DISC FOR AN AIRCRAFT TURBOMACHINE TURBINE

Abstract

The invention relates to a disk (14) for an aircraft turbomachine turbine (6, 7), the disk (14) comprising an annular body (18) having a longitudinal axis (X) and regularly distributed cells (19) on an outer periphery (18a) of the annular body (18), each cell (19) being intended to receive a foot (16) of a blade (15), the cells (19) being divided into a first series (S1) of cells (19) and a second series (S2) of cells (19), characterized in that the cells (19) of the first series (S1) have a first predetermined cross-section (s1'), and the cells (19) of the second series (S2) have a second predetermined cross-section (s2') which is different from the first cross-section (s1'). Abstract figure: Figure 6

Description

Title of the invention: DISC FOR AN AIRCRAFT TURBOMACHINE TURBINE Technical field of the invention

[0001] The invention relates to the field of discs for aircraft turbomachine turbines. The invention relates in particular to the field of discs comprising cells for high pressure or low pressure aircraft turbomachine turbines.

[0002] The invention also relates to the field of manufacturing methods for these discs, in particular manufacturing methods comprising a step of machining the cells. Technical background

[0003] An aircraft turbomachine, such as a turbojet, is annular and has a longitudinal axis. Such a turbomachine typically comprises, from upstream to downstream in the direction of gas flow along the longitudinal axis, a fan movable in rotation about the longitudinal axis, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and a gas exhaust nozzle.

[0004] The blower allows the suction of an air flow dividing into a primary flow and a secondary flow. The primary flow passes through a primary vein of the turbomachine while the secondary flow is directed towards a secondary vein surrounding the primary vein.

[0005] The primary flow is compressed within the compressors. The compressed air is then mixed with a fuel and burned within the combustion chamber. The gases resulting from the combustion pass through the turbines and then escape through the nozzle, the cross-section of which allows the acceleration of these gases to generate propulsion.

[0006] Each turbine and each compressor includes a rotor. The rotor of the low pressure turbine is typically connected to the rotor of the low pressure compressor by a low pressure shaft. The rotor of the high pressure turbine is connected to the rotor of the high pressure compressor by a high pressure shaft.

[0007] Each rotor may comprise at least one disc comprising an annular body centered on the longitudinal axis and cells regularly distributed on an external periphery of the body.

[0008] Each rotor further comprises blades extending radially from the disk. Each blade comprises a blade and a root connected to the blade. The root of each blade is received in a corresponding cell in order to hold the blade on the disk.

[0009] The turbines, and in particular the high pressure turbine, being located downstream of the combustion chamber, reside in a hot environment generated by the gases from combustion. The discs, and in particular the cells, as well as the blade roots, are exposed to high temperatures since they are located closest to the primary vein.

[0010] In this context, it has been proposed to equip the turbomachines with a cooling system comprising a ventilation circuit. The ventilation circuit makes it possible to cool the turbine disks, in particular the low-pressure turbine, in order to maintain a temperature of the disks below a certain threshold. The ventilation circuit typically comprises a flow of ventilation air taken from the high-pressure compressor and circulating to the turbine disks, in particular the low-pressure turbine. This flow of ventilation air then circulates in ventilation air passages delimited by the cells and the feet that they receive. The cells of the disk are then cooled.

[0011] Document FR-A1-2918104 describes a low-pressure turbine comprising a rotor rotatable about a longitudinal axis of the low-pressure turbine. The rotor comprises a disc comprising an annular body, a first fixing flange and blades extending radially outwards from the disc. The annular body comprises cells each receiving a blade root for fixing the blades to the disc. A ventilation air passage is provided between each cell and the blade root which it receives.

[0012] According to this document, the rotor further comprises a movable ring integral in rotation with the disc. The movable ring comprises a downstream radial end bearing against an upstream radial face of the disc and a second fixing flange connected to the first fixing flange of the disc by bolting.

