Integration of a stator blade into a fixing pylon

Abstract

The present document proposes a propulsion assembly for an aircraft comprising a turbomachine with a longitudinal axis (X) comprising an annular row of rotor blades (102) and an annular row of stator blades (103) which are not shrouded and mounted around a casing (108) of said turbomachine, the assembly further comprising a pylon for attaching said turbomachine to the aircraft, said pylon extending downstream of said annular row of stator blades, said pylon being aligned with a blade, called a connecting blade (104-1), of said stator blades, so as to form the same aerodynamic element, and in which the pylon comprises a joining portion (106) with the connecting blade,and wherein the difference between the outer radius (R1) of said joining portion (106) and the radius (R2) of the casing at the connecting vane (104-1) is between 75% and 100% of the difference between the outer radius (R3) of the rotor vanes (102) and the radius (R2) of the casing at the connecting vane (104). Figure to be published with the abstract: [Fig. 3],

Description

Title of the invention: Integration of a stator blade into a fixing pylon Technical field of the invention

[0001] This document relates to the field of turbomachine-type aircraft engines comprising an unducted propeller and rectifier. It relates more particularly to the attachment of such an engine to the aircraft in order to minimize disturbances to the air flow passing through the stator blades. State of the prior art

[0002] An example of an unducted engine, also called an “open rotor” in English, is shown in [Fig.l]. The engine 1 with an unducted propeller is attached to a support pylon 2 on the structure of an aircraft, which is not shown. The unducted nature of the propeller and rectifier assembly offers a much higher bypass ratio than current dual-flow engines. The engine 1 can be positioned, for example, either under a wing or against the tail cone of the aircraft fuselage. Upstream and downstream are understood here with respect to the general direction of the air flow F along the X axis of the engine. Said engine 1 comprises a power generator compartment 3 supplied with primary flow by an annular air inlet 4. The power generator compartment 3 drives an unducted propeller 5 placed upstream of the annular air inlet 4, comprising an annular row of moving blades 8.An annular row 6 of stator blades 9 is fixed to the casing 7 of the power generator compartment 3, downstream of the annular air inlet 4. This annular row 6 of stator blades 9 has the function of straightening the air flow F driven by the propeller 5, which passes around the casing 7 of said power generator compartment 3. The pylon 2 is fixed to the casing 7 of the power generator compartment 3, downstream of the annular row 6 of stator blades 9. In particular, the pylon 2 comprises a structural part 2a which is axially offset from the annular row 6 of stator blades, downstream of the latter.

[0003] The presence of the pylon 2 can disrupt the action of the stator blades in at least two ways. From an aerodynamic point of view, the flow modifications induced by the pylon reach the level of the stator blades, or even the propeller, and can degrade their efficiency. From an acoustic point of view, the pylon interacts in an unsteady manner with the wake of the propeller and the stator blades, which can create sources of noise.

[0004] To limit these disturbances, the pylon 2 comprises an aerodynamic part 2b, in its upstream part against the casing 7, which forms one of the blades of the annular row 6 of stator blades. Nevertheless, the improvement provided by this arrangement remains in- sufficient.

[0005] This document aims to remedy these drawbacks. Summary of the invention

[0006] The present document proposes a propulsion assembly for an aircraft comprising a turbomachine with a longitudinal axis comprising an annular row of rotor blades and an annular row of unducted stator blades mounted around a casing of said turbomachine, the assembly further comprising a pylon for attaching said turbomachine to the aircraft, said pylon extending downstream of said annular row of stator blades, said pylon being aligned with a blade, called a connecting blade, of said stator blades, so as to form a single aerodynamic element, and

[0007] wherein the pylon comprises a junction portion with the connecting blade, and wherein the difference between the external radius of said junction portion and the radius of the casing at the connecting blade is between 75% and 100% of the difference between the external radius of the rotor blades and the radius of the casing at the connecting blade.

[0008] The dimensioning of the junction part makes it possible to limit the acoustic and aerodynamic disturbances due to the absence of fairing around the stator blades and the rotor blades.

[0009] The outer radius of the joining portion may correspond to the radial distance between the longitudinal axis and the radially outer surface of the joining portion.

[0010] The outer radius of the rotor blades may be greater than the outer radius of the stator blades.

[0011] The outer radius of the connecting blade may correspond to the radial distance between the longitudinal axis and the radially outer surface of the connecting blade.

[0012] The outer radius of the rotor blades may correspond to the radial distance between the longitudinal axis and the radially outer surface of the rotor blades. In particular, the rotor blades may have the same dimensions, in particular the same radial dimension.

[0013] The radius of the casing may correspond to the radius of the inner surface of an aerodynamic vein delimited radially inside by said casing, at the level of the stator blades. In particular, this radius of the casing may be the radial distance between the longitudinal axis and a radially external surface of said casing at the level of the stator blades.

