FR3148255A1 - Reinforced anti-tilt wall for turbojet engine blade - Google Patents

Abstract

Reinforced anti-tilt wall for turbojet engine blade One aspect of the invention relates to a turbojet engine blade (10) extending along an X axis and comprising: a heel (30) in the upper part; a foot (20) in the lower part, having an upstream part and a downstream part, and comprising a platform (50), a bulb (60) and a stilt (90) interposed between the platform (50) and the bulb (60); an intermediate part formed by a blade (40) having an intrados face (41) and an extrados face (42), and extending between the foot (20) and the heel (30) along the X axis of the blade (10); which mobile blade (10) further comprising at least one anti-tilt wall (100) connecting a lower face of the platform (50) to the stilt (90), the anti-tilt wall (100) comprising at least one stiffening structure (110) in relief. Figure to be published with the abstract: Figure 4.

Description

Reinforced anti-tilt wall for turbojet engine blade TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is that of moving turbojet blades, particularly for aircraft.

The present invention relates to anti-tilt walls provided on the underside of the platform of the moving blades, in particular those of the moving blades of a low pressure turbine.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Conventionally, an axial turbine of a turbomachine consists of a succession of axial stages arranged in series. Each stage comprises a moving wheel with blades forming a rotor and a bladed distributor forming a stator.

The moving wheel, rotated about an axis of rotation R opposite the corresponding distributor, conventionally comprises a plurality of blades, a disk and a device for axially retaining the blades. The axis of rotation R of the moving wheel is also the general axis along which the turbojet extends.

An example of a classic dawn is shown in - . It extends along an axis X perpendicular to the longitudinal axis of the turbojet. A blade 10 generally has a lower part designated as a root 20 and by which it is fixed to the periphery of the disk (not shown), an upper part comprising a heel 30, and an intermediate part formed by a blade 40 having an intrados face 41 and an extrados face 42, and extending along the axis X of the blade 10 between the root 20 and the heel 30.

The foot 20 of each blade 10 comprises a platform 50 and a bulb 60 which is engaged in a housing opening at the periphery of the disk and extending axially between two opposite faces of the disk, the housings of a disk being separated by teeth. The housings and the teeth extend parallel to the axis of rotation R.

The axial blade retaining device axially locks the feet 20 relative to the axis of rotation of the disk. It may for example be in the form of a stop ring mounted on the upstream face of the disk, and the external peripheral part of which is received in a groove 70 provided in the lower face 51 of the platform 50 and oriented towards the axis of rotation R.

At its lower part, a blade 10 usually comprises an upstream spoiler 81 and/or a downstream spoiler 82, each of which extends the platform 50 upstream and/or downstream parallel to the axis of rotation R in order to reduce leaks and maximize the efficiency of the turbine. Conventionally, a blade 10 also comprises a stilt 90 having a substantially rectilinear shape which corresponds to the shape of the upper part of the bulb 60, and which provides the connection between the blade 40 and the root 20. The stilt 90 usually has a reduced thickness compared to that of the root 20.

The lower face 51 of the platform 50 can also be equipped with anti-tilt walls 100, the substantially horizontal lower edge 115 of which comes into wedging support on the external face of a neighboring tooth belonging to the disk in which the blade 10 is mounted in order to prevent the latter from tilting radially.

Typically, each blade 10 has a pair of anti-tilt walls 101, 102 provided on the intrados side and a pair of anti-tilt walls 103, 104 provided on the extrados side of the blade, each pair of anti-tilt walls comprising a wall 101, 103 provided in the upstream portion of the platform 50 and a wall 102, 104 provided in the downstream portion of the platform 50. Each wall 100 extends radially downward from the lower face 51 of the platform 50 in the direction of the axis of rotation R and perpendicular to this axis X.

In addition to their anti-tilt function for the blades, the 100 walls also guarantee sealing between the air stream, the disc and the stop ring.

After a certain period of operation of a low-pressure turbine of an aircraft turbojet, it has been observed for certain moving blades that the upstream wall on the extrados side 103 may exhibit cracks, or even ruptures, which leads to the scrapping of the blade concerned and lengthy and costly replacement operations.

The present invention provides a simple, effective and economical solution to this problem.