[0013] According to this document, the first and second fixing flanges delimit between them an air cavity opening into the cells of the disc. Thus, the ventilation circuit typically comprises a flow of ventilation air taken from the high pressure compressor and circulating to the air passages via the air cavity.

[0014] According to this solution, the ventilation circuit is therefore calibrated by the air cavities defined between the ring and the disc. In other words, the air flow in the alveoli is imposed by the air cavities.

[0015] Although this solution guarantees an adequate air flow for cooling the discs, it is dependent on the movable ring which is heavy, bulky and imposes significant mechanical constraints.

[0016] Furthermore, the air cavities are necessary for calibrating the air flow rate of the ventilation circuit because the air flow rate cannot be calibrated directly by the air passages.

[0017] Indeed, to ensure effective cooling of the cells and therefore of the disc, the disc must have a total ventilation section corresponding to a predetermined target value. The total ventilation section corresponds to the sum of the sections of the air passages.

[0018] Nevertheless, a major technical difficulty is to provide a disc having a total ventilation section corresponding to the predetermined target value. Indeed, the cells of the discs are typically produced by machining the annular body.

[0019] Machining can be carried out by broaching or milling. However, the broaching or milling devices wear out quickly and no longer guarantee the tolerances necessary to achieve the predetermined passage sections for each cell in order to achieve the target total ventilation section. It is therefore necessary to change the broaching or milling devices several times to form cells each having the predetermined passage section. Such a machining method is therefore particularly expensive and unthinkable on an industrial scale.

[0020] Furthermore, the machining of the cells can be carried out by electroerosion, also known by the acronym EDM for "Electrical Discharge Machining". Such a process allows very precise machining of the cells and therefore guarantees the predetermined passage section of each cell. However, the machining of a cell by this process is very long and the manufacture of the disc is therefore particularly long. Typically, the manufacture of a cell by the broaching process is four times faster than by the electroerosion process. Such a machining process is therefore also particularly expensive and unthinkable on an industrial scale.

[0021] In this context, there is a need to provide a disk for an aircraft turbomachine turbine, comprising an annular body and cells arranged on an external periphery of the body, which can be cooled by a precisely calibrated ventilation circuit, while being light, compact and simple to integrate, and achievable on an industrial scale. Summary of the invention

[0022] To this end, the invention proposes a disc for an aircraft turbomachine turbine, the disc comprising an annular body having a longitudinal axis and cells regularly distributed over an external periphery of the annular body, each cell being intended to receive a root of a blade, the cells being distributed into a first series of cells and a second series of cells.

[0023] The disc according to the invention is remarkable in that the cells of the first series have a first predetermined cross-section, and the cells of the second series have a second predetermined cross-section which is different from the first cross-section.

[0024] According to the invention, the air flow rate of the ventilation circuit of the turbomachine is calibrated directly by a total ventilation section of the disc corresponding to a target value. The target value of the total ventilation section corresponds to a value predetermined area considered sufficient to effectively cool the disc. The total ventilation section corresponds to the sum of the ventilation air passage sections defined between the root of a blade and the corresponding cell.

[0025] Thanks to such a calibration system, it is possible to do away with calibration by the air cavities of the prior art which are defined between a movable ring and the disk. Thus, thanks to such a system, it is possible to do away with the movable ring of the prior art and therefore to lighten the weight of the turbines, to reduce their size and to simplify their configuration.

[0026] According to the invention, the disc therefore comprises two series of cells which are distinguished by their cross sections.

[0027] The first cross-section of the first series of cells is different from the second cross-section of the second series of cells.

[0028] It is thus understood that, when the blades are mounted in the cells of the disc, the first air passages defined between the cells of the first series and the corresponding blade roots have a first ventilation section lower or higher than the ventilation section defined by the second air passages defined between the cells of the second series and the corresponding blade roots.

[0029] The second series of cells therefore constitutes adjustment cells with which the total ventilation section is adjusted to reach the target total ventilation section.

