STATOR RING FOR AN AIRCRAFT TURBINE ENGINE AND AIRCRAFT TURBINE ENGINE EQUIPPED WITH IT

Description

Technical field of the invention

[0001] The invention relates to a rectifier for an aircraft turbomachine, an aircraft turbomachine equipped with such a rectifier. Technical background

[0002] The technical background includes documents FR-A1-2 948 737, FR-A1-3 085 416 and WO-A1-2011 / 157956.

[0003] An aircraft turbomachine includes a compressor to compress air, specifically to give the air a suitable speed, pressure, and temperature to burn the air in a combustion chamber with fuel.

[0004] A compressor generally comprises several stages, each stage comprising a first rotating bladed element which forms a rotor, and a second fixed bladed element, called a rectifier, which forms a stator, and which is located downstream of the rotor in the direction of air flow in the turbomachine.

[0005] Each compressor stage thus comprises a sectorized rectifier, that is to say, a rectifier comprising several rectifier sectors arranged circumferentially end to end around a longitudinal axis of the turbomachine. Each sector comprises a plurality of fixed blades.

[0006] A rectifier comprises an outer and an inner shell spaced apart, and vanes that connect the outer and inner shells. The space between the outer and inner shells forms a flow channel for the airflow circulating in the compressor.

[0007] Sector rectifiers are complex components operating in an environment of increasing stress (high pressures, temperatures, and rotor speeds), which generates a high number of modes and vibration levels. The geometries of all rectifiers are very similar in terms of mechanical behavior. Following strong vibrational excitation, energy propagates efficiently throughout the sector via the highly rigid inner and outer shells.

[0008] The vibration responses predicted by the design criteria or observed during testing after analysis show that the rectifiers exhibit very high vibration levels. Thus, during turbomachine operation, the vibrations generated can lead to significant mechanical loads on the inner and outer shells, as well as on the blades. These significant loads can cause cracking. The present invention aims, in particular, to resolve all or part of the aforementioned problems. Summary of the invention

[0009] The invention proposes for this purpose a straightener for an aircraft turbomachine, this straightener comprising two coaxial annular shells, respectively internal and external, connected together by blades which are each solid and made of material with the shells, the external shell comprising an external annular surface connected to at least one fixing hook of the straightener, and the internal shell comprising an internal annular surface connected to a support of an abradable coating, characterized in that at least one of said internal and external surfaces comprises series of recesses which are located at the level of the blades and which are configured so that the blades are connected to the corresponding shell, at the level of the recesses, by webs of material which have a thickness less than that of this shell, and in that said at least one fixing hook is disposed between two series of recesses of the external surface of the external shell,and / or said support is arranged between two sets of recesses in the internal surface of the inner ferrule.

[0010] The invention consists, in particular, of modifying one or more parts of the ferrules by means of recesses located at the ends of the blades. By using one or more recessed areas, the ferrules are locally made more flexible. The advantages are numerous and, in particular: reduction of static stresses; attenuation of vibration propagation within the rectifier; and reduction of the rectifier mass.

[0011] The recesses located at the ends of the blades at the level of the inner and outer ferrules thus make it possible to dampen the vibratory and static responses by local softening of the inner and outer ferrules.

[0012] Furthermore, three main stakeholders are involved in the design of a turbomachine: mechanical engineers, aerodynamicists, and the integration team. Once the various iteration phases between these three stakeholders are completed, it is no longer possible to modify the properties of the stator, such as the blade design (aerodynamic aspect) or the interface between the different parts (integration aspect).

[0013] However, the shape of the internal ferrule is a purely mechanical concern, and its modification, particularly to create recesses according to the invention, does not affect the chosen design. The invention thus makes it possible to influence the post-iteration vibration resistance between the three components without modifying the design of the flow channel for the airflow circulating in the compressor or at the interfaces.

[0014] The invention thus makes it possible to reduce the vibrational and static responses on the rectifiers without impacting the specifications provided by other actors (aerodynamicists' drawings, interface defined by integration).

