Rotor blade for turbomachine

Abstract

Rotor blade (100) comprising a blade extending in a radial direction, a radially external platform (104) connected to a radially external end of the blade (102), and a sealing element (110) mounted radially outside the radially external platform (104), characterized in that the sealing element (110) is mounted to move freely in translation at least in the radial direction relative to the radially external platform (104). Abstract figure: Figure 5

Description

Title of the invention: Rotor blade for turbomachine technical field

[0001] This description relates to a rotor blade for a turbomachine. This description also relates to a turbomachine assembly comprising such a rotor blade and to a turbomachine turbine comprising such a turbomachine assembly. Finally, this description relates to a turbomachine comprising such a turbomachine assembly or such a turbine. Previous technique

[0002] Figure 1 illustrates a prior art turbomachine 1. This turbomachine comprises, from upstream to downstream in the direction of gas flow, a blower 2 which generates an airflow, a central portion of which is injected into a primary annular VP defined by a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, a low-pressure turbine 7, and a gas exhaust nozzle 8. The high-pressure compressor 4 and the low-pressure compressor 3 are respectively connected to a high-pressure turbine 6 and a low-pressure turbine 7 by a respective shaft 9 extending along the direction of a longitudinal axis X of the turbomachine 1. The turbine also supplies the blower 2.

[0003] A peripheral part of the airflow from the fan 2 circulates in a secondary annular vein VS. This peripheral part of the airflow is ejected into the atmosphere to provide most of the thrust of the turbomachine.

[0004] Each turbine stage 6, 7 is formed by an upstream distributor comprising an annular row of fixed blades 12 relative to the external annular casing 11 and a downstream moving wheel comprising an annular row of moving blades 10 inside the external annular casing 11. Each annular row of moving blades 10 or fixed blades 12 includes an internal platform 13 and an external platform 14 delimiting the primary annular channel VP of gas flow through the compressor 3, 4 or the turbine 6, 7.

[0005] As shown in [Fig.2], in the case of a turbine 6, 7, the radially external face of the external platform 14 of each moving blade 10 comprises sealing cooperative scrapers 15 with an annular abradable element 16, mounted in an external ring 17. In particular, the external ring 17 has a groove opening radially inwards, in which the abradable element 16 is mounted. The external ring 17 is carried by the external annular housing 11.

[0006] The abradable element 16 generally comprises an alveolar structure, also called a honeycomb structure, into which the licks 15 penetrate from It undergoes differential thermal expansion and mechanical deformation during operation. Following prolonged use, the abradable element 16 wears out and then needs to be replaced.

[0007] Moreover, the thermal inertia of the external annular casing 11 is less than the thermal inertia of the moving blades 10. As a result, as can be seen in [Fig.3], a radial clearance j can form between the blades 15 and the abradable element 16, which allows the passage of gases from the turbomachine (represented by arrow F in [Fig.3]) and reduces the performance of the turbomachine.

[0008] To achieve this, it is known to control the clearance between the moving blades 10 of the turbine 6, 7 and the external annular casing 11. A control valve 20, preferably of the LPTACC type (for "Low Pressure Turbine Active Clearance Control" or CAJTBP system for "Commandment Active du Jeu de Turbine Basse Pression" in French), is provided. Figure 4 schematically illustrates the architecture of the environment of this valve 20 and its active control. This control valve 20 allows continuous control of an air flow from the secondary annular vein VS, from a spigot 18, and directs it to the external annular casing 11 of the turbine 6, 7 located opposite the turbine blades 10 of the turbine 6, 7. The spigot 18 communicates with a supply duct 22 which brings the air flow to the control valve 20. A discharge duct 24 then carries this air from the control valve 20 to the casing 16.A calculation unit 40 receives, among other things, the engine speed value as input and calculates a flow control command which is converted into a position control command. This position control command is sent to an actuator 30 which actuates the valve 20. Position sensors (not shown) provide feedback to the calculation unit 40.

[0009] However, such a game control system proves to be cumbersome and complex to implement. Summary

[0010] A rotor blade is proposed for a turbomachine, intended to be mounted on the periphery of a rotating wheel centered on an axis, the rotor blade comprising: - a blade extending in a radial direction with respect to the axis, - a radially external platform connected to a radially external end of the blade, and - a sealing element mounted radially outside the radially external platform, characterized in that the sealing element is mounted free in translational movement at least in the radial direction relative to the radially external platform.

