FR3118792A1 - MODULE FOR AN AIRCRAFT TURBOMACHINE - Google Patents

Abstract

The invention relates to a module for an aircraft turbine engine (1), this module extending around a longitudinal axis (X) and comprising: - a hub (12), and - blades (13) at an angle of variable pitch mounted on the hub (12), each of the blades (13) comprising: - a blade (16) extending radially with respect to the longitudinal axis (X) between a head (16a) and a root (16b) , the blade (16) having a height (H1), - a platform (17) connected to the foot (16b) and having a generally circular shape from which the blade (16) extends, the platform (17) being movable in rotation around an axis of rotation extending radially with respect to the longitudinal axis (X) and passing through the center of the platform (17) and - at least one fin (18, 18a, 18b) provided at the least partly on the platform (17), the fin (18, 18a, 18b) extending radially with respect to the longitudinal axis (X) from the platform (17) between a first end (18a') and a second extrem opposite blade (18b'), the fin (18, 18a, 18b) having a height (H2) less than the height (H1) of the blade (16), and comprising a second leading edge (18c) and a second trailing edge (18c'), a second intrados face (18i) and a second extrados face (18e) connecting the second leading edge (18c) to the second trailing edge (18c'). Abstract Figure: Figure 3

Description

MODULE FOR AN AIRCRAFT TURBOMACHINE

Technical field of the invention

The invention relates to modules for aircraft turbine engines. The invention applies particularly to the fans of aircraft turbomachines.

Technical background

In a well-known manner, an aircraft turbine engine extends along a longitudinal axis and comprises a fan allowing the suction of an air flow which is divided into a primary flow and a secondary flow. The primary flow passes through the engine of the turbomachine while the secondary flow is directed outwards with respect to the primary flow, for example by being directed towards a secondary stream delimited externally by a casing fixed to a nacelle of the aircraft and internally by an engine support structure. Alternatively, on so-called non-ducted turbomachine architectures, which in essence do not have a nacelle external to the fan, the secondary stream is delimited externally by the fictitious surface swept by the top of the blades of a fan propeller.

The primary flow is compressed within, for example, a low pressure compressor then a high pressure compressor of the engine. The compressed air is then mixed with fuel and burned in an annular combustion chamber arranged downstream of the series of compressors. The gases formed by the combustion pass through a high pressure turbine and a low pressure turbine located downstream of the combustion chamber and which drive the compressors. The gases finally escape through a nozzle whose section allows the acceleration of these gases to generate propulsion.

The fan, the compressors or even the turbines are formed of a module comprising at least one hub driven in rotation around the longitudinal axis of the turbomachine and variable-pitch angle vanes mounted on the hub. Variable pitch angle vanes correspond to vanes whose orientation can be adjusted in order to modify the flow characteristics of the gases according to the operating regimes of the turbomachine. A turbomachine comprising a fan formed of a module comprising variable pitch angle vanes is known by the acronym VPF for Variable Pitch Fan in English.

Furthermore, the variable-pitch angle vanes fitted to a compressor stator are typically known by the acronym VSV for Variable Stator Vanes in English.

A variable-pitch vane typically includes a blade extending radially relative to the longitudinal axis between a tip and a root. The blade also has an aerodynamic profile and thus comprises an intrados face and an extrados face which connect a leading edge to a trailing edge of the blade. In addition, the root of the blade is connected to a platform, the platform being connected to the hub to which the blade is also mounted via a blade base associated with a blade support pivot which are arranged under the platform.

The variable nature of the blade pitch angle induces design constraints in the blade root area. For example, the blade root profile chord must be dimensioned in such a way as to avoid inter-blade contact during a change of pitch and/or the external aerodynamic surface of the hub can be modified.

Such constraints in the design of the blades degrade the aerodynamic behavior of the flow at the level of the roots. Detachments are thus observed on the intrados and/or extrados faces of the blades at the level of the trailing edge and/or the leading edge. This degradation of the flow of the stream leads to a reduction in performance in the area concerned, i.e. the fan, the compressor or even the turbine. When the performance of the fan is reduced then the compressor supply, which is located downstream of the fan, is directly impacted.

In order to prevent separations in a turbomachine, document WO-A1-2015092306 proposes forming one or more fins on a platform, between two consecutive blades. According to this document, the fin has a triangular section, that is to say it has two oblique faces meeting on a dorsal edge.

