JP5697667B2 - Outer shell sector for winged rings for aircraft turbomachine stators, including damping shims - Google Patents

Description

  The present invention generally relates to aircraft turbomachines, preferably of the turbojet or turboprop type.

  More specifically, the present invention supports a compressor or turbine stator of this type of turbomachine, more precisely, supporting a plurality of stator blades and blades and passing through the turbomachine inward and outward respectively. And a winged ring sector comprising two concentric shells designed to radially define a primary flow. This type of winged ring is usually made with several sectors arranged end-to-end and is typically used in compressors or turbines as guide vanes or nozzles.

  Turbomachines typically include a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine, and a low pressure turbine in succession. The compressor and turbine comprise several rows of movable blades spaced circumferentially, and these rows are separated by rows of stationary blades, also spaced circumferentially. In modern turbomachinery, high dynamic stresses are applied to the guide vanes and nozzles. Technological advances result in a reduction in the number of stages in order to obtain equal or better performance, resulting in higher loads on each stage. Furthermore, changes in manufacturing technology have led to a reduction in the number of parts, thereby reducing the damping effect of the connection between the parts. This is especially true when an abradable cartridge brazing technique is used that eliminates a significant source of vibration energy dissipation.

  FR-A-2902843 divides the outer shell sectors into basic sectors at regular intervals from one another along the tangential direction by using slits or radial cuts in an oblique or other direction. Thus, each basic sector supports a single wing of a winged ring sector. In addition, a damping insert in the form of a strip is inserted between the basic sectors. The principle of operation is based on introducing stiffness nonlinearity into the dynamic behavior of the structure. This non-linearity is triggered by the threshold vibration level of the system. This oscillating activity causes relative movement between the basic sector of the wing and the damping insert. This relative motion results in a continuous loss and recovery of the damping insert adhesion and, as a result, a continuous change in the local stiffness of the system. Thus, the mode (s) that cause vibrational activity are confused by persistent changes in the associated natural frequency. System resonances cannot be caused due to continuous changes in the state of the dynamic system. This reduces the vibration amplitude of the system.

  Nevertheless, even if this solution is satisfactory with respect to vibration reduction, this can be improved. Furthermore, in this solution disclosed in French Patent Application No. 2902843, the damping insert has a basic sector friction due to the effect of the pressure gradient between the aerodynamic flow path and the outside of the compressor. It is held in contact with the surface, resulting in a radially inward force being applied to these inserts. The disadvantage is that this pressure gradient cannot be sufficient to force the insert into satisfactory contact with the friction surface. In this case, the result is not only a possible non-leakage loss of the air flow path, but first of all a reduction in damping performance.

French Patent Application Publication No. 2902843

  Another disadvantage of this solution is that one of the blades of the winged ring sector is overloaded. The aerodynamic force applied to the wing includes a tangential component that cannot be resisted in the outer shell sector due to segmentation within the tangentially spaced basic sectors. Thus, these tangential components are combined and pass through the inner shell sector of the winged ring sector and then through the wings located adjacent to the anti-rotation stop attached to the ring sector. The wing is therefore subjected to a very high load by the inability of the outer shell sector to transmit a static force along the tangential direction.

  The object of the present invention is therefore to at least partly overcome the above-mentioned problems arising in the prior art embodiments.

  A first object of the present invention to achieve this is an assembly that forms an outer shell sector for a winged ring sector used in an aircraft turbomachine compressor or turbine stator, said outer shell sector comprising: Firstly, a plurality of basic sectors spaced from each other along the tangential direction of the assembly, and secondly, each of them being arranged directly in succession along the tangential direction An assembly comprising a damping shim inserted between two basic sectors associated therewith.

  According to the present invention, the contour of each damping shim is substantially the same as the contour of the basic sector.

  Due to the specific contour of the shim, the friction interface between the shim and the basic sector is large, thereby improving the damping effect.

