Turbine wheel for a turbomachine and turbomachine
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2026-01-16
- Publication Date
- 2026-07-30
Smart Images
Figure FR2026050040_30072026_PF_FP_ABST
Abstract
Description
Turbine wheel for a turbomachine comprising at least one ventilation channel Technical Field [OOOlJThe present invention relates to a turbine wheel for a turbomachine, as well as a turbomachine such as a turbojet or aircraft turboprop equipped with such a wheel.
[0002] The invention relates more particularly to the cooling of a sealing and damping element intended for use in the aforementioned turbine wheel. Previous technique
[0003] Typically, a high-pressure turbine wheel of a turbomachine, as shown in Figures 1 and 2, comprises a disk 1 carrying blades 3 regularly distributed circumferentially around the axis of rotation of the wheel and having feet 4 which are engaged in substantially axial recesses 2 positioned at the periphery of the disk 1. The blade feet 4 may be of the fir cross-section or dovetail type.
[0004] Each blade 3 comprises a blade 6 connected at its inner radial end to a platform 5, which is itself connected to the foot 4. The upstream and downstream ends of each platform 5 are connected respectively to an upstream radial wall 7 extending radially into the interior of the blade and to a downstream radial wall 8 extending radially into the interior of the blade. In the mounting position, the platforms 5 are arranged circumferentially end-to-end to form an internal annular flow wall for a primary airflow F originating from an airflow taken downstream of the last stage of a high-pressure compressor. Similarly, the upstream radial walls 7 and downstream radial walls 8 are arranged circumferentially opposite each other.
[0005] The wheel includes inter-blade cavities 9 distributed circumferentially around the axis of rotation of the wheel and defined radially outwards by the inner faces of two platforms 5 facing circumferentially, radially inwards by a tooth 31 of the disc 1, axially by two radial walls upstream 7 and downstream 8 whose ends are arranged circumferentially opposite, and circumferentially by the feet 4 of the blades 3.
[0006] However, during turboshaft engine operation, vibrations are induced in the turbine blades. These vibrations can lead to premature blade fatigue failure.
[0007] To dissipate the energy of these vibrations and thus reduce the amplitude of the vibrations and the associated stresses, it is known to mount vibration sealing and damping devices 13 (commonly called "candies") in the inter-blade cavities 9, as illustrated in Figure 2 and described in documents FR3027950 and EP1507960.
[0008] Each vibration-damping and sealing element 13 is held in position within the inter-blade cavity 9 by protruding lugs 32 within the cavity. As the turbine disk rotates, centrifugal force presses the vibration-damping and sealing elements 13 against the platforms 5, so that the lugs 32 no longer provide a retaining function. When the blades vibrate, the surfaces of the vibration-damping and sealing element 13 and the platforms 5 slide against each other to produce effective frictional forces that absorb vibrations and thus dissipate a large portion of the vibrational energy.
[0009] Furthermore, the blade platforms define the radially inner limits of the main flow and are therefore subjected to the high temperatures exiting the combustion chamber. Since the blades are sectored, there are inter-sector spaces or gaps 36 extending axially between circumferentially adjacent blade platforms, through which the hot air from the main flow can be radially drawn into the inter-blade cavities located radially beneath the platforms. It is known to use sealing and damping elements 13 that come into contact with the inner faces of the platforms and span these gaps 36 to block the radial flow of the primary air F. The sealing and damping elements 13 thus incorporate a gap-sealing function for the gaps 36.
[0010] However, such components need to be improved to better withstand the temperature constraints of the environment which can, in most cases, reach and exceed the operating temperature limit of the sealing and damping component.
[0011] We are familiar with document US5281097, which proposes drilling through the components to supply air from the inter-blade cavities into ducts machined on the internal surfaces of the platforms. The air circulates through these ducts and is then exhausted into the inter-sector spaces, thus cooling the blade platforms and the sealing and damping components. However, drilling through the sealing and damping components significantly reduces the lifespan of the component and leads to the formation of cracks around the holes.
