Abstract
A rotor disc for a turbomachine, the disc extending circumferentially around an axis and including a plurality of cells configured to receive blade roots and each cell including an upstream radial wall configured to axially block the blade root in the cell, each cell being connected to an upstream surface of the disc by a ventilation channel of the cell, the ventilation channel including an inlet orifice which opens onto the upstream surface of the disc and an outlet orifice which opens into the cell. An assembly of such a disc, of a plurality of blades and of a downstream retaining ring and a turbomachine including such an assembly.
Claims
1. A rotor disc for a turbomachine, the rotor disc extending circumferentially around an axis and comprising a plurality of cells configured to receive and radially retain blade roots and each cell comprising an upstream radial wall configured to axially block a corresponding blade root in the cell, each cell being connected to an upstream surface of the rotor disc by a ventilation channel of the cell, the ventilation channel comprising an inlet orifice which opens onto the upstream surface of the rotor disc and an outlet orifice which opens into the cell, each cell opening into a respective cavity for receiving a blade shank, wherein each respective cavity is delimited by inter-cavity walls disposed circumferentially and extending radially outward in continuation of teeth delimiting the cells.
2. The disc according to claim 1, wherein the upstream radial wall of each cell is prolonged outward in a radial direction to form an extended upstream radial wall.
3. The disc according to claim 1, wherein the rotor disc comprises a radial bearing surface configured to form a radial end stop of a blade platform.
4. The disc according to claim 3, wherein the radial bearing surface is prolonged to each respective cavity by a sealing bearing surface of a seal carried by a blade.
5. The disc according to claim 1, wherein the upstream radial wall comprises an upstream spoiler.
6. The disc according to claim 1, wherein the upstream radial wall comprises an axial stop surface configured to form an axial end stop of a blade.
7. The disc according to claim 1, wherein each respective cavity is configured to receive a blade shank and two damping elements disposed circumferentially on both sides the blade shank.
8. The disc according to claim 1, wherein the rotor disc comprises an attached crown at least partially defining the plurality of cells, the ventilation channel of each cell being partially defined in the rotor disc and in the crown.
9. An assembly of a rotor disc according to claim 1, of a plurality of blades, a blade root being received in each cell, and of a downstream retaining ring fastened on the rotor disc and configured to axially block the blade root in the cell.
10. The assembly according to claim 9, wherein the downstream retaining ring is made in one piece with a movable ring.
11. The assembly according to claim 9, wherein at least one blade of the plurality of blades comprises a seal receiving groove and a seal received in the groove, the rotor disc comprising a radial bearing surface configured to form a radial end stop of a blade platform, the radial bearing surface being prolonged to each of the respective cavities by a sealing bearing surface of the seal carried by the at least one blade, the seal cooperating with the sealing bearing surface of the rotor disc.
12. A turbomachine comprising an assembly according to claim 9.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Other characteristics and advantages of the object of the present disclosure will emerge from the following description of embodiments, given by way of non-limiting examples, with reference to the appended figures.
(2) FIG. 1 is a schematic longitudinal sectional view of a turbojet engine.
(3) FIG. 2 is a partial and perspective view in partial section of a portion of FIG. 1 showing an assembly according to a first embodiment.
(4) FIG. 3 is a side view of the assembly of FIG. 2.
(5) FIG. 4 is a partial perspective view of a blade of FIG. 3.
(6) FIG. 5 is a partial perspective view of the turbine disc of FIG. 3.
(7) FIG. 6 is a partial perspective view of a step of assembling the assembly of FIG. 3.
(8) FIG. 7 is a partial perspective view of a step of assembling the assembly of FIG. 3.
(9) FIG. 8 is a partial and perspective view in partial section of a portion of FIG. 1 showing an assembly according to a second embodiment.
(10) FIG. 9 is a side view of the assembly of FIG. 8.
(11) FIG. 10 is a partial perspective view of a blade of FIG. 9.
(12) FIGS. 11A and 11B are partial perspective views of the turbine disc of FIG. 9.
(13) FIG. 12 is a partial perspective view of a crown carrying teeth.
(14) FIG. 13 is a partial perspective view of a step of assembling the assembly of FIG. 9.
(15) FIG. 14 is a partial perspective view of a step of assembling the assembly of FIG. 9.
(16) FIG. 15 is a partial perspective view of a step of assembling the assembly of FIG. 9.