[0030] Thanks to the invention, it is therefore possible to machine, for example, the first series of cells by broaching or milling without changing the broaching or milling devices. The first series of cells then has an actual total ventilation section that is smaller than the target total ventilation section. Then, the second series of cells can be machined by electroerosion, for example, very precisely in order to reach the target total ventilation section.

[0031] The invention therefore makes it possible to precisely calibrate the ventilation circuit of the turbo-machines directly via the cells for cooling the turbine discs, while guaranteeing the speed of the disc manufacturing process.

[0032] According to the present invention, by "different" it is understood that the first cross-section is different from the second cross-section with respect to the fixed nominal values. Indeed, the nominal value of the cross-section of the cells differs from the actual measured value in that the manufacturing processes of the cells result in geometric deviations in a given range of values ​​with respect to the nominal value. This range of values ​​is called tolerance. In the present invention, manufacturing tolerances are not taken into account in the comparison of the cross-section of the cells. Thus, two cross-sections having an identical nominal value but a deviation in the tolerance range of manufacturing must be considered identical.

[0033] Generally, the manufacturing tolerance of the cells is less than 1%.

[0034] According to the present invention, the difference between the cross-sections is greater at 1%.

[0035] The invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

[0036] - the first cross-section of the first series of cells is lower or higher superior to the second cross-section of the second series of cells,

[0037] - the difference between the second and first cross sections is greater than 1%, between 5% and 50%, preferably between 10% and 30%, even more preferably between 10% and 20%,

[0038] - the cells of the second series are separated from each other by at least one cell of the first series,

[0039] - the cells of the second series are regularly distributed on the annular body,

[0040] - the second series comprises at least two cells, advantageously at least three alveoli and even more advantageously between three alveoli and five alveoli,

[0041] - each cell of the first and second series has a general tail shape dovetailed or fir, and comprises a base and two lateral flanks extending radially from the base to the outer periphery of the annular body,

[0042] - the first series of cells is made by broaching or milling and the second series of alveoli is carried out by electroerosion.

[0043] The invention also relates to a turbine for an aircraft turbomachine, comprising:

[0044] - a disc according to any one of the preceding characteristics,

[0045] - blades extending radially from the disc and each comprising a blade and a foot connected to the blade, each cell receiving the foot of one of the blades, each cell of the first series defining respectively with the foot that it receives a first ventilation air passage having a first predetermined passage section, and each cell of the second series defining respectively with the foot that it receives a second ventilation air passage having a second predetermined passage section and different from the first passage section, the sum of the first and second passage sections defining a total ventilation section of the disc corresponding to a target value.

[0046] The invention also relates to a turbomachine for an aircraft, comprising from upstream to downstream, a compressor, a combustion chamber, and a turbine according to the preceding characteristics, the turbomachine further comprising a ventilation circuit configured to convey air from the compressor to the first and second ventilation air passages of the cells of the disk according to a flow rate calibrated by the total ventilation section.

[0047] The invention also relates to a method of manufacturing a disk for an aircraft turbomachine turbine, the method comprising the following steps:

[0048] (a) providing an annular body having a longitudinal axis,

[0049] (b) machining dimples in the annular body, the dimples being regularly distributed over an external periphery of the annular body and each intended to receive a foot of a blade, the cells being distributed into a first series of cells and a second series of cells.

[0050] The method is remarkable in that step (b) comprises the following chronological sub-steps:

[0051] (bO) machining the first series of cells, each cell of the first series having a first predetermined cross-section,

[0052] (bl) determining a real total ventilation section of the cells of the first series, the real total ventilation section being the sum of first passage sections of the cells of the first series, the first passage section being the section of a first ventilation air passage delimited respectively by a cell of the first series and the foot which it is intended to receive,

[0053] (b2) comparing the actual total ventilation section to a total ventilation section disk target,

[0054] (b4) machining the second series of cells, each cell of the second series having a second predetermined cross-section different from the first cross-section so as to achieve a total ventilation section of the disc corresponding to the target total ventilation section, the total ventilation section corresponding to the sum of the actual total ventilation section of the alveoli of the first series and the actual total ventilation section of the alveoli of the second series.

