Mobile wheel

Abstract

The present document presents a turbomachine wheel (3) comprising: a disk (6); an annular row of blades (4) extending from the disk (6); and a device (20-28) for modifying the respective center of gravity (G) of each blade (4), the device comprising: a reservoir (26) of liquid (22); at least one cavity (20) formed in each blade (4); a liquid conveying channel (24) fluidly connecting the reservoir (26) to the at least one cavity (20); and at least one valve (28) preventing or allowing the circulation of the liquid (22) from the reservoir (26) to the at least one cavity (20, 20', 20''). Abstract Figure: Figure 2

Description

Title of the invention: Mobile wheel Technical field

[0001] The present disclosure relates to the design of a moving wheel and in particular of a turbomachine fan. Prior art

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation result in moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] In this context, the future seems to be driven by the choice of certain turbomachine structures, and in particular unducted fan structures, which make it possible to obtain high engine efficiency.

[0005] Since the fan is not shrouded, the question of the safety of the passages in the event of failure of a fan blade arises.

[0006] Armoring the aircraft fuselage is a technical solution which has the disadvantage of adding weight to the aircraft, which therefore at least partially cancels out the gains obtained by designing a less energy-intensive engine.

[0007] Therefore, there is a need to ensure passenger safety in the event of damage to unducted fan turbomachine blades without penalizing the aircraft's energy efficiency. Abstract

[0008] The present invention thus aims to propose a mobile wheel which guarantees the safety of passengers without affecting the efficiency of the turbomachine.

[0009] For this purpose, the present document relates to a turbomachine mobile wheel comprising: a disc; an annular row of blades extending from the disc; and a device for modifying the respective center of gravity of each blade, the device comprising: a liquid reservoir; at least one cavity formed in each blade; a liquid conveying channel fluidly connecting the reservoir to the at least one cavity; and at least one valve preventing or allowing the circulation of liquid from the reservoir to the at least one cavity.

[0010] The inventors have highlighted the fact that the location of the center of gravity of the blade plays a role in their speed of degradation and in particular in the propagation of cracks or fissures. Thus, by acting on the position of the center of gravity, during use, it is possible to minimize the risk of propagation of a crack. The aircraft can thus land safely and the blade is replaced before the aircraft takes off again. This technology does not add significant weight to the aircraft and does not penalize the efficiency gains obtained by the configuration of a turbomachine with an unducted fan.

[0011] The displacement of the center of gravity of the blades has several consequences and in particular the modification of the vibration modes. Thus, the amplitude of the oscillations at the crack is reduced, limiting the effects of tearing or fatigue.

[0012] The liquid reservoir may be a single reservoir common to all the blades. Alternatively, the liquid may be contained in a plurality of capsules, specific to each blade, or specific to a group of blades (for example a pair of diametrically opposed blades). The reservoir is completely full or partially full at takeoff and the blade cavities are empty. In flight, an event may require the displacement of the centers of gravity of the blades, in particular the detection of the formation of a crack. The respective valve(s) open and allow the liquid to escape into the cavities. The liquid may escape into the cavities by centrifugal force or under pressure (either by initial pressurization or by pumping), the pressure being able to allow a reduced reaction time for the propagation of the liquid into the cavities. The targeted durations between the detection of an event and the release of the liquid may thus be as low as one millisecond.

[0013] Each blade may comprise one or more cavities, in order to carefully control the position of the center of gravity of the blade. A network of channels may be provided for conveying liquid into all the cavities.

[0014] Respective valves are provided: for each reservoir and / or for each cavity and / or for each channel. Alternatively, a single valve may be provided to open a single reservoir distributing the liquid to all the blades.

[0015] The valve(s) may be normally closed valves. They may incorporate a non-return valve.

[0016] According to one embodiment, the reservoir is arranged radially internal to the blades. Thus, the propulsion of the liquid can be passive in the sense that the centrifugal acceleration resulting from the rotation of the impeller can be used to move the liquid from the reservoir (radially closer to the axis of rotation than the blades) into the cavities.

[0017] Alternatively or in addition, the liquid may be under pressure in the tank. Therefore, opening the valve(s) allows it to escape into the cavities.