[0015] In this application, a series of recesses means a plurality of recesses, which may be arranged in an annular row of recesses regularly spaced around a principal axis of the rectifier. At least two series of recesses means having at least two sets of recesses, for example, two annular rows of recesses regularly spaced around the axis of the rectifier. The rectifier, according to the invention, may comprise one or more of the following features, taken individually or in combination: said internal surface comprises a series of recesses located at the leading edges of the blades and / or a series of recesses located at the trailing edges of the blades; said external surface comprises a series of recesses located at the leading edges of the blades and / or a series of recesses located at the trailing edges of the blades; the blades are connected to the internal ferrule equipped with recesses by webs of material which have a thickness Eweb-in less than or equal to Eferrule-in / 3, and preferably less than or equal to Eferrule-in / 4, Eferrule-in being the thickness of the internal ferrule in the area containing the recesses; the blades are connected to the outer ferrule equipped with recesses by webs of material which have a thickness Eveil-ext less than or equal to Evirole-ext / 2, and preferably less than or equal to Evirole-ext / 2.5, Evirole-ext being the thickness of the outer ferrule in the area containing the recesses;Each of the recesses has a generally elongated shape along a camber line of the corresponding blade, each of the recesses having a generally trapezoidal or triangular shape in cross-section and / or in longitudinal section; each of the blades is connected to the ferrule or ferrule equipped with recesses by two lateral sails of material which extend respectively from the intrados and extrados sides of the blade and which are symmetrical with respect to a median plane passing through the middle of the recess and through an axis of elongation of the blade; the two sails of material extend from a first plane passing through the corresponding ferrule to a second plane passing through an end of the corresponding blade, the first and second planes being parallel and at a distance from each other.

[0016] The present invention also relates to an aircraft turbomachine, comprising at least one rectifier as described above. Brief description of the figures

[0017] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which: [ Fig.1 ] There figure 1 is a schematic half-section representation of a high-pressure compressor in a turbomachine; Fig. 2 ] There figure 2 is a schematic perspective representation of a sector of a high-pressure compressor rectifier according to the invention; [ Fig.3 ] There figure 3 is a schematic longitudinal cross-sectional representation of the sector of the figure 2 ; Fig. 4 ] There figure 4 is a schematic cross-sectional and perspective representation of a blade and internal and external ferrules according to the invention, in a transverse section taken at approximately 80% of the blade chord illustrated in the figure 3 ; Fig. 5 ] There figure 5is a schematic cross-sectional and perspective representation of an external end of the blade and the external ferrule according to the invention, in a transverse section taken at approximately 80% of the blade chord illustrated in the figure 3 ; And [ Fig. 6 ] There figure 6 is a schematic cross-sectional and perspective representation of an inner end of the blade and inner ferrule according to the invention, in a cross-section made approximately 80% of the blade chord illustrated in the figure 3 . Detailed description of the invention

[0018] There figure 1represents a high-pressure compressor 1 of a turbomachine 2 for an aircraft, comprising several stages. The compressor 1 includes several annular rows of fixed blades 11 with aerodynamic profiles and rows of rotating blades 5. The blades 11, 5 extend radially through the compressor 1 where a primary flow F circulates. Each stage of the compressor includes a rectifier (shown 10 on the figure 2 ) sectorized, that is, a rectifier 10 comprising several rectifier sectors 10' arranged circumferentially end to end around a longitudinal axis X of the turbomachine so as to form the rectifier 10. Each sector 10' comprises a plurality of fixed blades 11. The rectifiers 10 are configured to direct the primary flow F towards the rotating blades 5. The term "radial" is defined with respect to an axis substantially perpendicular to the longitudinal axis X of the turbomachine 2.

[0019] As depicted on the figure 2The rectifier 10 for an aircraft turbomachine has an inner ferrule 20 and an outer ferrule 30 which are spaced apart, the outer ferrule 30 being situated around the inner ferrule 20. The inner ferrule 20 and the outer ferrule 30 are both coaxial annular pieces.

[0020] The sectorized rectifiers 10 are complex components operating in an environment of increasing stress (high pressures, temperatures, and rotor speeds), which generates a number of modes and high vibration levels. Following strong vibrational excitation during operation, the energy propagates efficiently through all the sector rectifiers 10 via the inner 20 and outer 30 ferrules.