[0055] The method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0056] - sub-step (b4) is carried out by electro-erosion,

[0057] - sub-step (bO) is carried out by broaching or milling,

[0058] - sub-step (bl) comprises the following steps:

[0059] (b 10) measuring by probing with a three-dimensional measuring machine the first passage section of each cell of the first series (SI), and

[0060] (bl 1) deduce the actual total ventilation section of the cells of the first series,

[0061] - sub-step (b4) is carried out by rectification of a plurality of cells of the first series so as to form the second series of alveoli,

[0062] - sub-step (b4) is carried out by machining new cells in the body annular so as to form the second series of alveoli,

[0063] - step (b) further comprises the following sub-steps:

[0064] (b5) determine the actual total ventilation section of the second series of cells,

[0065] (b6) calculate the total ventilation section of the disc,

[0066] - the method comprises between sub-steps (b2) and (b4), the following sub-step:

[0067] (b3) calculating a recovery passage section, the recovery passage section being the difference between the target total ventilation section and the actual total ventilation section measured in step (bl), and calculate the distribution of the return passage section per cell of the second series. Brief description of the figures

[0068] Other characteristics and advantages will emerge from the following description of non-limiting embodiments of the invention with reference to the appended drawings in which:

[0069] [Fig.l] is a schematic representation in longitudinal section of a half-aircraft turbomachine according to the invention,

[0070] [Fig.2] is a partial schematic representation in longitudinal section of a turbine according to the invention,

[0071] [Fig.3] is a partial schematic representation in cross-section of the disc according to the invention equipping the turbine of [Fig.2],

[0072] [Fig.4] is a schematic cross-sectional representation of a first embodiment of a cell of the disc of [Fig.3], in which a blade root is mounted,

[0073] [Fig.5] is a schematic cross-sectional representation of a second embodiment of a cell of the disc of [Fig.3], in which a blade root is mounted,

[0074] [Fig.6] is a schematic cross-sectional representation of a cell of the first series and a cell of the second series,

[0075] [Fig.7] is a block diagram of the method of the invention. Detailed description of the invention

[0076] An example of an aircraft turbomachine 1 according to the invention is shown in [Fig.l]. The turbomachine 1 extends around and along a longitudinal axis X.

[0077] In the present application, the terms “upstream” “downstream” are defined in relation to the direction of circulation of the gases in the turbomachine 1 along the longitudinal axis X.

[0078] The terms “axial”, “axially”, “radial”, “radially”, “internal”, “interior”, “external”, “exterior”, “externally”, are defined relative to the longitudinal axis X of the turbomachine 1.

[0079] In particular, the terms “internal”, “interior”, “external”, “exterior”, “externally” are defined in relation to the distance from the longitudinal axis X of the turbomachine 1, along a radial axis Z extending perpendicular to the longitudinal axis X.

[0080] The turbomachine 1 is for example a turbojet. The turbojet is for example a double-flow and double-spool turbojet.

[0081] According to the example of [Fig.l], the turbomachine 1 comprises from upstream to downstream, a fan 2, at least one compressor such as a low pressure compressor 3 and a high pressure compressor 4, a combustion chamber 5, at least one turbine such as a high pressure turbine 6 and a low pressure turbine 7, and a nozzle (not shown).

[0082] The blower 2 allows the suction of an air flow F dividing into a primary flow Fl and a secondary flow F2. The primary flow Fl passes through a primary vein 1a of the turbomachine 1 while the secondary flow F2 is directed towards a secondary vein 1b surrounding the primary vein 1a.

[0083] The primary flow F1 is compressed within the low pressure compressor 3 then the high pressure compressor 4. The compressed air is then mixed with a fuel and burned within the combustion chamber 5. The gases formed by the combustion pass through the high pressure 6 and low pressure 7 turbines. The gases finally escape through the nozzle, the cross-section of which allows the acceleration of these gases to generate propulsion.

