INTAKE HOUSING FOR AN AIRCRAFT TURBOMACHINE

Abstract

The invention relates to an annular inlet housing (8) for an aircraft turbomachine (1), the inlet housing (8) extending around a first axis (X) and comprising: - an annular outer shell (20) centered on the first axis (X), and - sleeves (32) adapted to receive blades (18), the sleeves (32) being distributed around the first axis (X) and connected to the outer shell (20), each sleeve (32) having an annular wall (33) extending around a second axis (Y) oriented radially with respect to the first axis (X), characterized in that each sleeve (32) is connected to the outer shell (20) by a first axial connection (L1) with respect to the first axis (X) and at least one second radial connection (L2) with respect to the first axis (X). Figure 3

Description

Title of the invention: INLET CASING FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The invention relates to the field of inlet casings for aircraft turbomachines.

[0002] The invention relates in particular to the field of inlet casings carrying fixed vanes, in particular with variable pitch angle, also known by the English acronym OGV for “Outlet Guided Vanes”. Technical background

[0003] Among aircraft turbomachines, there are unducted fan turbomachines, known by the English acronym USF for "Unducted Single Fan". This type of turbomachine has a high propulsive efficiency compared to turbomachines with ducted fans.

[0004] This type of turbomachine typically extends around and along a longitudinal axis and comprises from upstream to downstream in the direction of flow of the gas flow along this longitudinal axis, an unducted fan, a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine and a low pressure turbine.

[0005] Unlike turbomachines with a shrouded fan, the turbomachine with an unshrouded fan does not include a fan casing surrounding the fan.

[0006] The low pressure turbine is conventionally connected to the low pressure compressor and the blower by a low pressure shaft, and the high pressure turbine is connected to the high pressure compressor by a high pressure shaft.

[0007] The blower allows an air flow to be compressed. The compressed air flow is divided into a primary air flow flowing in a primary vein of the turbomachine and a secondary air flow flowing in a secondary vein surrounding the primary vein. The primary air flow is compressed in the compressors and then burned in the combustion chamber. The gases resulting from the combustion pass through the turbines which then drive the blower and the low-pressure compressor.

[0008] Furthermore, the unducted fan turbomachine typically comprises an air inlet casing arranged axially between the fan and the low-pressure compressor. The inlet casing comprises, in a known manner, an inner shroud centered on the longitudinal axis and an outer shroud arranged coaxially around the inner shroud. The outer shroud internally delimits a portion of the secondary flow path and the inner shroud externally delimits a portion of the primary flow path.

[0009] To improve the performance of the turbomachine, the inlet casing carries fixed vanes also known by the English acronym OGV for "Outlet Guided Vanes". Such vanes are regularly distributed around the longitudinal axis and make it possible to compress the secondary air flow. These fixed vanes are typically of variable pitch angle making it possible to adapt their pitch angle to the speeds of the turbomachine.

[0010] In order to connect the blades to the inlet casing, the inlet casing typically comprises support sleeves for these fixed blades regularly distributed around the longitudinal axis and connected to the outer shell. Each support sleeve typically comprises a hollow annular wall into which the fixed blades are inserted for their attachment to the inlet casing.

[0011] However, integrating these sleeves onto the inlet housing presents many challenges.

[0012] Indeed, the inlet casing absorbs forces generated by the fan located upstream and forces generated by the compressors located downstream. The inlet casing is also connected to a pylon connecting the turbomachine to the aircraft, and which ensures the transfer of axial thrust force. Also, the inlet casing must allow the passage of services in the areas close to the inlet casing.

[0013] The large number of stress recovery points, the easements and the air veins imply a complex geometric definition of this inlet casing.

[0014] However, the fixing of the support sleeves of the fixed blades requires increasing the size of the casing, reducing the space available for the passage of the services. Also, this fixing of the support sleeves generates additional forces on the inlet casing, which requires reinforcing the inlet casing against these additional forces by adding, for example, stiffeners, ultimately impacting the feasibility of this inlet casing.

