FR3072122B1 - TURBOMACHINE WHEEL - Google Patents

Abstract

The invention relates to a wheel comprising a disc (12) having at its periphery a plurality of substantially axial cells, a plurality of blades (32) whose feet (21) are axially engaged and retained radially in said cells and which have stilts (19) for connecting the feet (2) to plates (16) designed to delimit radially outwardly, an annular vein of a gaseous flow, sealing devices (36) mounted in internal cavities scaffolds delimited circumferentially between two stilts (19) adjacent. According to the invention, the sealing devices (36) each comprise at least one sealing wall (34) whose circumferential edges (34a, 34b) are arranged end to end with adjacent second ends of stilts (19). , said second ends of the stilts (19) being opposite the first ends of the stilts (19).

Description

TURBOMACHINE WHEEL

FIELD

The present invention relates to the field of leakage zones under the platforms of the blades of a bladed wheel in a turbomachine.

CONTEXT

[002] Typically, each blade of a turbine wheel comprises a blade connected at its radially inner end to a platform connected to a foot by a stilt. The grooves of the disc are regularly distributed around the axis of the disc and define between them teeth. In the mounting position, the blade platforms are circumferentially arranged next to one another and surround the teeth of the disk. The longitudinal edges of the platforms of the blades are separated from each other in the circumferential direction by small clearances. It is known to mount between the stilts of the blades sealing devices which, in operation, are biased radially outwards by the centrifugal forces and come to bear radially on the radially inner faces of the platforms in order to limit leakage. gas between the longitudinal edges of the platforms. These sealing devices can also provide vibration damping to which the blades are subjected in operation.

[003] In the current art, these devices or sealing members, sometimes called "candies", are engaged in lateral cavities of the blades, which are formed radially inside the platforms and which open in the circumferential direction. Each sealing member includes a circumferential end portion engaged in the side cavity of a blade and an opposite circumferential end portion engaged in the side cavity of an adjacent blade.

[004] To limit reintroductions of air in the inter-vane or inter-stilt cavities, each stilt comprises a transverse wall at each of its upstream and downstream ends. These transverse walls extend transversely to the axis of rotation of the turbomachine but are not necessarily radial. The upstream transverse walls are thus arranged end to end and it is the same for downstream transverse walls. It is understood that the shape of each device is imposed by the shape of the blade, more specifically by the geometry of the cavity.

[005] To achieve the mounting of the wheel, the operator proceeds as follows. First, the operator engages a blade root, from a downstream end for example, in a cell of the disk. The operator then simultaneously mounts a pair of blades / sealing device and repeats this operation until fitting the penultimate blade. The installation of the last blade must be done at the same time as the two sealing devices on both sides of the blade. For this, know-how and technical training is necessary and it is common that the positioning of the latter dawn requires as much time as the positioning of all blades previously positioned.

SUMMARY OF THE INVENTION

The present invention relates first of all to a wheel, in particular a turbomachine turbine comprising a disk having at its periphery a plurality of substantially axial cells, a plurality of vanes whose feet are engaged axially and retained radially in said cells and which have feet connecting stilts to platforms for delimiting radially outwardly, an annular vein of a gaseous flow, sealing devices mounted in inter-stile cavities delimited circumferentially between two stilts of two adjacent blades, and axially by transverse walls connected externally to the platforms and all formed at the same first end upstream or downstream of the stilts and cooperating together end to end to close axially said inter-stilt cavities, characterized in that said devices each comprise at least one paro i sealing which circumferential edges are arranged end to end with adjacent second ends of stilts, said second ends of the stilts being axially opposed to the first ends of the stilts.

[007] According to the invention, at a first end of the stilts the sealing is performed in a conventional manner by placing end to end transverse walls while at a second end of the stilts sealing is performed by circumferential abutment of a sealing wall belonging to a sealing device with two adjacent second ends of adjacent stilts. This particular seal allows easier mounting of the blades and sealing devices on the disc. Indeed, it is thus possible in a first step to mount all the blades on the disk by an axial engagement of the feet in the cavities of the disc. In a second step, the operator proceeds to mount each of the sealing devices from the second ends of the stilts of the blades, this second step being made possible by the circumferential space left free between two second ends of stilts.