[0012] Documents US2013171003 and US2012063916 also describe another, more efficient solution for cooling blade platforms: creating internal cooling cavities within the blade platforms. The solution proposed in document US2013171003 reduces the temperature of the component due to heat conduction from the blade to the component, but it does not reduce the maximum temperature reached by the component in relation to the inter-sector space.
[0013] These solutions do not resolve the cooling issues for the sealing and damping components and result in a significant reduction in the material thickness of the platforms. These solutions require thickening the platform, which leads to a significant increase in the disk's mass. Description of the invention
[0014] The invention therefore aims to resolve at least in part these drawbacks by proposing a turbine wheel for a turbomachine that allows the sealing and damping components to be cooled more efficiently without reducing the thickness of the platform.
[0015] The invention relates to a turbine wheel for a turbomachine, the wheel being rotatable about an axis of rotation and comprising a disk having a plurality of recesses opening onto the outer periphery of the disk, and a plurality of circumferentially adjacent blades. Each blade comprises a foot mounted in one of the recesses, a platform from which a blade extends, an upstream radial wall, and a downstream radial wall extending radially towards the disk from the platform. An inter-blade cavity is arranged between a pair of two circumferentially adjacent blades.Each inter-blade cavity is bounded radially by one radially external face of the disc and by two radially internal faces of the respective platforms of the two circumferentially adjacent blades, and by two circumferential end faces of the respective roots of the pair of two circumferentially adjacent blades, and axially by two upstream radial walls and two downstream radial walls of the two circumferentially adjacent blades. Each inter-blade cavity houses a sealing and damping element. A gap is formed between the platforms of the two circumferentially adjacent blades. The gap is located radially opposite the sealing and damping element.
[0016] At least one of the inter-blade cavities includes at least one ventilation channel positioned in an upstream portion of the inter-blade cavity, which is partially delimited by the upstream radial walls. The ventilation channel is configured to fluidly connect the inter-blade cavity to the gap when the sealing and damping element is bearing against the platforms of the two circumferentially adjacent blades. The ventilation channel is formed by two circumferentially adjacent axial grooves, each formed as a recess on an inner face of one of the circumferentially adjacent blades that partially delimit the inter-blade cavity. Each axial groove is positioned radially opposite the sealing and damping element and opens into the gap.Each axial groove is cut into one of the upstream radial walls of one of the two blades of a blade pair, and extends axially over one of the platforms of one of the two blades which is connected to said upstream radial wall.
[0017] The invention thus provides a turbine wheel for a turbomachine that cools the sealing and damping components more efficiently than known solutions, without reducing the minimum platform thickness. This makes it possible to use platforms with a thin profile (less than 0.12 mm) and preferably at least 0.8 mm, corresponding to an acceptable minimum thickness.
[0018] Indeed, the axial groove and / or axial channels allow air to be drawn from the radially internal space beneath the component and directed into the radially external space above it, thus creating a film of cooled air within the gap. This improves the thermal resistance of the sealing and damping component without altering the turbine blade design or increasing its weight, unlike existing solutions.
[0019] In some embodiments, each axial groove is positioned radially opposite the sealing and damping element and opens into the gap, preferably along the entire length of the gap.
[0020] In some embodiments, each axial groove is cut into one of the upstream radial walls of one of the two blades of a blade pair, and extends axially over one of the platforms of one of the blades which is connected to said upstream radial wall.
[0021] In some embodiments, each axial groove comprises an upstream end portion, a downstream end portion and a main portion connecting the upstream and downstream end portions, the main portion having a circular arc-shaped cross-section and a constant depth P2.
[0022] In some embodiments, the upstream end portion of each axial groove extends radially inwards, beyond the sealing and damping element.
[0023] In some embodiments, each downstream end part has an elongated shape, and a depth and width that gradually decrease in the direction of the downstream radial wall.
[0024] This solution improves the efficiency of gap cooling, with the elongated downstream end portion of the axial groove guiding the airflow towards the downstream wall.
