Patent Application
20230091418
The present invention relates to a method for refitting vane shrouds of a rotor wheel in an aircraft turbomachine, as well as to a re-engagement device for carrying out such a method.
The state of the art is illustrated in document FR-A1-2 950 104.
Classically, a turbomachine axial turbine consists of a succession of axial stages (along the axis of circulation of the gas flows) arranged one behind the other. Each stage comprises a bladed movable wheel forming the rotor and a bladed turbine stator forming the stator. The movable wheel is rotated opposite the corresponding turbine stator.
In the present application, upstream and downstream are defined with respect to the normal flow direction of the air flows (upstream to downstream) through the turbomachine. The axis of rotation of the main rotor of the turbomachine is called the “axis of the turbomachine”. The axial direction is the direction of the turbomachine axis, and a radial direction is a direction perpendicular to the turbomachine axis and intersecting this axis. Similarly, an axial plane is a plane containing the axis of the turbomachine, and a radial plane is a plane perpendicular to that axis. The adjectives “inner” and “outer” are used in reference to a radial direction so that the inner part of an element is, along a radial direction, closer to the axis of the turbomachine than the outer part of the same element. The stacking axis of a vane is the axis perpendicular to the axis of the turbomachine, which passes through the centre of gravity of the innermost section of the blade of the vane (i.e. the section closest to the axis of the turbomachine). Typically, a turbomachine vane comprises a blade extending along the stack axis of the vane, between the proximal and distal (i.e. inner and outer) ends of the vane.
The movable wheel typically consists of an annular disc centred on the axis of rotation of the wheel, to which a plurality of vanes are attached.
An example of such a vane is shown in
The shroud 14 comprises a platform 20 externally delimiting the flow duct of the gas circulating between the blades 16, and having opposite lateral edges 21, 22. The platform 20 comprises an upstream portion 24 called the “upstream spoiler” and a downstream portion 28 called the “downstream spoiler”. The shroud 14 also comprises upstream 31 and downstream 32 sealing lips extending radially outward from the outer face of the platform 20. Each of the platform lateral edges 21, 22 has a substantially “U” shaped profile between the upstream 31 and downstream 32 lips. In the case of other vanes, this profile may take the form of a “Z” or a “V” for example.
In order to dampen the vibrations to which the vanes 10 are subjected during operation and to give rigidity to the assembly, the vanes 10 are mounted on their discs with a torsional stress about a torsional axis positioned in relation to the stacking axis X. The geometry of the shrouds 14 is such that each vane 10 is placed under torsional stress by bearing on the neighbouring vanes 10 at the lateral edges 21 and 22. These lateral edges 21, 22 therefore define inter-vane contact surfaces and are the site of significant friction during operation of the turbomachine.
The role of the lateral edges 21, 22, which are maintained in contact by the torsional stressing of the vane, is to dampen the first vibratory bending mode in order to prevent the vane from breaking dynamically, due to a resonance phenomenon. However, during operation, such a moving vane may be subject to interference from other parts and thus not return to its initial assembled position. This can lead to loss of contact between the lateral edges.
Such a loss of contact and the consequent play between the shrouds can cause the vane to become disengaged i.e. the male and female faces which should be in contact are no longer in contact, with an axial offset of the shroud of the vane. This disengagement leads to the removal and dismantling of the engine in order to put the shrouds back in the right position. If such removal and disassembly is not carried out, there is a loss of damping or even a risk of dynamic failure, which in the worst case can lead to an in-flight engine stoppage or partial/full turbine damage in flight. Apart from the risk of failure, there is also the consequence that the parts cannot be repaired and have to be scrapped during the maintenance visit or even before, which has a negative impact on costs.
There is therefore a need for a method of re-housing the vane shrouds of a rotor wheel in an aircraft turbomachine, without the need to remove or dismantle the engine or turbine from the turbomachine.
The invention thus provides a method of refitting vane shrouds of a rotor wheel in an aircraft turbomachine, the rotor wheel comprising a disc bearing vanes that each of which has a blade extending between a root and a shroud, the shroud of each vane comprising lateral edges comprising shapes complementary to the lateral edges of the shrouds of the adjacent vanes, the lateral edges of the shrouds being interlocked in engagement with one another such that anti-wear coatings of these edges contact each other in a desired interlocking engagement position, and at least one of the lateral edges of at least one of the shrouds being able to be disengaged from the lateral edge of an adjacent shroud in an undesired disengagement position.
