ROTOR VANE WITH ACTIVE CLEARANCE CONTROL, ROTARY ASSEMBLY AND OPERATING METHOD THEREOF

Abstract

The invention relates to a motor vane for a turbine engine, comprising a body (170) locally defining a blade provided at the radially outer end with a root (33), characterised in that it also comprises at least one sealing element (39) extending beyond the radially outer end of the root and connected to an area of the root by means of a movable mechanical link (37).

Claims

1. A rotor vane for a turbine engine, comprising a body locally defining a blade provided at the radially outer end with a blade head, and at least one sealing element connected with an area of the blade head by means of a mechanical link which can move between a rest position and an active position, wherein the sealing element radially protrudes from the blade head, wherein the movable mechanical link comprises a seal.

2. A rotor vane according to claim 1, wherein the blade head defines a root.

3. A rotor vane according to claim 1, wherein the movable mechanical link comprises a pin joint.

4. A rotor vane according to claim 1, wherein for the movable mechanical link: the sealing element has a base and the blade head has a protrusion, and one of the base and the protrusion defines a concave bowl in which an externally convex shape of the other one of the protrusion and the base is engaged.

5. A rotor vane according to claim 1, wherein the sealing element has a base having an externally convex shape movably engaged in a concave bowl of the blade head.

6. A rotor vane according to claim 4, wherein said concave bowl has an opening wherein the externally convex shape is engaged, with the edges of the opening defining abutments for the mobility of the external sealing element relative to the blade head.

7. A rotary assembly for a turbine engine comprising: a rotor disc rotatably mounted about an axis, a series of rotor vanes according to claim 1, each fixed to the rotor disc, a fixed casing provided with blocks for the contact with the sealing elements of the rotor vanes surrounded by said blocks, with the sealing elements thus being movable relative to said contact blocks.

8. An assembly according to claim 7, wherein on each rotor vane, the or each sealing element is so mounted as to move freely so that the rotor disc rotating the vanes moves the sealing elements towards the active position.

9. A method for operating a rotary assembly for a turbine engine according to claim 7, wherein: said moving sealing elements of the rotor vanes all come into contact with the contact blocks only from a predetermined speed of rotation of the vanes and/or said moving sealing elements of the rotor vanes are variably inclined, without necessarily flexing relative to the contact blocks, depending on the speed of rotation of the vanes.

10. A method for operating a rotary assembly for a turbine engine according to claim 7, wherein said moving sealing elements of the rotor vanes are variably inclined, without necessarily flexing, relative to the contact blocks, according to at least one speed of rotation of the vanes, the temperature of at least one of said vanes, and the cooling of the casing which the blocks are internally fixed to.

11. A method for producing a rotor vane for a turbine engine according to claim 4, wherein: the rotor vane is provided by orienting the concave bowl transversely to a longitudinal axis of the vane, the sealing element(s) is/are achieved, and the concave bowl and the externally convex shape are engaged together by sliding.

Description

[0044] The invention should be better understood, and other details, characteristics and advantages of the invention will appear upon reading the following description given by way of a non-restrictive example while referring to the appended drawings wherein:

[0045] FIGS. 1, 2, 3 relating to the prior art are thus respectively a schematic half view in axial section of a low-pressure turbine, a perspective view of blades each engaged by their lower end into the recesses of one of the rotor disks and a front view of a brush seal as disclosed in EP0708227;

[0046] FIG. 4 is an axial partial schematic view in section of the top of a vane according to the invention, opposite the concerned part of the stationary low pressure turbine casing then at rest;

[0047] FIG. 5 is a partial schematic view in perspective of the same area as that in FIG. 4, with the turbine rotating;

[0048] FIGS. 6, 7 are views identical with FIG. 4 but with the turbine respectively rotating at an intermediate speed and the highest speed;

[0049] and FIG. 8 is an alternative embodiment.

[0050] According to the invention, and as explained above, the solution exposed here thus requires replacing the brush seal of the embodiment of FIGS. 1, 3 with another solution that does not impose manufacturing each vane using composite material like the one mentioned in EP0708227.

[0051] FIG. 4 and the following schematically illustrate possible embodiments of such a solution. The elements identical to those of the preceding figures bear the same reference number, while still existing, but modified parts of the vanes bear a reference number incremented by a hundred. Thus, the vanes 13 become 130, which can be substituted for those of FIG. 1 and each be designed as schematically shown in FIG. 2, as regards their inner part.

[0052] Apart from the fact that it can be metallic, for example forged or cast, each rotor vane 130, which of course rotates around the axis 7, includes a body 170 locally defining a blade 190 provided at a radially outer end with a blade head 33, i.e. an end portion adapted to be (integrally or additionally) provided with at least one sealing element 39.

[0053] Preferably, each blade head 33 will be defined by or include a root 330, a possible illustration of which can be seen, more particularly in FIG. 5.

[0054] There is therefore a small platform, which defines a rim at the radially outer end of the blade considered.

[0055] Conventionally, all these roots 330 form a ring around the radiating blades 190 and directs the annular flow stream 27 outwards.

[0056] In the following description, it has been considered, in conjunction with the embodiment illustrated in FIGS. 4 to 7 and without limitation, that such a root is present on each blade.

[0057] Thus, beyond the radially outer end of its root, each vane 130 includes at least one, here two sealing element (s), with said sealing elements 39 so extending that the free end of the considered outer sealing element can be more or less spaced from the root, radially outwards, as can be seen when comparing the FIGS. 4, 6, 7.

[0058] Specifically, this ability is here provided by at least one, here two, movable mechanical link(s) 37 provided between at least one, here two, area (s) 35 of the root and the sealing element(s) 39.

