Variable timing stator vane for an aircraft turbomachine
The variable-pitch stator blade with a metallic trailing edge and elastomer leading edge with serrations addresses noise reduction challenges by adapting serration geometry to engine speed, enhancing noise reduction and durability.
Patent Information
- Application Number
- FR2023013824
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-12-08
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2043-12-08
AI Technical Summary
Existing aircraft turbomachine propeller blades with serrations for noise reduction face issues such as material fragility, complexity in production, and increased noise during thrust reversal modes, which are not effectively addressed by current technologies.
A variable-pitch stator blade design using a combination of metallic or composite material for the trailing edge and an elastically deformable material, such as an elastomer, for the leading edge with serrations, connected via an actuation system outside the blade, allowing adaptive geometry and noise reduction across various engine speeds.
The design effectively reduces noise across different engine operating conditions, including thrust reversal, while minimizing material fragility and manufacturing complexities, by enabling elastic deformation of the serrations based on engine speed and aerodynamic pressures.
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Abstract
Description
Title of the invention: Variable timing stator blade for an aircraft turbomachine Technical field of the invention
[0001] The present invention relates to a variable-pitch stator blade for an aircraft turbomachine. Technical Downstream Plan
[0002] The state of the art includes in particular document FR-A1-3 073 017.
[0003] An aircraft turbomachine conventionally comprises a gas generator that drives at least one propeller. The gas generator includes at least one compressor, one combustion chamber, and at least one turbine. The rotor or one of the rotors of the gas generator is connected to the propeller rotor for its rotational drive.
[0004] A propeller can be shrouded. This is the case of a fan in a turbomachine of the turbojet or turbofan type for example.
[0005] A propeller may be unfaired. This is the case of a turboprop engine, for example.
[0006] A propeller comprises a hub and an annular row of blades which are mounted all around the hub. The blades can be fixed and therefore have a fixed angular position around their elongation axes.
[0007] In the context of the present invention, the blades, on the contrary, have variable pitch, that is to say, they are capable of being moved in rotation about axes called pitch axes, which generally extend along the axes of extension of the blades. The pitch axes may be radial axes with respect to the axis of rotation of the propeller.
[0008] A variable-pitch rotor blade conventionally comprises a blade having an upper and lower surface, as well as a leading and trailing edge, and a platform connected to one end of the blade and defining the blade pitch axis. The platform is generally mounted in an opening in the hub and centered and guided in rotation within this opening around the pitch axis.
[0009] It is known to produce such blades from metallic, ceramic, or composite materials. A well-known composite material for a variable-pitch rotor blade comprises a body based on woven carbon fibers embedded in a polymer matrix, such as an epoxy-based matrix. The leading edge of the blade can be reinforced by a bonded metallic shield.
[0010] The evolution of turbomachine performance tends towards an increase in their bypass ratio, which is mainly achieved by increasing the diameter of the propellers and therefore the length and mass of their blades.
[0011] In addition, a so-called slow and high bypass ratio propeller comprises a reduced number of blades whose chord is increased to improve the propulsive efficiency of the turbomachine.
[0012] In the case of a shrouded propeller, the nacelle surrounding the propeller includes an internal acoustic treatment which reduces noise emissions outside the turbomachine.
[0013] In the case of an unfaired propeller, other solutions must be found for reducing propulsion noise. This is particularly the case for the turbomachine illustrated in [Fig. 1]. This turbomachine 10 comprises an upstream propeller 12, which includes rotor blades 14 with variable pitch, and a downstream stator 16, which includes stator blades 18 also with variable pitch.
[0014] To remedy the noise emission problem, a noise reduction technology already known on fans and inspired in particular by the wings of nocturnal birds of prey consists of providing serrations 20 on the trailing edges of the rotor blades 14 or on the leading edges of the stator blades 18 (figures 2 and 3).
[0015] Serrations 20 of a leading or trailing edge are formed by an alternation of teeth 20a and hollows 20b along this edge. The serrations can cause variations in the blade chord as a function of the radial height, with varying thicknesses and a very thin leading or trailing edge.
