension 56 around the tubular tongue 54 beyond the axial half-length I.

[0076] It will also be understood that the annular groove 60 of rectangular section is delimited by an external wall 74a of axis X of the second section 74 taken between respective transverse walls 72a and 76a of the first and third sections 72, 76 at their junction with the second section 74.

[0077] The dimensions of the groove 60 are decisive with regard to its capacity to oppose the formation of a lubricant bridge through it. The external wall 74a of axis X of the second section 74 determines a characteristic width L of the groove 60, and the transverse wall 76a of the third section 76 determines a characteristic height H of the groove 60.

[0078] According to the invention, the groove 60 is configured such that its height H is an affine function by intervals of its width L, according to a relation of type H = mx L + p of which coefficients m and p are associated with determined characteristics of the lubricating oil.

[0079] In the context of the invention, the characteristics of the lubricating oil used for the lubrication of the bearing 20 include a usage temperature of less than 120°C, a viscosity of between 20 and 30 centistokes at 40°C and 4.9 to 5 centistokes at 100°C with a density of between 0.9 and 1.05 Kg / L.

[0080] For such a lubricating oil, in accordance with the invention, the coefficients m and p of the affine function determining the height H of the groove 60 as a function of its width L vary as a function of three intervals: - for an interval of width L greater than or equal to 4 mm and less than 6 mm, m = -0.6 and p = 7,

[0081] - for a width interval L of 6 to 7mm, m = -0.2 and p =4.6,

[0082] - and finally, for a width L greater than 7mm, m = 0 and p = 3.2, which corresponds to a height H of the groove 60 which is constant.

[0083] Another important parameter of the groove 60 is the radius of curvature of the sections 72 to 76. To break the oil film, it is necessary that the radius of curvature allowing the connection of these sections be as small as possible in order to provide a groove 60 with a section as close as possible to a perfect rectangle. Thus, the first and second sections 72, 74 on the one hand, and the second and third sections 74, 76 on the other hand, are connected at the bottom of the groove by a radius of curvature R less than or equal to 0.6 mm.

[0084] It is also essential that the third section 76 has a minimum thickness E?6, in order to prevent the oil from passing through its free end 78. For this purpose, the third section 76 has a thickness E?6 which is greater than 1.2 mm.

[0085] Advantageously, the extension 56 can be arranged radially relative to the tubular tongue 54 with reduced clearance, a reduced clearance making it possible to limit the speed of the flow of the oil.

[0086] The invention advantageously makes it possible to avoid, for a given angle of inclination of the turbomachine which can be up to 4°, that, when stopped, the oil does not pass through the interface zone 46, that the latter is intended to receive a system for expelling the oil such as the spirals 67, 68 and lunules 69, 70 or another system. It therefore makes it possible to avoid oil spreading onto the tarmac via the drainage duct 41 or infiltrating into other hotter enclosures of the turbomachine such as an enclosure 80, with the risks of smoke release that this would imply, which would be detrimental to the perception that users could have of the quality of the turbomachine.

Claims

CLAIMS 1. Turbomachine (10) comprising first and second internal members (14, 16) movable in rotation relative to each other around an axis X, and at least one guide bearing (20) mounted between first and second tubular walls (32, 33) of axis X respectively of the first and second members (14, 16), the first member (14) comprising a third wall (36) substantially transverse to the axis X, the second member (16) comprising a fourth wall (34) substantially transverse to the axis X surrounded by said third wall (36), said third and fourth walls (34, 36) separating two enclosures (38, 40), respectively a first enclosure (38) for lubricating the bearing (20), and a second enclosure (40), the fourth wall (34) being bordered by an outer shell (42) of the second member (16) and the third wall (36) being bordered by an inner ferrule (44) of the first member (14),the inner shell (44) surrounding the outer shell (42) and said inner and outer shells (42, 44) delimiting an interface zone (46) between said enclosures, said turbomachine further comprising an oil recovery device comprising a tubular tongue (54) which extends the first tubular wall (32) of the first member (14) and which extends axially inside one end (43) of the outer shell (42) of the second member (16), this tongue (54) being configured to lead oil to be projected successively from the tongue (54) to the outer shell (42) of the second member (16), then from the outer shell (42) of the second member (16) to the third wall (36), said inner shell (42) of the second member (16) being extended by a tubular extension (56) which surrounds the outside of the tubular tongue (54) axially beyond one end (58) of the inner ferrule (44) of the first member (14),and in which is formed an external groove (60) of concavity facing away from the tubular tongue (54), characterized in that the extension (56) surrounds the exterior of the tubular tongue (54) axially beyond half an axial length (I) of said tubular tongue (54), has an internal diameter (d?2, d?4, d?e) equal to an internal diameter (d42) of the external ferrule (42) of the second member (16) and an external diameter (D72, D74, D76) less than or equal to an external diameter (D42) of the external ferrule (42), and in that its annular groove has a rectangular section.