Following extensive studies carried out by the applicant, it was discovered that these problems of cracking and breaking in the upstream walls on the extrados side are not due to sizing problems. Noting marks of friction and crushing on the horizontal faces of the walls, that is to say on the faces of the walls which are in the immediate vicinity of the teeth of the disks, the applicant deduced that too great a force must have been applied to the walls when fitting the blades on the disks. By continuing his studies, the applicant thus discovered that if a significant bending force is applied to a blade during fitting, this results in too great a force being exerted on the walls at their junction with the stilt on the extrados side and at their junction with the platform. This is when the walls are likely to crack or break.

The invention provides a solution to the problems mentioned above, by modifying the anti-tilt walls to strengthen their mechanical strength so that they are not damaged, in particular during the mechanical forces they undergo when mounting the blades on the disk. Although the anti-tilt walls concerned by the invention are preferably those provided in the upstream part of the platform and on the extrados side of the blade, the modifications according to the invention can concern any anti-tilt wall of a moving blade.

• un talon en partie supérieure ;
• un pied en partie inférieure, présentant une partie amont et une partie aval, et comportant une plateforme, un bulbe et une échasse interposée entre la plateforme et le bulbe ;
• une partie intermédiaire formée par une pale présentant une face d’intrados et une face d’extrados, et s'étendant entre le pied et le talon suivant l'axe X de l'aube mobile ;
• laquelle aube mobile comprenant en outre au moins un muret anti-basculement reliant une face inférieure de la plateforme à l’échasse, le muret anti-basculement comportant au moins une structure de rigidification en relief.

One aspect of the invention relates to a turbojet engine moving blade extending along an X axis and comprising:

• a heel in the upper part;
• a foot in the lower part, having an upstream part and a downstream part, and comprising a platform, a bulb and a stilt interposed between the platform and the bulb;
• an intermediate part formed by a blade having an intrados face and an extrados face, and extending between the foot and the heel along the X axis of the moving blade;
• which mobile blade further comprising at least one anti-tilt wall connecting a lower face of the platform to the stilt, the anti-tilt wall comprising at least one raised stiffening structure.

The raised stiffening structure advantageously reinforces the mechanical resistance of the anti-tilt wall.

According to one aspect of the invention, the anti-tilt wall comprising a stiffening structure is connected to the upstream part of the platform and/or is located on the extrados side of the moving blade. Indeed, the applicant has detected that it is the anti-tilt wall located in these specific regions which undergoes the greatest forces and which requires reinforcement as a priority.

According to another aspect of the invention, a stiffening structure is located on the downstream face of the anti-tilt wall. Indeed, the presence of a stiffening structure located on the upstream face would be likely to interfere negatively with the introduction of a stop ring into the groove intended to receive such a stop ring.

According to a further aspect of the invention, a stiffening structure is in the form of parallel ribs, preferably three in number. This is an embodiment of the invention which reinforces the mechanical resistance of the anti-tilt wall in a satisfactory manner.

According to one aspect of the invention, the parallel ribs are inclined at an angle α relative to the horizontal, α preferably being between 30° and 60°, more preferably between 40° and 50° and even more preferably substantially equal to 45°. Indeed, the studies carried out by the applicant have revealed that such an inclination advantageously reinforces the mechanical resistance of the anti-tilt wall in a satisfactory manner.

According to another aspect of the invention, a stiffening structure is in the form of a crosspiece formed of two intersecting ribs. This is another embodiment of the invention which reinforces the mechanical resistance of the anti-tilt wall in a satisfactory manner.

According to an additional aspect of the invention, in the upper part of the crosspiece, the two ribs intersect at an angle β, and β is between 90° and 130°, preferably between 100° and 120° and more preferably substantially equal to 110°. Indeed, the studies carried out by the applicant have revealed that such an intersection angle advantageously reinforces the mechanical resistance of the anti-tilt wall in a satisfactory manner.

According to one aspect of the invention, a stiffening structure comprises a rib connecting the anti-tilt wall to the stilt and located at the bottom of the anti-tilt wall, preferably along a bottom edge of the anti-tilt wall. This is an additional embodiment of the invention which reinforces the mechanical resistance of the anti-tilt wall in a satisfactory manner.

According to another aspect of the invention, the ribs each have a width L of between 0.5 and 1 cm, preferably between 0.7 and 0.9 cm and more preferably substantially equal to 0.8 cm, and/or a thickness E of between 0.5 and 1 cm, preferably between 0.7 and 0.9 cm and more preferably substantially equal to 0.8 cm. Indeed, the studies carried out by the applicant have revealed that such a width and such a thickness each advantageously reinforce the mechanical resistance of the anti-tilt wall in a satisfactory manner.