[0015] There is therefore a need to provide an inlet casing for an aircraft turbomachine, comprising variable pitch angle blade support sleeves, which are compact and have optimal force absorption. Summary of the invention

[0016] To this end, the invention proposes an annular inlet casing for an aircraft turbomachine, the inlet casing extending around a first axis and comprising:

[0017] - an annular external ferrule centered on the first axis, and

[0018] - sleeves capable of receiving blades, the sleeves being distributed around the first axis and connected to the outer shell, each sleeve having an annular wall extending around a second axis oriented radially relative to the first axis.

[0019] The inlet casing according to the invention is remarkable in that each sleeve is connected to the external shell by a first axial connection relative to the first axis and at least a second radial connection relative to the first axis.

[0020] By "axial connection" is meant a connection involving at least two bearing surfaces extending in a plane perpendicular to the first axis and cooperating together.

[0021] By "radial connection" is meant a connection involving at least two bearing surfaces extending in a plane parallel to the first axis and cooperating together.

[0022] The second connection allows the radial forces exerted on the sleeve to be taken up, i.e. the forces which are oriented perpendicular to the first axis, and the first connection allows the axial forces to be taken up, i.e. the forces which are oriented parallel to the first axis. Thus, each connection works in an operating range close to traction-compression. The sizing of the connections can thus be reduced, thereby reducing the size of the input casing.

[0023] The distribution of forces in the input casing according to the invention being optimal, it is possible to do without stiffeners which makes it possible to simplify the geometry of the input casing and therefore its manufacture. Also, the size of the input casing is reduced which facilitates the passage of the services.

[0024] Finally, optimizing the distribution of forces in the input casing makes it possible to reduce the deformation of the support during operation.

[0025] The invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

[0026] - each sleeve comprises a first connecting arm extending axially to from the annular wall and connected to the external shell by said first connection,

[0027] - the external ferrule comprises two annular flanges, respectively upstream and downstream, located at two axial ends of the outer shell, and an annular flange which is centered on the first axis and located axially between the upstream and downstream annular flanges, the flange being connected by said first connection to each sleeve,

[0028] - the flange has a first radial bearing surface cooperating with a second radial bearing surface of each first connecting arm, the first and second bearing surfaces extending in a plane perpendicular to the first axis and being connected to each other to form the first connection,

[0029] - each sleeve comprises at least one second connecting arm extending ra- dially from the annular wall and connected to the outer shell by said second connection,

[0030] - each sleeve is connected to the external ferrule by a third radial connection by report to the first axis,

[0031] - each sleeve comprises a third connecting arm extending radially to from the annular wall and connected to the external shell by said third connection,

[0032] - the second and third connecting arms are radially opposite with respect to the second axis,

[0033] - the outer ferrule comprises a plurality of first and second projecting studs extending radially, the second and third arms of each sleeve bearing radially on the respective first and second pads,

[0034] - each first and second stud has a first axial bearing surface cooperating with a second axial bearing surface of the second and third arms, the first and second axial bearing surfaces extending in a plane parallel to the first axis and being connected to each other to form the second and third links respectively.

[0035] The invention also relates to a turbomachine for an aircraft, comprising an inlet casing according to any one of the preceding characteristics. Brief description of the figures

[0036] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0037] [Fig.l] is a schematic representation in axial section of a half-aircraft turbomachine;

[0038] [Fig.2] is a schematic perspective representation of an inlet casing according to the invention in which the sleeves have been removed;

[0039] [Fig.3] is a perspective view of a sleeve connected to the inlet casing according to the invention;

[0040] [Fig.4] is another perspective view of the sleeve connected to the inlet casing according to the invention;

[0041] [Fig.5] is another perspective view of the sleeve connected to the inlet casing according to the invention. Detailed description of the invention

[0042] An example of a turbomachine 1 is illustrated in [Fig.l]. The turbomachine 1 extends around and along a first axis X.

[0043] In the remainder of the application, unless otherwise indicated, the terms “longitudinal”, “longitudinally”, “axial”, “axially”, “radial”, “radially”, are understood relative to the first axis X of the turbomachine 1.