[0011] The sealing element may include a block of abradable material having a radially external face adapted to cooperate in sealing with a complementary sealing element, such as at least one annular lip mounted radially opposite each other on a housing.

[0012] The rotor blade may include means for guiding translation in the radial direction connecting the sealing element to the radially external platform, the guiding means comprising a first side wall and a second side wall extending radially inwards from a radially internal face of the sealing element and parallel to each other so as to define an internal space between them, the guiding means further comprising an intermediate wall extending radially outwards from the radially external platform, the intermediate wall being received in the internal space formed by the first side wall and the second side wall.

[0013] The first side wall may include at least one first radial guide slot and the intercalated wall includes a second radial guide slot opposite said at least one first guide slot, the guide means including a pin passing through the first guide slot and the second the intercalated guide slot.

[0014] According to another aspect, a shaft-mounted turbomachine assembly is proposed, the assembly comprising an annular row of rotor blades as described above. The sealing elements of the rotor blades can be arranged circumferentially end-to-end around the shaft so as to form a first annular sealing element.

[0015] The sealing elements of at least two circumferentially adjacent rotor blades may be made, in whole or in part, of material.

[0016] The turbomachine assembly may further include an external annular housing surrounding the annular row of rotor blades, said external annular housing carrying on a radially internal face a second annular sealing element, the first annular sealing element and the second annular sealing element being adapted to cooperate in sealing with each other.

[0017] The sealing element of each rotor blade can be adapted to be moved freely radially outwards by centrifugal effect when the annular row of rotor blades is driven in rotation around the axis, up to a sealing position in which the sealing element of each rotor blade cooperates in sealing with the second annular sealing element.

[0018] The first annular sealing element may include an annular track of abradable material around the axis formed by the blocks of abradable material of the annular row of rotor blades. The second annular sealing element may include at least one ring lick, preferably two ring licks spaced along the longitudinal direction.

[0019] According to another aspect, a turbomachine turbine is proposed comprising a turbomachine assembly as described above.

[0020] According to another aspect, a turbomachine is proposed comprising a turbomachine assembly as described above or comprising a turbine as described above.

[0021] A method of using a turbomachine assembly as described above or a turbine as described above is further proposed, in which the annular row of rotor blades is driven in rotation around the longitudinal axis, the unit sealing element of at least one rotor blade among the annular row of rotor blades is moved freely radially outwards by centrifugal effect, preferably into a sealing position in which the unit sealing element cooperates in sealing with the second annular sealing element. Brief description of the drawings

[0022] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0023] [Fig-1] is a schematic axial cross-sectional view of a double-type turbomachine known flow.

[0024] [Fig.2] is a partial schematic axial cross-sectional view of a turbine of the turbomachine of [Fig.1].

[0025] [Fig.3] is a larger scale view of the dotted area in [Fig.2].

[0026] [Fig.4] is a schematic view illustrating the turbomachine of [Fig.1] and a active control device for the turbine set.

[0027] [Fig.5] is a partial schematic axial cross-sectional view of a turbine according to the present description.

[0028] [Fig.6] is an exploded schematic view of a rotor blade of the sealing turbine of [Fig.5].

[0029] [Fig.7] is a partial schematic view of an annular row of rotor blades of the turbine of [Fig.5], according to a first embodiment.

[0030] [Fig.8] is a partial schematic view of an annular row of rotor blades of the turbine of [Fig.5], according to a second embodiment. Description of the implementation methods

[0031] Reference is first made to [Fig.6] which represents a rotor blade 100 for an XI axis turbomachine.