[0014] The annular row of rotor blades may be arranged upstream of the annular row of stator blades.

[0015] In particular, the difference between the external radius of said joining part and the radius of the casing at the level of the connecting blade can be between 85% and 100%, more particularly between 90% and 100%, and even more particularly 95% and 100% of the difference between the outer radius of the rotor blades and the radius of the casing at the connecting blade.

[0016] The annular row of stator vanes may be configured to straighten at least a portion of a gas flow.

[0017] The joining portion may be a longitudinal section of the pylon arranged immediately downstream of the connecting vane.

[0018] The connecting vane may be structurally integrated, in whole or in part, with the pylon. Alternatively, the connecting vane may be structurally separated, in whole, from said pylon.

[0019] Each stator blade, in particular the connecting blade, may be at least partially arranged to rotate about a radial axis. This radial axis may be perpendicular to the longitudinal axis. For example, each stator blade may have a pitch angle variation greater than 3°.

[0020] The connecting blade may comprise a fixed part fixed on the one hand to the casing of the turbomachine and on the other hand to the junction part of the pylon. The connecting blade may also comprise a movable part arranged radially outside said fixed part and rotating around the radial axis. The movable part may further comprise a blade and a shaft passing through said fixed part.

[0021] The connecting vane may comprise a blade connected to a shaft arranged on the casing side. Said shaft may have a downstream surface longitudinally spaced from the fixing pylon. Said downstream surface may have a shape complementary to an upstream surface of the joining portion of the fixing pylon.

[0022] The connecting blade may comprise a leading edge, a downstream face and two aerodynamic faces extending on either side of said leading edge and said downstream face. The joining portion may comprise an upstream face opposite the downstream face of the connecting blade and two aerodynamic faces extending on either side of said upstream face.

[0023] Said assembly may comprise at least one flexible membrane fixed on the one hand to one of the aerodynamic faces of the junction part and on the other hand to one of the aerodynamic faces of the connecting blade so as to laterally cover the longitudinal space between the junction part and the connecting blade. Said membrane allows aerodynamic continuity between the connecting blade and the pylon.

[0024] The pylon may comprise a portion arranged downstream of the junction portion having a radial dimension greater than the radial dimension of the stator blades.

[0025] The assembly may include a stator vane timing control mechanism arranged inside the housing.

[0026] The turbomachine may comprise an annular air inlet to a combustion chamber of said turbomachine, said annular air inlet being arranged axially between the annular row of rotor blades and the annular row of stator blades. In particular, said annular inlet may be formed between the casing and a cover carrying the annular row of rotor blades.

[0027] The number of rotor blades may be different from the number of stator blades. This arrangement makes it possible to reduce the noise of the turbomachine. Indeed, when the number of rotor blades is equal to that of the stator blades, the wake assembly of the rotor blades interacts with the stator blades simultaneously, which increases the noise levels.

[0028] The annular row of rotor blades and / or the annular row of stator blades comprises between 3 and 25 rotor blades, respectively stator blades.

[0029] According to one embodiment, a strength parameter may be defined as the ratio between, on the one hand, the chord of the stator blades, i.e. the axial dimension of the stator blades at their radially external surface, and, on the other hand, the spacing between two consecutive stator blades in the azimuthal direction. The strength parameter may be less than 3 over the entire span, in particular less than 1 on the upstream side of the stator blades.

[0030] The joining part may be fixed to the second casing by any suitable fixing means, for example by welding, screwing, etc.

[0031] The present document also relates to an aircraft comprising an assembly as mentioned above. Brief description of the figures

[0032] [Fig. 1] already described represents an example of an aircraft engine according to the prior art,

[0033] [Fig.2] represents a first example of embodiment of an assembly of a turbomachine without fairing,

[0034] [Fig.3] represents a second example of an assembly of a turbomachine without fairing,

[0035] [Fig.4] Figure 4a represents a first section H2 of a stator blade of the turbomachine of [Fig.3] and Figure 4b represents a second section H1 of said stator blade of the turbomachine of [Fig.3],

[0036] [Fig.5] represents a third example of an assembly of a turbomachine without fairing,

[0037] [Fig.6] Figure 6a represents a first section H2 of a stator blade of the turbomachine of [Fig.5] and Figure 6b represents a second section H1 of said stator blade of the turbomachine of [Fig.5],

[0038] [Fig.7] represents a section of the stator blade of the turbomachine of [Fig.5] according to a fourth exemplary embodiment. Detailed description of the invention

[0039] [Fig. 2] represents a part of a turbomachine with longitudinal axis X and unducted propellers, also called "open rotor" in English. The turbomachine comprises, from upstream to downstream, an annular row of rotor blades 102, mounted around a first casing 112, and an annular row of stator blades 103, mounted around a second casing 108. The first casing 112 forms an inlet cone upstream of the turbomachine.