[008] The assembly sequence of the vanes and sealing devices on the disk is greatly simplified since it suffices to successively mount all the blades and then successively all the sealing devices without having to simultaneously manipulate a blade and a device. sealing.

[009] The term "transverse" in this document means a direction arranged across the axis of rotation of the moving wheel. Thus, a transverse wall is a wall whose definition plane intercepts the axis of rotation of the moving wheel, this wall is not necessarily purely radial but can be.

[010] Of course, each of the second ends of the stilts could be connected to a transverse wall as in the prior art. However, it must then be small enough circumferentially to allow the mounting of the sealing devices as described in the previous paragraph.

[011] In a particular configuration of the invention, the second end of each stilt or at least some of the stilts is devoid of radial wall.

[012] According to another characteristic of the invention, the sealing wall of each sealing device comprises a radially outer edge adapted to come, in operation, bearing radially outwardly on a spoiler extending the platform , to achieve sealing operation of the sealing device on a spoiler of the blade. Thus, in operation, the radially outer edge bears radially outwardly on a radially inner side of the spoiler.

[013] According to another characteristic of the invention, the sealing devices comprise notches or notches opening radially inwards and in which is engaged radially outwardly an annular ring locked axially on one side of the disc.

[014] This annular ring can be engaged in hooks carried by the second ends of the blades of the stilts.

[015] In this assembly, the ring simultaneously ensures the axial locking of the blades and sealing devices.

[016] Each sealing device can be made by stamping a sheet.

[017] The invention also relates to a turbomachine, such as a turbojet or an airplane turboprop, comprising a bladed wheel as described above.

[018] It also relates to a method of mounting the wheel according to the invention, the method comprising the following steps: - Axial engagement of each of the blade roots in the alveoli of the disk, since the first end of the stilts of the blades; and - Engagement of each of the sealing devices from the second end of the stilts.

[019] In a subsequent step, the annular ring is mounted in the hooks of the stilts and the notches of the sealing devices.

[020] The invention will be better understood and other details, features and advantages of the invention will become apparent on reading the following description given by way of non-limiting example with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a partial schematic half-view in axial section of a turbomachine low-pressure turbine according to the known technique; Figure 2 is a schematic perspective view of the radially inner portion of a blade of the turbine shown in Figure 1; Figure 3 is a schematic side view of the blade of Figure 2 with a sealing device mounted in a cavity or inter-stilt housing; Figures 4 and 5 are schematic views of a blade for use in a turbine of a turbomachine according to the invention; Figure 6 is a diagrammatic side view of the blade of Figure 4 with a sealing device integrated in an inter-stilt cavity; Figure 7 is a schematic perspective view of two adjacent turbine blades of a bladed wheel according to the invention, a sealing device being mounted in an inter-stilt cavity; Figure 8 is a schematic view showing the mounting of a sealing device in an inter-stile cavity of a bladed wheel according to the invention.

DETAILED DESCRIPTION

[021] We first refer to Figure 1 which is a schematic half-sectional view of a turbomachine low-pressure turbine, in a plane passing through the axis of rotation X of the rotor of the turbine to the figures 2 and 3 which illustrate in an isolated manner a turbine blade. The invention is obviously applicable to other parts of the turbomachine where sealing devices as described below can be used for an inter-blade sealing function.