[0021] In a conventional manner, the terms "internal" and "external" are understood with regard to the X-axis of the turbomachine, and the terms "upstream" and "downstream" are understood according to the direction of gas flow in the turbomachine.

[0022] The inner ferrules 20 and outer ferrules 30 are connected together by the fixed blades 11. The blades 11 are each solid and for example come from material with the ferrules 20, 30.

[0023] As depicted on the figures 2 , 3 , the external ferrule 30 has an external annular surface 31 connected to at least one hook 32 for fixing the straightener 10.

[0024] The inner ferrule 20 comprises an internal annular surface 21 connected to a support 22 of an abradable coating. The inner ferrule 20 notably has an I-shaped profile in longitudinal section.

[0025] At least one of the said internal surfaces 21 and external surfaces 31, and here both, have recesses 42', 42", 43', 43" which are located at the vanes 11. According to the geometric characteristics and the desired mechanical strength of the rectifier, the number of recesses and their geometry can be variable.

[0026] The internal surface 21 includes in particular a series of recesses 42' located at the leading edges 14 of the blades 11. The internal surface 21 includes for example a series of recesses 42" located at the trailing edges 15 of the blades 11.

[0027] The external surface 31 includes in particular a series of recesses 43' located at the leading edges 14 of the blades 11. The external surface 31 includes for example a series of recesses 43" located at the trailing edges 15 of the blades 11.

[0028] Each of the recesses 42', 42" in the inner surface 21 and each of the recesses 43', 43" in the outer surface 31 has, in particular, an elongated general shape along a camber or skeleton line C2, C3, respectively camber line C2 at the level of the inner surface 21 and camber line C3 at the level of the outer surface 31 of the corresponding blade 11. The geometry of the blade 11 can vary with height (i.e., radially); the recesses 42', 42", 43', 43" therefore follow the camber line of the section at the top of the blade 11 for the outer ferrule 30 and at the bottom of the blade 11 for the inner ferrule 20.

[0029] Each of the recesses 42', 42", 43', 43" has, for example, in cross-section and / or in longitudinal section with respect to the X axis a general trapezoidal or triangular shape.

[0030] The recesses 42', 42", 43', 43" have in particular a bowl shape and include in particular upstream edges 45 and downstream edges 46 oriented substantially parallel to the Y axis or inclined with respect to this axis.

[0031] THE figures 4 , 5 and 6 These are cross-sectional views of the blade 11 and / or the ferrules 20, 30, with a cutting plane that is perpendicular to the ferrules 20, 30 and to the trailing edge 15 of the blade 11, and passing in particular through the bottom of the bowl shape defined by the recesses 42", 43" located at the trailing edge 15 of the blade 11. If we consider the chord of the blade 11, that is to say the straight line connecting the leading edge 14 to the trailing edge 15, the cutting plane passes approximately at 80% of this chord measured from the leading edge 14 to the trailing edge 15. The cutting plane therefore passes at 20% of the trailing edge 15, particularly upstream and near the Y-axis as shown on the figure 3 .

[0032] As depicted on these figures 4 , 5, 6 The internal surfaces 21 and external surfaces 31 are configured so that the blades 11 are connected to the corresponding ferrule 20, 30, at the level of the recesses 42', 42", 43', 43", by material webs 52', 52", 53', 53". The upstream edges 45 and downstream edges 46 and the material webs 52', 52", 53', 53" of each recess 42', 42", 43', 43" form between them the bowl shape mentioned previously.

[0033] Each of the blades 11 is connected to the internal ferrule 20 equipped with recesses 42', 42" by two lateral material veils 52', 52" which extend respectively from the side of an intrados 16 and an extrados 17 of the blade 11 and which are symmetrical with respect to a median plane P passing through the middle of the recess 42', 42" and by an elongation axis Y of the blade 11 substantially perpendicular to the axis X.

