FR3079929A1 - VIBRATORY TEST DEVICE FOR TURBINE MACHINE BLADES. - Google Patents

Abstract

The invention relates to a vibration test device (500) for blades (1 0a, 1 0b, 10c) of a turbomachine turbine, said blades (10a, 10b, 10c) of turbine having a blade (1 1) s extending between a foot (1 4) and a heel (26), said testing device (500) being characterized in that it comprises: a base (51) having at least two locations (52, 53, 54) , each of the locations (52, 53, 54) being configured to receive a blade root (14) (10a, 10b, 10c), an excitation device (70) configured to transmit a vibration to said base (51) ; heel clamping means (60) configured to generate a predetermined contact pressure between each heel (26) of the blades (10) positioned in two consecutive locations (52, 53, 54) of said base (51).   

Description

VIBRATORY TEST DEVICE FOR TURBOMACHINE TURBINE BLADES

TECHNICAL FIELD OF THE INVENTION The field of the invention is that of the qualification of turbine engine turbine blades, and more particularly the qualification of the turbine blades under vibratory stresses.

The invention relates more particularly to the qualification under vibratory stresses of the low-pressure turbine blades of a turbomachine, and associated test devices.

STATE OF THE PRIOR ART In the present application, the terms “upstream” and “downstream” are defined with respect to the normal direction of flow of the gas (from upstream to downstream) through a turbomachine .

Also called "axis of the turbomachine" or "motor axis", the axis of rotation of the rotor of the turbomachine. The axial direction corresponds to the direction of the axis of the turbomachine and a radial direction is a direction perpendicular to the axis of the turbomachine and intersecting this axis. Likewise, an axial plane is a plane containing the axis of the turbomachine, and a radial plane is a plane perpendicular to this axis.

In a turbomachine with a longitudinal axis XX, the low pressure turbine 4, partially shown in Figure 1, recovers part of the energy from the combustion of gases for the operation of the blower, compressor and accessories of the turbomachine. One of the constituent elements of the low pressure turbine 4 is the rotor 1 which is an assembly of discs and blades on a shaft.

The rotor 1 comprises a plurality of stages of moving blades 10, an example of which is shown in FIG. 2. The moving blades 10 being arranged radially around the axis of rotation of the rotor 1. With reference to the FIG. 2, a movable blade 10 comprises a blade 11 which extends along an axis Z, between a proximal end 102 (interior end) and a distal end 101 (exterior end) of the blade 10. It is noted that the axis Z is perpendicular to the longitudinal axis XX of the turbomachine. The blade 11 has an upper surface (not visible) and a lower surface 43 (visible in FIG. 2) connected upstream by a leading edge 47 and downstream by a trailing edge 48.

At the proximal end 102 of the blade 11, the blade 10 comprises a foot 14 for fixing it to a disc 3 of the rotor 1, and more particularly in a cell complementary to the disc 3. The disc 3 conventionally comprises a plurality of cells distributed radially around its circumference to receive several feet 14 of blade 10. The blade 11 makes it possible to recover the forces of the gases passing through the turbomachine to transmit them to the disc 3 of the rotor 1.

At the distal end 101 of the blade 11, the blade 10 has a transverse platform 26, more commonly called heel. FIG. 3 illustrates more precisely the upper part of the blade 10 and more precisely a top view of the heel 26 of the blade shown in FIG. 2. The heel 26 comprises a platform 28 having an upstream spoiler 281 and a downstream spoiler 282 extending transversely to the direction of gas flow (along the X axis). The two spoilers 281, 282 are connected between two by two lateral edges 283, 284 having a so-called V-shaped profile, or even Z. The platform 28 has a first lateral edge 283 positioned on the upper surface side of the blade 11 and a second lateral edge 284 positioned on the lower side of the blade 11. To differentiate these two lateral edges, the following will be called "upper side edge 283 >> the side edge of the platform 28 located on the upper side of the blade 11, and" lower side edge 284 >> the side edge of the platform 28 located on the underside of the blade 11.