  In addition, being forced to contact the friction surface of the basic sector, the shim is independent of the pressure difference between the aerodynamic flow path and the outside of the compressor or turbine, between these elements. It can be a perfect seal. This seal is obtained by a structure having a shim that applies a force to the friction surface of the basic sector substantially along the tangential direction. The seal is further strengthened in operation because the force that causes the friction surface and the shim to contact each other is emphasized by adding a tangential component of the aerodynamic force applied to the stator blades to the basic sector. Please note that.

  With regard to the tangential component of the aerodynamic force applied to the wing, one of the essential advantages of the present invention is that the outer shell sector is reinforced significantly along the tangential direction by specific positioning of the damping shim. Thus, it should be noted that even if this is separated into sectors along this direction, this component can pass through the assembly forming the outer shell sector. The result is that there is no overload for the wings that are loaded almost uniformly.

  Finally, by adopting a contour that is approximately the same as the contour of the basic sector, the outer radial boundary delimiters of the primary annular flow, also called the air flow path, are perfectly reproduced between the basic sectors, spaced from each other. Please note that.

  The shims face each other along the tangential direction and are in contact with two parallel flat friction surfaces provided in the two basic sectors associated with the shim, the shims being parallel to each other And preferably have two complementary flat friction surfaces cooperating with two corresponding friction surfaces of the basic sector. The flat contact between the friction surface and the complementary friction surface provides satisfactory vibration damping due to friction. Also, in order to obtain a slit in the determined plane, in which a straight slit, in other words a corresponding shim inside it is fitted, is obtained simultaneously, for example by a single cutting operation, during a single machining operation. It is also possible to create a friction surface. This greatly simplifies the manufacture of the assembly according to the invention, thereby saving significant costs and time.

  The shim is provided with hooks to hold it in place on the compressor or turbine stator, and therefore these hooks preferably have the same contour as the hooks fixed to the basic sector.

  The basic sectors are preferably separated from each other by radial slits that are completely closed by the damping shims.

  It is preferable that the damping shim extends substantially along the axial direction or the oblique direction of the assembly.

  Another object of the present invention is to provide an assembly for forming an outer shell sector as described above, an inner shell sector, an assembly tangentially spaced from each other, and forming an outer shell sector. Applies to a winged ring sector designed to be attached to a compressor or turbine stator of an aircraft turbomachine with a plurality of wings inserted between the shell sector. In this case, each basic sector will carry a single stator blade, or possibly several blades, without extending outside the scope of the present invention.

  The bladed ring can form a guide vane for a compressor or a nozzle for a turbine.

  Further, the ring sector preferably extends over an angular range between 5 ° and 60 °, but can be as high as 360 ° to form the entire winged ring.

  Another object of the invention is an aircraft turbomachine comprising a compressor or turbine stator with at least one winged ring sector as described above.

  Other advantages and features of the invention will become apparent in the detailed non-limiting description set forth below.

  This description is made with reference to the accompanying drawings.

1 is a schematic cross-sectional view of a turbomachine with one or several winged ring sectors according to the invention. It is sectional drawing which shows a part of high-pressure compressor of the turbomachine shown by FIG. 1, and is a figure containing the ring sector with a blade | wing by this invention. FIG. 2 is a perspective view of the winged ring sector shown in the previous figure, wherein the sector comprises a preferred embodiment of the present invention. FIG. 3 is an axial view of a portion of the winged ring sector shown in the previous figure. FIG. 5 is a profile view of the shim and basic sector of the winged ring sector shown in the previous figure, taken along line V-V of FIG. 4. FIG. 6 schematically shows a step in the manufacturing process of the winged ring sector shown in the previous figure. FIG. 6 schematically shows a step in the manufacturing process of the winged ring sector shown in the previous figure. FIG. 6 schematically shows a step in the manufacturing process of the winged ring sector shown in the previous figure.

  Referring first to FIG. 1, the figure shows an aircraft turbojet 100 to which the present invention is applicable. This includes a low-pressure compressor 2, a high-pressure compressor 4, an annular combustion chamber 6, a high-pressure turbine 8, and a low-pressure turbine 10 in order from upstream to downstream.

