FR3152038A1 - DISTRIBUTOR, ESPECIALLY FOR A TURBINE OF AN AIRCRAFT TURBOMACHINE - Google Patents

Abstract

The invention relates to a distributor (34), in particular for an aircraft turbomachine turbine, comprising a plurality of sectors (40) arranged circumferentially next to each other around a main axis, each sector (40) comprising an external annular platform sector (52) and an internal annular platform sector (54) and at least one blade (42) having an extrados wall and an intrados wall connected to each other by a leading edge (BA) and a trailing edge (BF) extending respectively between the external annular platform sector (52) and the internal annular platform sector (54), the trailing edge (BF) comprising at least one notch (60b) comprising a bottom (62) offset relative to a plane (M) passing through the trailing edge (BF) of the blade (42) and perpendicular to the main axis (Z). Abstract: Figure 10

Description

DISTRIBUTOR, ESPECIALLY FOR A TURBINE OF AN AIRCRAFT TURBOMACHINE Technical field of the invention

The present invention relates to a distributor for an aircraft turbomachine turbine. The invention also relates to an aircraft turbomachine turbine equipped with such a distributor and to an aircraft turbomachine comprising such a turbine or such a distributor.

Technological background

There is an axial (or longitudinal) sectional view of an aircraft turbomachine 10 generally comprising, from upstream to downstream, a fan 12 and several modules, such as a low-pressure compressor 14 followed by a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20 followed by a low-pressure turbine 22, which drive the corresponding low-pressure compressor 14 or high-pressure compressor 16, and a gas ejection system 24.

The terms “upstream” and “downstream” are defined in relation to the normal flow direction of the gas in a flow vein of the turbomachine 10, i.e. from the fan 12 upstream to the gas ejection system 24 downstream.

A high-pressure body and a low-pressure body are crossed by a primary air flow P and the blower 12 produces a secondary air flow S which circulates in the turbomachine 10, between a casing 11 and an external casing 13 of the turbomachine 10, in a cold flow channel 15.

At the outlet of the gas ejection system 24, the gases from the primary flow P are mixed with the secondary flow S to produce a propulsion force, the secondary flow S here providing the majority of the thrust.

There represents a detailed view of the turbines of the turbomachine 10 of the . More particularly, the high-pressure turbine 20 and the low-pressure turbine 22 of the turbomachine 10 typically comprise one or more stages comprising respectively

- an annular row 30, or crown, of fixed blades or vanes carried by the casing 11 of the turbine and

- an annular row 32 of blades or vanes mounted to rotate around a central axis of rotation.

The fixed blade rings of a turbine are commonly referred to as distributors 34. A distributor 34 deflects and accelerates a gas flow from the combustion chamber 18 toward the moving turbine blades at an appropriate angle and speed to rotate the moving blades and the turbine rotor.

In order to facilitate assembly and reduce manufacturing costs, fixed blade rings are often made as an assembly of angular sectors which are juxtaposed next to each other to form an entire fixed blade ring.

The distributors 34 of the high-pressure turbine 20 of the turbomachine 10, and consequently the blades which constitute them, are parts exposed to very high thermal stresses. They are in fact placed at the outlet of the combustion chamber 18 and are therefore crossed by extremely hot gases which subject them to very high thermal stresses. The distributors 34, in particular the blades, therefore need to be cooled.

In order to ensure efficient cooling of a distributor blade, it is desirable to have a cooling device that is thermally efficient to allow high thermal power to be dissipated using a moderate air flow.

One of the most widespread solutions currently consists of using one or more sleeves or inserts placed inside the distributor blades. Sleeves are cooling devices formed from multi-perforated sheets to cool the inner face of the blade by cooling air impacts. The inner face of the blade is thus cooled by jet impacts and a forced convection phenomenon between the insert and the inner face of the blade.

The terms "cooling air" or "cold air" refer to air whose temperature is lower than the temperature of the gas circulating in the flow path of the turbomachine and which makes it possible to lower the temperature of the elements located in the flow path.