This solution does not give complete satisfaction. Indeed, this solution is not suitable for blades with variable pitch angle. Indeed, the triangular section of the fins weakens the resistance of the fins which does not prevent the risks of aerodynamic separation and stall in the case of a variation in incidence of the adjacent blades.

There is thus a need to provide a turbomachine module having variable-pitch vanes in which the flow of the flux is improved.

To this end, the invention proposes a module for an aircraft turbomachine, this module extending around a longitudinal axis and comprising:

- a hub, and

- vanes with variable pitch angle mounted on the hub, each of the vanes comprising:

- a blade extending radially relative to the longitudinal axis between a head and a root, the blade having a height H1 and comprising a first leading edge and a first trailing edge, a first intrados face and a first face extrados connecting the first leading edge to the first trailing edge,

- a platform connected to the foot and having a generally circular shape from which the blade extends, the platform being rotatable around an axis of rotation extending radially with respect to the longitudinal axis and passing through the center of the platform and

- at least one fin provided at least in part on the platform, the fin extending radially with respect to the longitudinal axis from the platform between a first end and a second opposite end, the fin having a height H2 lower than the height H1 of the blade, and comprising a second leading edge and a second trailing edge, a second intrados face and a second extrados face connecting the second leading edge to the second trailing edge.

The module according to the invention therefore comprises a fin. The fin is used to guide the flow of the gas flow along the hub in order to reduce the separation on the lower surface and/or upper surface of the blades of the blades with variable pitch angle at the inner limit of the stream near the hub. According to the invention, the fin is arranged at least in part directly on the platform. This ensures a relative orientation of the fin with respect to the constant blade regardless of the pitch angle. In addition, according to the invention, the fin has an aerodynamic profile, that is to say that the fin comprises, like the blade of the dawn, a second leading edge and a second trailing edge, a second intrados face and a second extrados face connecting the second leading edge to the second trailing edge. Such a profile makes it possible to guide the flow in an efficient manner near the hub, that is to say by minimizing the aerodynamic losses associated with this guidance, with the quality of the guidance of the root of the adjacent blade and this whatever the pitch angle of this blade.

The module according to the invention may comprise one or more of the following characteristics, taken separately from each other or in combination with each other:

- the first extrados face is opposite the second intrados face,

- the first intrados face is opposite the second extrados face,

- the fin has a root profile chord having a middle aligned with the middle of a root profile chord of the blade,

- the fin is arranged between a tangential diameter of the platform extending tangentially with respect to the longitudinal axis of the module and an upstream edge of the platform,

- the fin is arranged between a tangential diameter of the platform extending tangentially with respect to the longitudinal axis of the module and a downstream edge of the platform,

- the fin overlaps an upstream or downstream edge of the platform,

- the platform comprises a housing in its center in which is arranged the foot and a pivot mounted on the hub, the module comprising a blade setting control device connected to the pivot,

- the height H2 of the fin is between 10 mm and 300 mm, more particularly between 50 mm and 300 mm, for example between 50 mm and 200 mm.

The invention also relates to a fan comprising a module according to any one of the preceding characteristics, the fan being shrouded or not shrouded.

The invention also relates to a turbine engine for an aircraft comprising a module according to any one of the preceding characteristics or the above fan.

Brief description of figures

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:

there is a schematic representation of an example of an aircraft turbine engine;

there is a schematic representation of another example of an aircraft turbine engine,

there is a schematic representation of another example of an aircraft turbine engine,

there is a cross-sectional view of a variable pitch angle vane according to the invention,

there is a simplified cross-sectional view of a variable-pitch vane according to the invention,

there is a cross-sectional view of a variable pitch angle vane according to the invention,

[Fig.5a-5r] Figures 5a-5r show alternative embodiments of the embodiment of the .

Detailed description of the invention

An aircraft turbomachine 1 is for example represented on the . The turbomachine 1 is according to this example a turbofan engine. According to an example not shown, the turbomachine 1 is a turboprop.

The turbomachine 1 extends along a longitudinal axis X. The turbomachine 1 comprises, from upstream to downstream in the direction of flow of the gases F along the longitudinal axis X, a fan 2, a compressor comprising for example a compressor low pressure 3, a high pressure compressor 4, a combustion chamber 5, a turbine comprising for example a high pressure turbine 6, a low pressure turbine 7, and a nozzle 8.