(17) FIG. 16 is a partial perspective view of a step of assembling the assembly of FIG. 9.
(18) FIG. 17 is a partial perspective view of a step of assembling the assembly of FIG. 9.
(19) FIG. 18 is a partial perspective view of a blade according to a third embodiment.
(20) FIG. 19 is a partial and perspective view in partial section of a portion of FIG. 1 showing an assembly according to the third embodiment.
(21) FIG. 20 is a partial view of the assembly of the third embodiment.
(22) In all of the figures, the common elements are identified by identical reference numerals.
DETAILED DESCRIPTION
(23) FIG. 1 shows in section along a vertical plane passing through its main axis A, a bypass turbojet engine 10 which is an example of a turbomachine. The bypass turbojet engine 10 includes, from upstream to downstream according to the circulation of the air flow F, a fan 12, a low pressure compressor 14, a high pressure compressor 16, a combustion chamber 18, a high pressure turbine 20, and a low pressure turbine 22.
(24) The terms “upstream” and “downstream” are defined relative to the direction of air circulation in the turbomachine, in this case, according to the circulation of the air flow F in the turbojet engine 10.
(25) The turbojet engine 10 includes a fan casing 24 prolonged rearward, that is to say downstream, by an intermediate casing 26, including an outer shroud 28 as well as an inner shroud 30 which is coaxial and disposed, in a radial direction R, internally relative to the outer shroud 28. The radial direction R is perpendicular to the main axis A. The main axis A is the axis of rotation of the turbomachine.
(26) The terms “outer” and “inner” are defined relative to the radial direction R so that the inner portion of an element is, in the radial direction, closer to the main axis A than the outer portion of the same element.
(27) The intermediate casing 26 further includes structural arms 32 distributed circumferentially and extending radially between the inner shroud 30 to the outer shroud 28. For example, the structural arms 32 are bolted on the outer shroud 28 and on the inner shroud 30. The structural arms 32 allow stiffening the structure of the intermediate casing 26.
(28) The main axis A is the axis of rotation of the turbojet engine 10 and of the low pressure turbine 22. This main axis A is therefore parallel to the axial direction.
(29) The low pressure turbine 22 includes a plurality of blade wheels which form the rotor of the low pressure turbine 22.
(30) FIG. 2 is a partial and perspective view in partial section of a portion of FIG. 1 showing an assembly 34 according to a first embodiment and FIG. 3 is a side view of the assembly 34 of FIG. 2.
(31) The assembly 34 of FIGS. 2 and 3, for example a rotor stage of the low pressure turbine, includes a rotor disc 36 extending circumferentially around the main axis A and on the periphery of which are assembled blades 38. The assembly 34 also includes a downstream retaining ring 40.
(32) In the embodiment of FIGS. 2 and 3, the downstream retaining ring 40 is made in one piece with a movable ring 42. Thus, the blade 38 is devoid of a hook for holding the downstream retaining ring 40.
(33) As can be seen in particular in FIGS. 5 to 7, the disc 36 of the rotor includes at its periphery a plurality of cells 44.
(34) The disc 36 of the rotor includes at least one connecting shroud 46 allowing in particular to assemble the movable ring 42 and the disc 36, for example by means of a plurality of bolts disposed in a circumferential direction C in axial orifices carried by the downstream connecting shroud 46 of the disc 36 and by the movable ring 42.
(35) As shown in FIGS. 2 and 3, the blade 38 is assembled on the first disc 36 by inserting a blade root 48 into the blade root receiving cell 44. In cross-sectional view in a radial plane, the blade root 48 has a general bulb shape with a wider portion towards the inner end of the blade 38 and a portion whose width decreases towards the shank of the blade 60.
(36) As can be seen in FIG. 5, the cell 44 is delimited in the circumferential direction C by teeth 52 forming portions of the disc 36. Each cell 44 includes an upstream radial wall 54. The upstream radial wall 54 is integral with the teeth 52 of the disc 36 and therefore is integral with the disc 36 and allows axially blocking the blade root 48 in the cell 44.
(37) In the embodiment of FIGS. 2 and 3, the blade root 48 is coated with a foil 50. The foil 50 allows in particular protecting the blade root 48 and the teeth 52 against wear.