According to the invention, the method comprises, when such an undesired disengagement position is detected, a step of inserting a re-engagement device into the turbomachine, and a step of moving the at least one shroud from this undesired position to the desired interlocking engagement position by bearing on and exerting a force on the vane or each vane whose shroud is disengaged.
Thanks to the insertion of such a re-engagement device in the turbomachine, and to the step of moving the shroud from the undesired position to the desired interlocking engagement position, the method according to the invention enables to refit the disengaged moving vane(s) directly under the wing, without the need to dismantle the engine or the turbine of the turbomachine. In this way, it is possible to avoid premature removal or dynamic breakage of the part and therefore of the engine or turbine. The process according to the invention therefore maximises and optimises the use of the engine, while at the same time ensuring a healthier operation of the moving vanes. Such a process also allows for a reduction in costs (the number of parts to be changed being reduced due to the maximisation of part utilisation as well as the reduction of anticipated turbine removals), as well as a reduction in the number of repairs to be carried out in maintenance operations.
The method according to the invention may comprise one or more of the following features, taken in isolation from each other or in combination with each other:
The present invention also relates to a re-engagement device for carrying out the method as described above, wherein it comprises an endoscope comprising lighting and viewing means as well as at least one of the elements selected from:
The invention will be better understood and other details, features and advantages of the invention will become clearer from the following description made by way of non-limiting example and with reference to the attached drawings in which:
The invention relates to a method and a re-engagement device 40 for refitting shrouds 14 of vanes 10 of a turbomachine movable wheel. Such a movable wheel (not visible in the figures) forms the rotor of the axial turbine of the turbomachine, and is conventionally constituted by an annular disc centred on the axis of rotation of the wheel, to which the vanes 10 are attached. Such a vane 10 is shown in
The vane 10 comprises a blade 16 extending along the stacking axis X of the vane, between the proximal 10A and distal 10B ends of the vane 10. At its proximal end 10A, the vane comprises a platform 19 and a root 12 by which it is attached to the disc (not shown). At its distal end 10B, the vane 10 has the shroud 14. When several vanes 10 are attached to the disc, their shrouds 14 are arranged edge to edge so as to form a circumferential ring delimiting a surface of revolution about the axis A of rotation of the wheel. The function of this ring is, in particular, to delimit the outer surface of the flow duct of the gas flows circulating between the blades 16 and to limit gas leaks at the distal end 10B of the vanes 10.
The shroud 14 comprises a platform 20 externally delimiting the flow duct of the gas circulating between the blades 16, and having opposite lateral edges 21, 22. The platform 20 comprises an upstream part 24 called “upstream spoiler” and a downstream part 28 called “downstream spoiler”. The shroud 14 also includes upstream 31 and downstream 32 sealing lips extending radially outward from the outer face of the platform 20. Each of the platform lateral edges 21, 22 has a substantially “U” shaped profile between the upstream 31 and downstream 32 lips. In the case of other vanes, this profile may take the form of a “Z” or a “V” for example.
In order to dampen the vibrations to which the vanes 10 are subjected during operation and to give rigidity to the assembly, the vanes 10 are mounted on their discs with a torsional stress about a torsional axis positioned in relation to the stacking axis X. The geometry of the shrouds 14 is such that each vane 10 is placed under torsional stress by bearing on the neighbouring vanes 10 at the lateral edges 21 and 22. The lateral edges 21, 22 of each vane 10, which comprise complementary shapes to the lateral edges 22, 21 of the shrouds 14 of the adjacent vanes 10, therefore define inter-vane contact surfaces and are the site of significant friction during operation of the turbomachine. In order to be protected against wear, these edges are provided with a coating which is made of anti-wear material resistant to friction. This may, for example, be a material marketed under the brand name Stellite®. This coating 36 can be seen in
Typically, this anti-wear coating 36 is deposited on the lateral edges 21, 22 by welding, for example by drop welding, involving the creation of an electric arc to melt the material. This is often a manual operation, with the Stellite® alloy in the form of a liquid drop during deposition.
Stellite® alloy is a steel alloy with a high chromium (Cr) and cobalt (Co) content. It may also contain a small amount of tungsten (W) or molybdenum (Mo) and a small amount of carbon (C). Stellite® alloy is not forgeable and must be either cast or welded onto an object of which it forms a part or into which it is inserted. The lateral edges 21, 22 of the shrouds 14 are interlocked in engagement with one another such that the anti-wear coatings 36 on the edges 21, 22 contact each other in a desired interlocking engagement position.