[0084] The fan 2 is for example shrouded. It is surrounded by an annular casing 2b centered on the longitudinal axis X. The casing 2b is for example surrounded by a nacelle (not shown) of the turbomachine 1.

[0085] The low pressure turbine 7 comprises a rotor connected to a rotor of the low pressure compressor 3 by a low pressure shaft 8a. The high pressure turbine 6 comprises a rotor 9 connected to a rotor of the high pressure compressor 4 by a high pressure shaft 8b. The high pressure shaft 8b is arranged coaxially outside the low pressure shaft 8a.

[0086] With reference to [Fig.2], the rotor 9 of the high pressure turbine 6 comprises wheels 10a, 10b movable in rotation around the longitudinal axis X. Each wheel 10a, 10b is separated by a fixed distributor 11.

[0087] The distributor 11 comprises a fixed ring 12 and a plurality of fixed vanes 13 regularly distributed on the ring 12.

[0088] Each wheel 10a, 10b comprises a disc 14 rotatable about the longitudinal axis X and blades 15 rotatable about the longitudinal axis X and extending radially from the disc 14. The blades 15 are regularly distributed around the disc 14. Advantageously, the blades 15 are made of metallic material or of a composite material such as a ceramic matrix composite (CMC) material. Each blade 15 comprises a root 16 and a blade 17 connected to the root 16.

[0089] Each blade 17 has an aerodynamic shape and comprises a lower surface face and an upper surface face connected by a leading edge and a trailing edge. The blade 17 also extends between a head and the root 16.

[0090] The foot 16 has for example a dovetail shape illustrated for example in [Fig.4] or a fir tree shape illustrated for example in [Fig.5].

[0091] Advantageously, the disc 14 is made of an electrically conductive material, in particular a metallic material. The disc 14 comprises an annular body 18 centered on the longitudinal axis X and cells 19 regularly distributed on the annular body 18. The annular body 18 comprises an upstream face and a downstream face from which respectively an upstream flange 20a and a downstream flange 20b extend. The upstream flange 20a cooperates with the downstream flange 20b of the adjacent disc 14. The upstream and downstream flanges 20a, 20b are fixed together for example by bolting 21. Advantageously, the upstream flange 20a carries wipers 12a which cooperate with the ring 12 of the distributor 11 to form a labyrinth seal. Such a configuration makes it possible to ensure the sealing of the rotor 9.

[0092] As best seen in [Fig.3], the annular body 18 further has an external periphery 18a and an internal periphery 18b.

[0093] The cells 19 are distributed regularly on the external periphery 18a of the annular body 18. Each cell 19 opens onto the external periphery 18a of the annular body 18. Thus, each cell 19 receives the root 16 of a blade 15 to retain the blade 15 on the disc 14. The cell 19 and the root 16 cooperate for example by fitting. The cells 19 are separated from each other by bulbs 22.

[0094] Each cell 19 comprises in cross section a bottom 23 and two lateral flanks 24 extending radially from the bottom to the external periphery 18a of the annular body 18.

[0095] According to a first embodiment shown in [Fig.4], each cell 19 has a general dovetail shape in cross section. According to this first embodiment, the bottom 23 is extended radially by the two lateral flanks 24 in a first region 24a in which the two lateral flanks 24 are inclined towards each other and in a second region 24b in which they move away from each other from the first region 24a to the external periphery 18a of the annular body 18.

[0096] According to a second embodiment shown in [Fig. 5], each cell 19 has a general fir tree shape in cross section. According to this second embodiment, the bottom 23 is extended radially by the two lateral flanks 24 in a first region 24a in which the two lateral flanks 24 are inclined towards each other and in a second region 24b in which they move away from each other from the first region 24a and a third region 24c in which they come closer together. approach from the second region 24b to a fourth region 24d in which they move away from each other to the outer periphery 18a of the annular body 18.