[0032] In the present description, the longitudinal direction X corresponds to the direction of axis XI. Axis XI coincides with an axis of rotation of the rotor parts of the turbomachine. Orientation qualifiers, such as "longitudinal," "radial," or "circumferential," are defined, unless otherwise specified, with reference to axis XL. A radial direction is a direction perpendicular to the direction of axis XL. A circumferential direction, at a point far from axis XI, corresponds to a direction perpendicular to both the longitudinal and radial directions. Furthermore, unless otherwise specified, the adjectives "inner," "internal," "outer," and "external" are used with reference to a radial direction, such that the inner / internal (i.e., radially inner / internal) part of an element is closer to axis XI than the outer / external (i.e., radially outer / external) part of the same element.Finally, the relative qualifiers "upstream" and "downstream" are defined in relation to the normal direction of fluid flow (from upstream AM to downstream AV) in the turbomachine.

[0033] The rotor blade 100 includes a blade 102 extending radially about the axis XL. The rotor blade 100 may include a foot at its radially inner end. The blade 102 of the rotor blade 100 may extend radially outward from the foot of the rotor blade 100. The blade also includes a radially outer platform 104 connected to a radially outer end of the blade 102.

[0034] Finally, and remarkably, the rotor blade 100 includes a sealing element 110 mounted radially outside the radially external platform. More specifically, the sealing element can be mounted on a radially external face of the radially external platform 104. The sealing element 110 is free to translate at least in the radial direction relative to the radially external platform 104. In another formulation, the sealing element 110 is free to translate in a direction that includes at least one component in the radial direction. In other words, the sealing element 110 has at least one degree of freedom in translation in the radial direction. In the illustrated example, the sealing element 110 is free to translate in the radial direction relative to the radially external platform 104.

[0035] The degree of freedom along the radial direction of the sealing element 110 allows it to be moved automatically outwards by centrifugal effect when the rotor blade 100 is driven rotation around the axis XL II is thus obtained a "self-adaptation" of the radial position of the sealing element 110 relative to the radially external platform 104 in order to limit, or even avoid, a radial play between the sealing element 110 and a radially external component with which it can cooperate in sealing.

[0036] Furthermore, the degree of freedom of the sealing element 110 advantageously avoids the application of excessive forces on the latter, thus avoiding inappropriate wear of the sealing element 110 and / or damage to it.

[0037] The sealing element 110 may include a block of abradable material 112, one radially external face of which is adapted to cooperate in sealing with a complementary sealing element, such as at least one annular lip 222 mounted on a housing as described in more detail below. For this purpose, the sealing element 110 may include a support plate 114. The block of abradable material 112 may be supported by a radially external face of the support plate 114. The block of abradable material 112 and / or the support plate 114 may have a parallelepiped shape. Alternatively, the block of abradable material 112 and / or the support plate 114 may have an arc shape around the axis XL. The abradable material may include a honeycomb structure, for example, of the honeycomb type.

[0038] The blade may include translational guiding means 120 in the radial direction connecting the sealing element 110 to the radially external platform 104. The guiding means 120 may include a first side wall 121 and a second side wall 122 extending radially inward from a radially internal face of the sealing element 110 and parallel to each other so as to define an internal space between them. As in the illustrated example, the first side wall 121 and the second side wall 122 may be spaced apart from each other, in particular in the longitudinal direction X. The first side wall 121 may be an upstream wall and the second side wall 122 may be a downstream wall.

[0039] The guiding means 120 may further comprise an interlayer wall 123 extending radially outwards from the radially external platform 104, the interlayer wall 123 being received in the internal space formed by the first side wall 121 and the second side wall 122. The interlayer wall 123 may be received between the first side wall 121 and the second side wall 122, in particular along the longitudinal direction X as in the illustrated example. According to another formulation, the interlayer wall 123 may be interposed, preferably longitudinally, between the first side wall 121 and the second side wall 122. The interlayer wall 123 is thus able to slide radially between the first side wall 121 and the second side wall 122. This provides translational guidance of the sealing element 110 relative to the radially external platform 104.

[0040] The first side wall 121 may include at least one first radial guide slot 124; 125 and the intercalated wall 123 may include a second A radial guide slot 126 is positioned opposite the first guide slot. The first guide slot 124; 125 and the second guide slot 126 can be positioned opposite each other along the longitudinal direction X. The guiding means 120 can further include a pin 127 passing through the first guide slot and the second through the intermediate guide slot. Such an arrangement allows translational guidance of the sealing element 110 relative to the external radial platform 104 only in the radial direction.