The heel 26 further comprises two wipers 30, 31 protruding from the platform 28 and extending in a transverse direction relative to the direction of flow of the gases (along the X axis). The wipers 30, 31 ensure the seal by complementarity with a stator 2, visible in FIG. 1, during the operation of the low pressure turbine 4.

When the movable blades 10 are mounted in a crown on the disc 3, each platform 28 is in contact with two other platforms 28 of two adjacent blades, and more precisely by contacting the side edges 283, 284 as illustrated in FIG. 4 The shape of the platforms 28 makes it possible to place the movable blades 10 in torsional stress when they are in position on the disc 3, in particular by pressing a blade with the neighboring blades at the side edges 283, 284 platforms 28. This stressing makes it possible in particular to dampen the vibrations to which they are subjected in operation.

Due to the vibrations and the forces transmitted between two contacting surfaces, this results in friction under tension of the contact zones which is an important factor of wear at the level of the lateral edges 283, 284 of the platforms.

28.

The material constituting the movable blade 10 is generally not very resistant to these wear phenomena under the operating conditions of the turbomachine. To extend the life of the blades, it is known to protect and create localized contact zones at the level of the upper 283 and lower 284 lateral edges of the platform 28 by interposing an anti-wear material 285 or by depositing an anti- -local wear. It can be, for example, specific alloy wafers having a high hardness which is brazed on the metal substrate formed by the platforms 28 of the moving blade 10, as described in particular in document US 6164916. These wafers antiwear material are brazed on each blade 10, at the contact surfaces between the lower side edge 284 of a first blade and the upper side edge 283 of a second blade.

According to another known technique, for the manufacture of new parts, one proceeds by progressive loading of the surface to be protected, possibly after having locally removed material by grinding, by means of a rod of an anti-material. wear that is melted at the same time as the upper layer of the metal substrate. The necessary heat is supplied by an appropriate source. This can be produced by an electric arc sheathed with neutral gas or by a laser beam. This technique is designated in the field by the term "stellitage". This technique uses a cobalt-based alloy. These cobalt alloys are sold, for example, under the brand name "Stellite".

However, these techniques are not entirely satisfactory because they are capable of creating cracks in the moving blade, around the anti-wear material 285, or even at the interface with the anti-wear material 285 during the material removal operation. Therefore, it is interesting to turn to other technical solutions to overcome these drawbacks.

However, to validate a new technique of "stellitage", it is necessary to carry out a test in operating condition, what is called an engine test. However, such engine tests represent significant costs due to the complexity of the tools to be used and the parts required, and very long lead times which hamper the development and validation of new "stellitage" techniques.

PRESENTATION OF THE INVENTION In this context, the invention aims to propose a test device making it possible to qualify the movable blades of the turbine under vibratory conditions under conditions close to the conditions representative of engine operation without, however, requiring complete assembly. of a test engine and carrying out an engine test campaign.

To this end, the invention relates to a vibration test device for turbine engine turbine blades, said turbine blades having a blade extending between a foot and a heel, said test device being characterized in that that it includes:

a base having at least two locations, each of the locations being configured to receive a dawn;

an excitation device configured to transmit a vibration to said base;

heel clamping means configured to generate a predetermined contact pressure between each heel of the blades positioned in two consecutive locations of said base.

In addition to the characteristics mentioned in the previous paragraph, the test device according to the invention may have one or more complementary characteristics among the following, considered individually or in all the technically possible combinations:

said at least two locations of said base are configured so that two blades positioned in two consecutive locations have a contact zone at the heels;

said at least two locations of said base are configured so that the heels of two blades positioned in two consecutive locations are in contact with an anti-wear material formed on the lateral edges of said heels;

said heel clamping means is configured to create a contact pressure between each heel of the blades positioned in two consecutive locations, said contact pressure being representative of the contact pressure existing between the heels of consecutive blades of a complete moving wheel turbine;

said heel clamping means is formed by a clamp or by a spring cooperating at each of its ends with peripheral attachment elements;

each peripheral attachment element of the clamping means has a section along a transverse YZ L-shaped plane having a first wall configured to come to bear on a part of the inner face of the heel of a blade and a second wall configured to come to rest on a lateral edge of the heel of a blade;

each peripheral attachment element of the clamping means has a third wall configured to come to bear on a portion of a spoiler upstream of a heel of a blade;

a first peripheral attachment element is configured to bear on an upper surface edge of a heel (26) of a first blade having a free upper surface edge;

a second peripheral attachment element is configured to bear on a lower surface edge of a heel of a second blade having a free lower surface border;

said base is a portion of a turbine rotor disc.