[0018] The channel connecting the reservoir to the cavity can advantageously open radially internally at the blade. It is thus at a distance from the aerodynamic surfaces guiding the air flow.

[0019] According to one embodiment, the at least one cavity comprises a first cavity and a second cavity, arranged in series or in parallel.

[0020] The first and second cavities may be arranged in series. In this case, a channel connects the reservoir to the first cavity and a second channel connects the first cavity to the second cavity. The cavities may be substantially axially aligned and they may have a distinct radial position: the second cavity is further from the axis of rotation and will be filled first.

[0021] Alternatively, the first and second cavities may be arranged in parallel. It is thus possible to fill the cavities independently of each other.

[0022] The first and second cavities can have different capacities: it is thus possible to finely regulate the position of the center of gravity of the blade, by filling a smaller or a larger cavity as desired. Also, it is possible to provide a filling sequence to choose the velocity with which the changes take place: quickly modify the position of the center of gravity or on the contrary avoid modifying the dynamics of the moving wheel too abruptly.

[0023] The choice of the sequencing of filling the cavities can be linked to the rotation speed of the moving wheel or to a severity threshold of the defect detected on the blades.

[0024] The first and second cavities may be supplied by the same reservoir, synchronously or not. Alternatively, a reservoir dedicated to each cavity may be provided.

[0025] According to one embodiment, the at least one cavity is arranged in a radially inner half of the blade. It is in this area that the cracks are statistically located. It is thus possible to optimize the position of the cavities so that they add weight radially below the cracks, thus radially lowering the center of gravity of the blades. The cavity can potentially be partly located in the root of the blade, i.e. a portion circumferentially wider than the blade of the blade which directs the air flow.

[0026] According to one embodiment, the at least one cavity is arranged in one half axially downstream of the blade. Since cracks generally appear on the leading edge, it may be advisable to protect the cavities by arranging them downstream, so that if the cracks propagate, they do not reach the cavities.

[0027] According to one embodiment, the at least one cavity has a larger direction which is inclined relative to the radial direction by an angle of between 30 and 60°. Such a cavity makes it possible to both shift the center of gravity radially inwardly and downstream.

[0028] According to one embodiment, the at least one cavity has a volume of between 2% and 5% of the volume of material of the blade. Such a value range is a good compromise for obtaining a notable effect on the position of the center of gravity of the blade without unnecessarily weighing down the engine assembly.

[0029] According to one embodiment, the channel has an axial width at least 5 times smaller than the axial width of the at least one cavity. The ratio of their circumferential widths may be of the same order. Alternatively, the circumferential width of the channel may be identical to that of the cavity and may be approximately one third of the circumferential thickness of the blade.

[0030] According to one embodiment, the device for modifying the center of gravity comprises means for detecting the formation of a crack on each blade and control means controlling the opening of the at least one valve following the detection of the formation of a crack.

[0031] If other events (acoustic, vibratory, etc.) may require moving the center of gravity, the present disclosure focuses more particularly on the formation of a defect (crack, fissure) on a blade. A strain gauge, the detection of an unbalance or the visual detection of a crack, may be techniques used to identify the formation of a crack on a blade. Following the detection of such a defect, one or more valves may be opened to modify the position of the center(s) of gravity of the blades. Preferably but not limitingly, all the blades are simultaneously supplied with liquid to move their center of gravity accordingly. The detection of a crack may be accompanied by the quantification of a level of deterioration, for example discrete (low, medium, or high deterioration) and the filling of the cavities may be correlated to the level of deterioration of the blade.Filling the cavities can also help to maintain the position of the center of gravity of the rotating assembly on the axis of rotation, by folding the cavities appropriately to correct an imbalance that could occur during operation, for example in the event of damage to a blade.

[0032] According to one embodiment, the reservoir is carried by the disc in a position close to the axis of rotation of the moving wheel. Thus, the reservoir does not constitute an additional mass to be rotated during normal operation.