(38) In the embodiment of FIGS. 2 to 7, the upstream radial wall 54 is prolonged outward in the radial direction R to form an extended upstream radial wall 56. It is therefore understood that the upstream radial wall 54 includes the extended upstream radial wall 56.
(39) In the embodiment of FIGS. 2 to 7, each cell 44 opens into a cavity 58 for receiving a blade shank 60.
(40) Thus, the extended upstream radial wall 56 extends in the radial direction R up to a distance allowing an inner platform 62 of the blade to abut against the extended upstream radial wall 56 of the disc 36. Thus, the disc 36 and particularly the extended upstream radial wall 56 includes a radial bearing surface 64 configured to form a radial end stop of the inner platform 62 of the blade 38.
(41) In the embodiment of FIGS. 2 to 7, the disc 36 and particularly the extended upstream radial wall 56 of the upstream radial wall 54 includes an axial stop surface 66 forming an axial end stop of the blade 38 when the blade 38, particularly the blade shank 60, is inserted into the cavity 58.
(42) In the embodiment of FIGS. 2 to 7, each cavity 58 receives a blade shank 60 and two damping elements 68. The damping elements 68 are disposed circumferentially on both sides of the blade shank 60.
(43) In the embodiment of FIGS. 2 to 7, the cavity 58 is delimited by inter-cavity walls 70 disposed circumferentially and which extend radially outwards in the continuation of each tooth 52.
(44) In the embodiment of FIGS. 2 to 7, the radial bearing surface 64 allows a bearing of the inner platform 62 of the blade 38 on three sides of the blade 38, an upstream bearing on the extended upstream radial wall 56 and two lateral bearings in the circumferential direction C on the inter-cavity walls 70. The radial bearing surface 64 also allows ensuring that there is a space E between the walls of the cell 44 and the blade root 48 so that the cooling air flow V may circulate in the cell 44. It is understood that the radial bearing surface 64 is carried by the extended upstream wall 56 and the inter-cavity walls 70.
(45) In the embodiment of FIGS. 2 to 7, the extended upstream radial wall 56 includes an upstream spoiler 72 integral with the disc 36, particularly with the extended upstream radial wall 56. It is understood that the upstream radial wall 54, including the extended upstream radial wall 56, the upstream spoiler 72 and the disc 36 are made in one piece, that is to say that these elements are not assembled with each other after manufacturing the various elements.
(46) In the embodiment of FIGS. 2 to 7, the upstream radial wall 54 has a stepped shape, a first section of the upstream radial wall 54 and a second section of the upstream radial wall 54 being connected by an intermediate section extending in the continuation of the upstream spoiler 72. It is understood that the first and the second section are not in a same radial plane. However, this embodiment is a non-limiting example.
(47) In the embodiment of FIGS. 2 to 7, each cell 44 is connected to an upstream surface 74 of the disc 36 by a ventilation channel 76 of the cell 44. Each ventilation channel 76 includes an inlet orifice 78 which opens onto the upstream surface 74 of the disc 36 and an outlet orifice 80 which opens into the cell 44.
(48) As shown in FIG. 3, in an axial cross-sectional plane, that is to say including the main axis A, the ventilation channel 76 has an inclination relative to the radial direction R. Thus, the axis of the ventilation channel 76 has an angle α with the radial direction R. It is understood that in a radial plane, that is to say a plane perpendicular to the main axis A, the inlet orifice 78 and the outlet orifice 80 are not aligned. Considering that the ventilation channel 76 has the general shape of a circular cylinder, it is understood that the center of the inlet orifice 78 and the outlet orifice 80 are not included in the same radial plane. Thus, when the ventilation channel 76 has the general shape of a circular cylinder and according to the orientation of the axis of the ventilation channel 76 and of the planes including the inlet orifice 78 and the outlet orifice 80, it is understood that these orifices may have a shape between the circle (surface perpendicular to the axis of the ventilation channel 76) and the ellipse (surface not perpendicular to the axis of the ventilation channel 76).
(49) In the embodiment of FIGS. 2 to 7, each cell 44 is cooled by a cooling air flow V coming from upstream of the disc 36. The cooling air flow V enters the ventilation channel 76 through the inlet orifice 78 disposed on the upstream surface 74 of the disc 36, traverses the ventilation channel 76 and penetrates in the cell 44 through the outlet orifice 80 of the ventilation channel 76. The cooling air flow V passes through the cell 44 and exits downstream from the disc 36. The cooling air flow V is then channeled between the disc 36 and the movable ring 42, particularly between the connecting shroud 46 of the disc 36 and the movable ring 42 and then passes through a ventilation orifice 82 of the movable ring 42.