The invention also relates to a vibration test system comprising a vibration test device according to the invention and at least two turbomachine blades positioned in said at least two locations of the base of the test device.

The invention also relates to a method of vibrating at least two turbomachine turbine blades by means of the vibratory test device according to the invention, said method comprising:

a step of placing two blades in two consecutive locations of said base;

a step of positioning the heel clamping means so as to generate a predetermined contact pressure between each heel of the blades positioned in said base;

a step of vibratory stresses of the blades by the vibration of said base by means of the excitation device.

BRIEF DESCRIPTION OF THE FIGURES [0021] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate:

FIG. 1, already described previously, illustrates a portion of a low pressure turbine of a turbomachine;

FIG. 2, already described previously, is a perspective view of a moving blade of a low pressure turbine of a turbomachine;

Figure 3, already described above, is a top view of the movable blade illustrated in Figure 2;

FIG. 4, already described above, illustrates in perspective, the upper part of an assembled crown portion of a low pressure turbine of a turbomachine;

FIG. 5 illustrates a vibratory test device according to the invention allowing the qualification under vibratory stresses of mobile blades of a turbomachine illustrated in FIG. 2;

FIG. 6 illustrates an exemplary embodiment of a clamping means of a vibratory test device according to the invention allowing the clamping of the heels of moving blades of a turbomachine;

Figures 7 and 8 illustrate an exemplary embodiment of the fastening elements of the clamping means according to the invention illustrated in Figure 6.

For the sake of clarity, identical or similar elements are identified by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT [0023] FIG. 5 illustrates a vibration test device according to the invention allowing the qualification under vibratory stresses of moving blades of a turbomachine. In the example shown, the blades 10 are movable blades of a low pressure turbine 4.

As previously described in Figure 2, a movable blade 10 has a blade 11 extending along an axis Z, between a proximal end 102 (inner end) and a distal end 101 (outer end) of the blade 10 Note that the Z axis is perpendicular to the longitudinal axis XX of the turbomachine.

The blade 11 has an upper surface 42 and a lower surface 43 connected upstream by a leading edge 47 and downstream by a trailing edge 48.

At the proximal end 102 of the blade 11, the blade 10 comprises a foot

14. At the distal end 101 of the blade 11, the blade 10 has a heel 26.

The adjectives "inside" and "outside" are used in the present application with reference to the Z axis so that the inner part of an element is, in the axial direction Z, closer to the base (ie of the foot 14) of the blade 11 as the external part of the same element.

The heel 26 has a platform 28 having an upstream spoiler 281 and a downstream spoiler 282 extending transversely to the direction of flow of the gases (along the X axis). The two spoilers 281, 282 are connected between two by two lateral edges 283, 284 having a so-called V-shaped profile. According to another embodiment not shown, the two lateral edges 283, 284 can have a so-called Z-shaped profile.

The platform 28 has a first lateral edge 283 on the upper side and a second lateral edge 284 on the lower side. To differentiate these two lateral edges, the following will be called “upper side edge >> 283 the side edge of the platform 28 located on the upper surface side of the blade 11, and“ lower side edge >> 284 the lateral edge of the platform 28 located lower side of the blade 11.

In the embodiment illustrated in Figures 5 to 8, the test device 500 has a base 51 having at least three locations 52, 53, 54 allowing the mounting and blocking of three blades 10, as described previously. Advantageously, the testing device 500 thus makes it possible to characterize both the lower surface contact area of a blade and the upper surface contact area of the same blade. For this, it is therefore necessary to position three blades in three consecutive locations 52, 53, 54 of the base 51.