[0033] According to one embodiment, the liquid has a density of between 1 and 5 g / cm3. This density makes it possible to guarantee good control of the change in the position of the center of gravity: higher densities, often for heavy and toxic metals, would, for a small difference between the theoretical volume and the actual volume transmitted to the cavities, have too great an influence on the position of the center of gravity. Conversely, lower densities require too large a volume of liquid to impact the position of the center of gravity, and therefore a very bulky reservoir in the turbomachine. The liquid used may be, for example, glycerin or dibromine. Alternatively, any liquid available in sufficient quantity in the turbomachine may be used (fuel, oil, etc.), and the reservoir of the device may be the main fuel or oil reservoir.

[0034] The invention also relates to a method of using a movable wheel according to one of the embodiments mentioned above, the method comprising: rotating the movable wheel; and while the movable wheel is rotating, moving the center of gravity of the blades by conveying liquid into at least one of the cavities of each blade.

[0035] As mentioned above, the flow of liquid can result from the opening of valves, simultaneously or not.

[0036] According to one embodiment, the liquid delivery is controlled according to a sequence chosen as a function of the rotational speed of the moving wheel. For example, when the rotational speed of the moving wheel (and therefore the engine speed) is greater than a threshold value, it may be harmful to alter the position of the centers of gravity of the blades too abruptly (due in particular to a sudden variation in the resistive torque on the shaft). Progressive filling, by alternately opening and closing the valves, or by progressive filling of different cavities, will be preferred. Alternatively, progressive filling by pairs of diametrically opposed blades may be chosen. When the rotational speed is lower than a (other) threshold value, all of the cavities of all the blades may be filled simultaneously.

[0037] Other criteria may be used for the selection of the sequencing (for example, temperature, aircraft speed, altitude, etc.).

[0038] The invention also relates to a turbomachine comprising a fan consisting of a moving wheel according to one of the embodiments mentioned above. Alternatively or in addition, the moving wheel mentioned above may constitute a moving compressor wheel.

[0039] The invention also relates to a turbomachine blade comprising at least one cavity intended to receive and contain a liquid and at least one channel for conveying liquid towards the at least one cavity.

[0040] As mentioned above, according to certain embodiments: the conveying channel opens radially internally to the blade; and / or the at least one cavity comprises a first cavity and a second cavity, arranged in series or in parallel; and / or the at least one cavity is arranged in a radially internal half of the blade; and / or the at least one cavity is arranged in an axially downstream half of the blade and / or the at least one cavity has a volume of between 2% and 5% of the volume of material of the blade; and / or the channel has an axial width at least 5 times smaller than the axial width of the at least one cavity.

[0041] It has been found that moving the center of gravity dynamically during use makes it possible to protect the passengers of an aircraft without having to provide armoring which would weigh down the aircraft and penalize the energy efficiency of a flight. Also, the solution envisaged is compact, light and reliable. Brief description of the drawings

[0042] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0043] [Fig-1] is a schematic sectional view of a turbomachine;

[0044] [Fig.2] is a sectional view of a moving wheel;

[0045] [Fig.3] is a radial view from below of a blade;

[0046] [Fig.4] is a sectional view of a blade;

[0047] [Fig.5] is a sectional view of a blade. Description of the embodiments

[0048] In the following description, the terms "internal" and "external" refer to a positioning relative to the axis of rotation of a turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine or the moving wheel. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the direction of flow of a stream in the turbomachine.

[0049] The figures show the elements schematically and are not drawn to scale. In particular, certain dimensions are enlarged to facilitate reading of the figures.

[0050] [Fig.l] illustrates a turbomachine 2. An unducted fan 3 (or “propeller” or “fan”) has an annular row of blades 4 secured to a hub 6 (or “rotor”) which rotates around an axis 8.

[0051] The turbomachine 2 moves in an air flow F whose movement relative to the turbomachine 2 is generated by the rotation of the fan 3 and the advancement of the aircraft.

[0052] In a variant not illustrated, the fan 3 is arranged in a downstream part of the turbomachine 2 and may optionally be supplemented with a second propeller having an opposite direction of rotation.

[0053] The air flow F is split into a primary flow F1 and a secondary flow F2 at a separation nozzle 10. The primary flow F1 encounters a rectifier inlet vane (“IGV”) 11 and enters a vein 12 while the secondary flow F2 remains radially outside any fairing. The compressor blades 13 to 16 compress the primary flow for entry into a combustion chamber (not shown).