[0034] Each of the blades 11 is connected to the external ferrule 30 equipped with recesses 43', 43" by two lateral material veils 53', 53" which extend respectively from the side of the intrados 16 and the extrados 17 of the blade 11 and which are symmetrical with respect to the median plane P passing through the middle of the recess 43', 43" and by the elongation axis Y of the blade 11.

[0035] The two sails of material 52', 52" connecting each of the blades 11 to the internal ferrule 20 extend from a first plane Q2 passing through the internal ferrule 20 to a second plane R2 passing through a lower or internal end 12 of the corresponding blade 11, the first Q2 and second planes R2 being parallel and at a distance from each other and for example perpendicular to the Y axis.

[0036] The two sails of material 53', 53" connecting each of the blades 11 to the external ferrule 30 extend from a first plane Q3 passing through the external ferrule 30 to a second plane R3 passing through an upper or external end 13 of the corresponding blade 11, the first Q3 and second planes R3 being parallel and at a distance from each other and for example perpendicular to the Y axis.

[0037] The two material webs 52', 52" connecting each of the blades 11 to the inner ferrule 20 have a thickness 62' less than the thickness 62 of this inner ferrule 20. The thickness 62' of the webs 52', 52", also called Eweb-internal, has a minimum value of 0.5 mm. The area of ​​the inner ferrule 20, including the recesses 42', 42", has a thickness 62, also called Einternal. The thickness 62' of the webs 52', 52" is, for example, less than or equal to 1 / 3 of the thickness 62 of the inner ferrule 20, and preferably less than or equal to 1 / 4 of the thickness 62 of the inner ferrule 20. In other words, Eweb-internal is less than or equal to Einternal / 3, and preferably less than or equal to Einternal / 4.

[0038] The two material webs 53', 53" connecting each of the blades 11 to the outer ferrule 30 have a thickness 63' less than the thickness 63 of this outer ferrule 30. The thickness 63' of the webs 52', 52", also called Eveil-ext, has a minimum value of 0.5 mm. The area of ​​the outer ferrule 30, including the recesses 43', 43", has a thickness 63, also called Evirole-ext. The thickness 63' of the webs 53', 53" is, for example, less than or equal to 1 / 2.5 of the thickness 63 of the outer ferrule 30. In other words, Evoile-ext is less than or equal to Evirole-ext / 2, and preferably less than or equal to Evirole-ext / 2.5.

[0039] Said at least one fixing hook 32 is for example disposed between two sets of recesses 43', 43" of the outer ferrule 30. More precisely, at least one fixing hook 32 is disposed between the set of recesses 43' of the outer ferrule 30 located at the leading edges 14 of the blades 11 and the set of recesses 43" of the outer ferrule 30 located at the trailing edges 15 of the blades 11.

[0040] The support 22 is in particular arranged between two sets of recesses 42', 42" of the inner ferrule 20. More precisely, the support 22 is arranged between the set of recesses 42' of the inner ferrule 20 located at the leading edges 14 of the blades 11 and the set of recesses 42" of the inner ferrule 20 located at the trailing edges 15 of the blades 11.

[0041] By using one or more recesses 42', 42", 43', 43", the invention makes it possible to lower the static stresses of the rectifier, in particular by locally relaxing the ferrules 20, 30. For example, for a blade 11 which has a maximum stress at its leading edge 14 near the outer ferrule 30, it is possible to reduce, in particular by 8%, i.e. 25 MPa, the static stresses of the blade 11, thanks to all or part of the recesses 42', 42", 43', 43".

[0042] The recesses 42', 42", 43', 43" further help to attenuate vibration propagation within the rectifier. Indeed, the more flexible the ferrules 20 and 30 are, the more vibration propagation is attenuated. This observation depends on the type of vibration mode involved and the location of its maximum criticality. It is notably possible to analyze the vibration responses using the energy criterion of modal responses.

[0043] Depending on the need, the desired attenuation can be specific to a mode or a range of modes. This can be achieved by modifying the thickness of the sails, partitioning the cutout areas differently (blade to blade), or adapting the geometry of the cutouts to the vibration requirements.

[0044] The recesses also have a positive effect on the rectifier's mass. Indeed, post-design modifications through material removal contribute to a mass reduction, which can reach, for example, up to 4% for a 10' sector of 10 rectifiers.