According to an alternative embodiment (not shown) the test device comprises a base having at least two locations allowing the mounting and blocking of two blades 10 positioned in two consecutive locations, the test device then making it possible to characterize at least either a lower surface contact area of a vane under conditions similar to engine mounting conditions, or an upper surface contact area of a blade under conditions similar to engine mounting conditions.

Thereafter, these three identical blades will be referenced by the references 10a, 10b, and 10c so as to differentiate them because of their position, the blade 10b being positioned between the blade 10a and the blade 10c.

The locations 52, 53, 54 allow the mounting of the blades 10a, 10b, 10c by insertion of the feet 14. Advantageously, the locations 52, 53, 54 have a cell shape equivalent to the cells present on a disc of a low pressure turbine. Thus, the feet 14 of the blades 10 are inserted axially along the axis X in the locations 52, 53, 54 of the base 51. Advantageously, the base 51 corresponds to a portion of a low-pressure turbine disk of a turbomachine.

According to a second embodiment, not shown, the blades 10a, 10b, 10c are mounted directly in a clamping and holding device for the feet, such as a jaw or a vice comprising an endless screw for the tightening of two plates or jaws on either side of the feet 14.

When the movable blades 10a, 10b, 10c are mounted in the locations 52, 53, 54 of the base 51, they have a positioning with respect to each other similar to the positioning, called the crown, which is found on a movable wheel complete with a low pressure turbine. In this configuration, the heel 26 of the central blade 10b is in contact with the heel 26 of the two adjacent blades 10a, 10c, and more precisely with the lower side edge 284 of the blade 10a and the upper side edge 283 of the blade 10c, in a manner identical to the representation of FIG. 4 and of FIG. 6.

The test device 500 also includes a means 60 for clamping the heels 26 making it possible to tighten the heels 26 of the three adjacent blades 10a, 10b, 10c when they are positioned on the base 51. The means clamping 60 of the heels 26 is configured to grip the heels 26 to each other and to generate a contact force, at the heels 26 of each blade 10a, 10b, 10c, representative of the crown effect existing on a movable wheel complete. Thus, the clamping means 60 of the heels 26 makes it possible to apply a force, substantially equivalent to the existing force during a complete assembly of a movable wheel of a low pressure turbine of a turbomachine, at the contact zones of the platforms, and more precisely anti-wear materials 285 (stellites) present on the lateral edges 283, 284 of the heels 26.

The clamping means 60 of the heels 26 is a removable and removable device comprising two peripheral attachment elements 62, 63 and a clamping element 61 integral with the two peripheral attachment elements 62, 63. The clamping element 61 is configured to generate an approximation of the two peripheral attachment elements 62, 63 and to enclose with a certain force the differences in parts positioned between the two peripheral attachment elements 62, 63. In the embodiment illustrated in FIGS. 5 at 8, the clamping element 61 is a spring, for example a return spring, the stiffness of which is determined so as to obtain a contact force at the contact zones of the platforms 28 substantially equal to the force existing when the blades 10 are mounted in a crown on a turbine rotor disc.

The two peripheral attachment elements 62, 63 have a shape adapted to come to fit on a specific part of the platforms 28 of the blades 10, and more precisely at a region of the lateral edges 283, 284 nearby. upstream spoiler 281 as illustrated in FIG. 6.

The first peripheral attachment element 62, said upper surface peripheral attachment element, has a shape adapted to cooperate with the shape of the upper side edge 283 and the upstream spoiler 281 of a blade 10 and the second element of peripheral attachment 63, said intrados peripheral attachment element, has a shape adapted to cooperate with the shape of the intrados lateral edge 284 and of the upstream spoiler 281 of a blade 10. According to a first embodiment illustrated in FIGS. 6 to 8, the peripheral attachment elements 62, 63 are caps made of a material which is stiff enough not to sag due to the pressure exerted. The caps are for example made of plastic or rubber having a stiffness sufficient not to sag due to the pressure exerted.