[0025] In some embodiments, a first blade comprises a first axial groove cut into a first upstream radial wall of the first blade and extending axially onto a first platform of the first blade, and a second blade circumferentially adjacent to the first blade comprising a second axial groove cut into a second upstream radial wall of the second blade and extending axially onto a second platform of the second blade. The first axial groove and the second axial groove are positioned circumferentially opposite each other, with the gap positioned between the first axial groove and the second axial groove.
[0026] In some embodiments, the first and second grooves have the same hollow shape.
[0027] In some embodiments, the ventilation channel is formed by a circumferential groove formed in the foot and platform of one of the two circumferentially adjacent blades, the circumferential groove being positioned at the location of the upstream part of the inter-blade cavity.
[0028] This solution improves the efficiency of gap cooling.
[0029] The invention also relates to a turbomachine comprising a turbine wheel as defined above.
[0030] The terms "upstream" and "downstream" are defined with respect to the direction of airflow in the turbomachine.
[003] The aforementioned characteristics and advantages, as well as others, will become apparent from the detailed description that follows, along with examples of wheel embodiments. This detailed description refers to the attached drawings. Brief description of the drawings
[0032] The attached drawings are schematic and are primarily intended to illustrate the principles of the presentation.
[0033] In these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference symbols.
[0034] [Fig. 1] Figure 1 schematically represents two adjacent turbine wheel blades, according to the known technique;
[0035] [Fig. 2] Figure 2 schematically represents, according to an axial section, a portion of a sealing and damping element housed in an inter-blade cavity, according to the known technique;
[0036] [Fig. 3] Figure 3 schematically represents a sealing and damping element comprising an axial groove, according to one embodiment of the invention;
[0037] [Fig. 4] Figure 4 schematically represents an axial cross-sectional view of the sealing and damping element of Figure 3 positioned in an inter-blade cavity;
[0038] [Fig. 5] Figure 5 schematically represents a perspective view of the sealing and damping element of Figure 3 positioned in the inter-blade cavity;
[0039] [Fig. 6] Figure 6 schematically represents a variant of the sealing and damping device;
[0040] [Fig. 7] Figure 7 schematically represents an axial cross-sectional view of the sealing and damping element of Figure 6 positioned in an inter-blade cavity;
[0041] [Fig. 8] Figure 8 schematically represents a cross-sectional view axial of an axial groove formed in a wall of a blade, according to another embodiment;
[0042] [Fig. 9] Figure 9 schematically represents an axial cross-sectional view of the axial groove of Figure 8 in relation to a sealing and damping element;
[0043] [Fig. 10] Figure 10 schematically represents a view of two contiguous axial grooves;
[0044] [Fig. 11] Figure 11 schematically represents a view of two contiguous axial grooves according to one variant;
[0045] [Fig. 12] Figure 12 schematically represents an axial cross-sectional view of one of the axial grooves of Figure 11 opposite a sealing and damping element. Description of the implementation methods
[0046] To make the explanation more concrete, an example of a turbine wheel is described in detail below, with reference to the attached drawings. It should be noted that the invention is not limited to this example.
[0047] Figure 1 partially represents a high-pressure turbine wheel of a prior art turbomachine comprising a disk 1 carrying blades 3 regularly distributed circumferentially around an axis of rotation of the wheel and having feet 4 engaged in substantially axial recesses 2 positioned at the periphery of the disk 1. The axis of rotation extends along an axial direction X. The blade feet 4 may be of the fir-tree or dovetail cross-section type. The wheel is free to rotate about the axis of rotation.
[0048] Each blade 3 comprises a blade 6 connected at its inner radial end to a platform 5, which is itself connected to the foot 4. The blade 6 extends in a radial direction Y. The upstream and downstream ends of each platform 5 are connected respectively to an upstream radial wall 7 extending radially into the interior of the blade 3 and to a downstream radial wall 8 extending radially into the interior of the blade 3. In the mounting position, the platforms 5 are arranged circumferentially end-to-end, in a tangential direction Z, to form an internal annular flow wall for a primary airflow F originating from an airflow taken downstream of the last stage of a high-pressure compressor. Similarly, the upstream radial walls 7 and downstream radial walls 8 are arranged circumferentially opposite each other.