Another aspect of the invention relates to a comprising a moving blade according to the invention as described above.

The invention and its various applications will be better understood by reading the description which follows and by examining the figures which accompany it.

BRIEF DESCRIPTION OF THE FIGURES

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

is a perspective view of the intrados side of a moving blade.

is a perspective view of the extrados side of a moving blade.

is a detailed view of the framed part on .

is a detailed view of the framed part on .

is a perspective view of the extrados side of the lower part of a moving blade.

is a perspective view from the extrados side of the lower part of a moving blade according to an example of the invention in which the anti-tilt wall comprises a stiffening structure in the form of parallel ribs.

is a perspective view from the extrados side of the lower part of a moving blade according to an example of the invention in which the anti-tilt wall comprises a stiffening structure in the form of a crosspiece.

is a perspective view from the extrados side of the lower part of a moving blade according to an example of the invention in which the anti-tilt wall comprises a stiffening structure in the form of a rib connecting the wall to the stilt.

DETAILED DESCRIPTION

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

By convention, in the present application, the terms “upstream” and “downstream” are defined in relation to the normal direction of air flow in the turbojet engine. Similarly, the terms “lower”, “upper”, “on” and “under” are defined in relation to the position of the moving blade as shown in the figures. Thus, the lower part of a blade is its proximal part, i.e. the closest to the general axis along which the turbojet engine extends, while the upper part of a blade is its distal part.

The mobile blade 10 according to the invention is intended to equip an aircraft turbojet. It is preferably intended to be mounted on the mobile disk of a low-pressure turbine having an axis of rotation R which is also the general axis along which the turbojet extends.

The turbojet engine blade 10 extends along an axis X and perpendicular to the axis of rotation R of the turbojet engine. Conventionally, it comprises a lower part designated as a root 20, an upper part comprising a heel 30, and an intermediate part formed by a blade 40 extending between the root 20 and the heel 30 of the blade 10.

The blade 40 extends along the X axis and has an intrados face 41 and an extrados face 42.

The foot 20 comprises a platform 50 extending in a substantially horizontal plane and a bulb 60 which is designed to be engaged in a housing opening at the periphery of the movable disk.

The mobile blade 10 further comprises a stilt 90 interposed between the blade 40 and the foot 20 and extending in a plane comprising the axes X and R, and at least one anti-tilt wall 100 extending orthogonally to the plane of the stilt 90 and connecting the lower face of the platform 50 to the stilt 90.

• un muret anti-basculement 100, 101 prévu dans la partie amont de la plateforme 50 du côté intrados de l’aube mobile 10 ;
• un muret anti-basculement 100, 102 prévu dans la partie aval de la plateforme 50 du côté intrados de l’aube mobile 10 ;
• un muret anti-basculement 100, 103 prévu dans la partie amont de la plateforme 50 et du côté extrados de l’aube mobile 10 ; et
• un muret anti-basculement 100, 104 prévu dans la partie aval de la plateforme 50 du côté extrados de l’aube mobile 10.

Conventionally, the mobile blade 10 can include the following anti-tilt walls 100:

• an anti-tilt wall 100, 101 provided in the upstream part of the platform 50 on the intrados side of the moving blade 10;
• an anti-tilt wall 100, 102 provided in the downstream part of the platform 50 on the intrados side of the moving blade 10;
• an anti-tilt wall 100, 103 provided in the upstream part of the platform 50 and on the extrados side of the moving blade 10; and
• an anti-tilt wall 100, 104 provided in the downstream part of the platform 50 on the extrados side of the moving blade 10.

The mobile blade 10 according to the invention is characterized in that at least one anti-tilt wall 100, preferably the anti-tilt wall 100, 103 provided in the upstream part of the platform 50 and on the extrados side of the mobile blade 10, comprises a stiffening structure 110 in relief.

A stiffening structure 110 is preferably located on the downstream face 106 of the anti-tilt wall 100, in particular when the upstream face 105 of the anti-tilt wall 100 is provided in the groove 70 intended to receive a stop ring. A stiffening structure 110 may also be provided on the upstream 105 and downstream 106 faces of the anti-tilt wall 100.

Several forms of reinforcement can be considered for the stiffening structure 110.