[0054] [Fig. 1] shows in dotted lines the possible position of an annular row of blades 18, fixed around the axis 8 and straightening the flow F2. The blades 18 as well as the vanes 4 of the fan 3 can have a variable orientation (around the direction of their largest dimension).

[0055] Since the fan 3 is not shrouded, no casing element prevents, in the event of failure, a blade 4 or a part thereof from detaching and damaging the structure of the aircraft and / or threatening the health of the passengers. The present disclosure therefore aims to guard against this risk.

[0056] [Fig.2] illustrates a first example of a moving wheel 3. The moving wheel 3 of the present disclosure may relate to the fan of [Fig.2] or alternatively a compressor moving wheel.

[0057] The mobile wheel 3 comprises an annular row of blades 4, distributed circumferentially around the rotor which here takes the form of a disc 6, with an axis of symmetry the longitudinal axis 8 of the turbomachine. Each blade has a root 4.1 which may be in the form of a dovetail, linked to a corresponding groove in the disc 6. The blade 4 extends mainly in a radial direction up to its external radial end 4.2. The radial height of the blade 4 is noted H.

[0058] The blade 4 comprises a leading edge 4.3 and a trailing edge 4.4. The axial length, i.e. the maximum distance along the axis 8 between the leading edge 4.3 and the trailing edge 4.4 is denoted L.

[0059] The blade 4 has a center of gravity denoted G, that is to say the center of mass for the blade 4 considered alone, in its nominal dimensions.

[0060] In order to modify the position of the center of gravity G, the following device is provided: the blade 4 comprises a hollow and sealed cavity 20, capable of receiving and containing a liquid 22. The cavity 20 can take different shapes or dimensions. The cavity 20 can be formed during the manufacture of the blade 4 (additive manufacturing, or lost wax casting for example). Alternatively, the cavity 20 can be hollowed out after the manufacture of the blade 4.

[0061] The liquid 22 reaches the cavity 20 via a channel 24 connected to a reservoir 26. A valve 28 allows the passage of the liquid 22 from the reservoir 26 to the cavity 20 to be authorized or prohibited.

[0062] The liquid 22 may have a density of between 1 and 5 g / cm3. Its viscosity allows it to flow into the channel 24 with a section much smaller than that of the cavity 20.

[0063] The rotation of the movable wheel 3 induces a centrifugal acceleration for the liquid 22 which is here represented at the top of the cavity 20 and at the top of the reservoir 26, the valve 28 being closed in the illustrated configuration.

[0064] By introducing liquid 22 into the cavity 20, the center of gravity G of the blade 4 has been moved to occupy the position Gl, since the cavity 20 was initially empty. In this example, Gl is radially closer to the axis 8 but other configurations are also possible.

[0065] In this example, the channel 24 fluidly connecting the reservoir 26 to the cavity 20 is illustrated as extending purely radially but other designs are possible. The channel 24 may open radially internally at the root 4.1 of the blade 4. The channel 24 as well as a portion of the cavity 20 may be formed in the root 4.1 of the blade 4. The channel 24 is schematically represented as a single element but it may be formed of several sub-elements communicating with each other and in particular a portion of the channel may be part of the disk 6. Preferably, the channel 24 is directly formed in the solid parts (disk and blade). Alternatively, a pipe may be attached to these elements to act as a channel.

[0066] The reservoir 26 is here radially inside the blade 4 and axially aligned with the blade 4. Alternatively, the reservoir 26 can be offset axially upstream or downstream. Also, the reservoir 26 is here illustrated as rotating but it can alternatively be arranged at a fixed location of the turbomachine, a rotating joint being able to be provided to fluidically connect the rotating blades 4 to the fixed reservoir 26.

[0067] As mentioned previously, the reservoir 26 can be arranged in the center of the disk 6 in a position close to, or aligned with, the axis 8. Alternatively, as many reservoirs 26 as there are blades can be provided, in particular in the form of capsules embedded in the root of the blade.