However, in operation, the vanes 10 may experience interference from other parts and at least one of the vanes 10 may not return to its original assembled position. This can cause loss of contact between adjacent lateral edges 21, 22. Such a loss of contact and the consequent play between the shrouds 14 may cause one vane to become disengaged, i.e. the male and female faces which should be in contact are no longer in contact, with an axial offset of the vane shroud. For the remainder of the description, it will be assumed that the shroud 14A of a vane 10A (shown in
References CR10, CR50 and CR90 in
The re-engagement device 40 comprises an endoscope 42.
The endoscope 42 has a generally elongated shape and is preferably flexible. It comprises a proximal end located on the operator's side, and a distal end which must be located as close as possible to the vane to be re-engaged, only this distal end being represented in the drawings. This distal end comprises a head 46.
The endoscope 42 is equipped with optical elements for illumination and visualisation, such as a first optical fibre, a proximal end of which is connected to a camera and a distal end 48a of which opens onto at least one lens, for example at the level of the head 46, and a second optical fibre, a proximal end of which is connected to a light source and a distal end 48b of which opens at the level of the head 46.
The head 46 is located at one end of a body 50 of the endoscope 42. This body 50 is generally tubular in shape and is used in particular to support positioning clamps 52, 54.
In the example shown, the endoscope 42 comprises two positioning clamps 52, 54. The two positioning clamps 52, 54 are oriented in an inverted manner with respect to the direction of extension of the body 50. The clamps 52, 54 have jaws 56 or fixed jaws. The clamps 52, 54 each have a general V-shape with the angle between the jaws 56 determined so that the clamps can be engaged on the leading edge 26a or trailing edge 26b of a blade. More specifically, a first clamp 52 is configured to grip the leading edge 26a of a blade, while the second clamp 54 is configured to grip the trailing edge 26b of an adjacent blade, or vice versa.
The clamps 52, 54 have free ends which are advantageously each equipped with a contact element which is preferably made of a material which is not likely to damage the blade during contact. This is, for example, PTFE or any other plastic material, or Teflon.
The clamps 52, 54 are each carried by a separate retractable arm 58, 60. Each retractable arm 58, 60 is straight in shape and comprises a longitudinal end 58a, 60a hinged to the head 46 or body 50, and an opposite longitudinal end 58b, 60b where the corresponding clip 52, 54 is located.
Each clamp 52, 54 may be formed in one piece with its corresponding arm 58, 60, but may also be movable along the arm 58, 60 to allow its position to be adjusted to best suit each vane. They extend in an opposite direction, substantially parallel to the direction of extension of the body 50. The jaws 56 of each clamp 52, 54 lie in planes parallel to each other.
Each arm 58, 60 is movable from a deployed position shown in
The movement of each arm 58, 60 is here provided by two corresponding rods 62, 64. Each first rod 62 extends along the direction of extension of the body 50 and comprises a longitudinal end articulated to the end 60a of the arm 60, and an opposite longitudinal end connected to a traction member accessible by the user or controlled by the user, from the proximal end of the endoscope 42. Such a pulling member is, for example, a jack (not shown in the drawings). Each second rod 64 extends obliquely between a first rod 62 and the corresponding arm 58, 60, and comprises a longitudinal end hinged to the end 60b of the arm, and an opposite longitudinal end hinged to the rod 62, in the vicinity of its end connected to the traction member.
When a tensile force according to arrow F1 is applied to the end of each rod 62 connected to the traction member, the rods move away from the distal end of the endoscope and drag the rods 64 and the arms 58, 60 along with them, which are then moved from the position in
Preferably, the distance between the clamps 52, 54 corresponds to the distance between CR10 and CR90.
In use, the endoscope 42 may be inserted in a first step through an endoscopy port of the turbo machine, or through the rear or downstream of the turbo machine in the case of rear stages. Once inserted and in its deployed position, the endoscope 42 can be used in the following manner in a second step: a first clamp 52 is used to clamp the leading edge 26a of the blade of the disengaged vane in CR10, while the second clamp 54 is used to pull or push the trailing edge 26b of an adjacent blade in CR90, in order to re-engage the disengaged vane shroud. Thus, in this second step, the shroud is moved via the joint action of the clamps 52, 54, to bring it from its disengaged position to a desired interlocking engagement position.