[0016] The teeth 20a are defined so as to reduce noise in the mid-emission spectrum without significantly worsening other frequencies at other engine speeds.
[0017] The angular setting of the blades implies variable acoustics of the blades depending on the engine speed and the orientation of the blades.
[0018] It has been observed that, in most engine operating conditions, serrations help to reduce noise. However, a significant increase in noise has also been observed when the blades are set in reverse or thrust reversal mode. In the case of a rotor blade, the trailing edge serrations are oriented upstream in reverse mode, which greatly disrupts the aerodynamic flow. The serrations then become counterproductive.
[0019] The thrust reversal phase is a phase which, on the contrary, should be as quiet as possible because it generally takes place in a nearby urban environment.
[0020] Another disadvantage of the prior art is that the serrations cannot be made of the same material as the woven or ceramic blades because the serrations are too thin, and they would be too fragile and in particular brittle.
[0021] For metal blades, the problem stems from the risk of serrations tearing off and the complexity of producing these serrations, which leads to significant scrap due to geometric defects.
[0022] The present invention offers a solution to at least some of the problems of the prior art, which is simple, effective, and economical. Summary of the invention
[0023] The invention relates to a variable-pitch stator blade for an aircraft turbomachine, this blade comprising:
[0024] - a blade comprising an intrados and an extrados, as well as a leading edge and a trailing edge, the leading edge of the blade featuring serrations formed by an alternation of teeth and hollows,
[0025] - a platform connected to one end of the blade and defining a pitching axis dawn,
[0026] characterized in that the blade comprises:
[0027] - a first body made of metallic or composite material defining the trailing edge of the blade, and
[0028] - a second body made of elastically deformable material defining at least one part of the leading edge of the blade and including at least part of the serrations, the second body being fixed to the first body and connected to an actuation system which is located entirely outside the blade.
[0029] The invention thus proposes to make the rotor blade from two distinct materials. The first body of the blade is made of a metallic or composite material and includes the trailing edge of the blade. The second body of the blade is made of an elastically deformable material such as an elastomer. This second body defines at least part of the leading edge and includes all or part of the serrations. It is therefore understood that these serrations are made of an elastic material and are capable of elastic deformation.
[0030] The elastic deformation of the second body, and therefore of the leading edge, is caused by the actuation system, which is offset from the blade. This actuation system therefore has little or no impact on the design and manufacture of the blade.
[0031] The invention allows, for example, the integration of variability in the geometry and radial position of the serration teeth as a function of engine speed and aerodynamic pressure forces exerted by the airflow during operation. Since a rotor blade tends to untwist under centrifugal force, it is advantageous to have a deformable material to avoid interfering with the internal forces within the blade and its proper operation.
[0032] The second body is fixed to the first body, for example by gluing, as is the case with a shield of the prior art.
[0033] The blade according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - the second body defines the entire leading edge of the blade and includes all the serrations; - the second body extends over the entire longitudinal extent of the blade along the pitch axis; - the second body defines an upstream part of the intrados and extrados of the blade; - the second body is connected to at least one actuation finger on the side of said platform; - this actuating finger passes through at least one opening in the platform; - said at least one actuation finger has an elongated shape along the alignment axis; - the platform opening has a curved shape and extends circumferentially around the alignment axis, at a predetermined angle, the actuating finger being able to move circumferentially in this opening; - the actuating finger is able to come into contact with at least one of the circumferential ends of the orifice and to transmit to the second body a force which is a function of a force generated by the contact of the actuating finger on this end; - at least some of the teeth are hollow and include, for example, internal cavities; the cavities allow the dynamic behavior of the teeth to be modified during operation; - at least some of the teeth are full.
[0034] The present invention also relates to an assembly comprising a blade as described above and a stator housing, the stator housing being fixed and the blade being mounted on the stator housing so that its platform is mobile in rotation around the alignment axis with respect to the housing.