According to a first variant represented on , the stiffening structure 110 is in the form of parallel ribs 111. It preferably comprises three parallel ribs 111. These parallel ribs 111 are preferably provided diagonally and are inclined at an angle α relative to the horizontal, with α being for example between 30° and 60°, preferably between 40° and 50° and more preferably substantially equal to 45°. On , for example the parallel ribs 111 extend from the top, on the side of the stilt 90, downwards, to the outside of the blade 10. They could however be inclined in the other direction.

According to a second variant shown on , the stiffening structure 110 comprises a crosspiece 112 formed of two intersecting ribs 113, the upper branches of the crosspiece 112 being spaced apart by an angle β for example between 90° and 130°, preferably between 100° and 120° and more preferably substantially equal to 110°.

According to a third variant shown on , the stiffening structure 110 comprises a rib 114 located at a distance from the platform 50 and connecting the anti-tilt wall 100 to the stilt 90. This rib 114 is located in the lower part of the anti-tilt wall 100. It is preferably located along the edge 115 of the anti-tilt wall 100.

Being provided in a corner provided between the anti-tilt wall 100 and the stilt 90, the rib 114 can have a substantially triangular shape.

The ribs 111, 113, 114 preferably have a length allowing them to extend over the entire available surface of the anti-tilt wall 100. They are preferably rectilinear and are preferably oblong in shape.

The ribs 111, 113, 114 each have a width L of between 0.5 and 1 cm, preferably between 0.7 and 0.9 cm and more preferably substantially equal to 0.8 cm. The width L corresponds to the smallest dimension of the surface occupied by the ribs 111, 113, 114 on the anti-tilt wall 100.

Similarly, the ribs 111, 113, 114 each have a thickness E of between 0.5 and 1 cm, preferably between 0.7 and 0.9 cm and more preferably substantially equal to 0.8 cm. This thickness E corresponds to the height of the reliefs of the stiffening structure 110.

The mobile blade 10 according to the invention is notably intended to equip the low pressure turbine of an aircraft turbojet.

Claims (10)

Movable blade (10) of a turbojet engine extending along an axis X and comprising:

• a heel (30) in the upper part;
• a foot (20) in the lower part, having an upstream part and a downstream part, and comprising a platform (50), a bulb (60) and a stilt (90) interposed between the platform (50) and the bulb (60);
• an intermediate part formed by a blade (40) having an intrados face (41) and an extrados face (42), and extending between the foot (20) and the heel (30) along the axis X of the moving blade (10);

which mobile blade (10) further comprising at least one anti-tilt wall (100) connecting a lower face of the platform (50) to the stilt (90), characterized in that the anti-tilt wall (100) comprises at least one stiffening structure (110) in relief. Moving blade (10) according to claim 1, characterized in that the anti-tilt wall (100, 101, 103) comprising a stiffening structure (110) is connected to the upstream part of the platform (50) and/or is located on the extrados side of the moving blade (10). Moving blade (10) according to claim 1 or 2, characterized in that a stiffening structure (110) is located on the downstream face (106) of the anti-tilt wall (100). Moving blade (10) according to any one of the preceding claims, characterized in that a stiffening structure (110) is in the form of parallel ribs (111), preferably three in number. Moving blade (10) according to claim 4, characterized in that the parallel ribs (111) are inclined at an angle α relative to the horizontal, α being preferably between 30° and 60°, more preferably between 40° and 50° and even more preferably substantially equal to 45°. Movable blade (10) according to any one of the preceding claims, characterized in that a stiffening structure (110) is in the form of a crosspiece (112) formed of two intersecting ribs (113). Moving blade (10) according to the preceding claim, characterized in that, in the upper part of the crosspiece (112), the two ribs (113) cross at an angle β, and in that β is between 90° and 130°, preferably between 100° and 120° and more preferably substantially equal to 110°. Moving blade (10) according to any one of the preceding claims, characterized in that a stiffening structure (110) comprises a rib (114) connecting the anti-tilt wall (100) to the stilt (90) and located in the lower part of the anti-tilt wall (100), preferably along a lower edge (115) of the anti-tilt wall (100). Moving blade (10) according to any one of claims 4 to 8, characterized in that the ribs (111, 113, 114) each have a width L of between 0.5 and 1 cm, preferably between 0.7 and 0.9 cm and more preferably substantially equal to 0.8 cm, and/or a thickness E of between 0.5 and 1 cm, preferably between 0.7 and 0.9 cm and more preferably substantially equal to 0.8 cm. Turbojet, characterized in that it comprises a moving blade (10) according to any one of the preceding claims.