Document FR-A1-2 899 271 describes such a device for cooling a blade.

The blades comprise an intrados wall and an extrados wall connected to each other by a leading edge BA directed upstream and a trailing edge BF directed downstream.

However, such high-pressure distributor blades have thin surfaces of large dimensions, particularly on one half of the extrados wall and at the trailing edge. These are subjected to high compression which can cause buckling or buckling damage.

Indeed, when a structure is compressed in the length direction, it tends to bend perpendicular to the axis of the applied force, due to a phenomenon of elastic instability. Thus, such areas behave like plates undergoing significant deformation perpendicular to the direction of stress.

Here, a direction of stress is in a plane of the plate, the resulting deformation is then out of plane. Such out of plane deformation can lead to swelling of the center of the plate, surrounded by cracks.

Such damage leads to premature failure of the affected distributor sector, which must then be replaced.

There represents a sector 40 of a high-pressure distributor having two blades 42, at least one of which has a swelling zone 44 of the extrados wall of the blade 42.

Additionally, another buckling mode was observed on the blades of a high-pressure distributor sector at the BF trailing edge.

There represents such another buckling mode at the trailing edge BF of one of the blades 42 of the sector 40 of the distributor 34.

More specifically, the illustrates such a phenomenon experienced in a zone 46 of the trailing edge BF of one of the blades 42 of a sector 40 of the high-pressure distributor.

The trailing edge BF of the blades 42 of the high-pressure distributor being straight, it is similar to a plate subjected to compression, stiffened on its three edges, the fourth edge being free in the vein. Being in a very hot zone, it is also subject to expansion constraints.

The cooler remainder of the blade 42 prevents such expansion. Furthermore, since the remainder of the blade 42 is more massive, the trailing edge BF takes up a large part of the expansion stresses up to a certain threshold beyond which such stress becomes sufficient to deform the trailing edge BF by buckling.

Thus, when the trailing edge BF finds itself in a state of intense compression, it seeks to release the energy relative to the compression by deformation leading to a state of ultimate irreversible deformation.

Also, an objective of the present invention is to propose a solution limiting the phenomenon of buckling of high-pressure distributors at the trailing edge.

A distributor is therefore proposed, in particular for a turbine of an aircraft turbomachine, comprising a plurality of sectors arranged circumferentially next to each other around a main axis. Each sector comprises an external annular platform sector and an internal annular platform sector and at least one blade having an extrados wall and an intrados wall connected to each other by a leading edge and a trailing edge extending respectively between the external annular platform sector and the internal annular platform sector.

More particularly, the trailing edge of the blade comprises at least one notch comprising a bottom offset relative to a plane passing through the trailing edge of the distributor blade and perpendicular to the main axis.

Thus, thanks to the distributor according to the invention, a reduction in the deformation of the trailing edges of the blades of the distributor sectors is ensured. Indeed, the presence of one or more notches makes it possible to reduce the stiffness of the trailing edge edge, in other words this makes it possible to reduce the loading of the forces undergone by the blade.

Thus, the invention makes it possible to improve the resistance of the blades of the distributor sector to the thermomechanical and mechanical constraints undergone by the blades and platforms of the distributor.

In the present application, a depth of a notch is a dimension measured in a direction perpendicular to the aforementioned plane, which may be parallel to the main axis. Furthermore, a height of a notch is a dimension measured in the aforementioned plane, preferably being oriented radially relative to the main axis.