[0044] The terms “exterior”, “interior” are understood in relation to the distance from the first axis X along a radial axis.

[0045] The terms “upstream” and “downstream” are understood in relation to the circular direction of an air flow F in the turbomachine 1 along the first axis X.

[0046] The turbomachine 1 comprises from upstream to downstream a fan 2, a compressor low pressure 3, a high pressure compressor 4, a combustion chamber 5, a high pressure turbine 6, a low pressure turbine 7.

[0047] The fan 2 comprises movable blades 2a regularly distributed around the first axis X. The blades 2a are movable in rotation around this first axis X. Advantageously, the blades 2a have a variable pitch angle. They are connected to a pitch change system 2b to vary the pitch angle of these blades 2a according to the speed of the turbomachine 1.

[0048] The blower 2 allows the suction of an air flow F which is divided downstream of the blower 2 into a primary air flow F1 and a secondary air flow F2. The primary air flow F1 flows in an annular primary vein v1 and the secondary air flow F2 flows in an annular secondary vein v2 surrounding the primary air vein v1.

[0049] The primary air flow Fl is compressed within the low pressure and high pressure compressors 3, 4. Then the primary air flow Fl is mixed with a fuel within the combustion chamber 5. The gases resulting from the combustion flow into the high pressure and low pressure turbines 6, 7.

[0050] The secondary air flow F2 flows into the secondary vein v2 and provides propulsion.

[0051] The turbomachine 1 further comprises an inlet casing 8 arranged axially between the fan 2 and the low-pressure compressor 3.

[0052] The turbomachine 1 further advantageously comprises an inter-compressor casing 9 arranged axially between the low and high pressure compressors 3, 4, an inter-turbine casing 10 arranged axially between the high and low pressure turbines 6, 7 and a gas exhaust casing 11 located downstream of the low pressure turbine 7.

[0053] The turbomachine 1 further comprises a low pressure shaft 12 centered on the first axis X and a high pressure shaft 13 arranged coaxially around the low pressure shaft 12.

[0054] The low pressure shaft 12 mechanically connects the low pressure compressor 3 to the low pressure turbine 7 and the high pressure shaft 13 mechanically connects the high pressure compressor 4 to the high pressure turbine 6.

[0055] Advantageously, the turbomachine 1 further comprises a fan shaft 14 connecting the fan 2 to the low pressure shaft 12, in particular via a mechanical speed reducer 15.

[0056] The fan shaft 14 is guided in rotation by a first bearing 16a. The first bearing 16a is for example a double ball bearing. The first bearing 16a is for example arranged between the inlet casing 8 and the fan shaft 14.

[0057] The low pressure shaft 12 is guided in rotation upstream by second, third and fourth bearings 16b, 16c, 16d. The second, third and fourth bearings 16b, 16c, 16d are ball and / or roller bearings. The second and third bearings 16b, 16c are for example arranged between the inlet casing 8 and the low pressure shaft 12. The fourth bearing 16d is arranged between the inter-compressor casing 9 and the low pressure shaft 12.

[0058] The low pressure shaft 12 is guided in rotation downstream by sixth and seventh bearings 16e, 16f. These sixth and seventh bearings 16e, 16f are for example roller bearings. The sixth and seventh bearings 16e, 16f are for example located between the exhaust casing 11 and the low pressure shaft 12.

[0059] The high pressure shaft 13 is guided in rotation upstream by an eighth bearing 16g, for example of the double type, and downstream by a ninth bearing 16h. The eighth and ninth bearings 16g, 16h are for example roller and / or ball bearings. The eighth bearing 16g is for example located between the inter-compressor casing 9 and the high pressure shaft 13 and the ninth bearing 16h is for example located between the inter-turbine casing 10 and the high pressure shaft 13.

[0060] In order to allow the bearings to be lubricated optimally, the turbomachine 1 further comprises lubrication enclosures in which said bearings for guiding the rotation of the shafts are arranged.

[0061] The turbomachine 1 comprises for example an upstream enclosure 17a in which the first, second and third bearings 16a, 16b, 16c and the speed reducer 15 are arranged. The upstream enclosure 17a is for example located in the inlet casing 8.