[0049] The wheel includes inter-blade cavities 9 distributed circumferentially around the axis of rotation of the wheel and defined radially outwards by radially internal faces 11 of the respective platforms 5 of the two adjacent blades 3 circumferentially opposite each other, radially inwards by a radially external face 10 of a tooth 31 of the disc 1, axially by two radial walls upstream 7 and downstream 8 whose ends are arranged circumferentially opposite each other, and circumferentially by two circumferential end faces 12 of the respective feet 4 of the two blades 3.
[0050] However, during the operation of the turboshaft engine, vibrations are induced in the turbine blades 3. These vibrations can lead to premature fatigue failure of the blades 6.
[0051] To dissipate the energy of these vibrations and thus reduce the amplitude of the vibrations and the associated stresses, the wheel includes vibration sealing and damping elements 13 (commonly called "candies") housed in the inter-blade cavities 9. The sealing and damping elements 13 are made of metal.
[0052] Each sealing and vibration-damping element 13 is held in position in the inter-blade cavity 9 by protruding lugs 32 in the inter-blade cavity 9.
[0053] The lugs 32 can be positioned on the upstream radial walls 7 and downstream walls 8 of each blade 3 as illustrated in Figure 2 according to the prior art or be positioned on the circumferential end faces 12 of the feet 4 of each blade 3, as illustrated according to one of the embodiments of the invention in Figure 17. These lugs 32 thus form supports for the sealing and damping elements 13 when the turbomachine is stopped and when the sealing and damping elements 13 are mounted in the inter-blade cavities 9.
[0054] When the turbine disc 1 rotates, the centrifugal force presses the sealing and damping elements 13 against the platforms 5 so that the lugs 32 no longer provide a retaining function.
[0055] Since the blades 3 are sectorized, there are inter-sector spaces called "interstices" 36 which extend axially between the platforms 5 of the circumferentially adjacent blades 3 through which the hot air from the main vein can be ingested radially into the inter-blade cavities 9.
[0056] As illustrated in the embodiment of Figure 3, each sealing and damping element 13 comprises an upstream edge 33 and a downstream edge 34 flared radially inwards, as well as two circumferential end edges 28, 30 flared and curved which follow the sides of the blades 3 radially under the platforms 5.
[0057] The upstream edges 33 and downstream edges 34 are designed to be in the immediate vicinity of the upstream radial walls 7 and downstream radial walls 8 of the two adjacent blades, in order to limit leakage through the gap 36 separating the circumferentially adjacent platforms 5. Each sealing and damping element 13 comprises an external face 22 including a radially external face 41 connected to the upstream edges 33 and downstream edges 34 and to the circumferential end edges 28, 30 which extend radially inwards.
[0058] The radially external face 41 presses against the radially internal faces 11 of two circumferentially adjacent platforms 5 under the action of centrifugal force when the wheel is rotating, which ensures the sealing of the gap 36 separating the circumferentially adjacent platforms 5.
[0059] The sealing and damping element 13 comprises an upstream end portion 23 which is adjacent to the upstream radial walls 7 of the two circumferentially adjacent blades 3. The upstream edge 33 is positioned on the upstream end portion 23, facing the upstream radial walls 7.
[0060] At least one of the inter-blade cavities 9 includes a ventilation channel 64 positioned in an upstream portion 53 of the inter-blade cavity 9, which is partially delimited by the upstream radial walls 7, 7a, 7b. The ventilation channel 64 is configured to fluidly connect the inter-blade cavity 9 to the gap 36 when the sealing and damping element 13 is bearing against the platforms 5, 5a, 5b of the two circumferentially adjacent blades 3, 3a, 3b. The ventilation channel 64 is a hollow space within the material.
[0061] According to an embodiment illustrated in figures 3 to 7, the ventilation channel 64 is formed by at least one axial groove 21' formed on the sealing and damping element 13. The axial groove 21' is positioned at an upstream part 53 of the inter-blade cavity 9 or in other words, on the side of the two upstream radial walls 7. The axial groove 21' extends along the gap 36, and is configured to fluidly connect the inter-blade cavity 9 to the gap 36 when the sealing and damping element 13 is in contact with the platforms 5 of the two circumferentially adjacent blades. The upstream part 53 is partly delimited by the two upstream radial walls 7. The upstream part 53 is the most upstream part of the inter-blade cavity 9. The upstream end part 23 of the sealing and damping element 13 is housed in the upstream part 53 of the inter-blade cavity 9.