[022] The rotor of the low-pressure turbine comprises wheels 10 assembled axially to each other by annular flanges and each having a disc 12 carrying blades 14 individual. These blades each comprise a blade 15 connected by a platform 16 and a stub 19 to a foot 21 which is for example a dovetail or the like, and which is engaged in a longitudinal recess formed at the outer periphery of a disc 12 (Figure 1). The cells or housing groove of the blade roots define between them teeth which are arranged vis-à-vis the radial platforms of the blades. The rotor is connected to the turbine shaft via a drive cone 17. Between the wheels 10 are annular rows of stationary blades 18 which are mounted by appropriate means at their radially outer ends on a housing 21 of the low-pressure turbine. The fixed vanes 18 of each row are joined together at their radially inner ends by annular sectors 20 placed circumferentially end to end. Upstream and downstream circumferential plates or flanges 22 are formed in axial projection on the annular sectors 20, and constitute baffles with other spoilers or circumferential flanges 24 upstream and downstream of the platforms of the blades 14, to limit the passage of the gases. combustion, from the combustion chamber upstream of the turbine, radially from the outside to the inside. The term "radially" in relation to the terms "internal" and "external" are to be interpreted with respect to the axis of the moving wheel or axis of rotation of the turbomachine. The terms "upstream" and "downstream" are to be interpreted in relation to the direction of flow of air through the wheel when it is integrated with a turbomachine.

[023] Each blade 14 also comprises a first downstream transverse wall 26 formed at the downstream end or first end of the stilt 19 and a second upstream transverse wall 28 formed at the upstream end or second end of Péchasse 19. Like this 2 and 3, these upstream and downstream transverse walls 26 are connected radially outward to the upstream and downstream edges, respectively, of the platform 16. The circumferential edges of the upstream transverse walls 28 are arranged butt end, that is to say circumferentially juxtaposed, and it is the same circumferential edges of the downstream transverse walls 26, to limit the reintroduction of hot gas in the inter-stilt cavities defined by two stilts 19 consecutive or adjacent circumferentially.

[024] As can be seen in FIG. 3, these inter-stilt cavities each house a sealing device 30 mounted for one part in a half-cavity of one blade 14 and for the other part in a half-cavity of an adjacent blade 14. These sealing members 30 allow radial support on the inner faces of the platforms 16 to limit reintroductions of hot gases between the interstices at the junction between two consecutive platforms 16.

[025] As mentioned above, the mounting of the sealing devices 30 and blades 14 may be difficult to achieve making the assembly operation of a long and expensive wheel.

[026] Thus, according to the invention shown in Figure 4, it is proposed to remove the second transverse wall (Figure 5) of the blade 32, that is to say the upstream transverse wall 28 and to retain the first transverse wall 26 and circumferential sealing by a transverse wall 34 of each sealing device 36 (Figures 6 and 7).

[027] To this end, each sealing device 36 comprises a first end, here the downstream end, similar to that described in connection with the prior art and coming in axial vis-à-vis two downstream transverse walls 26 abutments , end to end by their circumferential ends, two adjacent blades 32 and a second end, here the upstream end, which comprises a transverse sealing wall 34 whose circumferential edges 34a, 34b are arranged end to end with the seconds ends, here the upstream ends of two stilts 19 adjacent. Each sealing device 36 or "candy" can be made by stamping a sheet whose upstream sealing wall 34 is thicker than the rest of the sheet and in particular the lateral sails 38 intended to cooperate with the lateral faces. stilts 19, the downstream veil 40 abutment on the downstream transverse walls 26 and the upper web 42 connecting the side webs 38, the downstream web 40 and the upstream sealing wall 34. As can be seen in FIG. 6, the sealing wall 34 of each sealing device 36 bears radially outwardly, in use, on two adjacent spoilers 24 so as to ensure a seal there between two pieces which was carried out in the prior art by the transverse wall 28 which is removed.

[028] Each sealing device 36 comprises a recess 44 at its second end intended to cooperate with the downstream end of two adjacent spoilers 24 to maintain the sealing device 36 in the inter-stile cavity. Each sealing device 36 may be hollow internally so that the radially inner edges 38a of the side webs 38 and the downstream web 40 are free.