  FIG. 2 shows a part of the high-pressure compressor 4. In a known manner, the compressor comprises a row of stator blades 14 and a row of rotor blades 16 alternating in an axial direction parallel to the compressor axis 12. Stator blades 18 arranged circumferentially / tangentially about the axis 12 are included in a part of the stator, preferably a winged ring 20, which is composed of sectors along the circumferential direction 22. Therefore, in the following to refer to the winged ring sector 20, this sector 20 preferably extends over an angle range between 5 ° and 60 °, possibly approximately 360 ° to form the entire winged ring. It is understood that it extends.

  Thus, the sector 20 that forms all or part of a turbine nozzle or compressor guide vane comprises an inner shell sector 24 that forms an inner surface that radially defines a primary annular flow 26 passing through the turbomachine. The sector 24 supports the fixed root portion of the stator blade 18. In addition to these wings 18, the sector 20 also includes an assembly that forms an outer shell sector 28 that forms an outer surface that radially defines a primary annular flow and supports a fixed top of the wing 18. .

  In this regard, the sector 20 is also supported by a rotor stage 16 that supports the rotating blades and forms a radially inner ablation that forms an annular seal track that is contacted by a sealing device 31 disposed downstream of the sector 20. Note that it is provided with known additional elements that are attached to the shell sector 24, such as a double sheath 29. The rotary sealing device 31 is a known labyrinth or lip seal type sealing device.

  FIG. 3 shows a winged ring sector 20. In the preferred embodiment described, the entire turbine nozzle or compressor guide vane is obtained by arranging a plurality of these sectors 20 end to end, and therefore each is an angular or Form a circumferential portion. The angular sectors 20 (only one of which can be seen in FIG. 3) preferably do not have any rigid and direct mechanical links connecting them together, their adjacent ends being They are simply placed facing each other with or without a gap.

  More specifically, with reference to FIGS. 3 and 4, the figures show that the inner ring sector 24 is made of a single piece and is not segmented. On the other hand, the assembly 28 forming the outer shell sector 28 is segmented by straight radial or slightly oblique slits 32 to become basic sectors 30 spaced from one another along the tangential direction 22. Therefore, a gap is created between directly consecutive sectors 30. Each slit 32 is made along an intermediate straight line between two directly continuous blades 18 so that each basic sector 30 supports a single fixed stator blade 18. One of the two basic sectors 30 arranged at the end of the sector 20 supports a rotation stop 33 projecting radially outward, which is the other part of the compressor stator in a known manner. Collaborate with.

  The assembly 28 also includes a damping shim 34 that is fitted between the directly continuous basic sectors 30.

  More precisely, each damping shim 34 is fitted between two flat parallel friction surfaces 38 facing each other along the tangential direction 22 and corresponding tangential ends of the two basic sectors associated with the shim facing each other. Installed in the department. Similarly, each shim 34 has two complementary flat friction surfaces 40 that are in contact with two corresponding flat friction surfaces 38 that are parallel and also parallel to each other.

  Thus, each shim 34 having a shape that is complementary to the shape of the friction surface 38 is pushed between two directly consecutive basic sectors 30.

  Contact between each pair of two friction surfaces 38 and 40 is preferably obtained as soon as the shim 34 is in place between its two associated basic sectors 30. Thus, the shims 34 apply a force that is directed in a generally tangential direction in contact with the friction surface 38 of the basic sector, resulting in their complementary flat friction surface 40. These forces are advantageously increased during operation by additionally applying a tangential component of the aerodynamic force applied to the stator blades to the basic sector.

  As schematically shown in FIG. 5, one particular feature of the present invention is that the contour of shim 34 is approximately the same as the contour of the basic sector, and this same contour corresponds to the contour of the outer shell sector. There is. In this disclosure, the outline refers to the overall shape of the element as seen along the tangential direction 22, although the cross-sectional view is shown in FIG.