[0097] Each foot 16 has a shape complementary to the corresponding cell 19. Furthermore, each bulb 22 has a counter-shape of the adjacent cells 19.

[0098] Furthermore, according to the invention, with reference to [Fig.6], the cells 19 of the disc 14 are divided into a first series S1 and a second series S2.

[0099] The second series S2 advantageously comprises at least two cells 19, at least three cells 19 and even more advantageously between three cells 19 and five cells 19. The rest of the cells 19 of the disc 14 forms the first series SL Advantageously, the number of cells 19 of the first series SI is greater than the number of cells 19 of the second series S2.

[0100] Each cell 19 of the first series SI has a first predetermined cross-section si' and each cell 19 of the second series S2 has a second predetermined cross-section s2' different from the first section si'.

[0101] The cross-section of a cell corresponds to the surface of the cell in a cutting plane perpendicular to the axis of the foot 16.

[0102] Each cell 19 of the first series S1 has a first predetermined cross-section si' and each cell 19 of the second series S2 has a second predetermined cross-section s2' greater or less than the first section si'.

[0103] Preferably, the difference between the second section s2' and the first section si' is greater than 1%, between 5% and 50%, preferably between 10% and 30%, even more preferably between 10% and 20%.

[0104] The first section si' of each cell 19 of the first series SI of a disc 14 is identical and the second section s2' of each cell 19 of the same disc 14 may be identical or different. By identical, it is understood that the cross sections have the same value to within tolerances.

[0105] Advantageously, each cell 19 of the first series S1 has a first radial dimension DR1 less than or greater than a second radial dimension DR2 of each cell 19 of the second series S2. The radial dimension DR1, DR2 is measured radially between the bottom 24 of the cell 19 and the external periphery 18a of the annular body 18 of the disc 14.

[0106] According to an example not shown, each cell 19 of the first series S1 has a first circumferential dimension less than or greater than a second circumferential dimension of each cell 19 of the second series S2. The circumferential dimension corresponds to the circumferential width of the bottom 23.

[0107] Advantageously, the cells 19 of the second series S2 are regularly distributed over the annular body 18. The cells 19 of the first and second series SI, S2 having sections si', s2' respectively distinct, an imbalance could be created in the disc 14. Such a characteristic therefore makes it possible to maintain the balance of the disc 14 and to limit the risks of imbalance.

[0108] Advantageously, the cells 19 of the second series S2 are separated from each other by at least one cell 19 of the first series S1. The cells 19 of the second S2 advantageously each having a second section s2' greater than the first section si' of the cells 19 of the first series S1, the dimension of the bulbs 22 located between two adjacent cells 22 of the second series S2 could be greatly reduced and degrade the mechanical strength of the disc 14. Indeed, the bulbs 22 are particularly mechanically stressed. Such a characteristic therefore makes it possible to maintain a dimension of the bulbs 22 sufficient to preserve the mechanical strength of the disc 14.

[0109] The discs 14 of the rotor 9, and in particular the feet 16 and the cells 19 being located downstream of the combustion chamber 5 and in the primary flow path 1a, they are subjected to high temperatures which can damage the discs 14. For this purpose, it is necessary to ensure the cooling of each disc 14.

[0110] For this purpose, each cell 19 of the first series S1 defines with the foot 16 a first ventilation air passage 25a and each cell 19 of the second series S2 defines with the foot 16 a second ventilation air passage 25b.

[0111] Each first passage 25a has a first passage section spl and each second passage 25b has a second passage section sp2 greater than or less than the first passage section spl. Indeed, the first section si' of the cells 19 of the first series SI being less than or greater than the second section s2' of the cells 19 of the second series S2, the first passage section spl is less than or greater than the second passage section sp2.

[0112] Furthermore, the disc 14 according to the invention has a total ventilation section St corresponding to a predetermined target value. This target value is predetermined according to the cooling requirements of the disc 14 in order to preserve the integrity of the disc 14. The total ventilation section St corresponds to the sum of the first and second passage sections spl, sp2.