The upper surface peripheral attachment element 62 has a substantially L-shaped section along a transverse plane YZ comprising a first wall 623 bearing with an inner face of the platform 28, that is to say the face of the platform 28 opposite the blade 11, and a second wall 622 arranged perpendicularly to the first wall 623 and bearing with at least part of the V shape of the upper side edge 283 of the platform 28. A third wall 624 cooperates with an outer face of the platform 28. The first wall 623 and the third wall 624 are parallel to each other and are spaced apart by a distance substantially equivalent to the thickness of the platform 28 so as to block the movement of the upper surface peripheral attachment element 62 in a radial direction Z when the upper surface peripheral attachment element 62 is in position ion on the heel 26 of the blade 10a. Advantageously, the third wall 624 has at least one part positioned at the upstream spoiler 281 of the platform 28 28 and cooperates with a fourth wall 625 so that the upper surface peripheral attachment element 62 present at the upstream spoiler 281 has a section substantially U-shaped in an XZ plane.

The fourth wall 625 is configured to come to bear on the upstream spoiler 281 of the platform 28.

The second wall 622 has at least one curved part, the internal face of which is substantially convex and adapted to cooperate and come into abutment with the part of the V shape of the upper side edge 283 of the platform 28. The second wall 622 also has a tongue 621, substantially rectilinear, forming a vertical extension of the second wall 622 and projecting relative to the platform 28. The tongue 621 is adapted to cooperate with the clamping element 61.

The intrados peripheral attachment element 63 also has a substantially L-shaped section along a transverse plane YZ comprising a first wall 633 bearing with the inner face of the platform 28 and a second wall 632 arranged perpendicularly with respect to to the first wall 633 and coming to bear with at least part of the V shape of the lower side edge 284 of the platform 28. A third wall 634 cooperates with the external face of the platform 28. The first wall 633 and the third wall 634 are parallel to each other and are spaced by a distance substantially equivalent to the thickness of the platform 28 so as to allow the movement of the intrados peripheral attachment element 63 to be blocked according to a radial direction Z when the intrados peripheral attachment element 63 is in position on the heel 26 of the blade 10c. Advantageously, the third wall 634 has at least one part positioned at the level of the upstream spoiler 281 of the platform 28 and cooperates with a fourth wall 635 so that the lower surface peripheral attachment element 63 present at the level of the upstream spoiler 281 has a section substantially U-shaped in an XZ plane.

The fourth wall 635 is configured to come to bear on the upstream spoiler 281 of the platform 28.

The second wall 632 has at least one curved part, the internal face of which is substantially concave and adapted to cooperate and to come into abutment with the part of the V shape of the intrados lateral edge 284 of the platform 28. The second wall 632 also has a tongue 631, substantially rectilinear, forming a vertical extension of the second wall 632 and projecting relative to the platform 28. The tongue 631 is adapted to cooperate with the clamping element 61.

The clamping means 60 of the heels 26 is positioned so as to enclose the heels 26 of the blades 10 at a region close to the upstream spoilers 281 of the platforms 28, and more particularly at the contact areas of the lateral edges upper surfaces 283 and lower surface 284 of the platforms 28 of the different blades 10a, 10b, 10c, zones having the anti-wear material 285.

The particular shape of the peripheral attachment elements 62, 63 thus makes it possible to exert a tangential force on the heels 26 of the blades 10 while ensuring good positioning of the peripheral attachment elements 62, 63 on the platforms 28 of the vanes 10 and preventing unwanted sliding or movements of the peripheral attachment elements 62, 63 during the vibrational stresses of the vanes 10.

According to a second embodiment not shown, the heel clamping means is formed by a clamp.

As shown schematically in Figure 5, the base 51, or the equivalent foot tightening device, is mechanically connected to an excitation device 70 adapted to transmit a vibration. The excitation device is typically a vibrating pot, an exciter or a vibrator, or any other device making it possible to excite a structure in a vibratory mode. The base 51, or the equivalent clamping device for the feet, is mechanically connected to the excitation device by ad hoc means.

The excitation device 70 allows the blades 10a, 10b, 10c to be urged on their first natural modes of oscillation.