[029] For the purpose of axial locking of the sealing devices in the inter-stilt cavities, each of them comprises a recess 46 or a notch formed in the radially inner edge 38a of the side webs 38 (Figure 6). As can be seen in FIG. 7, each second end, here the upstream end, of a stag 19 comprises a hook 48 oriented radially inwards. An annular ring 50 is thus engaged radially outwards in the indentations 46 or notches of the sealing devices 36 and in the hooks 48 of the blades 32, the ring 50 bearing on the upstream or second face of the disc 12 ( similar to that shown in Figure 1) for axially locking the sealing devices 36 and the blades 32.

[030] The assembly of the blades and sealing devices 36 on a disk 12 is made in the following manner. In a first step, all the blades 32 are mounted successively on the disk 12 by an axial translational movement of the feet 21 in the cavities of the disk 12 from the first end or downstream end of the disk 12 towards the second end or upstream end of the disk. 12. In a second step illustrated in FIG. 8, the sealing devices 36 are mounted successively from the second end of the disc 12 by an axial movement oriented towards the first end and followed by a pivoting movement, the edges 34a, 34b walls 34 of the sealing devices 36 coming in circumferential vis-à-vis second ends or upstream ends of two stilts 19 consecutive. The annular ring 50 is then mounted in the indentations 46 of the sealing devices and the hooks 48 of the vanes 19 as indicated with reference to FIG. 7.

[031] If the invention has been described with reference to the figures, with the first end of the blade 32 formed at the downstream end of the blade 32 and the second end of the blade 32 formed at the upstream end of the blade 32, it is understood that the invention is applicable to reverse assemblies where the first end is formed at the upstream end of the blade 32 and the second end is formed at the downstream end of the blade 32 It is easily understood that the upstream / downstream placement of the first and second ends is a function of the axial assembly direction of the blades in the cavities of the disk 12.

Claims (8)

A wheel, in particular a turbine wheel, for a turbine engine extending longitudinally along an axis X comprising a disk (12) having at its periphery a plurality of substantially axial cells, a plurality of blades (32) whose feet ( 21) are engaged axially and retained radially in said cells and which have stilts (19) for connecting the feet (2) to platforms (16) intended to define radially outwardly an annular stream of a gas stream , sealing devices (36) mounted in inter-stilt cavities delimited circumferentially between two stilts (19) of two adjacent blades and axially by transverse walls (26) connected externally to the platforms (16) and all formed to a same first upstream or downstream end of the stilts, characterized in that said sealing devices (36) each comprise at least one transverse wall sealing e (34) whose circumferential edges (34a, 34b) are arranged end to end with adjacent second ends of stilts (19), said second ends of the stilts (19) being axially opposed to the first ends of the stilts (19) . 2. Wheel according to claim 1, characterized in that the sealing wall (34) of each sealing device (36) comprises a radially outer edge adapted to come, in operation, bearing radially outwardly on a spoiler (24) extending the platform (16). 3. Wheel according to claim 1 or 2, characterized in that the sealing devices (36) comprise indentations (46) or notches opening radially inwards and in which is engaged radially outwardly an annular ring ( 50) locked axially on one side of the disc (12). 4. Wheel according to claim 3, characterized in that the annular ring (50) is engaged in hooks (48) carried by the second ends of the stilts (19) of the blades (32). 5. Wheel according to one of claims 1 to 4, characterized in that each sealing device (36) is made by stamping a sheet. 6. Turbomachine, such as a turbojet engine or a turboprop engine, characterized in that it comprises a wheel according to one of claims 1 to 5. 7. A method of mounting the wheel according to one of claims 1 to 5, comprising the following steps: Axial engagement of each of the feet (21) of the blades (32) in the cavities of the disk (12), from the first end stilts (19) of the blades (32); and engaging each of the sealing devices (36) from the second end of the stilts (19). 8. The method of claim 7 when dependent on claim 4, comprising a step of mounting an annular ring (50) in the hooks (48) of the stilts (19) and the notches (46) of the devices. sealing (36).