[0045] Furthermore, the modification of the ferrules 20, 30 by the recesses 42', 42", 43', 43" has no impact on the other design actors.

[0046] Creating this type of geometry, i.e., after hollowing, is particularly well-suited to additive manufacturing, notably laser melting. The present invention also relates to an aircraft turbomachine 2, comprising at least one rectifier 10 as described above.

Claims

1. A stator ring (10) for an aircraft turbine engine (2), said stator ring (10) comprising two coaxial annular shrouds (20, 30), an internal shroud (20) and an external shroud (30) respectively, connected together by vanes (11) which are each solid and integral with the shrouds (20, 30), the external shroud (30) comprising an external annular surface (31) connected to at least one attachment catch (32) for attaching the stator ring (10), and the internal shroud (20) comprising an internal annular surface (21) connected to a support (22) for an abradable coating, characterised in that at least one of said internal (21) and external (31) surfaces comprises series of recesses (42', 42", 43', 43") which are located in line with the vanes (11) and which are configured so that the vanes (11) are connected to the corresponding shroud (20, 30), at the level of the recesses (42', 42", 43', 43"), by webs of material (52', 52", 53', 53") which have a thickness (62', 63') less than that (62, 63) of said shroud (20, 30), and in that said at least one attachment catch (32) is arranged between two series of recesses (43', 43") of the external surface (31) of the external shroud (30), and / or said support (22) is arranged between two series of recesses (42', 42") of the internal surface (21) of the internal shroud (20).

2. The stator ring (10) according to claim 1, wherein said internal surface (21) comprises a series of recesses (42') located in line with the leading edges (14) of the vanes (11) and / or a series of recesses (42") located in line with the trailing edges (15) of the vanes (11).

3. The stator ring (10) according to one of the preceding claims, wherein said external surface (31) comprises a series of recesses (43') located in line with the leading edges (14) of the vanes (11) and / or a series of recesses (43") located in line with the trailing edges (15) of the vanes (11).

4. The stator ring (10) according to one of the preceding claims, wherein the vanes (11) are connected to the internal shroud (20) fitted with recesses (42', 42") by webs (52', 52") of material which have a thickness Evoile-int (62') less than or equal to Evirole-int / 3, and preferably less than or equal to Evirole-int / 4, Evirole-int being the thickness (62) of the internal shroud (20) in the area comprising the recesses (42', 42").

5. The stator ring (10) according to one of the preceding claims, wherein the vanes (11) are connected to the external shroud (30) fitted with recesses (43', 43") by webs of material (53', 53") which have a thickness Evoile-ext (63') less than or equal to Evirole-ext / 2, and preferably less than or equal to Evirole-ext / 2.5, Evirole-ext being the thickness (63) of the external shroud (30) in the area comprising the recesses (43', 43").

6. The stator ring (10) according to any of the preceding claims, wherein each of the recesses (42', 42", 43', 43") has a generally elongate shape along a camber line (C2, C3) of the corresponding vane (11), each of the recesses (42', 42", 43', 43") having in cross-section and / or in longitudinal section a generally trapezoidal or triangular shape.

7. The stator ring (10) according to one of the preceding claims, wherein each of the vanes (11) is connected to the or each shroud (20, 30) fitted with recesses (42', 42", 43', 43") by two lateral webs of material (52', 52", 53', 53") which extend respectively towards the side of the intrados (16) and of the extrados (17) of the vane (11) and which are symmetrical with respect to a median plane (P) passing through the middle of the recess (42', 42", 43', 43") and through an axis of elongation (Y) of the vane (11).

8. The stator ring (10) according to the preceding claim, wherein the two webs of material (52', 52", 53', 53") extend from a first plane (Q2, Q3) passing through the corresponding shroud (20, 30) to a second plane (R2, R3) passing through one end (12, 13) of the corresponding vane (11), the first (Q2, Q3) and second (R2, R3) planes being parallel and at a distance from each other.

9. An aircraft turbine engine (2), comprising at least one stator ring (10) according to one of the preceding claims.