(50) It will be noted that in the embodiment of FIGS. 2 to 7, the inner platform 62 of the blade 38 includes a downstream spoiler 84 and that the blade 38 is devoid of a downstream holding hook. In a sectional view in a radial plane, the blade root 48 has a general bulb shape with a wider portion towards the inner end of the blade 38 and a portion whose width decreases towards the blade shank 60.
(51) For example, the disc 36 may be produced by additive manufacturing, particularly by an additive manufacturing method on a powder bed. The disc 36 may also be produced by conventional machining, for example by milling.
(52) Assembling the assembly 34 according to the first embodiment will be described with reference to FIGS. 3, 4, 6 and 7.
(53) As shown in FIG. 4, each blade root 48 is coated with a foil 50.
(54) As shown in FIG. 6, the blades 38 are assembled on the disc 36 by axial insertion of the blade root 48 in the cell 44 and the blade shank 60 in the cavity 58 until the blade 38 comes into contact with the axial stop surface 66 of the disc 36. When the blade 38 is inserted into the disc 36, the blade 38, particularly the inner platform 62 of the blade 38, rests on the radial bearing surface 64 of the disc 36.
(55) As shown in FIGS. 6 and 7, the damping elements 68 are then inserted into the cavity 58 on both sides of the blade shank 60.
(56) Assembling the blades 38 on the disc 36 may be done by inserting all the blades 38 on the disc 36 and by inserting the damping elements 68, once all the blades 38 inserted or the damping elements 68 may be inserted into a cavity 58 before proceeding to the insertion of the next blade. It may also be considered that an operator inserts the blades 38 and that another operator inserts the damping elements 68, both operations taking place on the same workstation, so that the blades 38 are inserted one after the other by one operator and the damping elements 68 are inserted one after the other by another operator, both operators not working on the same cavity 58.
(57) The movable ring 42 including the downstream retaining ring 40 is then attached on a downstream face of the disc 36 in order to axially block the blades 38 in the disc 36, particularly in the cell 44 and the cavity 58. The disc 36 of the rotor is assembled to the movable ring 42, for example by means of a plurality of bolts disposed in a circumferential direction C in axial orifices carried by the downstream connecting shroud 46 the disc 36 and by the movable ring 42.
(58) Thus, the assembly 34 of FIG. 3 is obtained.
(59) In what follows, the elements common to the various embodiments are identified by the same reference numerals.
(60) FIGS. 8 to 17 show a second embodiment of the assembly 34.
(61) In the embodiment of FIGS. 8 to 17, some elements are included partly in the disc 36 and partly in the crown 86. The elements included in the disc are identified by the letter “A” and the elements included in the crown are identified by the letter “B”. As shown in FIG. 12, the crown 86 includes a plurality of teeth 52B of the crown 86, two adjacent teeth 52B partially delimiting the cell 44, the crown 86 includes a plurality of ventilation channels 76B of the crown 86, each ventilation channel 76B of the crown 86 including an outlet orifice 80 which opens into a cell 44 and a plurality of inter-cavity walls 70B of the crown 86. Similarly, the disc 36 includes a plurality of ventilation channels 76A of the disc 36, each ventilation channel 76A of the disc 36 including an inlet orifice 78 which opens onto the upstream surface 74 of the disc 36, a plurality of inter-cavity walls 70A of the disc 36, each inter-cavity wall 70A of the disc 36 being prolonged radially inwards by a disc 36 tooth wall 52A, as in particular shown in FIGS. 11A and 11B.
(62) It is understood that the crown 86 and the disc 36 are two separate elements.
(63) When the crown 86 is assembled with the disc 36, the teeth 52B of the crown 86 cooperate with the disc 36 tooth walls 52A to form the teeth 52. Similarly, the inter-cavity wall 70A of the disc 36 cooperates with the inter-cavity wall 70B of the crown 86 to form an inter-cavity wall 70. Similarly, the ventilation channel 76 is formed by the ventilation channel 70A of the disc 36, a space E2 present between the disc 36 and the crown 86 and the ventilation channel 70B of the crown 86.