[0062] According to an embodiment illustrated in figures 3 to 7, the axial groove 21' extends at least radially over an upstream edge 33 of the sealing and damping element 13, the axial groove 21' being positioned opposite the gap 36 and running along the gap 36.
[0063] Preferably, the axial groove 21' extends radially (along the radial direction Y) over an upstream edge 33 of the sealing and damping member 13, from an upstream end 50 of the sealing and damping member 13, and axially (along the axial direction X) over the radially external face 41 of the sealing and damping member 13, towards the downstream edge 34 of the sealing and damping member 13.
[0064] The axial groove 21' has a curved shape along the axial direction X.
[0065] The axial groove 21' comprises an upstream end portion 57, a downstream end portion 52 and an intermediate portion 51 connecting the downstream and upstream end portions 52, 57. The intermediate portion 51 has a circular arc-shaped cross-section with a depth PI and a width 11. The depth PI and / or the width 11 and / or the radius of the intermediate portion 51 are constant.
[0066] The upstream end portion 57 and the intermediate portion 51 have the same radius, depth PI, and width. The downstream end portion 52 has a curved bottom 59 and two opposing curved edges 60. The downstream end portion 52 has a rounded (or spherical) shape.
[0067] As illustrated in Figure 5, the axial groove 21' is adjacent to two upstream radial walls 7 of two circumferentially adjacent blades 3. The axial groove 21' is located at the junction (the gap 36) of two circumferentially adjacent blades 3.
[0068] Preferably, the axial groove 21' is aligned with the gap 36 and is centered with respect to the gap 36.
[0069] For example, the wall of the sealing and damping element 13 has a thickness greater than or equal to 0.3 mm, a radius greater than 1 mm, a depth PI greater than 0.5 mm and a width 11 greater than 3 mm.
[0070] Advantageously, the width 11 is greater than a width 12 of the gap 36, as illustrated in Figure 5. Preferably, the width 11 is greater than at least twice the width 12 of the gap 36, and even more preferably, greater than at least three times the width 12 of the gap 36.
[0071] Figure 4 represents a single upstream radial wall 7 and an axial section of the sealing and damping element 13 passing through the middle of the axial groove 21'. A half axial groove 21' is thus represented.
[0072] The axial half-groove 21' runs along the inner face 58 of one of the two circumferentially adjacent blades 3.
[0073] The complete axial groove 21' runs along each inner face 58 of the two circumferentially adjacent blades 3. The upstream end portion 57 of the axial groove 21' is positioned opposite the two upstream radial walls 7.
[0074] The intermediate part 51 of the axial groove 21' which is located at the place of the upstream edge 33 of the sealing and damping element 13, runs radially along the two upstream radial walls 7 and then axially along the two platforms 5 of the two circumferentially adjacent blades 3.
[0075] The inter-blade cavity 9 comprises a radially internal space 16 and a radially external space 17, which are separated by the sealing and damping element 13. The radially internal space 16 is bounded radially by the radially external face 10 of the disc 1 and a radially internal face of the sealing and damping element 13, opposite the radially external face 41 of the sealing and damping element 13. The radially external space 17 is bounded radially by the radially external face 41 of the sealing and damping element 13 and two radially internal faces 11 of two circumferentially adjacent platforms 5. The radially external space 17 communicates with the gap 36.
[0076] An air inlet 61 is formed between the upstream end portion 57 of the axial groove 21' and the two upstream radial walls 7. The air inlet 61 allows air from the radially internal space 16 of the inter-blade cavity 9, located radially below the sealing and damping element 13, to enter a channel 63 formed between the axial groove 21' and the two upstream radial walls 7, and then into the radially external space 17, located radially above the sealing and damping element 13, when the sealing and damping element 13 is pressed against the platform 5 by the centrifugal force caused by the rotation of the impeller. The air inlet 61 and the channel 63 are open and communicate with the gap 36.