[0041] More specifically, according to the example shown, the first side wall 121 and the second side wall 122 may respectively comprise a first radial guide slot 124 and a second radial guide slot 125, and the intercalated wall 123 may comprise a third radial guide slot 126 opposite, preferably longitudinally, the first and second guide slots. The pin 127 may pass through each of the first, second, and third guide slots.

[0042] The pin 127 can extend longitudinally. The pin 127 can extend between a first end and a second end. A portion of the pin 127 at the first end can be positioned on one side of the first lateral wall 121 opposite the side of which the second lateral wall 122 is located and can be widened to prevent it from passing through the first guide slot. A portion at the second end of the pin 127 can be positioned on one side of the second lateral wall 122 opposite the side of which the first lateral wall 121 is located and can be widened to prevent it from passing through the second guide slot.

[0043] The pin 127 can be fixed to any one of the walls. More particularly, the pin 127 can be fixed to the first side wall 121, the second side wall 122 and / or the intermediate wall 123.

[0044] The first guide slot 124 and / or the second guide slot 125 may each open at a radially inner end of the respective side wall. The guide slot 126 through the third wall may have the shape of an oblong hole whose major axis extends in the radial direction.

[0045] Each slot may have dimensions that limit the passage of gas through it. Alternatively or additionally, the pin 127 may have a head configured to partially or completely obstruct the passage of gas through the slots.

[0046] According to an alternative not shown, the pin 127 may be formed from the material of the interlayer wall 123. In other words, the pin 127 may extend, for example longitudinally, from one face of the interlayer wall 123. The pin 127 may pass through a radial guide slot formed in the side wall opposite said face of the interlayer wall 123. Two pins 127s may be provided, each extending respectively from opposite faces, preferably longitudinally, of the wall intercalary 123, each pin 127 passing through a radial guide slot formed in the side wall opposite the face of the intercalary wall 123 from which said pin 127 extends.

[0047] According to another alternative not shown, a pin 127 may be provided, made of material with one of the lateral walls and passing through a radial guide slot formed in the intercalated wall 123. Also, two pins 127s may be provided, each made with a respective lateral wall between the first lateral wall 121 and the second lateral wall 122 and each passing through a radial guide slot formed in the intercalated wall 123.

[0048] A turbomachine assembly is now described with reference to Figures 5, 7, and 8. The turbomachine assembly comprises an annular row of rotor blades 100 as described above. The annular row of rotor blades 100 is adapted to be driven in rotation about the axis XL. The turbomachine assembly may include a rotor disk mounted to rotate about the axis XI, preferably on a shaft extending along the axis XL. Each rotor blade 100 of the annular row may be mounted on the rotor disk, in particular at an internal radial end. In other words, the rotor disk may carry the annular row of rotor blades 100 on its outer periphery. More specifically, the rotor disk may include an annular row of grooves or recesses on its outer periphery, in each of which the root of one of the rotor blades 100 is received by complementary shapes.

[0049] The sealing elements 110 of the rotor blades 100 form a first annular sealing element 210. In other words, the sealing elements 110 of the rotor blades 100 of the annular row arranged circumferentially end to end so as to form the first annular sealing element 210. [Fig.7] illustrates two circumferentially adjacent sealing elements 110.

[0050] According to a particular embodiment illustrated in [Fig. 8], the sealing elements 110 of at least two circumferentially adjacent rotor blades 100 are, in whole or in part, made from a single piece of material. Assembly of the entire turbomachine is thus faster. In other words, the sealing elements 110 of at least two circumferentially adjacent rotor blades 100 can be made from a single piece of material. In particular, as illustrated, the blocks of abradable material 112 of said at least two circumferentially adjacent rotor blades 100 can be made from a single piece of material. In other words, a circumferential end of the abradable material block 112 of one of two circumferentially adjacent rotor blades 100 may have come from, or been confused with, a circumferential end of the abradable material block 112 of the other of the two circumferentially adjacent rotor blades 100.Similarly, the 114 support plates of said at least two rotor blades 100. Circumferentially adjacent may be made of material. Also, the first side wall 121 and the second side wall 122 of the guiding means 120 of said at least two circumferentially adjacent rotor blades 100 may be made of material.