  Thus, like the basic sector 30, the lower surface 46 of each shim 34 serves as the outer radial boundary delimiter of the air flow path. Thus, the overall annular delimiting surface of the air flow path consisting of a series of these surfaces 46 formed in the shim 34 and sector 30 is substantially from an aerodynamic point of view since there are no steps between the continuous surfaces 46. Is continuous.

  Each shim 34 and each sector 30 also projects a hook to hold it in place with respect to another portion of the compressor stator, more precisely a locking hook 48 projecting forward and a rear projecting hook. A fixing hook 50 is provided. As shown in FIG. 2, hooks 48 and 50 are inserted into corresponding annular slits 52 and slits 54 provided in another portion of the compressor stator to secure sector 20 to this other portion of the stator. Inset.

  The shim 34 which completely closes the slit 32 is damped by friction in contact with the friction surface 38, based on the physical principle described above for the shim disclosed in the document FR-A-2902843. Perform the function. They also perform the sealing function and the function through which the tangential component of the aerodynamic force applied to the stator blades passes. More generally, at this point, each shim 34 can transmit a tangential force between the two basic sectors 30 in which it is inserted.

  The nature of the materials used for the basic sector 30 and the shim 34 is approximately the same, preferably metallic, and is selected so that the shim wears preferentially rather than the basic sector 30.

  It should also be noted that the ratio between the size of each shim along the tangential direction and the size of each basic sector, which also corresponds to the thickness, is between 0.5 and 1.

  FIGS. 6 a to 6 c schematically show a process for the manufacture of the winged ring sector 20. First, as can be seen in FIG. 6 a, the unitary assembly 100 is made by casting or machining to form the inner shell sector 24, the outer shell sector 28, and the stator blades 18. The next step is to make a straight radial slit 32 in the outer shell sector 28 by simple and inexpensive machining to obtain the basic sector 30 as shown schematically in FIG. 6b. For example, these slits 32 can be made by simply cutting the sector 28.

  Finally, FIG. 6c shows the final step consisting of placing the damping shim 34 at the appropriate position of the slit 32 forming the friction surface by simply sliding the shim into their corresponding holes. Show.

  An accurate sliding adjustment gap makes it relatively easy to insert each shim into its associated slit while holding the shim in its slit by simply forcing a force between the two friction surfaces 38. Please note that it is preferred.

  Obviously, those skilled in the art can make various modifications of the invention as described above, merely using non-limiting examples.

Claims (5)

A winged ring sector (20) designed to be installed in a compressor stator of an aircraft turbomachine,
Inserted between the assembly forming the outer shell sector (28), the inner shell sector (24), tangentially spaced from each other and between the assembly forming the outer shell sector and the inner shell sector was provided with a plurality of the blades (18), said assembly the wing is fixed to each of the assembly and the inner shell sector to form the outer shell sector, to form the outer shell sector (28) but the first, a plurality of basic sectors (30) spaced from each other along the tangential direction (22) of the assembly, the second, directly along the tangential direction, each associated with it is successively inserted between the arranged two basic sectors, provided with a plurality of damping shims (34),
Contours of the damping shim (34) state, and are substantially the same as the contour of the base sector (30),
The vibration damping shim (34), characterized in that extending substantially along the oblique direction of the assembly, said sectors.   The shim faces each other along the tangential direction (22) and is in contact with two parallel flat friction surfaces (38) provided in each of the two basic sectors (30) associated with the shim. The shim (34) has two complementary flat friction surfaces (40) parallel to each other and cooperating with two corresponding friction surfaces of the basic sector. The sector of claim 1.   The sector according to claim 1 or 2, characterized in that the shim (34) is provided with hooks (48, 50) to hold it in place in the compressor or turbine stator.   4. The basic sector according to claim 1, wherein the basic sectors are separated from each other by a radial slit that is completely closed by the damping shim. Sectors. Aircraft turbomachine comprising a compressor stator having at least one winged ring sectors as claimed in any one of claims 1 to 4.

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