FR3107922A1 - FLASHING FOR MOBILE TURBOMACHINE Dawn - Google Patents

Abstract

FLASHING FOR MOBILE TURBOMACHINE Dawn The invention relates to a foil (14) for a turbomachine moving blade (10) configured to be mounted on a foot (13) of said moving blade (10) comprising, at a lower surface (13-2) , a recess (13-2), the foil (10) comprising: a base (14-2) connecting two lateral branches (14-1) between them which form means for maintaining the foil (14) on the foot (13) of the mobile blade (10), first blocking means (14-3) configured to block the relative movements between the foot (13) of the movable blade (10) and the foil (14), the first blocking means (14-3) projecting from a surface of the base (14-2) intended to be in contact with the foot (13) of the movable blade (10) and being able to cooperate with the recess (13-2) present in the foot (13) of the moving blade (10). Figure to be published with the abstract: 5

Description

TURBOMACHINE VANE FOILER

TECHNICAL FIELD OF THE INVENTION

The invention relates to the general field of turbomachines.

The invention relates more particularly to a shim for a moving blade of a turbine engine, as well as a system comprising a moving blade whose root is provided with said shim.
TECHNOLOGICAL BACKGROUND OF THE INVENTION

In the present application, the terms "internal" and "external", "lower", "upper", "radial" and "axial" are used in reference to the position of a part or a surface with respect to the longitudinal axis of the turbomachine. In addition, the terms "upstream" and "downstream" are used in reference to the direction of flow of the air flow in the turbine illustrated in the figures by an arrow.

In known manner, a moving rotor blade comprises a blade provided, in the lower part, with a foot intended to be inserted into a cavity made in the outer periphery of a disc of the rotor. The root of the moving blade is retained radially in the cavity of the disc by cooperation of shapes between the root, generally in the shape of a dovetail, with the cavity, generally in the shape of a cell. In the upper part, the blade is provided with a heel intended to be arranged edge to edge with the heel of the adjacent moving blades so as to form a rotating circumferential ring delimiting a surface of revolution around the axis of rotation of the disc.

During rotor operation, contact between the blade roots, generally made of titanium aluminide, and the disc, generally made of nickel-based alloy, causes premature wear of the blade roots. However, significant wear of the blade roots can cause the heels of the moving blades to overlap or even to disengage from each other and thus lead to a loss of contact between the heels.

In order to limit the wear of the blade roots, it is known to place a contact part, called foil, at the level of the contact interfaces, commonly called bearing surfaces, between the blade roots and the cavities of the disk. The shim, integral with the root of the blade and in contact with the disc, takes up a major part of the energy dissipated by friction in the contact between the root of the blade and the disc, which makes it possible to limit the wear of the foot of dawn.

Figure 1 is a perspective view of a moving rotor blade fitted with a foil. Figure 2 is an enlargement of the root of the blade shown in Figure 1.

Referring to Figures 1 and 2, the moving blade 1 comprises a blade 2 delimited, in the upper part, by a heel 3 and, in the lower part, by a platform 5 which is extended radially inwards by a foot 6. A shim 7 is mounted on the foot 6 of the moving blade 1.

Figure 3 is a perspective view of the shim 7 shown in Figures 1 and 2.

As can be seen in Figure 3, the shim 7, of generally U-shaped section, comprises two lateral branches 7-1 intended to cover the lateral flanks 6-1 of the foot 6 of the moving blade 1 and to maintain the foil 7 on the foot 6 as well as a base 7-2 connecting the branches 7-1 to each other and covering a lower surface 6-2 of the foot 6.

In order to prevent the shim 7 from disengaging from the foot 6, the base 7-2 of the shim 7 comprises, at its upstream edge and its downstream edge, tabs 7-3 which are folded between the branches 7- 1 and which bear axially against the upstream and downstream faces of the foot 6. Thus, the tongues 7-3 form abutments which make it possible to block the relative movements between the foot 6 and the shim 7.

However, despite the presence of these tabs 7-3, shims 7 continue to disengage from the feet 6 of the moving blades 1.

The invention offers a solution to the problems mentioned above, by proposing a shim comprising locking means making it possible to prevent its disengagement from a root of a moving blade.

A first aspect of the invention relates to a shim for a turbine engine moving blade configured to be mounted on a foot of said moving blade comprising, at a lower surface, a recess.

The shim comprises a base connecting two lateral branches together which form means for holding the shim on the root of the moving blade.

Furthermore, the shim comprises first blocking means configured to block the relative movements between the foot of the moving blade and the shim, the first blocking means protruding from a surface of the base intended to be in contact with the foot of the moving blade and being capable of cooperating with the recess present in the root of the moving blade.