[0051] According to another formulation, the first annular sealing element 210 can be formed by a plurality of groups of sealing elements 110 joined together. To facilitate its manufacture, the first annular sealing element 210 can be formed from two or more groups of sealing elements 110 joined together. In the case where the first annular sealing element 210 is formed from at least two groups of sealing elements 110 joined together, the first annular sealing element 210 can be divided into sections.

[0052] An embodiment in which the unit element of each rotor blade 100 is structurally independent, or distinct, from the unit elements of circumferentially adjacent rotor blades 100 is not excluded.

[0053] As particularly visible in [Fig. 5], the turbomachine assembly may further comprise an external annular casing 201 surrounding the row of moving blades. The external annular casing 201 may carry a second annular sealing element 220 on a radially internal face. The first annular sealing element 210 and the second annular sealing element 220 may be adapted to cooperate in sealing with each other. In other words, when the first annular sealing element 210 and the second annular sealing element 220 cooperate in sealing with each other, a gas flow circulating from upstream to downstream through the turbomachine assembly cannot pass radially between the first annular sealing element 210 and the second annular sealing element 220.Such a turbomachine assembly advantageously presents increased radial sealing between the first annular sealing element 210 and the second annular sealing element 220.

[0054] A radially internal face of the radially external platforms 104 of the rotor blades 100 can radially delimit within a primary annular gas flow channel VP at the turbomachine assembly. The sealing cooperation between the first annular sealing element 210 and the second annular sealing element 220 limits, or even prevents, gas leakage radially outside the primary annular gas flow channel VP.

[0055] More particularly, the sealing element 110 of each rotor blade 100 can be adapted to move freely radially outwards by centrifugal force when the annular row of rotor blades 100 is rotated about the axis XI, up to a sealing position in which the sealing element 110 of each rotor blade 100 cooperates in sealing with the second annular sealing element 220.

[0056] During the operation of the turbomachine assembly, i.e., during the rotation of the annular row of rotor blades 100 around the axis XI, a flush fit, or even contact, is maintained between the first annular sealing element 210 and the second annular sealing element 220 by the centrifugal effect resulting from the rotation of the annular row of rotor blades 100 around the axis XL. The seal between the annular row of rotor blades 100 and the external annular housing 201 is thus maintained "automatically" throughout the operation of the turbomachine assembly. In particular, it is not necessary to provide an active radial clearance control device between the first annular sealing element 210 of each rotating blade and the second annular sealing element 220.

[0057] In particular, a sealing cooperation can be obtained between the first annular sealing element 210 and the second annular sealing element 220 when the sealing element 110 of each rotor blade 100 is in its sealing position.

[0058] The first annular sealing element 210 can therefore include an annular track of abradable material 212 around the axis XI formed by the blocks of abradable material 112 of the annular row of rotor blades 100. In particular, the annular track of abradable material 212 can be formed by the radially external face of the blocks of abradable material 112 of the sealing elements 110 of the annular row of moving blades. The annular track of abradable material 212 can be circumferentially continuous around the axis XL. To achieve this, the blocks of abradable material 112 of the sealing elements 110 of the rotor blades 100 can be arranged end to end around the axis XL. The block of abradable material 112 of each sealing element 110 can extend circumferentially between a first end and a second end.The first end of the abradable material block 112 of each rotor blade 100 can be circumferentially joined with the second end of the abradable material block 112 of the circumferentially adjacent rotor blade 100. The annular track of abradable material 212 can have a circular shape in a cutting plane perpendicular to the axis XL. The annular track of abradable material can also have a polygonal shape in a cutting plane perpendicular to the axis XI, the number of sides of which coincides with the number of groups of sealing elements 110 made of material between them or with the number of rotor blades 100. However, it is not excluded that a radial step may be formed between the radially external surface of the abradable material blocks 112 of two circumferentially adjacent rotor blades 100.

[0059] The second annular sealing element 220 may include at least one annular lip 222, preferably two annular lips 222 spaced along the longitudinal direction X. Each annular lip 222 may cooperate by friction with the annular track of abradable material 212 in order to ensure sealing.

[0060] The second annular sealing element 220 may include a ring 224 carried by the radially internal face of the external annular housing 201, each annular lip 222 extending radially inwards from a radially internal face of the ring 224.