The rotor of the low pressure turbine 7 is connected to the rotors of the fan 2 and of the low pressure compressor 3 by a low pressure shaft 10. Advantageously, the rotor of the low pressure turbine 7 is connected to the rotor of the fan 2 by the intermediary of a speed reducer 11. The speed reducer 11 is arranged axially between the fan 2 and the low pressure compressor 3. The drive of the fan 2 via the speed reducer 11 makes it possible to increase the diameter of the fan 2 thus making it possible to obtain a higher dilution rate. Fuel consumption is therefore optimized. The speed reducer 11 comprises a ring gear 11a, satellites 11b and a planetary shaft carried by a planet carrier shaft 11c. In the example of the , the crown 11a is fixed in rotation and the planet carrier 11c is mobile in rotation. The planet carrier 11c is connected to the fan 2 and the crown 11a is connected to a fixed structure of the turbomachine 1. The speed reducer 11 is then called a planetary gear speed reducer. According to an alternative not shown, the planet carrier 11c is fixed in rotation and the crown 11a is mobile in rotation. It is connected to the fan 2. The speed reducer 11 is then of the planetary type.

The high pressure turbine rotor 6 is connected to the high pressure compressor rotor 4 by a high pressure shaft 9.

The blower 2 allows the suction of an air flow F0 dividing into a primary flow F1 and a secondary flow F2. The primary flow F1 passes through a primary flow of the turbomachine 1 while the secondary flow F2 is directed for example towards a secondary flow of the turbomachine 1.

The primary flow F1 is compressed within the low pressure compressor 3 then the high pressure compressor 4. The compressed air is then mixed with a fuel and burned within the combustion chamber 5. The gases formed by the combustion pass through the turbines high pressure 6 and low pressure 7. The gases finally escape through the nozzle 8 whose section allows the acceleration of these gases to generate propulsion for example.

The fan 2, the compressor or even the turbine are formed of a module extending around the longitudinal axis X. The module comprises a hub 12, vanes 13 with variable pitch angle mounted on the hub 12 and advantageously a control device 20 for setting the blades 13.

On the example of the , the fan 2 is equipped with such a module. The turbomachine 1 is known in the technical field of the invention by the acronym VPF for “Variable Pitch Fan” in English. According to this example, the hub 12 is annular. It internally delimits a circulation passage for the air flow F0 upstream of the primary and secondary veins. The hub 12 is for example rotatable around the longitudinal axis X.

According to the example of , the fan 2 comprises a first annular row 13a of vanes 13 with variable pitch angle mounted on the hub 12. The first annular row 13a of vanes 13 with variable pitch angle is rotatable about the longitudinal axis X According to this example, the annular row 13a of vanes with variable pitch angle is arranged inside a nacelle 15. The internal surface of the nacelle 15 externally delimits the secondary flow path of the secondary flow F2. According to this example, the fan 2 is therefore streamlined.

In the case of a turboprop (not shown), the first annular row 13a of variable-pitch angle vanes is not surrounded by the nacelle 15. The fan 2 is unducted.

According to another example shown in the , the fan 2 is also unducted. The fan 2 comprises a first annular row 13a of vanes 13 with variable pitch angle and a secondary annular row 13b of vanes 13, for example also with variable pitch angle, mounted on the hub 12. The first annular row 13a of vanes 13 and the second annular row 13b of vanes 13 are rotatable around the longitudinal axis X. The first and second annular rows 13a, 13b of vanes 13 with variable pitch angle are for example counter-rotating. Such a turbomachine 1 is known by the acronym CROR for “Contra Rotating Open Rotor” in English.

According to another example shown in the , the first annular row 13a of blades 13 is rotatable. An additional annular row 13b' of blades 13 fixed in rotation around the longitudinal axis X is mounted downstream of the fan 2 on a fixed hub 12a. Such a turbomachine 1 is known by the acronym USF for “Unducted Single Fan” in English.

The vanes 13 of the first row 13a and/or of the second row 13b and/or of the additional row 13b' have variable pitch angles.

Each vane 13 with variable pitch angle comprises a blade 16, a root 16b, a platform 17 and a fin 18.

The blade 16 extends radially with respect to the longitudinal axis X between a head 16a and the foot 16b. The blade 16 has a height H1 measured between the head 16a and the foot 16b for example between 700 mm and 2000 mm, for example between 700 mm and 800 mm for a turbomachine 1 of the VPF type and 1500 mm for a USF type turbomachine 1. The blade 16 is rotatable around an axis radial with respect to the longitudinal axis X, which passes through the center of the foot 16b and which constitutes the main axis of the blade 16.