[0068] [Fig.2] shows a single reservoir and a single valve 28 but it is understood that the device can contain as many reservoirs as there are blades 4, or even as many reservoirs as there are channels 24 or cavities 20 present in each blade 4.

[0069] Advantageously, the modification of the position of the center of gravity G can be carried out following the detection of the formation of a crack 30 by means of a detector 32 which can be of any type (strain gauge, vibration detection element, optical detector, etc.).

[0070] Control means (not shown) control the opening of the valve 28 as a function of detection of the start of formation of a crack by the detector 32.

[0071] The cavity 20 can be arranged radially in the inner half (H / 2) of the blade 4 and / or in the downstream half (L / 2) of the blade 4. These positions provide the advantages discussed above.

[0072] [Fig. 3] shows a bottom view of the blade 4 in a plane perpendicular to the radial direction R. It shows in particular the channel 24 which is here represented with a circular section of diameter d. Other sections are naturally conceivable. The cavity 20, hidden, is represented in dotted lines. The cavity 20 has a dimension in a direction substantially parallel to the chord which is noted 1 and the cavity 20 has a thickness e in the direction of the thickness of the blade 4. (It will be assumed here for simplification that the axial length L is measured substantially parallel to the chord of the blade 4 but other blade orientations are conceivable). The ratio 1 / L can be between 0.10 and 0.30. The ratio e / E can be between 0.10 and 0.60. The diameter d of the channel 24 can be less than one fifth of 1.

[0073] [Fig. 4] shows a variant of blade 4. In this design, blade 4 comprises three cavities 20, 20', 20” arranged in series, i.e. a first channel 24 communicates with the first cavity 20, a second channel 24' connects the first cavity 20 to the second cavity 20' and a third channel 24' connects the second cavity 20' to the third cavity 20”. In the example illustrated, the third cavity 20” is at a greater radial distance from the axis 8 than the other cavities and will therefore (by centrifugal force) be the first to be filled with a liquid (liquid which has passed through the first and second cavities as well as through the three channels 24, 24' and 24”).

[0074] The geometric centers of the cavities 20, 20', 20” are respectively noted a, b, c. The average radius of the cavities is noted Ra, Rb, Rc.

[0075] Thus, the displacement vector D, from the center of gravity G to G1 can be calculated as a function of the position of the cavities and their filling volume.

[0076] For example, the following formulation can be used: the radius of point Gl, modified center of gravity, verifies the following equality: Where Volcavity is the volume of liquid contained in cavities a, b, or c; p is the density of the material constituting the blade or the liquid; R(G1) is the radius of point Gl; and R(G) is the radius of point G.

[0077] The same calculation can be carried out in the other directions of space (axial and circumferential).

[0078] The volume contained in the channels 24 being much lower (< 10%) than the volume contained in the cavity, the volume of liquid contained in the channels 24 is negligible during these calculations.

[0079] It is thus possible to control a desired displacement of the center of gravity by supplying each cavity with a chosen volume of liquid.

[0080] [Fig.4] also shows that at least one of the cavities (here cavity 20) can have a larger direction which is inclined relative to the axial direction. This inclination is here materialized by the angle a.

[0081] [Fig.5] shows a variant in which the cavities 20, 20' are arranged in parallel.

[0082] This configuration makes it possible to independently fill the cavity 20 and the cavities 20' and 20”. Separate channels 24 connecting the reservoir (or separate reservoirs) may be provided for this purpose. Separate valves (not shown) may complete this device.

[0083] The volume of the cavity 20 (or the cumulative volume of the cavities 20, 20', 20” of the blade 4) may be between 2% and 5% of the volume of material of the blade.

[0084] The present disclosure also relates to the method of modifying the position of the center of gravity of the blades while the moving wheel rotates. As mentioned above, depending on certain parameters and in particular the rotation speed, the sequencing of the filling (total or partial) of the cavities can be adapted, for example to gradually move the center of gravity.

[0085] It is understood that the illustrations are only examples and the invention cannot be limited to a particular number or shape of cavities, or to a type (series / parallel) of channel network.