[0040] An annular opening 110 separates the first casing 112 and the second casing 108. The annular opening 110 is arranged axially between the annular row of rotor blades 102 and the annular row of stator blades 103 and allows the passage of an air flow F towards a combustion chamber of the turbomachine, not shown.

[0041] The mounting of the turbomachine to an aircraft, for example to a wing or the rear cone of the fuselage of said aircraft, is ensured by an assembly mast, or pylon, which on the one hand is connected to the aircraft and on the other hand to a junction part 106 attached to the second casing 108.

[0042] The joining portion 106 is joined to one of the stator blades, called the connecting blade 104, so as to form a single aerodynamic element. This arrangement makes it possible to limit the noise pollution generated by the turbomachine.

[0043] To further limit the disturbances due to the absence of fairing, the junction part 106 is dimensioned so that the difference between the external radius RI of the junction part 106 and the radius R2 of the second casing 108 at the level of the connecting blade 104 is between 75% and 100% of the difference between the external radius R3 of the rotor blades 102 and the radius RI of the second casing 108 at the level of the connecting blade 104, that is to say at the level of the anchoring of the connecting blade 104.

[0044] In the embodiment of [Fig.2], the timing of the stator blades and / or the rotor blades is not variable.

[0045] According to the embodiment shown in Figures 3 and 4, the connecting blade 104-1 is arranged to rotate about a radial axis Y, so that the setting of the connecting blade 104-1 is variable. For this purpose, the connecting blade 104-1 comprises a movable part 114 carrying a shaft 118 which extends radially towards the inside of the second casing 108. The connecting blade 104-1 also comprises a fixed part 116 crossed by said shaft 118.

[0046] The movable part 114 has an aerodynamic profile, represented by a section in FIG. 4a, at the level of the axis H2. The movable part 114 has a leading edge 126-1, a downstream face 126-2 and two aerodynamic faces 124-1 and 124-2 extending on either side of the leading edge 126-1 and the downstream face 126-2. The downstream face 126-2 can be configured to form a trailing edge.

[0047] Similarly, the fixed part 116 has an aerodynamic profile represented by a section in Figure 4b, at the level of the axis HL. The fixed part 116 has an edge leading edge 128 and two aerodynamic faces 130-1 and 130-2 extending on either side of the leading edge 128-1.

[0048] The junction part 106 is connected downstream to a downstream part 122 of the assembly mast and has two aerodynamic faces 106-1 and 106-2.

[0049] Preferably, the aerodynamic faces 130-1 and 130-2 of the fixed part 116 and the aerodynamic faces 106-1 and 106-2 of the joining part 106 are configured to ensure aerodynamic continuity between the fixed part 116 and the joining part 106.

[0050] The shaft 118 is mounted in a control mechanism 120 for controlling the timing of the stator blades. The control mechanism 120 is configured to control the incidence of the stator blades, in particular of the connecting blade 104-1. The timing of all the stator blades and / or all the rotor blades may be variable.

[0051] The downstream part 122 of the assembly mast has a radial thickness greater than that of the junction part 106.

[0052] The fixed part 116 can be fixed to the second casing 108 by any suitable fixing means, for example by welding, screwing, etc.

[0053] According to the embodiment shown in Figures 5 and 6, the connecting blade 104-2 is also arranged to rotate around the radial axis Y, so that the setting of the connecting blade 104-2 is variable. For this purpose, the connecting blade 104-2 comprises a movable part 214 carrying a shaft 218 which extends radially towards the inside of the second casing 108.

[0054] The movable part 114 has an aerodynamic profile, represented by a section in FIG. 6a, at the level of the axis H2. The movable part 214 has a leading edge 226-1, a downstream face 226-2 and two aerodynamic faces 224-1 and 224-2 extending on either side of the leading edge 226-1 and the downstream face 226-2. The downstream face 226-2 can be configured to form a trailing edge.

[0055] Similarly, the shaft 218 also has an aerodynamic profile represented by a section in FIG. 6b, at the level of the axis HL. The shaft 216 has a leading edge 228-1, a downstream face 228-2 and two aerodynamic faces 230-1 and 230-2 extending on either side of the leading edge 228-1.

[0056] The junction portion 106 is connected downstream to a downstream portion 122 of the assembly mast and has two aerodynamic faces 106-1 and 106-2. The junction portion 106 also has an upstream face 106-3 arranged at a distance from the downstream face 228-2, so as to maintain a space 202 between these two surfaces 106-3 and 228-2. In particular, the upstream face 106-3 of the junction portion 106 has a shape complementary to the downstream surface 228-2 of the shaft 216, so as to allow rotation of the shaft 216 when the setting of the connecting vane 104-2 is varied.