[0077] As illustrated in Figure 3, the axial groove 21' extends over a length L1 which corresponds to at least l / 6 èmeof the axial length of the sealing and damping element 13. The length must be sufficient to create a cold air film on the external face 22 of the sealing and damping element 13 and in the gap 36.
[0078] According to another embodiment shown in Figures 6 and 7, the downstream end portion 52 has an elongated shape. The downstream end portion 52 extends axially in the direction of the downstream edge 34 of the sealing and damping element 13 over a non-zero length L2, which preferably corresponds to at least l / 6 èmeof the length L1 of the axial groove 21'. The downstream end portion 52 has a depth and width that gradually (or regularly) decrease to zero, respectively, following the direction of the downstream edge 34. The downstream end portion 52 includes a pointed end 62. This elongated shape improves cooling efficiency, as the elongated downstream end portion of the axial groove guides the airflow towards the downstream wall.
[0079] According to another embodiment shown in figures 8 to 12, the ventilation channel 64 is formed by two adjacent axial grooves 14a, 14b each formed on an internal face 58a, 58b of one of the circumferentially adjacent blades 3a, 3b partially delimiting the inter-blade cavity 9. Each axial groove 14a, 14b is positioned in the upstream portion 53 of the inter-blade cavity 9, or in other words, on the upstream radial wall side 7. The axial groove 14a, 14b is configured to fluidly connect the inter-blade cavity 9 to the gap 36 when the sealing and damping element 13 is bearing against the platforms 5a, 5b of the two circumferentially adjacent blades. Each axial groove 14a, 14b extends along the gap 36.
[0080] Each axial groove 14a, 14b is positioned opposite the sealing and damping element 13 and opens into the gap 36 along the entire length of the axial groove 14a, 14b.
[0081] Each axial groove 14a, 14b extends radially over one of the circumferentially adjacent upstream radial walls 7a, 7b of one of the blades 3a, 3b, and axially over one of the circumferentially adjacent platforms 5a, 5b of one of the blades 3a, 3b which is connected to said upstream radial wall 7a, 7b.
[0082] Each axial groove 14a, 14b comprises an upstream end portion 54a, 54b, a downstream end portion 56a, 56b, and a main portion 55a, 55b connecting the upstream end portions 54a, 54b and the downstream end portions 56a, 56b. The main portion 55a, 55b has a circular arc-shaped cross-section, a depth P2, and a width 13. The depth P2 and / or the width 13 and / or the radius of the main portion 55a, 55b are constant.
[0083] Each upstream end part 54a, 54b extends radially beyond the sealing and damping member 13 in the direction of the disk 1, when the sealing and damping member 13 is in contact with the platforms 5a, 5b of the two circumferentially adjacent blades 3a, 3b.
[0084] As illustrated in Figure 10, a first blade 3a comprises a first axial groove 14a extending radially over a first upstream radial wall 7a of the first blade 3a and axially over a first platform 5a of the first blade 3a. A second blade 3b, circumferentially adjacent to the first blade 3a, comprises a second axial groove 14b extending radially over a second upstream radial wall 7b of the second blade 3b and axially over a second platform 5b of the second blade 3b. The first axial groove 14a and the second axial groove 14b are positioned opposite each other, forming the ventilation channel 64. The gap 36 opens radially into the ventilation channel 64 and between the first axial groove 14a and the second axial groove 14b.
[0085] The first axial groove 14a and the second axial groove 14b have the same length and are positioned exactly opposite each other. The first axial groove 14a and the second axial groove 14b are cut into the respective platforms 5a, 5b.
[0086] The first axial groove 14a comprises a first upstream end portion 54a positioned opposite a second upstream end portion 54b of the second axial groove 14b. The first axial groove 14a comprises a first main portion 55a positioned opposite a second main portion 55b of the second axial groove 14b. The first axial groove 14a comprises a first downstream end portion 56a positioned opposite a second downstream end portion 56b of the second axial groove 14b.