The control device 20 is connected to the foot 16b of the blade 16 to cause the blade 16 to rotate via the foot 16b and adjust its orientation.

As best seen on the where vane 18 has been omitted for clarity, blade 16 has an airfoil. The blade 16 comprises a first leading edge 16c and a first trailing edge 16c', a first intrados face 16i and a first extrados face 16e connecting the first leading edge 16c to the first trailing edge 16c'. The blade 16 has a root profile chord C1 with a length between 200 mm and 700 mm, for example between 200 mm and 400 mm for a turbomachine 1 of the VPF type and between 400 mm and 700 mm for a turbomachine 1 USF type. The profile of the blade 16 has a maximum thickness E1 for example between 15 mm and 200 mm. For an architecture of the VPF or USF type, the maximum thickness E1 is for example between 15 mm and 60 mm and for a turboprop the maximum thickness E1 is for example between 60 mm and 200 mm.

Platform 17 is arranged directly on hub 12. According to another example, platform 17 may comprise a pivot (not visible) mounted on hub 12. The pivot is centered on platform 17. Control device 20 is then connected to the feet 16b via the pivot of the platform 17.

The platform 17 is rotatable around an axis of rotation extending radially with respect to the longitudinal axis X and passing through the center of the platform 17. The axis of rotation of the platform 17 coincides with the pivot axis and blade axis 16.

The platform 17 is circular and has a radius R1. The platform 17 has a diameter DR which extends along a tangential axis Y. The Y axis extends tangentially with respect to the longitudinal axis X. The platform 17 comprises an upstream edge 17a and a downstream edge 17b. The upstream and downstream edges 17a, 17b are semi-circular and symmetrical with respect to the tangential diameter DR. The upstream and downstream edges 17a, 17b meet at a first and a second opposite end. The upstream and downstream edges 17a, 17b are defined with respect to the flow direction of the flow F along the longitudinal axis X.

The platform 17 has a circular surface from which extend the blade 16 and the fin 18. The surface of the platform 17 comprises four sectors:

- a first upstream sector SAe delimited by the tangential diameter DR, the first extrados surface 16th of the blade 16 and the upstream edge 17a,

- a second upstream sector SAi delimited by the tangential diameter DR, the first intrados surface 16i of the blade 16 and the upstream edge 17a,

- a first downstream sector SAe' delimited by the tangential diameter DR, the first extrados surface 16e of the blade 16 and the downstream edge 17b,

- a second downstream sector SAi' delimited by the tangential diameter DR, the first intrados surface 16th of the blade 16 and the downstream edge 17b.

The blade 16 is for example centered on the platform 17. By centered on the platform 17, it is understood that the middle of the chord C1 coincides with the center O of the platform 17. The root 16b of the blade 13 is connected to the platform 17. The platform 17 comprises for example a housing (not visible) in its center O in which the foot 16b is arranged.

The length of the foot profile chord C1 may be greater than the diameter D1 of the platform 17. According to another example indicated in dotted lines on the , the length of the foot profile chord C1 may be equal to the diameter D1 of the platform 1. According to yet another example shown in thick solid lines, the length of the foot profile chord C1 may be less than the diameter D1 of platform 1.

As best seen on the Advantageously, the platforms 17 are interconnected in particular by an outer wall of the hub 12 delimiting an internal aerodynamic surface of the flow of the air flow F0 of the fan 2.

Furthermore, according to the invention, the blade 13 with variable pitch angle comprises at least one fin 18 in order to reduce separations on the intrados and/or extrados face 16i, 16e of the blade 16. The fin 18 is at the less partly formed on the platform 17 and extends radially relative to the longitudinal axis X from the platform 17 between a first end 18a 'and a second end 18b' opposite. The fin 18 has a height H2 measured between the first end 18a' and the second end 18b' lower than the height H1 of the blade 16. The height H2 of the fin 18 is for example between 10 mm and 300 mm, and more particularly between 50 mm and 300 mm and more particularly between 50 mm and 200 mm, depending in particular on the height H1 of the blade, and/or the turbulence to be processed. The height H2 of the fin 18 is for example less than or equal to 10% of the height H1 of the blade 16. The profile of the fin 18 has a maximum thickness E2 less than the maximum thickness E1 of the profile of the blade 16. The maximum thickness E2 is for example between 5 mm and 50 mm.