[0062] The turbomachine 1 may comprise an intermediate enclosure 17b in which the fourth and eighth bearings 16d, 16g are arranged. The intermediate enclosure 17b is for example located in the inter-compressor casing 9.

[0063] The turbomachine 1 may comprise a first downstream enclosure 17c in which the ninth bearing 16h is arranged and a second downstream enclosure 17d in which the fifth and sixth bearings 16e, 16f are arranged. The first downstream enclosure 17c is for example located in the inter-turbine casing 10 and the second downstream enclosure 17d is for example located in the exhaust casing 11.

[0064] The number of bearings and enclosures may vary depending on the configuration of the turbomachine 1.

[0065] According to the invention, the turbomachine 1 further comprises fixed vanes 18 regularly distributed around the first axis X. These vanes 18 are advantageously fixed in rotation around the first axis X. They are also known by the English acronym OGV for “Outlet Guided Vanes”. These vanes 18 make it possible to compress the secondary air flow F2 downstream of the fan 2 to improve the propulsive efficiency of the turbomachine 1.

[0066] These blades 18 are advantageously of variable pitch angle. The blades 18 are thus movable in rotation around a pitch axis Y extending radially by relative to the first axis X. Such a characteristic makes it possible to improve the propulsive efficiency of the turbomachine 1 according to the speed of the turbomachine 1. They are thus connected to a pitch change system 19.

[0067] The blades 18 are carried by the inlet casing 8.

[0068] The inlet casing 8 according to the invention will now be described in detail.

[0069] As best seen in [Fig.2], the inlet casing 8 comprises an outer shell 20 and an inner shell 21 connected by arms 22. The outer shell 20 internally defines a part of the secondary vein v2 and externally a part of the primary vein v1.

[0070] The arms 22 cross the primary vein vl. The arms 22 are regularly distributed around the first axis X. They advantageously have an aerodynamic shape in order to minimize the impact on the primary air flow FL

[0071] The outer shell 20 is annular, centered on the first axis X and located coaxially around the inner shell 21 which is also annular. The outer shell 20 has an annular body 23 delimited axially by an upstream annular flange 24 and a downstream annular flange 25. The upstream annular flange 24 is thus located at an upstream end of the outer shell 20 and the downstream annular flange 25 is located at a downstream end of the outer shell 20 axially opposite the upstream end of the outer shell 20. The upstream annular flange 24 is for example connected to an air inlet nozzle of the turbomachine 1 while the downstream annular flange 25 is for example connected to a casing of the low-pressure compressor 3.

[0072] Furthermore, the inlet casing 8 advantageously comprises a flange 26. The flange 26 is annular and centered on the first axis X. The flange 26 is located axially between the upstream and downstream annular flanges 24, 25.

[0073] The flange 26 has an annular wall 27 centered on the first axis X and extending radially from the outer shell 20. The annular wall 27 has a first radial bearing surface 27a extending in a plane perpendicular to the first axis X. Advantageously, the flange 26 further comprises radial projections 28 extending radially from the annular wall 27. The radial projections 28 are regularly distributed around the first axis X. The flange 26 may also comprise corners 29 regularly distributed around the first axis X. The corners 29 are located between the radial projections 28. Each corner 29 extends downstream from the annular wall 27 of the flange 26 and is fixed to the annular body 23 of the outer shell 20. Each corner 29 is thus located axially between the annular wall 27 and the downstream annular flange 25. The corners 29 make it possible to mechanically reinforce the inlet casing 8 against the axial forces EL

[0074] The input casing 8 advantageously comprises pairs of pads 30, each pair of pads 30 comprising first and second pads 30a, 30b. The pairs of pads 30 are regularly distributed around the first axis X. Each pair of studs 30 is located axially between the upstream annular flange 24 and the end plate 26. Each first and second studs 30a, 30b extend projecting and radially from the outer shell 20, in particular from the annular body 23. Each first and second studs 30a, 30b have a cross-section along an axis parallel to the first axis X that is polygonal, for example rectangular, square or diamond-shaped. Each first and second studs 30a, 30b has a first axial bearing surface 31. Each first bearing surface 31 extends in a plane parallel to the first axis X. Each first bearing surface 31 is radially opposite the annular body 23 of the outer shell 20.