The endoscope 42 has a generally elongated and preferably cylindrical shape. The endoscope 42 comprises a proximal end located on the operator's side, and a distal end which is to be located as close as possible to the vane to be re-engaged, only this distal end being represented in the drawings. This distal end comprises hooks 66. The endoscope 42 further comprises means 68, 70, 72, 74, 76, 78 for transmitting a generally axial mechanical force (along the motor axis) between the hooks 66.
In the particular embodiment illustrated in
According to a first variant, illustrated in
According to a second alternative embodiment, illustrated in
According to a third embodiment, illustrated in
Preferably, as illustrated in
Even more preferably, as illustrated in
The cable 68 is attached at one end to the slidably mounted hook and is intended to be actuated by an operator of the endoscope 42 to exert the generally axial force between the two hooks 66. In the example shown, the cable 68 is attached to the first hook 66a via a planar support, typically via a slider 72 provided on the first hook 66a.
According to a second embodiment shown in
In use, the endoscope 42 may be inserted in a first step through an endoscopy port of the turbomachine, or through the rear or downstream of the turbomachine in the case of rear stages. During this first step, the hooks 66 are positioned so as to bear on a spoiler 24, 28 of the disengaged shroud 14a, or a leading edge 26a or trailing edge 26b of a blade. Once the endoscope 42 has been inserted and the hooks 66 correctly positioned, the endoscope 42 can be used in the following manner in a second step: a generally axial mechanical force is applied to the hooks 66, and thus to the adjacent vanes 10 on which the hooks 66 are positioned, via means 68, 70, 72, 74, 76, 78. Thus, during this second step, the disengaged shroud 14a is moved via the joint action of the hooks 66, to bring it from its disengaged position to a desired interlocking engagement position.
The endoscope 42 comprises a proximal end located on the operator's side, and a distal end which is to be located as close as possible to the vane 10A to be refitted, only this distal end being shown in the drawings. This distal end comprises a member 86 which is rotatable about an axis X.
In the particular embodiment shown in
The member 86 is preferably made of a material which is not likely to damage the blades 16 on contact. This is, for example, PTFE or any other plastic material, or Teflon. When the member 86 is in the form of a roller, the latter has a substantially elliptical shape, which is defined according to the stage of the turbomachine in which the roller is to be used. Preferably, the roller 86 has an elliptical shape with a small width of substantially 7 mm and a large width of between 15 mm and 30 mm. The dimensions of the roller 86 are also chosen to be compatible with the dimensions of the endoscopy port of the turbomachine.
In use, the endoscope 42 may be inserted in a first step through an endoscopy port of the turbomachine, or through the rear or downstream of the turbomachine in the case of rear stages. During this first step, and as illustrated in
The endoscope 42 comprises a proximal end located on the operator's side, and a distal end which must be located as close as possible to the vane to be re-engaged, only this distal end being shown in
In the particular embodiment shown in
In use, the endoscope 42 may be inserted in a first step through the aft or downstream of the turbine of the turbomachine for the aft stages. In this first step, the inflatable member 88 is positioned between two adjacent blades of two vanes, the vane of which comprising the shroud disengaged. Once inserted, the endoscope 42 can be used in the following manner in a second step: the inflatable member 88 is inflated via the air supply means. Under the pressure of the air blown into it, the inflatable member 88 thus comes to bear on the two adjacent blades and biases them in substantially opposite directions. This inflation of the member 88 allows the two corresponding vanes to be moved in a tangential direction, which gives the disengaged vane more freedom to return to its normal position. In this way, the shroud is moved by the action of the member 88 from its disengaged position to a desired interlocking engagement position.
The use of such an endoscope 42 having an inflatable member 88 has the advantage that it does not require the operator to use any special handling system for the member 88, but simply to operate the air supply means.
It is therefore understood that the refitting method and re-engagement device 40 according to the invention allows for the refitting of vane shrouds of a rotor wheel in an aircraft turbomachine, without the need to remove or dismantle the engine or turbine of the turbomachine. In this way, it is possible to avoid early removal or dynamic failure of the vanes and thus of the engine or turbine. The method and device according to the invention therefore maximise and optimise the use of the engine, while at the same time ensuring a healthier operation of the moving vanes. In addition, they allow a reduction in costs, as well as a reduction in the number of repairs to be carried out in maintenance operations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002179 | Mar 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2021/050341 | 3/1/2021 | WO |