As best visible for example on the , the fin 18 has an aerodynamic profile. The fin 18 comprises a second leading edge 18c and a second trailing edge 18c', a second intrados face 18i and a second extrados face 18e connecting the second leading edge 18c to the second trailing edge 18c'. The fin 18 has a root profile chord C2 of a length less than the root profile chord C1 of the blade 16.

The fin 18 extends at least partly over the surface of the platform 17.

According to an exemplary embodiment, the first intrados face 16i is opposite the second extrados face 18e.

According to another exemplary embodiment, the first extrados face 16e faces the second intrados face 18i.

The fin 18 advantageously extends over the first upstream sector SAe. As shown on the , the first extrados face 16e of the blade 16 is opposite the second intrados face 18i of the fin 18. The fin 18 is arranged between the tangential diameter DR of the platform 17 and the upstream edge 17a of platform 17.

According to a variant embodiment, the fin 18 extends over the first downstream sector SAe'. As shown on the , the first extrados face 16e of the blade 16 is opposite the second intrados face 18i of the fin 18. The fin 18 is arranged between the tangential diameter DR of the platform 17 and the downstream edge 17b of the platform 17. Preferably, the respective master torque of the root profile of the blade 16 and of the fin 18 is located between 10% and 70% of the length of the chords C1, C2 of the root profile of the fin 18 and of the blade 16, preferably at 30%.

According to yet another variant embodiment, the fin 18 extends over the second upstream sector SAi. As shown on the , the first intrados face 16i of the blade 16 is opposite the second extrados face 18e of the fin 18. The fin 18 is arranged between the tangential diameter DR of the platform 17 and the upstream edge 17a of platform 17.

According to yet another variant embodiment, the fin 18 extends over the second downstream sector SAi'. As shown on the , the first intrados face 16i of the blade 16 is opposite the second extrados face 18e of the fin 18. The fin 18 is arranged between the tangential diameter DR of the platform 17 and the downstream edge 17b of platform 17.

According to yet another variant embodiment, the fin 18 extends astride the first upstream sector SAe and the first downstream sector SAe'. As shown on the , the first extrados face 16e of the blade 16 is opposite the second intrados face 18i of the fin 18.

Advantageously, the middle of the root profile chord C2 of the fin 18 is aligned with the middle of the root profile chord C1 of the blade 16.

According to a first example represented on the , the middle of the root profile chord C2 of the fin 18 is located equidistant from the middle of the root profile chord C1 of the blade 16 and the end of the platform 17. According to another example shown on the , the middle of the chord C2 of the foot profile of the fin 18 is relatively closer to the end of the platform 17 than to the center O of the platform 17.

According to another example shown in the , the middle of the foot profile chord C2 of the fin 18 is relatively closer to the center O of the platform 17 than the end of the platform 17.

According to yet another variant embodiment, the fin 18 extends astride the second upstream sector SAi and the second downstream sector SAi'. As shown on the , the first intrados face 16i of the blade 16 is opposite the second extrados face 18e of the fin 18.

Advantageously, the middle of the root profile chord C2 of the fin 18 is aligned with the middle of the root profile chord C1 of the blade 16.

According to a first example represented on the , the middle of the root profile chord C2 of the fin 18 is located equidistant from the middle of the root profile chord C1 of the blade 16 and the end of the platform 17. According to another example shown on the , the middle of the chord C2 of the foot profile of the fin 18 is relatively closer to the end of the platform 17 than to the center O of the platform 17.

According to another example shown in the , the middle of the foot profile chord C2 of the fin 18 can be relatively closer to the center O of the platform 17 than to the end of the platform 17.

According to yet another variant shown in Figures 5j to 5m, the fin 18 overlaps the upstream 17a or downstream 17b edge of the platform 17.

According to yet another variant shown in Figures 5n and 5o, the fin 18 overlaps one end of the platform 17 joining the upstream 17a and downstream 17b edges. The fin 18 straddles the platform 17 and the corresponding wall of the hub 12 at the edge of the platform 17. The fin 18 is according to this example partially provided on the platform 17 and is locally attached to the platform 17. According to In this example, there is play between hub 12 and fin 18.

Advantageously, variable pitch angle vane 13 comprises a plurality of fins 18. As shown in FIGS. 5p to 5r, a first fin 18a and a second fin 18b are provided on platform 17. First fin 18a and second fin 18b can be arranged according to any of the modes described above taken in combination with each other.