[0086] Finally, while the present disclosure focuses on the detection of cracks or fissures, other parameters may be used to induce a displacement of the center of gravity of the blades. For example, the radially outward displacement of the center of gravity may generate a resistive torque that may assist a rapid decrease in the rotational speed of the wheel, for example in an emergency situation.

Claims

Claims

1. A mobile wheel (3) of a turbomachine (2) comprising: a disk (6); an annular row of blades (4) extending from the disk (6); and a device (20-28) for modifying the respective center of gravity (G) of each blade (4), the device comprising: a reservoir (26) of liquid (22); at least one cavity (20, 20', 20”) formed in each blade (4); a liquid conveying channel (24) fluidly connecting the reservoir (26) to the at least one cavity (20, 20', 20”); and at least one valve (28) preventing or allowing the circulation of the liquid (22) from the reservoir (26) to the at least one cavity (20, 20', 20”).

2. A movable wheel (3) according to claim 1, wherein the reservoir (26) is arranged radially internal to the blades (4).

3. A mobile wheel (3) according to one of the preceding claims, wherein the at least one cavity (20, 20', 20”) comprises a first cavity (20) and a second cavity (20', 20”), arranged in series or in parallel.

4. A movable wheel (3) according to one of the preceding claims, wherein the at least one cavity (20, 20', 20”) is arranged in a radially inner half of the blade (4).

5. A movable wheel (3) according to one of the preceding claims, wherein the at least one cavity (20, 20', 20”) is arranged in an axially downstream half of the blade (4).

6. A movable wheel (3) according to one of the preceding claims, wherein the at least one cavity (20, 20', 20”) has a larger dimension direction which is inclined relative to the radial direction (R) by an angle (a) of between 30 and 60°.

7. Movable wheel (3) according to one of the preceding claims, in which the at least one cavity (20, 20', 20”) has a volume of between 2% and 5% of the volume of material of the blade (4).

8. Mobile wheel (3) according to one of the preceding claims, in which the channel (24) has an axial width (d) at least 5 times smaller than the axial width (c) of the at least one cavity (20, 20', 20”).

9. Mobile wheel (3) according to one of the preceding claims, in which the device for modifying the center of gravity (G) comprises

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20. means (32) for detecting the formation of a crack (30) on each blade (4) and control means controlling the opening of the at least one valve (28) following detection of the formation of a crack (30). Movable wheel (3) according to one of the preceding claims, in which the reservoir (26) is carried by the disc (6) in a position close to the axis (8) of rotation of the movable wheel (3). Movable wheel (3) according to one of the preceding claims, in which the liquid (22) has a density of between 1 and 5 g / cm3. A method of using a movable wheel (3) according to one of the preceding claims, the method comprising: rotating the movable wheel (3); and while the movable wheel (3) is rotating, moving the center of gravity (G) of the blades (4) by conveying liquid (22) into at least one of the cavities (20, 20', 20”) of each blade (4). Method according to the preceding claim, in which the conveyance of liquid (22) is controlled according to a sequence chosen as a function of the rotation speed of the moving wheel (3). Turbomachine (1) comprising a fan (3) consisting of a mobile wheel (3) according to any one of claims 1 to 13. Turbomachine blade (4) comprising at least one cavity (20, 20', 20”) intended to receive and contain a liquid and at least one channel for conveying liquid towards the at least one cavity (20, 20', 20”). Blade (4) according to the preceding claim, in which the conveying channel (24) opens radially internally to the blade (4). Blade (4) according to one of claims 15 or 16, in which the at least one cavity (20, 20', 20”) comprises a first cavity (20) and a second cavity (20', 20”), arranged in series or in parallel. Blade (4) according to one of claims 15 to 17, wherein the at least one cavity (20, 20', 20”) is arranged in a radially inner half of the blade (4). Blade (4) according to one of claims 15 to 18, in which the at least one cavity (20, 20', 20”) is arranged in an axially downstream half of the blade (4). Blade (4) according to one of claims 15 to 19, in which the at least one cavity (20, 20', 20”) has a volume of between 2% and 5% of the volume of material of the blade (4).

21. Blade (4) according to one of claims 15 to 20, in which the channel (24) has an axial width (d) at least 5 times less than the axial width (c) of the at least one cavity (20, 20', 20”).

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