(64) In the embodiment of FIGS. 8 to 17, the disc 36 includes the downstream spoiler 84. Thus, the blade 38 is devoid of an upstream spoiler 72 and downstream spoiler 84.
(65) In the embodiment of FIGS. 8 to 17, the radial bearing surface 64 allows a bearing of the inner platform 62 of the blade 38 on four sides of the blade 38, an upstream bearing, a downstream bearing and two lateral bearings in the circumferential direction C. The radial bearing surface 64 also allows ensuring that there is a space E1 between the walls of the cell 44 and the blade root 48 so that the cooling air flow V may circulate in the cell 44.
(66) It will also be noted that in the embodiment of FIGS. 8 to 17, the axial stop surface 66 is carried by the portion of the upstream radial wall 54 which is not the extended upstream radial wall 56.
(67) In the embodiment of FIGS. 8 to 17, the downstream retaining ring 40 and the movable ring 42 are two separate elements. The downstream retaining ring 40 includes a plurality of ventilation orifices 92 and the movable ring 42 is devoid of a ventilation orifice.
(68) Assembling the assembly 34 according to the second embodiment will be described with reference to FIGS. 8 to 17.
(69) As shown in FIG. 10, each blade root 48 is coated with a foil 50.
(70) As shown in FIG. 13, the blades 38 are assembled on the disc 36 by radial insertion of the blade root 48 into the cavity 58 until the blade 38 comes into contact with the axial stop surface 66 of the disc 36. When the blade 38 is inserted into the disc 36, the blade 38, particularly the inner platform 62 of the blade 38, rests on the radial bearing surface 64 of the disc 36.
(71) As shown in FIGS. 14 and 15, once all the blades 38 inserted, the crown 86 is put in place.
(72) As shown in FIG. 16, the damping elements 68 are then inserted into each cavity 58 on both sides of the blade shank 60.
(73) As shown in FIG. 17, the downstream retaining ring 40 is then attached on a downstream face of the disc 36 in order to axially block the blades 38 in the disc 36, particularly in the cell 44 and the cavity 58. The downstream retaining ring 40 may for example be shrink-fitted onto the external periphery 94 thereof. The downstream retaining ring 40 may also be shrink-fitted onto the external and internal periphery thereof.
(74) As shown in FIG. 17, the movable ring is attached on the downstream retaining ring 40 and the disc 36 of the rotor is assembled to the movable ring 42, for example by means of a plurality of bolts disposed in a circumferential direction C in orifices carried by the downstream connecting shroud 46 of the disc 36 and by the movable ring 42.
(75) Thus, the assembly 34 of FIG. 17 is obtained.
(76) The third embodiment is similar to the first embodiment. It differs therefrom in that the radial bearing surface 64 is prolonged to the cavity 58 by a sealing bearing surface 100 of a seal 98 carried by a blade 38.
(77) In the embodiment of FIGS. 18-20, the sealing bearing surface 100 is carried by the extended upstream wall 56 and the inter-cavity walls 70.
(78) Particularly, in the embodiment of FIGS. 18-20, by a projection in the circumferential direction C of the external radial end of the inter-cavity walls 70.
(79) In the embodiment of FIGS. 18-20, the seal 100 has a “U” shape and is received in a seal receiving groove 96, the groove 96 being carried by the blade 38. The seal 98 being received in the seal receiving groove 96, the position of the seal 98 is determined by the groove 96 and the seal 98 is blocked in the groove 96.
(80) It is understood that the seal 98 may be integrated into the second embodiment.
(81) Although the present disclosure has been described with reference to specific exemplary embodiments, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. For example, the inlet orifice may not be aligned in a direction parallel to the main axis A with the outlet orifice; the cell may not open into a blade shank receiving cavity, that is to say that the upstream radial wall may not be prolonged to the inner platform of the blade; an inlet orifice of the ventilation channel may be common to several ventilation channels, that is to say that an inlet orifice may be in fluid communication with several outlet orifices and therefore with several cells; the blade may include a downstream hook for holding a downstream ring for retaining a blade in the cell; the ventilation channel may not have the shape of a circular cylinder; the ventilation channel may not have the shape of a cylinder of revolution.
(82) Furthermore, individual characteristics of the various mentioned embodiments may be combined in additional embodiments. Consequently, the description and the drawings are to be regarded in an illustrative rather than restrictive sense.