[0057] Preferably, the aerodynamic faces 230-1 and 230-2 of the fixed part 116 and the aerodynamic faces 106-1 and 106-2 of the joining portion 106 are configured to provide aerodynamic continuity between the shaft 218 and the joining portion 106.

[0058] A control mechanism 120 for the timing of the stator vanes is connected to the shaft 216 and is configured to control the incidence of the stator vanes, in particular of the connecting vane 104-2.

[0059] To limit the aerodynamic disturbance created by the gap 202, flexible membranes 204-1 and 204-2 are provided to cover said gap 202 in the third embodiment of [Fig.7]. Each flexible membrane 204-1 and 204-2 is arranged to connect the aerodynamic surface 230-1 and 230-2 of the shaft 216 to the aerodynamic surface 106-1 and 106-2 of the joining portion 106, respectively.

[0060] The flexible membranes 204-1 and 204-2 extend radially from the second casing 108 to the height of the shaft 218 at the level of the beginning of the movable part 214.

[0061] The number of rotor blades 102 is different from the number of stator blades 103. In particular, the annular row of rotor blades 102 and / or the annular row of stator blades 103 comprises between 3 and 25 rotor blades, respectively stator blades.

[0062] Furthermore, the outer radius of the rotor blades 102 is greater than the radius of the stator blades 103.

[0063] The joining portion 106 may be fixed to the second casing 108 by any suitable fixing means, for example by welding, screwing, etc.

Claims

Claims

1. Propulsion assembly for aircraft comprising a turbomachine with a longitudinal axis (X) comprising an annular row of rotor blades (102) and an annular row of stator blades (103) which are not shrouded and mounted around a casing (108) of said turbomachine, the assembly further comprising a pylon (122) for fixing said turbomachine to the aircraft, said pylon extending downstream of said annular row of stator blades, said pylon being aligned with a blade, called a connecting blade (104, 104-1, 104-2), of said stator blades, so as to form the same aerodynamic element, and in which the pylon comprises a junction portion (106) with the connecting blade, and in which the difference between the external radius (RI) of said junction portion (106) and the radius (R2) of the casing at the level of the connecting vane (104,104-1,104-2) is between 75% and 100% of the difference between the external radius (R3) of the rotor blades (102) and the radius (R2) of the casing at the connecting blade (104), the joining part being a longitudinal section of the pylon arranged immediately downstream of the connecting blade.,

2. An assembly according to claim 1, wherein each stator blade is at least partially rotatably arranged about a radial axis (Y).

3. Assembly according to claim 2, in which the connecting blade (104-1) comprises a fixed part (116) fixed on the one hand to the casing (108) of the turbomachine and on the other hand to the junction part (106) of the pylon, the connecting blade also comprising a movable part (114) arranged radially outside said fixed part and rotating around the radial axis (Y), the movable part further comprising a blade and a shaft (118) passing through said fixed part (116).

4. An assembly according to claim 2, wherein the connecting vane (104-2) comprises a blade connected to a shaft (216) arranged on the side of the casing (108), said shaft having a downstream surface (228-2) longitudinally spaced from the fixing pylon, and wherein said downstream surface (228-2) has a shape complementary to an upstream surface (106-3) of the joining part (106) of the fixing pylon.

5. Assembly according to the preceding claim, in which the connecting blade (104-2) comprises a leading edge (226-1), a downstream face (226-2) and two aerodynamic faces (230-1, 230-2) extending on either side of said leading edge and said downstream face, the joining part (106) comprises an upstream face (106-3) facing the downstream face (228-2) of the connecting blade and two aerodynamic faces (106-1, 106-2) extending on either side of said upstream face (106-3), said assembly comprising at least one flexible membrane (204-1, 204-2) fixed on the one hand to one of the aerodynamic faces (106-1, 106-2) of the joining part (106) and on the other hand to one of the aerodynamic faces (230-1, 230-2) of the connecting blade so as to laterally cover the longitudinal space (202) between the joining part and the connecting blade.

6. Assembly according to one of the preceding claims, in which the pylon comprises a part (122) arranged downstream of the junction part (106) having a radial dimension greater than the radial dimension of the stator blades.

7. Assembly according to one of the preceding claims, comprising a control mechanism (120) for the timing of the stator blades arranged inside the casing (108).

8. An assembly according to one of the preceding claims, wherein the turbomachine comprises an annular air inlet (110) to a combustion chamber of said turbomachine, said annular air inlet being arranged axially between the annular row of rotor blades (102) and the annular row of stator blades (103).

9. An assembly according to one of the preceding claims, wherein the number of rotor blades (102) is different from the number of stator blades (103).

10. Aircraft comprising an assembly according to one of the preceding claims.

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