The dispenser according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

- the notch has a substantially straight profile, in particular with the bottom substantially parallel to the plane;

- the notch has a triangular profile;

- the notch has a concave profile;

- the bottom of the notch is defined by a depth whose dimension is greater than a height of the notch;

- the bottom of the notch is defined by a depth whose dimension is less than a height of the notch;

- the trailing edge has several notches arranged along the trailing edge;

- the trailing edge has a single notch along the trailing edge;

- the single notch represents between 50% and 97%, in particular between 75% and 95%, of a radial dimension of the trailing edge extending between the external annular platform sector and the internal annular platform sector, in particular considered in a zone of the trailing edge downstream of slots in the blade;

- the notch has a depth of between 0.6 mm and 6 mm, in particular between 3 mm and 6 mm, in particular between 4.5 mm and 5.7 mm;

- the bottom of the notch has a depth of between 10% and 100%, in particular between 50% and 95%, in particular between 75% and 95%, of a zone of the trailing edge located downstream of slots in the blade;

-- the blade slots are cooling slots and have the function of allowing a flow of cooling air to pass, particularly from the inside to the outside of the blade.

The invention also relates to a turbine of an aircraft turbomachine comprising at least one distributor as described above.

The invention also relates to an aircraft turbomachine comprising at least one distributor as described above and/or a turbine as described above.

Of course, the various features, variants and/or embodiments of the present invention can be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Brief description of the figures

The invention will be better understood and other characteristics and advantages will become apparent with the aid of the detailed description which follows, comprising embodiments given solely for illustrative purposes with reference to the appended figures, which may serve to complete the understanding of the present invention and the description of its embodiment and, where appropriate, contribute to its definition, in which:

There is an axial (or longitudinal) sectional view of a turbomachine to which the invention can be applied;

There is a detailed view of the turbines of the turbomachine of the ;

There represents a distributor sector having a swelling zone of an extrados wall;

There represents another mode of buckling at a trailing edge of a blade of a distributor sector;

There represents a schematic perspective view of a distributor sector according to the prior art;

There represents a schematic cross-sectional view of a vane of the distributor sector of the ;

There represents a schematic view of the trailing edge of a vane of the distributor sector of the ;

There represents a schematic perspective view of a distributor sector according to a first embodiment of the invention;

There represents a schematic view of a trailing edge of a vane of the distributor sector of the ;

There represents a schematic perspective view of a distributor sector according to a second embodiment of the invention;

There represents a schematic view of a trailing edge of a vane of the distributor sector of the ;

There represents a schematic perspective view of a distributor sector according to a third embodiment of the invention; and

There represents a schematic view of a trailing edge of a vane of the distributor sector of the .

Detailed description of the invention

The invention applies to a turbomachine 10 of the type of that of the and to a turbine thereof. Such a turbine is, for example, a high-pressure turbine 20 as illustrated in .

As already indicated, a turbine distributor 34 is conventionally sectorized and formed of several distributor sectors juxtaposed to each other on a circumference centered on an axis of the turbine, that is to say an axis Z of the turbomachine 10 as illustrated in the . The Z axis is also called the main axis of the distributor 34.

For convenience, the description and figures which follow relate to a sector 40 of the distributor 34. What is described in relation to the sector 40 can thus apply to all the sectors of the distributor 34.

There represents, by way of example, a schematic perspective view of the sector 40 of the distributor 34, as generally used.

Conventionally, such a sector 40 comprises, relative to the Z axis, an external annular platform sector 52 and an internal annular platform sector 54. The external annular platform sector 52 and the internal annular platform sector 54 delimit between them an annular gas flow vein in the turbine.

The terms "lower", "inner" or "internal" refer to any element whose position is close to the Z axis in the radial direction, while the terms "upper", "outer" or "external" refer to any element whose position is further from the Z axis, in the radial direction, than the lower position.

Thus, the outer annular platform sector 52 is radially outer to the inner annular platform sector 54. The outer annular platform sector 52 and the inner annular platform sector 54 are coaxial.

It is understood that the outer annular platform sector 52 and the inner annular platform sector 54 are configured to respectively form an outer annular platform and an inner annular platform within the frame of the dispenser 34.

The sector 40 of the distributor 34 further comprises at least one blade 42 which extends between the external annular platform sector 52 and the internal annular platform sector 54.

The blade 42 extends longitudinally in a first direction, substantially in a radial direction R.

The blade 42 can, furthermore, be defined by a chord 48 which corresponds to the length of the profile, that is to say the distance separating the leading edge BA and the trailing edge BF.