For example, and as illustrated in the , the blade 16 is arranged between the first fin 18a and the second fin 18b, the middles of the chords C1, C2 of the foot profile being aligned.

According to yet another example shown in the , the second intrados faces 18i of the first and second fins 18a, 18b face the first extrados face 16e of the blade 16. The first fin 18a is arranged between the tangential diameter DR and the downstream edge 17b of the platform 17. The second fin 18b is arranged between the tangential diameter DR and the upstream edge 17a of the platform 17.

According to yet another example shown in the , the second intrados face 18i of the first fin 18a faces the first extrados face 16th of the blade 16. The second extrados face 18th of the second fin 18b faces the first face intrados 16i of the blade 16. According to this example, the first fin 18a is arranged between the tangential diameter DR and the downstream edge 17b of the platform 17. The second fin 18b is arranged between the tangential diameter DR and the upstream edge 17a of the platform 17.

The fins 18, 18a, 18b according to the invention make it possible to guide the flow of the flow in the zone of the foot 16a of the blade 16. The fins 18, 18a, 18b thus make it possible to reduce the separation on the intrados 16i or extrados face. 16th of the blade 16. In addition, according to the invention, the orientation of the fins 18, 18a, 18b with respect to the blade 16 is constant thanks to the formation of the fins directly on the platform 17 carrying the blade 16.

Claims (11)

Module for an aircraft turbine engine (1), this module extending around a longitudinal axis (X) and comprising:
- a hub (12), and
- blades (13) with variable pitch angle mounted on the hub (12), each of the blades (13) comprising:
- a blade (16) extending radially relative to the longitudinal axis (X) between a head (16a) and a foot (16b), the blade (16) having a height (H1) and comprising a first edge d 'attack (16c) and a first trailing edge (16c'), a first intrados face (16i) and a first extrados face (16e) connecting the first leading edge (16c) to the first trailing edge (16c') ,
- a platform (17) connected to the foot (16b) and having a generally circular shape from which the blade (16) extends, the platform (17) being rotatable around an axis of rotation extending radially with respect to the longitudinal axis (X) and passing through the center of the platform (17) and
- at least one fin (18, 18a, 18b) provided at least in part on the platform (17), the fin (18, 18a, 18b) extending radially with respect to the longitudinal axis (X) from of the platform (17) between a first end (18a') and an opposite second end (18b'), the fin (18, 18a, 18b) having a height (H2) less than the height (H1) of the blade (16), and comprising a second leading edge (18c) and a second trailing edge (18c'), a second intrados face (18i) and a second extrados face (18e) connecting the second leading edge (18c ) to the second trailing edge (18c'). Module according to Claim 1, characterized in that the first extrados face (16e) faces the second intrados face (18i). Module according to Claim 1, characterized in that the first intrados face (16i) faces the second extrados face (18e). Module according to any one of the preceding claims, characterized in that the fin (18, 18a, 18b) has a chord (C2) of foot profile having a middle aligned with the middle of a chord (C1) of profile of the foot of the blade (16). Module according to any one of Claims 1 to 3, characterized in that the fin (18, 18a, 18b) is arranged between a tangential diameter (DR) of the platform (17) extending tangentially with respect to the longitudinal axis (X) of the module and an upstream edge (17a) of the platform (17). Module according to any one of Claims 1 to 3, characterized in that the fin (18, 18a, 18b) is arranged between a tangential diameter (DR) of the platform (17) extending tangentially with respect to the longitudinal axis (X) of the module and a downstream edge (17b) of the platform (17). Module according to any one of Claims 1 to 3, characterized in that the fin (18, 18a, 18b) overlaps an upstream (17a) or downstream (17b) edge of the platform (17). Module according to any one of the preceding claims, characterized in that the platform (17) comprises a housing in its center in which the foot (16b) and a pivot mounted on the hub (12) are arranged, the module comprising a device control (20) of the wedging of the blade (13) connected to the pivot. Module according to any one of the preceding claims, characterized in that the height (H2) of the fin 18 is between 10 mm and 300 mm, more particularly between 50 mm and 300 mm, for example between 50 mm and 200 mm . Fan (2) comprising a module according to any one of the preceding claims, the fan (2) being ducted or unducted. Turbomachine (1) for an aircraft comprising a module according to any one of Claims 1 to 9 or a fan (2) according to Claim 10.