Thus, when the shim is mounted on the foot of a moving blade provided, at its lower surface, with a recess, the first blocking means are positioned in the recess so as to be axially in abutment against the peripheral wall delimiting said recess which makes it possible to block the movement of the foot of the moving blade with respect to the shim and thus to avoid disengagement of the shim

In addition to the characteristics which have just been mentioned in the previous paragraph, the foil according to the first aspect of the invention may have one or more additional characteristics among the following, considered individually or in all technically possible combinations.

According to a non-limiting embodiment, the first blocking means are formed by first tongues extending radially from the surface of the base intended to be in contact with the root of the moving blade.

According to a non-limiting embodiment, the number of first tabs is between three and six.

According to a non-limiting embodiment, the first blocking means are formed by a pin which extends radially from the surface of the base intended to be in contact with the root of the moving blade.

According to a non-limiting embodiment, the base comprises an orifice, the first blocking means being arranged at the periphery of said orifice.

According to a non-limiting embodiment, the first blocking means are formed by a flanged edge bordering the orifice and which extends radially from the surface of the base intended to be in contact with the root of the moving blade.

According to a non-limiting embodiment, the first blocking means are arranged in a central region of the base of the foil.

According to a non-limiting embodiment, the shim comprises second locking means formed by second tongues, each of the second tongues projecting with respect to the base of the shim, at the level of an edge of said base, and being intended to be in contact with one of the upstream or downstream faces of the root of the moving blade.

• une aube mobile comportantun pied présentant une surface inférieure dans laquelle est ménagé un renfoncement délimité par une paroi périphérique,
• le clinquant selon le premier aspect de l’invention, monté sur le pied de l’aube mobile de sorte que les premiers moyens de blocage soient positionnés à l’intérieur du renforcement et en butée contre la paroi périphérique dudit renfoncement.

In addition, the invention according to a second aspect relates to a system for a turbomachine rotor, comprising:

• a mobile blade comprising a root having a lower surface in which a recess delimited by a peripheral wall is formed,
• the shim according to the first aspect of the invention, mounted on the root of the moving blade so that the first blocking means are positioned inside the reinforcement and in abutment against the peripheral wall of said recess.

In addition to the characteristics which have just been mentioned in the previous paragraph, the system according to the second aspect of the invention may have one or more additional characteristics among the following, considered individually or in all technically possible combinations.

According to a non-limiting embodiment, the second shim blocking means comprise two second tongues, one of the second tongues being axially in abutment against the upstream face of the root of the moving blade and the other second tongue being axially in abutment against the downstream face of the moving blade.

According to a non-limiting embodiment, the recess made in the foot and the orifice made in the shim are circular and have the same radius.

According to a non-limiting embodiment, the radius of the recess and the radius of the orifice are between 2 and 3.5 mm.

According to a non-limiting embodiment, the first tabs and the recess have, respectively, an equal height and depth, for example between 1 and 2 mm.

According to a non-limiting embodiment, the stud and the recess have, respectively, an equal height and depth, for example between 1 and 2 mm.

According to a non-limiting embodiment, the dropped edge and the recess have, respectively, an equal height and depth, for example comprised between 1 and 2 mm.

According to a non-limiting embodiment, the shim holding means comprise two second tongues, one of the second tongues bearing axially against an upstream face of the foot of the moving blade and the other second tongue bearing axially against a downstream face of the moving blade.

A third aspect of the invention relates to a turbomachine comprising a rotor comprising at least one system according to the second aspect of the invention.

The invention and its various applications will be better understood on reading the following description and examining the accompanying figures.

BRIEF DESCRIPTION OF FIGURES

The figures are presented for information only and in no way limit the invention.

shows a moving blade provided with a foil according to the prior art.

is an enlargement of the root of the blade shown in Figure 1.

shows the foil shown in Figures 1 and 2.

shows a system according to one embodiment of the invention, comprising a moving blade and a foil.

shows the foil shown in Figure 4.

shows the root of the blade shown in Figure 4.

DETAILED DESCRIPTION

Unless specified otherwise, the same element appearing in different figures has a single reference.

The invention relates to a shim for a moving blade of a turbomachine as well as to a system for a turbomachine rotor comprising a moving blade provided with such a shim.

It is recalled that a turbomachine generally comprises, from upstream to downstream in the direction of gas flow, a fan, one or more compressor stage(s), for example a low-pressure compressor and a high-pressure compressor, a combustion chamber, one or more turbine stages, for example a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle. Each turbine, i.e. low and high pressure, consists of a succession of axial stages arranged one behind the other. Each stage comprises a wheel of moving blades forming the rotor and a wheel of fixed blades forming the distributor. The mobile wheel is set in rotation vis-à-vis the corresponding distributor.