[0087] The depth P2 and / or the width 13 and / or the radius of each main part 55a are constant.
[0088] The two axial grooves 14a, 14b have identical dimensions. The two axial grooves 14a, 14b are machined into the material and produced simultaneously.
[0089] The axial grooves 14a, 14b have a length L3 greater than 10 mm and a radius greater than or equal to 1 mm. The depth P2 is greater than or equal to 0.5 mm. The width 13 is greater than or equal to 1 mm.
[0090] According to a variant shown in Figures 11 and 12, each downstream end part 56a, 56b has an elongated shape, and a depth and / or width that gradually (or regularly) decreases in the direction of the downstream radial wall 8a, 8b. The downstream end parts 56a, 56b extend axially along the respective platforms 5a, 5b, from the respective main parts 55a, 55b towards the respective downstream radial walls 8a, 8b.
[0091] The depth of each downstream end part 56a, 56b evolves from depth P2 to zero depth.
[0092] Each downstream end part 56a, 56b has a length L4 which is greater than 3 mm.
[0093] According to another embodiment (not shown), the inter-blade cavity 9 comprises a first ventilation channel 64 formed by an axial groove 21' and a second ventilation channel formed by two axial grooves 14a, 14b. The axial groove 21' and the two axial grooves 14a, 14b overlap at least partially so as to create air circulation in the ventilation channels 64, between the axial grooves 14a, 14b and the axial groove 21'.
[0094] According to another embodiment (not shown), the inter-blade cavity 9 comprises, in addition to the axial groove 21' and / or the axial groove 14a, 14b, a circumferential groove which extends circumferentially (along the circumferential direction Z) on the external face 22 of the sealing and damping member 13 so that a part of the circumferential groove is positioned near, and preferably opposite, a part of the gap 36. A part of the circumferential groove covers or crosses a part of the gap 36. The inter-blade cavity 9 then comprises two ventilation channels 64, a first ventilation channel 64 formed by the axial groove 21' and / or the axial groove 14a, 14b and a second ventilation channel 64 formed by the circumferential groove.
[0095] The circumferential groove extends at least from a circumferential end edge 28 of the sealing and damping member 13 to an intermediate zone 25 of the sealing and damping member 13. The intermediate zone 25 is positioned opposite the gap 36.
[0096] The circumferential groove is positioned at the upstream end part 23 of the sealing and damping member 13. The circumferential groove runs at least partially and parallel to the upstream edge 33 of the sealing and damping member 13. More precisely, the circumferential groove runs along a curved upstream portion 42 of the sealing and damping member 13 connecting the upstream edge 33 to the radially external face 41 of the sealing and damping member 13.
[0097] The circumferential groove is formed by stamping.
[0098] According to another embodiment (not illustrated), at least one of the blades 3 comprises at least one circumferential groove formed in the foot 4 of the blade 3, along the circumferential end face 12 of the foot 4 and in the platform 5 of the blade 3, along the radially internal face 11, forming a blade with a circumferential groove. The circumferential groove is positioned at the upstream part 53 of the inter-blade cavity 9 and is formed on an inner face 58 of one of the two circumferentially adjacent blades 3 which partially delimit the inter-blade cavity 9. The circumferential groove extends from the circumferential end face 12 of the foot 4 to the radially inner face 11 of the platform 5. The circumferential groove is positioned inside the inter-blade cavity 9 and runs at least partially along the upstream radial wall 7 of the blade 3.
[0099] The circumferential groove and the circumferential channel are arranged at least partially opposite each other. The circumferential channel and the circumferential groove overlap at least partially so as to create fluidic communication between the circumferential groove and the circumferential channel. [OlOOJThe circumferential groove is cut into the material. The circumferential groove has a generally elongated shape forming a furrow or groove. The circumferential groove also has a curved shape.
[0101] The circumferential groove is adjacent to the upstream radial wall 7 of the blade 3 and runs parallel to the upstream radial wall 7. The circumferential groove may have a cross-section of regular or irregular dimensions. The circumferential groove has a C-shaped cross-section, that is, an arc of a circle.
[0102] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.