The blade 42 can be connected to the internal annular platform sector 52 and to the external annular platform sector 54 by a connection fillet 43a, 43b or connection over the entire periphery of the blade 42 from the leading edge BA to the trailing edge BF on the intrados side 56 and the extrados side 58.

The blade 42 is hollow in a height from which cooling air circulates. The cooling air comes from a supply enclosure (not shown) and is, for example, the air taken from the outlet of the high-pressure compressor 16.

There illustrates a schematic cross-sectional view of blade 42 of sector 40 of the The blade 42 comprises an intrados wall 56 and an extrados wall 58 connected to each other by a leading edge BA directed upstream and a trailing edge BF directed downstream.

There represents a schematic view of the trailing edge BF of the blade 42 of the as commonly used.

Figures 8 to 13 show different embodiments according to the invention.

In the embodiments according to the invention presented in Figures 8 to 13, the trailing edge BF comprises at least one notch 60a, 60b, 60c.

In this description, the term “notch” is understood to mean a cutting of the trailing edge BF.

The notch 60a, 60b, 60c further comprises a bottom 62 offset relative to a plane M passing through the trailing edge BF of the blade 42 of the distributor 34 and perpendicular to the main axis Z of the distributor 34, i.e. the axis of the turbomachine 10.

The blade 42 may comprise means for cooling the blade communicating with the outside of the blade 42 by slots 50 arranged in the vicinity of the trailing edge BF. These slots 50 are cooling slots and have the function of allowing a flow of cooling air to pass, in particular from the inside to the outside of the blade.

Alternatively or in addition, the notch 60a, 60b, 60c of the trailing edge BF may have a depth of between 10% and 100%, in particular between 50% and 95%, in particular between 75% and 95%, of a zone A of the trailing edge BF located downstream of the slots 50 of the distributor 34 of the blade 42.

In particular, the notch 60a, 60b, 60c of the trailing edge BF can therefore be offset relative to the plane M by a distance whose value is between 10% and 100%, in particular between 50% and 95%, in particular between 75% and 95%, of a zone A of the trailing edge BF located downstream of the ejection slots 50 of the blade 42.

More specifically, the notch 60a, 60b, 60c of the trailing edge BF may have a depth of between 0.6 mm and 6 mm, in particular between 3 mm and 6 mm, in particular between 4.5 mm and 5.7 mm.

Advantageously, the notch 60a, 60b, 60c may have a different shape and/or profile. The choice of the shape and/or profile depends on the distribution of the stresses in the trailing edge BF and is determined beforehand during the design phase of the distributor 34.

Indeed, the shape and/or profile can influence the aerodynamics and/or the integration of the desired part. For example, several consecutive notches along the BF trailing edge make it possible to maintain a distribution of the air flow of the vein.

In addition, the notch 60a, 60b, 60c makes it possible to increase the threshold of the first buckling mode. In other words, this provides better thermomechanical resistance to the trailing edge BF.

Figures 8 and 9 show schematic perspective views of the sector 40 of the distributor 34 and the trailing edge BF of the blade 42 of the sector 40 of the distributor 34 of the according to a first embodiment of the invention.

More particularly, Figures 8 and 9 illustrate the first embodiment according to the invention in which the trailing edge BF comprises at least one notch 60a having a substantially straight profile. According to an alternative, the notch 60a with a substantially straight profile is unique. According to the first embodiment of the invention, the bottom 62 of the notch 60a can be substantially parallel to the plane M.

The single notch may represent between 50% and 97%, in particular between 75% and 95%, of a height of the trailing edge BF, in particular considered downstream of the slots of the distributor 34, corresponding to a radial dimension, relative to the main axis Z, of the trailing edge BF extending between the external annular platform sector 52 and the internal annular platform sector 54.

Figures 10 and 11 show schematic perspective views of the sector 40 of the distributor 34 and the trailing edge BF of the blade 42 of the sector 40 of the distributor 34 of the according to a second embodiment according to the invention.