FIG. 4 shows the system 20 for a turbomachine rotor according to one embodiment of the invention, comprising a moving blade 10 and a shim 14. FIGS. 5 and 6 show, respectively, the shim 14 and the foot 13 of the moving blade 10 of system 20.

Referring to Figure 4, the moving blade 10 of the rotor comprises a blade 11 extending radially between a radially outer end and a radially inner end. At its radially outer end, the moving blade 10 includes a heel (not shown). At its radially inner end, the moving blade 10 comprises a platform 12 extended internally by a foot 13 by which it is fixed to the disk (not shown) of the rotor.

The root 13 of the moving blade 10 is engaged in a cavity made in the outer periphery of the disc and held radially in said cavity by shape cooperation between the root 13 and the cavity. Advantageously, the foot 13 of the moving blade 10 is in the shape of a dovetail and the cavity of the disc in the shape of an alveolus. In particular, the root 13 of the moving blade 10 comprises a lower surface 13-1, two lateral flanks 13-3, an upstream face 13-4 and a downstream face 13-5.

When the rotor disc rotates, the moving blades 10 are subjected to centrifugal forces and the bearing surfaces of the feet 13 of the moving blades 10 come into abutment against the bearing surfaces of the cavities of the disk. By “span” is meant the surfaces of the feet 13 of the moving blades 10 and the surfaces of the cavities of the disc which come into abutment against one another, under the effect of the centrifugal forces during the rotation of the disc. The bearing surfaces of the feet 13 of the moving blades 10 are formed here by the lateral flanks 13-3 of said feet 13 while the bearing surfaces of the cavities are formed by the parts of the disk in the form of lips which border the outer opening of the cavities of the disk.

In order to limit the wear of the feet 13 of the moving blades 10, a foil 14 is positioned at the contact interface between the feet 13 of the moving blades 10 and the cavities of the disc.

As can be seen in Figure 5, the shim 14 has a general U-shape suitable for surrounding the foot 13 of the moving blade 10. In particular, the shim 14 comprises a base 14-2 covering the lower surface 13- 1 of the foot 13 as well as two side branches 14-1, connected by the base 14-2, which cover the side flanks 13-3 of the foot 13. The side branches 14-1 form means for holding the shim 14 on the foot 13 of the moving blade 10 by bearing on the side flanks 13-3 of the foot 13 of the moving blade 10. Advantageously, the foil 14 is made of titanium aluminide.

In order to block the relative movements between the shim 14 and the root 13 of the moving blade 10, the shim 14 comprises first blocking means 14-3 and second blocking means 14-4.

The first blocking means 14-3 are configured to cooperate with a recess 13-2 formed in the lower surface 13-1 of the foot 13 of the moving blade 10. The first tabs 14-3 project from the surface of the base 14-2 of the shim 14, which is intended to be in contact with the lower surface 13-1 of the foot 13. Thus, when the first tabs 14-3 are positioned in the recess 13-2, they come into abutment against the peripheral wall delimiting the recess 13-2 so as to block the relative movements between the foot 13 and the shim 14. Advantageously, the first tabs 14-3 are arranged in a central region of the base 14-2 in order to facilitate their insertion into recess 13-1.

Advantageously, the first tongues 14-3 are arranged at the periphery of an orifice 14-5 made in the base 14-2 of the shim 14. Preferably, the orifice 14-5 and the recess 13-2 have the same shape. and the same dimensions. In a variant embodiment, the base 14-2 does not include an orifice 14-5.

In the example illustrated in Figure 5, the shim 14 comprises four first tabs 14-3 which are distributed uniformly around the periphery of the orifice 14-5. Naturally, the number of first tongues 14-3 can be less than or more than four, preferably between three and six. Advantageously, the first tabs 14-3 have a height equal to the depth of the recess 13-2. Thus, the height of the first tabs 14-3 and the depth of the recess 13-2 are for example between 1 and 2 mm, preferably 1.5 mm.

According to the embodiment illustrated in Figures 4 to 6, the orifice 14-5 and the recess 13-2 are circular. Advantageously, the orifice 14-5 and the recess 13-2 have a radius of between 2 and 3.5mm, preferably 2.7mm. In a variant embodiment, the orifice 14-5 and the recess 13-2 have a shape other than circular, for example square, rectangular, elliptical, etc. In addition, in order to leave enough material between each of the side flanks 13-3 of the foot 13 and the peripheral wall delimiting the recess 13-2, the distance separating each of the side flanks 13-3 from the peripheral wall of the recess 13-2 is preferably between 1 and 2 mm.