[0075] Furthermore, according to the invention, with reference for example to Figures 3, 4 and 5, the inlet casing 8 comprises sleeves 32 for supporting the blades 18. Each blade 18 is carried by a respective sleeve 32. The sleeves 32 are regularly distributed around the first axis X.

[0076] Each sleeve 32 comprises an annular wall 33 and an internal housing 34 delimited by the annular wall 33 and receiving a fixed blade 18. The annular wall 33 extends around a second axis Y extending radially relative to the first axis X. The second axis Y thus corresponds to the setting axis of the blades 18. The annular wall 33 has a cross-section relative to the second axis Y that is circular.

[0077] According to the invention, each sleeve 32 is connected to the outer shell 20 by a first axial connection L1 relative to the first axis X and at least one second radial connection L2 relative to the first axis X. Preferably, each sleeve 32 is connected to the outer shell 20 by a third radial connection L3 relative to the first axis X. By "axial connection" is meant a connection involving at least two bearing surfaces extending in a plane perpendicular to the first axis X and connected to each other. In particular, these bearing surfaces are connected by a set of means for securing the outer shell 20 to the sleeve 32 located in a plane parallel to the first axis X. By "radial connection" is meant a connection involving at least two bearing surfaces extending in a plane parallel to the first axis X and connected to each other.In particular, these bearing surfaces are connected by a set of means for securing the external ferrule 20 to the sleeve 32 located in a plane perpendicular to the first axis X.

[0078] Preferably, each sleeve 32 further comprises a first connecting arm 35 and advantageously second and third connecting arms 36, 37.

[0079] Each first connecting arm 35 connects the annular wall 33 of the sleeve 32 to the flange 26. Each first connecting arm 35 extends axially relative to the first axis X from the annular wall 33 to the flange 26.

[0080] Each first connecting arm 35 has a predetermined axial length L such that as measured along the first axis X. The axial length L is predetermined according to the center of rotation of the input casing 8. This length can thus be modulated according to the position of this center of rotation.

[0081] Each first connecting arm 35 comprises a first axial end 38 secured to the annular wall 33 of the sleeve 32 and a second opposite axial end 39 connected to the flange 26 by the first connection 26. Each first connecting arm 35 further comprises a flange 40 located on the second axial end 39 of the first arm 35. The flange 40 has a second radial bearing surface 40a extending in the plane perpendicular to the first axis X.

[0082] The second radial bearing surface 40a cooperates axially with the first radial bearing surface 27a of the wall 27 of the flange 26. In particular, the second radial bearing surface 40a bears axially against the annular wall 27 of the flange 26 located between the projections 26. The second radial bearing surface 40a is in particular axially aligned with the corner 29.

[0083] The second radial bearing surface 40a and the first radial bearing surface 27a of the wall 27 of the flange 26 are axially connected to each other by screwing to form the first connection LL. The flange 40 has for example an orifice 40b which has an axis parallel to the first axis X. A screw (not shown) passes through the orifice to connect the arm 35 to the flange 26. The screw has an elongation axis parallel to the first axis X.

[0084] The second and third connecting arms 36, 37 extend radially inwardly from the annular wall 33 of the sleeve 32. The second and third connecting arms 36, 37 are radially opposite with respect to the second axis Y.

[0085] Each second and third connecting arm 36, 37 has a first end 41 secured to the annular wall 33 of the sleeve 32 and a second end 42 axially opposite relative to the second axis Y. Each second and third connecting arm 36, 37 also has a second axial bearing surface 42a which extends in the plane parallel to the first axis X.

[0086] Each second axial bearing surface 42a cooperates with the first axial bearing surface 31 of the first and second pads 30a 30b.