Thus, thanks to the test device according to the invention, it is possible to carry out vibration tests under real conditions (i.e. engine mounting conditions) of the moving blades, in particular for:

- study their behavior under vibrational stresses;

- test and validate different anti-wear materials;

- test and validate different techniques for depositing anti-wear material.

The objective of the vibration tests, carried out using the test device according to the invention, is for example to measure the power which it is necessary to provide to the moving blades, at a specific vibration frequency, to obtain a certain displacement given. Thus, such tests make it possible to qualify different technologies of "stellitage" and to quantify the criterion of damping of the different anti-wear materials used.

The test device according to the invention also makes it possible to easily and quickly perform fatigue tests of the blades and in particular of the different technologies of wear-resistant materials used on the lateral edges of the platforms, without the need for an expensive test engine.

The invention is not limited to the embodiments previously described with reference to the figures and variants could be envisaged without departing from the scope of the invention.

Claims (11)

1. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine, said blades (10a, 10b, 10c) of turbine having a blade (11) extending between a foot (14) and a heel (26), said test device (500) being characterized in that it comprises: a base (51) having at least two locations (52, 53, 54), each of the locations (52, 53, 54) being configured to receive a blade stand (14) (10a, 10b, 10c); an excitation device (70) configured to transmit a vibration to said base (51); heel clamping means (60) configured to generate a predetermined contact pressure between each heel (26) of the blades (10) positioned in two consecutive locations (52, 53, 54) of said base (51). 2. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to claim 1, characterized in that said at least two locations (52, 53, 54) of said base (51) are configured so that two blades (10) positioned in two consecutive locations (52, 53, 54) have a contact area at the heels (26). 3. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to claim 2, characterized in that said at least two locations (52, 53, 54) of said base (51) are configured so that the heels (26) of two blades positioned in two consecutive locations (52, 53, 54) are in contact with an anti-wear material (285) formed on lateral edges (283, 284) of said heels (26). 4. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to one of claims 1 to 3, characterized in that said clamping means (60) of the heels (26) is configured to create a contact pressure between each heel (26) of the vanes (10) positioned in two consecutive locations (52, 53, 54), said contact pressure being representative of the contact pressure existing between the heels (26) d 'blades (10) consecutive of a movable impeller complete with turbine. 5. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to one of claims 1 to 4, characterized in that said clamping means (60) of the heels (26) is formed by a clamp or by a spring (61) cooperating at each of its ends with peripheral attachment elements (62, 63). 6. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to claim 5, characterized in that each peripheral attachment element (62, 63) of the clamping means (60) has a cross section along an L-shaped transverse plane (YZ) having a first wall (623, 633) configured to come to bear on a part of the inner face of the heel (26) of a blade (10a, 10c) and a second wall (622, 632) configured to come to bear on a lateral edge (283, 284) of the heel (26) of a blade (10a, 10c). 7. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to claim 5, characterized in that each peripheral attachment element (62, 63) of the clamping means (60) has a third wall (625, 635) configured to come to bear on a part of an upstream spoiler (281) of a heel (26) of a blade (10a, 10c). 8. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to one of claims 6 to 7, characterized in that; a first peripheral attachment element (62) is configured to come to bear on an upper edge (283) of a heel (26) of a first blade (10a) having a free upper edge (283); a second peripheral attachment element (63) is configured to come to bear on a lower surface edge (284) of a heel (26) of a second blade (10c) having a free lower surface border (284). 9. Vibration test device (500) for blades (10a, 10b, 10c) of a turbomachine turbine according to one of claims 1 to 8, characterized in that said base (51) is a portion of a disc turbine rotor. 10. Method for vibrating at least two blades (10a, 10b, 10c) of a turbomachine turbine by means of the vibration test device (500) according to one of claims 1 to 9, said method comprising: A step of placing two blades in two consecutive locations (52, 53, 54) of said base (51); a step of positioning the clamping means (60) of the heels (26) so as to generate a predetermined contact pressure between each heel (26) of the blades (10) positioned in said base (51); 15 - a step of vibratory stresses of the blades (10) by vibrating said base (51) by means of the excitation device (70).