More particularly, figures 10 and 11 illustrate the second embodiment according to the invention in which the trailing edge BF comprises at least one notch 60b having a triangular profile.

The trailing edge BF may have several consecutive 60b notches with a triangular profile along the trailing edge BF.

In the example of Figures 10 and 11, the trailing edge BF comprises two notches 60b with a triangular profile. As a variant, not shown, the trailing edge BF may comprise more than two notches 60b with a triangular profile. Generally speaking, the number of notches 60b may vary according to the desired mechanical specifications, as described above.

Alternatively, the trailing edge BF may comprise at least two notches 60b having different triangular profiles respectively. Thus, a first notch 60b may be different from the triangular profile of a second notch 60b. In other words, the shape of the triangular profile may be different from one notch 60b to another.

In the case of the notch 60b with a triangular profile according to the second embodiment, the bottom 62 of the notch 60b can be defined by a depth p whose dimension is less than or equal to a height h of the notch 60b.

The height h denotes an opening of the notch 60b. The height h is preferably oriented radially relative to the main axis Z. Furthermore, the depth p is a dimension which extends perpendicular to the height h.

Alternatively, not shown, the depth p has a dimension which is greater than or equal to the height h of the notch 60b with a triangular profile according to the second embodiment.

In the particular case where the trailing edge BF has several consecutive notches 60b, the triangular profile has hollows 64 and at least one apex 66. The hollows 64 can be assimilated to the bottom 62. The apex 66 can be located in the plane M.

Alternatively, the vertex 66 can be offset relative to the plane M. It is understood that, in this case, the vertex 66 is located, relative to the plane M, at a distance whose value, non-zero, is strictly less than the value of the depth p of the bottom 62.

In such an embodiment, the triangular profile notches 60b may be contiguous, such that the apex 66 may form a point. Alternatively, the triangular profile notches 60b may be spaced apart, such that the apex 66 may form a flat.

Figures 12 and 13 show schematic perspective views of the sector 40 of the distributor 34 and the trailing edge BF of the blade 42 of the sector 40 of the distributor 34 of the a third embodiment according to the invention.

More particularly, figures 12 and 13 illustrate the third embodiment according to the invention in which the trailing edge BF comprises at least one notch 60c having a concave profile.

The term "concave" refers to a rounded shape, such as an arc or elliptical.

The profile of the 60c notch with a concave profile can also take the form of a “spline”, an Anglo-Saxon term designating the shape of a function defined piecewise by polynomials.

The BF trailing edge may have several consecutive 60c notches with a concave profile along the BF trailing edge.

In the example of Figures 12 and 13, the trailing edge BF has three notches 60c with a concave profile. Alternatively, not shown, the trailing edge BF may have fewer or more than three notches 60c with a concave profile. Generally speaking, the number of notches 60c may vary depending on the desired mechanical specifications, as described above.

Alternatively, the trailing edge BF may comprise at least two notches 60c having different concave profiles respectively. Thus, a first notch 60c may be different from the concave profile of a second notch 60c. In other words, the shape of the concave profile may be different from one notch 60c to another.

In the case of the notch 60c with a concave profile according to the third embodiment, the bottom 62 of the notch 60c can be defined by a depth p whose dimension is greater than or equal to a height h of the notch 60c.

The height h denotes an opening of the notch 60c. The height h is preferably oriented radially relative to the main axis Z. Furthermore, the depth p is a dimension which extends perpendicular to the height h.

Alternatively, not shown, the depth p has a dimension which is less than or equal to the height h of the notch 60c with a concave profile according to the third embodiment.

In the particular case where the trailing edge BF has several consecutive notches 60c, the concave profile has hollows 64 and at least one peak 66. The hollows 64 can be assimilated to the bottom 62. The peak 66 can be located in the plane M.

Alternatively, the vertex 66 can be offset relative to the plane M. It is understood that, in this case, the vertex 66 is located, relative to the plane M, at a distance whose value, non-zero, is strictly less than the value of the depth p of the bottom 62.