[0087] Each second axial bearing surface 42a is radially connected to the first axial bearing surface 31 of the first and second studs 30a 30b, for example by screwing, to form the second and third connections L2, L3. Each screw (not visible) has an elongation axis perpendicular to the first axis X.

[0088] The blades 18 transmit axial forces E1 and radial forces E2 to the sleeves 32. The radial forces are taken up by the second and advantageously third links L2, L3 and the axial forces are taken up by the first link LL. Thus, each link L1, L2, L3 works in an operating range close to the traction-com- pressure. The sizing of the connections L1, L2, L3 can thus be reduced.

[0089] The distribution of forces in the casing 8 according to the invention being optimal, the deformation of the support 32 in operation is reduced.

[0090] Also, thanks to such a solution, it is possible to do without stiffeners, which makes it possible to simplify the geometry of the inlet casing 8 and therefore its manufacture.

[0091] Furthermore, advantageously, by simply modulating the length L of the first connecting arm 35, it is possible to modify the position of the second axis Y corresponding to the setting axis of the blades 18.

[0092] Finally, the size of the input casing 8 is reduced, which facilitates the passage of the services.

Claims

Claims

1. Annular inlet casing (8) for an aircraft turbomachine (1), the inlet casing (8) extending around a first axis (X) and comprising: - an annular outer shell (20) centered on the first axis (X), and - sleeves (32) capable of receiving blades (18), the sleeves (32) being distributed around the first axis (X) and connected to the outer shell (20), each sleeve (32) having an annular wall (33) extending around a second axis (Y) oriented radially relative to the first axis (X), characterized in that each sleeve (32) is connected to the outer shell (20) by a first axial connection (L1) relative to the first axis (X) and at least one second radial connection (L2) relative to the first axis (X).

2. Inlet casing according to the preceding claim, characterized in that each sleeve (32) comprises a first connecting arm (35) extending axially from the annular wall (33) and connected to the external ferrule (20) by said first connection (L1).

3. Inlet casing according to the preceding claim, characterized in that the outer shell (20) comprises two annular flanges (24, 25), respectively upstream and downstream (24, 25), located at two axial ends of the outer shell (20), and an annular flange (26) which is centered on the first axis (X) and located axially between the upstream and downstream annular flanges (24, 25), the flange (26) being connected by said first connection (L1) to each sleeve (32).

4. Inlet casing according to the preceding claim, characterized in that the flange (26) has a first radial bearing surface (27a) cooperating with a second radial bearing surface (40a) of each first connecting arm (35), the first and second bearing surfaces (27a, 40a) extending in a plane perpendicular to the first axis (X) and being connected to each other to form the first connection (L1).

5. Inlet casing according to any one of the preceding claims, characterized in that each sleeve (32) comprises at least one second connecting arm (36) extending radially from the annular wall (33) and connected to the external shell (20) by said second connection (L2).

6. An inlet housing according to any preceding claim, characterized in that each sleeve (32) is connected to the external ferrule (20) by a third connection (L3) radial relative to the first axis (X).

7. Inlet casing according to all of claims 5 and 6, characterized in that each sleeve (32) comprises a third connecting arm (37) extending radially from the annular wall (33) and connected to the external shell (20) by said third connection (L3).

8. Inlet casing according to the preceding claim, characterized in that the second and third connecting arms (36, 37) are radially opposite relative to the second axis (X2).

9. Inlet casing according to one of claims 7 or 8, characterized in that the outer shell (20) comprises a plurality of first and second projecting studs (30a, 30b) extending radially, the second and third arms (36, 37) of each sleeve (32) bearing radially on the respective first and second studs (30a, 30b).

10. Inlet casing according to the preceding claim, characterized in that each first and second stud (30a, 30b) has a first axial bearing surface (31) cooperating with a second axial bearing surface (42a) of the second and third arms (36, 37), the first and second axial bearing surfaces (31, 42a) extending in a plane parallel to the first axis (X) and being connected to each other to form the second and third links (L2, L3) respectively.

11. Turbomachine (1) for an aircraft, characterized in that it comprises an inlet casing (8) according to any one of the preceding claims.

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