[0035] The assembly according to the invention may comprise one or more of the following features, taken individually or in combination with each other:
[0036] - the housing includes a housing for receiving a free end of the finger actuation;
[0037] - the free end of the actuating finger is mounted without play in the housing of so as to be fixed relative to the casing during a rotation of the platform around the alignment axis;
[0038] - in which the housing has a curved shape and extends in a circumferential direction around the alignment axis, at a predetermined angle, the actuating finger being able to move in a circumferential direction within this housing;
[0039] - the actuating finger is able to bear against at least one of the ends circumferential of the housing and to transmit a force to the second body which is a function of a force generated by the pressure of the actuating finger on this end.
[0040] The invention further relates to a turbomachine for an aircraft, comprising a rotor equipped with blades as described above. Brief description of the figures
[0041] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:
[0042] [Fig-1] [Fig.1] is a schematic perspective view of a turbomachine unfaired propeller and unfaired straightener, the propeller and straightener having variable pitch blades;
[0043] [Fig.2] [Fig.2] is a schematic view of a variable pitch rotor or propeller blade;
[0044] [Fig.3] [Fig.3] is a schematic view of a stator or rectifier blade with variable pitch;
[0045] [Fig.4] [Fig.4] is a schematic view of a stator or rectifier blade with variable pitch, according to one embodiment of the invention;
[0046] [Fig.5] [Fig.5] is a schematic view of a variable-pitch stator or rectifier blade, according to an embodiment of the invention, and further shows a stator housing associated with this blade;
[0047] [Fig.6] [Fig.6] is a cross-sectional view along line VLVI of [Fig.5];
[0048] [Fig.7a-7b] Figures 7a and 7b are views similar to that of [Fig.6] and show two positions for blade alignment and deformation of its leading edge; and
[0049] [Fig. 8a-8b] Figures 8a and 8b are views similar to those of Figures 6a and 6b and show a variant of the realization of the two blade alignment positions and deformations of its leading edge. Detailed description of the invention
[0050] Figures 1 to 3 have been described above.
[0051] The invention relates to a variable-pitch stator blade for an aircraft turbomachine, which may be the turbomachine of [Fig.1] or another turbomachine.
[0052] Figure 4 illustrates a first embodiment of a stator blade 30 according to the invention. This is a variable-pitch stator blade 30 for an aircraft turbomachine, which comprises:
[0053] - a blade 32 comprising an intrados 32a and an extrados 32b, as well as an edge a leading edge 32c and a trailing edge 32d, and
[0054] - a platform 34 connected to one end of the blade 32 and defining an axis A of blade alignment 30.
[0055] The leading edge 32c of the blade 32 has serrations 35 formed by an alternation of teeth 35a and hollows 35.
[0056] The distinctive feature of the blade 30 is that its blade 32 comprises:
[0057] - a first body 36 made of metallic or composite material defining the edge of leak 32d of blade 32, and
[0058] - a second body 38 made of elastically deformable material defining at least a part of the leading edge 32c of the blade 32 and comprising at least part of the serrations 35, the second body 38 being fixed to the first body 36.
[0059] As can be seen in the drawing, the platform 34 can be made of the first material. The first body 36 and the platform 34 can be made monolithically.
[0060] In the example shown in [Fig.4], the second body 38 defines the entire leading edge 32c of the blade 32 and includes all the serrations 35.
[0061] The second body 38 can extend over the entire longitudinal extent of the blade 32 along the pitch axis A.
[0062] In the example shown in [Fig.5], the second body 38 defines only a part of the leading edge 32c of the blade 32 and includes a part of the serrations 35.
[0063] The second body 38 can extend over approximately 50 to 80% of the longitudinal extent of the blade 32 along the pitch axis A.
[0064] The second body 38 is preferably made of elastomer.
[0065] The second body 38 can define a downstream part of the intrados 32a and the extrados 32b of the blade 32.
[0066] The second body 38 can be fixed to the first body 36 by gluing it to the body 36.
[0067] In the embodiment shown in Figures 4 and 5, the teeth 35a are solid. It can be seen that these teeth 35a can have different shapes and / or dimensions, all the teeth 35a being able to be different.