2. Turbomachine (10) according to the preceding claim, characterized in that the tubular extension (56) successively comprises, from the outer shell (42) of the second member (16): - a first section (72), extending the outer ferrule (42) of the second member (16), and with the same internal (d72) and external (D72) diameters as the internal (d42) and external (D42) diameters of said outer ferrule (42) in the interface zone (46), - a second section (74), adjoining the first section (72), with an internal diameter (d74) equal to the internal diameter (d42) of the outer shell (42) in the interface zone (46), and with an external diameter (D74) less than the external diameter (D42) of the outer shell (42) in the interface zone (46), and - a third section (76), adjoining the second section (74), with an internal diameter (d74) equal to the internal diameter (d42) of the outer ferrule (42), and with an external diameter (D76) determined equal to the external diameter (D42) of the outer ferrule (42), the annular groove being delimited by an external wall (74a) of axis X of the second section and by transverse walls (72a, 76a) of the first and third sections (72, 74) at their junction with the second section (74).

3. Turbomachine (10) according to the preceding claim, characterized in that the first enclosure (38) for lubricating the bearing (20) contains lubricating oil, in that the external wall (74a) of axis X of the second section (74) determines a width L of the groove (60), in that the transverse wall (76a) of the third section (76) determines a height H of the groove, and in that the groove is such that its height H is an affine function by intervals of its width L, according to a relation H = mx L + p of which coefficients m and p are associated with specific characteristics of the lubricating oil.

4. Turbomachine (10) according to the preceding claim, characterized in that the characteristics of the lubricating oil include a use temperature of less than 120°C, a viscosity of between 20 and 30 centistokes at 40°C and 4.9 to 5 centistokes at 100°C with a density of between 0.9 and 1.05 Kg / L.

5. Turbomachine (10) according to the preceding claim, characterized in that: - for an interval of width L greater than or equal to 4 mm and less than 6 mm, m = -0.6 and p = 7, - for a width interval L of 6 to 7mm, m = -0.2 and p =4.6, - for a width L greater than 7mm, m = 0 and p = 3.

2.

6. Turbomachine (10) according to one of claims 4 or 5, characterized in that the first and second sections (72, 74) on the one hand, and the second and third sections on the other hand (74, 76), are connected at the bottom of the groove (60) by a radius of curvature R less than or equal to 0.6 mm.

7. Turbomachine (10) according to one of claims 4 to 6, characterized in that the third section (76) has an axial thickness (E?e) greater than or equal to 1.2 mm.

8. Turbomachine (10) according to one of the preceding claims, characterized in that the first member (14) is an inter-turbine casing, in that the second member (16) is a bearing support secured to a low pressure shaft (15), in that the first bearing lubrication enclosure (38) communicates with an oil recovery conduit (50) connected to an oil circuit of the turbomachine, and in that the second enclosure (40) is a pressurized enclosure communicating with an oil drainage conduit (41) connected to the outside of the turbomachine (10).

9. Turbomachine according to the preceding claim, characterized in that the interface zone (46) is a receiving zone for a system for expelling the oil comprising a front spiral (67) and front lunules (69) and a rear spiral (68) and rear lunules (70) interposed between the inner and outer shells (44, 46).

10. Turbomachine according to one of claims 8 or 9, characterized in that the interface zone (46) is a zone for receiving a sealing system comprising at least one dynamic seal.

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