[0059] Thus, by varying the specifically radial position of the sealing element (s) 39 (s) via the movable mechanical coupling(s) 37 thereof, it is possible to adapt the peripheral sealing between each root 330 and the track of the opposite casing or enclosure defined in the preferred example considered by the block 22 made of abradable material.

[0060] The issue of predicting the wear between both contacting parts and of planning maintenance will also be all the less a problem since, as shown, each movable mechanical link 37 includes a seal which enables, by pivoting, a retraction of the sealing element 39 concerned, in case of an excessive force.

[0061] In the preferred embodiment of FIGS. 4 to 6, each movable mechanical link 37 thus comprises a pin seal, with each one being rotatably mounted about an axis, respectively 41a, 41b, substantially transverse to the axis 7.

[0062] Besides, to structurally achieve the or each movable mechanical link, it is more particularly recommended, as schematically shown in FIGS. 6 and 8:

[0063] that the sealing element 39 should have a base 39a and the root 330 a protrusion 33a, on its outer face 33b,

[0064] and that one of the base and the protrusion should define a concave bowl 43 in which an externally convex shape 45 of the other one of the protrusion and the base is engaged.

[0065] In addition, in order to also ensure a good mechanical strength and easy manufacturing and maintenance, it is recommended that each sealing element 39 should have, instead, as shown in the embodiments of FIGS. 4 to 7, an externally convex base 39a movably engaged into a concave bowl 43 of the root 330.

[0066] Radially outwards, each base 39a will preferably be extended by a blade-shaped portion 39b adapted to come at its free end in abutment with a circular sector against the face 22a opposite the track adjacent thereto, and which, in the preferred example, belongs to the block 22 concerned.

[0067] To promote seal movements, or more generally for ensuring the mobility of the outer sealing element 39 relative to the root 330, the matching concave bowl 43 shall preferably have an opening 47 in which the externally convex shape 45 provided will be engaged.

[0068] The edges of each opening 47 may laterally define abutments for the outer sealing element 39 relative to the root 330, such as 49a, 49b in FIG. 6.

[0069] As illustrated in FIGS. 4 to 6, each root 330 of a rotor vane 130 preferably comprises two outer sealing elements 39, one upstream the other one downstream, thereby forming a double barrier.

[0070] In order to combine lightness, mechanical strength, easy manufacture and maintenance, it is also recommended that each sealing element 39 should be made of a composite material, such as ceramic matrix composite, or CMC.

[0071] Such a solution will more particularly and contrary to the brush 21 solution of the prior art mentioned above, make it possible for the sealing elements 39 to be movable relative to the blocks 22 made of abradable material, without necessarily flexing, with the aforementioned mobility not having to cause flexing.

[0072] When at rest as shown in FIG. 4, the sealing elements 39 illustrated elements are, by gravity, resting against one of their abutments 49a, 49b.

[0073] On the contrary, when the rotor is rotating, the matching sealing element 39 is raised further radially as shown in FIGS. 6, 7.

[0074] The downstream abutment 49b can also be so positioned that the matching sealing element 39 cannot go beyond the radial direction 51, so that it always impedes the flow of gas in the downstream direction, in this area, while the rotor is rotating.

[0075] As part of this operation, it is moreover provided that said movable sealing elements 39 will preferably be inclined relative to the body 170, and particularly to the concerned root 330, again without necessarily flexing and especially variably relative to the considered blocks 22 made of abradable material, depending on the rotational speed of the vanes 130.

[0076] In this regard, FIGS. 5, 6 show that, relative to the rest position of FIG. 4, the movable sealing elements 39, then in operative position, are more inclined outwardly and the radial axis 51 when the turbine rotates at an intermediate speed (FIG. 6) than when it rotates at a higher speed (FIG. 7), specifically at full rated speed (with the sealing blocks 22 being assumed in good condition). This is due to differential expansions, which occur, and to the radial approximation which then occurs between the roots 33 and the sealing blocks 22. It should also be noted that the distance between the blade heads and the matching abradable ring, defined by the circumferential array of blocks 22 will depend on the speed of rotation of the vanes, but on other operating conditions too, such as the expected engine power output, via an injection of more or less fuel and/or the duration of the high load and/or high rotational speed of the turbine.

[0077] Thus, the above distance is shorter in FIG. 7 than in FIG. 6 and accordingly the movable sealing elements 39 are further inclined to the radial direction 51 in FIG. 6 than in FIG. 7.

[0078] It is also provided that the same moving sealing elements 39 will variably be inclined, again without necessarily flexing with respect to the sealing blocks 22, according to the wear of the abradable material. A downstream abutment 49b is located so that the matching sealing element 39 will not be able to go beyond the radial direction 51 will be relevant.

[0079] As an alternative solution to the embodiment of FIGS. 4 to 7, FIG. 8 shows a (not preferred) solution wherein:

[0080] the sealing element 39 has a base 39a and the root 330 a protrusion 33a, on its outer face 33b,

[0081] and the base defines a concave bowl 43, wherein the externally convex shape 45 of the protrusion 33a of the root is engaged.

[0082] As regards now with the articulated sealing elements 39, the mounting will, in particular for the illustrated pin seal, be obtained by fit-sliding (axis 41a, 41b) each sealing element, in compliance with the slight clearance required for pivoting (preferably freely pivoting), as in the case of a dovetail mounting. Sliding locking will preferably be obtained by the considered sealing element abutting against the adjacent vanes, as can be understood when looking at FIG. 5.

[0083] As for the abradable material which each contact block 22 may be made of, it will preferably be made of a softer material than the materials of the sealing elements 39. These may be made of ceramic matrix composite, or CMC, with the same advantages as those mentioned above.