[0068] Alternatively, the teeth 35a or at least some of the teeth could be hollow and include internal cavities that are empty or filled, for example, with weights (not shown).
[0069] The second body 38 can define an upstream part of the intrados 32c and the extrados 32d of the blade 32.
[0070] To allow elastic deformation of the second body 38, the second body 38 is advantageously connected to an actuation system which preferably includes at least one actuation finger 40 located on the side of the platform 34.
[0071] The actuation system and therefore the actuation finger 40 is entirely located outside the blade 32.
[0072] This actuating finger 40 has an elongated shape along a direction of movement of the second body 38 vis-à-vis the first body 36. This direction is preferably parallel to the axis A.
[0073] The platform 34 may include at least one orifice 42 through which the actuating finger 40 passes.
[0074] In the context of the present invention, the combination of a stator blade 30 as described above with a stator housing 50 is called an “assembly”.
[0075] The stator housing 50 is fixed and the blade 30 is mounted on the stator housing 50 so that its platform 34 is mobile in rotation around the alignment axis A vis-à-vis the housing 50.
[0076] Advantageously, a rotation of the platform 34 around the alignment axis A causes, over all or part of its stroke, a torque force on the second body 38 which will then deform elastically.
[0077] Figures 5 and 6 show an example of an embodiment of the platform 34 and the stator housing 50.
[0078] The orifice 42 of the platform 34 has a curved shape and extends in a circumferential direction around the alignment axis A, over a predetermined angle a.
[0079] The actuating finger 40 is able to move in a circumferential direction in the orifice 42. The actuating finger 40 is able to come to rest on at least one of the circumferential ends of the orifice 42 and to transmit a force to the rest of the second body 38 which is a function of a force generated by the bearing of the actuating finger 40 on this end.
[0080] The free end of the finger 40 is here engaged in a housing 52 of the housing 50.
[0081] This housing 52 can have a shape complementary to that of the free end of the finger 50 so that the second body 38 is deformed from a first rotation of the blade 30 around its alignment axis A.
[0082] Alternatively, the orifice 52 could have a curved shape like the orifice 42, and extend circumferentially around the alignment axis A, over a predetermined angle.
[0083] The orifice 42 and the housing 52 may or may not have different angular ranges depending on the desired deformations for the second body 38. In the case where the orifice 42 and the housing 52 have the same angular range, they are preferably angularly offset from each other around axis A. In the case they have different angular extents, they can be superimposed and centered with respect to each other, or they can also be offset.
[0084] The position of the end of the finger 40 in the orifice 42 and the housing 52, when the turbomachine is stopped or at rest, can be chosen according to the deformations envisaged for the different engine speeds.
[0085] Figures 7a and 7b, on the one hand, and 8a and 8b, on the other hand, illustrate two scenarios in this regard.
[0086] These figures show the behavior of the second body 38 and the serrations 35 as a function of the regime of the turbomachine equipped with the rotor blades according to the invention.
[0087] In Figure 7a, the turbomachine is in cruising mode and the finger 40 of the blade 32 is centered in the orifice 42 of the platform. It can be seen that the finger 40 does not transmit any force to the second body, which is not deformed.
[0088] In Figure 7b, the turbomachine takes off. The blade 30 is locked in place and the finger 40 bears against a circumferential end of the orifice 42. The finger 40 then transmits a force to the second body 38, which deforms elastically, causing deformation of at least some of its teeth 35a. The teeth 35a located near the platform 34 may be deformed more than the teeth 35a located on the opposite side of the platform 34.
[0089] Alternatively, in Figure 8a, the turbomachine is in cruising mode and the finger 40 of the blade 32 is already located at one circumferential end of the orifice 42 of the platform. It can be seen that the finger 40 does not transmit any force to the second body 38, which is not deformed.
[0090] In Figure 8b, the turbomachine is in thrust reversal mode. The blade 30 is locked and the finger 40 bears against the circumferential end of the orifice 42. The finger 40 transmits a force to the second body 38, which deforms elastically and causes deformation of at least some of its teeth 35a. The teeth 35a located near the platform 34 may be deformed more than the teeth 35a located on the opposite side of the platform 34.