In such an embodiment, the concave profile notches 60c may be spaced apart, such that the apex 66 may form a flat. Alternatively, the concave profile notches 60c may be contiguous, such that the apex 66 may form a point.

The distributor 34, as described above, allows a reduction in the deformation of the trailing edges BF of the blades 42 of the sectors 40 of the distributor 34. Indeed, the presence of one or more notches 60a, 60b, 60c allows a reduction in the stiffness of the trailing edge BF, in other words this allows a reduction in the loading of the forces undergone by the blade 42.

Another advantage of the invention is to allow an improvement in the resistance of the blades 42 of the distributor 34 to the thermomechanical and mechanical constraints undergone by the blades 42 and the platforms of the distributor 34.

Another advantage of the invention is to allow for easier design. Indeed, the distributor 34 according to the invention does not require modification of the aerodynamic profile of the blades 42 which ensures the performance of the part while deflecting its loading to limit the load on the extrados wall. Thus, the efficiency of the cooling which impacts both the performance of the engine and the holding of the part by maintaining it at an acceptable temperature is preserved.

Claims (13)

Distributor (34), in particular for a turbine (20) of an aircraft turbomachine (10), comprising a plurality of sectors (40) arranged circumferentially next to each other around a main axis (Z),
each sector (40) comprising
- an external annular platform sector (52),
- an internal annular platform sector (54) and
- at least one blade (42) having an extrados wall (58) and an intrados wall (56) connected to each other by a leading edge (BA) and a trailing edge (BF) extending respectively between the external annular platform sector (52) and the internal annular platform sector (54),
characterized in that the trailing edge (BF) of the blade (42) comprises at least one notch (60a, 60b, 60c) comprising a bottom (62) offset relative to a plane (M) passing through the trailing edges (BF) of the blade (42) of the distributor (34) and perpendicular to the main axis (Z). Dispenser (34) according to claim 1, in which the notch (60a) has a substantially straight profile, in particular with the bottom (62) substantially parallel to the plane (M). Dispenser (34) according to claim 1, in which the notch (60b) has a triangular profile. The dispenser (34) of claim 1, wherein the notch (60c) has a concave profile. Dispenser (34) according to any one of the preceding claims, in which the bottom (62) of the notch (60b, 60c) is defined by a depth (p) whose dimension is greater than a height (h) of the notch (60b, 60c). Dispenser (34) according to any one of claims 1 to 4, in which the bottom (62) of the notch (60b, 60c) is defined by a depth (p) whose dimension is less than a height (h) of the notch (60b, 60c). A dispenser (34) according to any preceding claim, wherein the trailing edge (BF) comprises a plurality of notches (60a, 60b, 60c) arranged along the trailing edge (BF). A dispenser (34) according to any one of claims 1 to 6, wherein the trailing edge (BF) comprises a single notch (60a, 60b, 60c) along the trailing edge (BF). Dispenser (34) according to claim 8, wherein the single notch (60a) represents between 50% and 97%, in particular between 75% and 95%, of a radial dimension of the trailing edge (BF) extending between the external annular platform sector (52) and the internal annular platform sector (54). Dispenser (34) according to any one of the preceding claims, in which the notch (60a, 60b, 60c) has a depth of between 0.6 mm and 6 mm, in particular of between 3 mm and 6 mm, in particular of between 4.5 mm and 5.7 mm. Distributor (34) according to any one of claims 1 to 8, in which the bottom (62) of the notch has a depth of between 10% and 100%, in particular between 50% and 95%, in particular between 75% and 95%, of a zone (A) of the trailing edge (BF) located downstream of slots in the blade (42). Turbine (20) of an aircraft turbomachine, characterized in that it comprises at least one distributor according to any one of the preceding claims. Aircraft turbomachine (10), characterized in that it comprises at least one turbine distributor (34) according to any one of claims 1 to 11 and/or a turbine (20) according to claim 12.