Furthermore, in a variant embodiment not shown, the first blocking means 14-3 are formed by a pin which extends radially from the surface of the base 14-2 intended to be in contact with the foot 13 of the moving blade 10. Thus, in the same way as the first tongues previously described, the stud is positioned inside the recess 13-2 and is in abutment against the peripheral wall delimiting the recess 13-2. Furthermore, in another alternative embodiment not shown, the first blocking means 14-3 are formed by a flange bordering the orifice 14-5 which extends radially from the surface of the base 14-2 intended to be in contact with the foot 13 of the moving blade 10. In the same way as the first tongues previously described, the dropped edge is positioned inside the recess 13-2 and is in abutment against the peripheral wall delimiting the recess 13 -2.

Furthermore, the second blocking means 14-4 are formed by second tabs 14-4 projecting from the base 14-2, at the level of the upstream and downstream edges of the base 14-2, and which are folded between the side branches 14-1 of the shim 14. Thus, the second tabs 14-4 form abutments which bear axially against the upstream 13-4 and downstream 13-5 faces of the foot 13 of the moving blade 10 so as to block the relative movements between the foot 16 and the shim 14. According to the embodiment illustrated in Figure 5, the shim 14 comprises a second tongue 14-4 for each edge, i.e. upstream and downstream, of the base 14-2.

Advantageously, the first tongues, the second tongues, the stud, the flanged edge are obtained by stamping.

Naturally, the invention is not limited to the various embodiments which have been described, and variant embodiments are possible.

Claims (11)

Foil (14) for a turbine engine blade (10) configured to be mounted on a root (13) of said blade (10) comprising, at a lower surface (13-2), a recess (13-2 ), the shim (10) comprising a base (14-2) connecting two lateral branches (14-1) to each other which form means for holding the shim (14) on the foot (13) of the moving blade (10) , characterized in that it comprises first blocking means (14-3) configured to block the relative movements between the root (13) of the moving blade (10) and the shim (14), the first blocking means (14-3) protruding from a surface of the base (14-2) intended to be in contact with the root (13) of the moving blade (10) and being capable of cooperating with the recess (13-2) present in the root (13) of the moving blade (10). Foil (14) according to the preceding claim, characterized in that the first blocking means (14-3) are formed by first tongues extending radially from the surface of the base (14-2) which is intended to be in contact with the root (13) of the moving blade (10). Foil (14) according to the preceding claim, characterized in that the number of first tabs is between three and six. Foil (14) according to Claim 1, characterized in that the first blocking means (14-3) are formed by a pin which extends radially from the surface of the base (14-2) intended to be in contact with the foot (13) of the moving blade (10). Foil (14) according to any one of the preceding claims, characterized in that the base (14-2) comprises an orifice (14-5), the first blocking means (14-3) being arranged at the periphery of the said orifice (14-5). Foil (14) according to the preceding claim, characterized in that the first blocking means (14-3) are formed by a flange bordering the orifice (14-5) and which extends radially from the surface of the base (14-2) intended to be in contact with the root (13) of the moving blade (10). Foil (14) according to any one of the preceding claims, characterized in that the first blocking means (14-3) are arranged in a central region of the base (14-2) of the foil (14). Foil (14) according to any one of the preceding claims, characterized in that it comprises second locking means (14-4) formed by second tongues, each of the second tongues projecting with respect to the base (14- 2) of the shim (14), at the level of an edge of the said base (14-2), and being intended to be in contact with one of the upstream or downstream faces (13-4, 13-5) of the foot (13 ) of the moving blade (10). System (20) for a turbomachine rotor, characterized in that it comprises:

• a moving blade (10) comprising a root (13) having a lower surface (13-2) in which is provided a recess (13-2) delimited by a peripheral wall,

• the shim (14) according to any one of claims 1 to 7, mounted on the root (13) of the moving blade (10) so that the first blocking means (14-3) are positioned inside reinforcement (13-2) and in abutment against the peripheral wall of said recess (13-2).

System (20) for a turbomachine rotor, characterized in that the second locking means (14-4) of the shim (14) according to claim 8 comprise two second tongues, one of the second tongues being axially in abutment against the upstream face ( 13-4) of the foot (13) of the moving blade (10) and the other second tongue being axially in abutment against the downstream face (13-5) of the moving blade (10). Turbomachine (10) comprising a rotor comprising at least one system (20) according to any one of claims 9 or 10.