[0091] The teeth 35a can thus adopt different positions depending on the engine speed. These positions are advantageously designed to reduce noise generated during operation. It is therefore understood that, regardless of the engine speed, the serrations 35 can reduce noise generated during operation, including in thrust reversal mode.
[0092] The serrations are thus adaptable according to several operating points. This allows for an acoustic reduction of the stator blades or a reduction in degradation on, for example, transient phases of the variable pitch.
Claims
Demands
1. A variable-pitch stator blade (30) for an aircraft turbomachine, said blade (30) comprising: - a blade (32) having an intrados (32a) and an extrados (32b), as well as a leading edge (32c) and a trailing edge (32d), the leading edge (32c) of the blade (32) having serrations (35) formed by alternating teeth (35a) and grooves (35b), - a platform (34) connected to one end of the blade (32) and defining a blade pitch axis (A), characterized in that the blade (32) comprises: - a first body (36) of metallic or composite material defining the trailing edge (32d) of the blade (32), and - a second body (38) of elastically deformable material defining at least a portion of the leading edge (32c) of the blade (32) and comprising at least part of the serrations (35), the second body (38) being fixed to the first body (36) and connected to an actuation system which is located entirely outside the blade (32).
2. Blade (30) according to claim 1, wherein the second body (38) defines the entirety of the leading edge (32c) of the blade (32) and includes all the serrations (35).
3. Blade (30) according to claim 1 or 2, wherein the second body (38) extends over the entire longitudinal extent of the blade (32) along the pitch axis (A).
4. Blade (30) according to any one of claims 1 to 3, wherein the second body (38) defines an upstream part of the intrados (32c) and extrados (32d) of the blade (32).
5. Blade (30) according to any one of claims 1 to 4, wherein the second body (38) is connected to at least one actuating finger (40) on the side of said platform (34), this actuating finger (40) passing through at least one orifice (42) of the platform (34).
6. Blade (30) according to claim 5, wherein said at least one actuating finger (40) has an elongated shape along the shimming axis (A).
7. Blade (30) according to claim 5 or 6, wherein the orifice (42) of the platform (34) has a curved shape and extends in a circumferential direction around the alignment axis (A), at an angle (a) predetermined, the actuating finger (40) being able to move in a circumferential direction in this orifice (42).
8. Blade (30) according to claim 7, wherein the actuating finger (40) is able to bear against at least one of the circumferential ends of the orifice (42) and to transmit to the second body (38) a force which is a function of a force generated by the bearing of the actuating finger (40) on this end.
9. Blade (30) according to any one of claims 1 to 8, wherein at least some of the teeth (35a) are hollow.
10. Blade (30) according to any one of claims 1 to 8, wherein at least some of the teeth (35a) are solid.
11. Assembly comprising a blade (30) according to any one of claims 1 to 10 and a stator housing (50), the stator housing (50) being fixed and the blade (30) being mounted on the stator housing (50) so that its platform (34) is movable in rotation about the mounting axis (A) with respect to the housing (50).
12. Assembly according to claim 11, the blade (30) being as defined in any one of claims 7 to 9, wherein the housing (50) includes a housing (52) for receiving a free end of the actuating finger (40).
13. Assembly according to claim 12, wherein the free end of the actuating finger (40) is mounted without play in the housing (52) so as to be fixed relative to the housing (50) during a rotation of the platform (34) around the shimming axis (A).
14. Assembly according to claim 13, wherein the housing (52) has a curved shape and extends circumferentially around the shimming axis (A), over a predetermined angle, the actuating finger (40) being able to move circumferentially in this housing (52).
15. Assembly according to claim 14, wherein the actuating finger (40) is able to bear against at least one of the circumferential ends of the housing (52) and to transmit a force to the second body (38) which is a function of a force generated by the bearing of the actuating finger (40) on this end.
16. Turbomachine for an aircraft, comprising blades (30) according to any one of claims 1 to 10.