[0061] According to another aspect, a turbomachine turbine 200 is described which comprises a turbomachine assembly as described above. Remarkably, the turbine 200 can be devoid of an active radial clearance control device between the radially external outer edge of the blades and the external annular casing 201, in particular by cooling the external annular casing 201 by means of an airflow taken upstream in the turbomachine.

[0062] The turbine 200 can be of the high-pressure type or the low-pressure type. As seen in [Fig. 5], the turbine 200 can comprise a succession of rotor stages 202 and stator stages 204. At least one of the rotor stages 202 can comprise the turbomachine assembly as described above.

[0063] A turbomachine may be provided that comprises a turbomachine assembly as described above or comprising a turbine 200 as described above. The turbomachine may be of the twin-scroll type. The turbomachine may include a fan that generates an airflow, a central portion of which is injected into a primary annular VP defined by a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, and an exhaust nozzle. A peripheral portion of the airflow from the fan may flow into a secondary annular VP.

Claims

Demands

1. Rotor blade (100), for a turbomachine, intended to be mounted on the periphery of a rotating wheel centered on an axis (XI), the rotor blade comprising: - a blade extending in a radial direction with respect to the axis (XI), - a radially external platform (104) connected to a radially external end of the blade (102), and - a sealing element (110) mounted radially outside the radially external platform (104), characterized in that the sealing element (110) is mounted free in translational motion at least in the radial direction with respect to the radially external platform (104).

2. Rotor blade (100) according to the preceding claim, wherein the sealing element (110) comprises a block of abradable material (112) having a radially external face adapted to cooperate in sealing with a complementary sealing element, such as at least one annular scraper (222) mounted radially opposite on a housing.

3. Rotor blade (100) according to any one of the preceding claims, which includes translational guiding means (120) in the radial direction connecting the sealing element (110) to the radially external platform (104), the guiding means (120) comprising a first side wall (121) and a second side wall (122) extending radially inwards from a radially internal face of the sealing element (110) and parallel to each other so as to define an internal space between them, the guiding means (120) further comprising an intercalated wall (123) extending radially outwards from the radially external platform (104), the intercalated wall (123) being received in the internal space formed by the first side wall (121) and the second side wall (122).

4. Rotor blade (100) according to the preceding claim, wherein the first side wall (121) comprises at least one first radial guide slot (124; 125) and the intermediate wall (126) comprises a second radial guide slot (123) opposite said at least one first guide slot (124; 125), the guiding means (120) comprising a pin (127) passing through the first guide slot (124; 125) and the second through the intermediate guide slot (126).

5. A shaft (XI) turbomachine assembly, the assembly comprising an annular row of rotor blades (100) according to any one of the preceding claims, wherein the sealing elements (110) of the rotor blades (100) are arranged circumferentially end to end around the shaft (XI) so as to form a first annular sealing element (210).

6. Turbomachine assembly according to the preceding claim, wherein the sealing elements (110) of at least two circumferentially adjacent rotor blades (100) are, in whole or in part, made of material.

7. Turbomachine assembly according to any one of claims 5 or 6, further comprising an external annular housing (201) surrounding the annular row of rotor blades (100), said external annular housing (201) carrying on a radially internal face a second annular sealing element (220), the first annular sealing element (210) and the second annular sealing element (220) being adapted to cooperate in sealing with each other.

8. Turbomachine assembly according to the preceding claim, wherein the sealing element (110) of each rotor blade (100) is adapted to be moved freely radially outwards by centrifugal effect when the annular row of rotor blades (100) is driven in rotation about the axis (XI), up to a sealing position in which the sealing element (110) of each rotor blade (100) cooperates in sealing with the second annular sealing element (220).

9. Turbomachine assembly according to any one of the preceding claims 5 to 8, taken in combination with claim 2, the first annular sealing element (210) comprising an annular track of abradable material (212) around the axis (XI) formed by the blocks of abradable material (112) of the annular row of rotor blades (100), and in which the second annular sealing element (220) comprises at least one annular flap (222), preferably two annular flaps (222) spaced along the longitudinal direction (X).

10. Turbomachine turbine (200) comprising a turbomachine assembly according to any one of claims 5 to 9.

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