[0113] In order to ensure the cooling of the disk 14 by circulation of cold air in the first and second passages 25a, 25b, with reference to [Fig.l], the turbomachine 1 further comprises a ventilation circuit 1e configured to convey air from the compressor 3, 4, in particular from the high-pressure compressor 4, to the first and second passages 25a, 25b.

[0114] According to the invention, the air flow rate of the ventilation circuit 1c is calibrated by the total ventilation section St.

[0115] A method of manufacturing the disc 14 will now be described with reference to [Fig.7].

[0116] The manufacturing process comprises the following steps:

[0117] (a) providing the annular body 18,

[0118] (b) machine the cells 19 in the annular body 18.

[0119] In step (a) the annular body 18 is devoid of cells 19.

[0120] According to the invention, step (b) comprises the following chronological sub-steps:

[0121] (b0) machining the first series SI of cells 19,

[0122] (bl) determining a real total ventilation section of the cells 19 of the first series SI, the real total ventilation section being the sum of the first passage sections spl of the cells 19 of the first series SI,

[0123] (b2) compare the actual total ventilation section to a total ventilation section disc target 14,

[0124] (b3) optionally, calculate a recovery passage section Sr, the section of return passage Sr being the difference between the target total ventilation section and the actual total ventilation section measured in step (bl), and calculate the distribution of the return passage section Sr per cell 19 of the second series S2,

[0125] (b4) machine the second series S2 of cells 19 so as to reach a section of ven total ventilation St of the disc 14 corresponding to the target total ventilation section, the total ventilation section St of the disc 14 corresponding to the sum of the total ventilation section of the second series S2 of alveoli 19 and the actual total ventilation section of the alveoli 19 of the first series SI,

[0126] (b5) determine a total ventilation section of the second series S2 of cells 19, And

[0127] (b6) calculate the total ventilation section St of the disc 14.

[0128] Advantageously, sub-step (b0) is carried out by broaching or milling. Such machining processes have the advantage of being rapid.

[0129] Advantageously, sub-step (bl) comprises the following sub-steps:

[0130] (blO) measuring by probing with a three-dimensional measuring machine (CMM) the first passage section spl, and

[0131] (bl 1) calculate the actual total ventilation section of the cells 19 of the first series SI.

[0132] According to a first embodiment, during step (bl0), the foot 16 is received in the cell 19. According to this embodiment, the cell 19 and the foot 16 are felt.

[0133] According to a second embodiment, during step (bl0), the foot 16 is not received in the cell 19. In this case, nominal dimensions of a foot 16 are taken as a reference to deduce the first passage section spl and only the cell 19 is felt.

[0134] Advantageously, during step (b3), the number of cells 19 of the second series S2 is predetermined.

[0135] Advantageously, sub-step (b4) is carried out by electro-erosion. Such a machining method has the advantage of allowing precise machining of the cells 19 with low manufacturing tolerances.

[0136] According to a first embodiment, in particular when the cross-section s2' of the cells 19 of the second series S2 is greater than the cross-section si' of the cells of the first series SI, the sub-step (b4) is carried out by grinding a plurality of cells 19 of the first series SI so as to form the second series S2 of cells 19.

[0137] According to a second embodiment, sub-step (b4) is carried out by machining new cells in the annular body 18 so as to form the second series S2 of cells 19.

[0138] According to a first example, the cells 19 of the first series S1 may have a first cross-section si' corresponding to the maximum tolerances. The cells 19 of the second series S2 will then have a second cross-section s2' smaller than the first cross-section si' to reach the target total ventilation section.

[0139] According to another example, the cells 19 of the first series S1 may have a first cross-section si' far from the maximum tolerances. The cells 19 of the second series S2 will then have a second cross-section s2' greater than the first cross-section si' to reach the target total ventilation section.

[0140] Sub-steps (b5) and (b6) are verification steps.

[0141] Advantageously, sub-step (b5) is carried out in the same way as sub-step (bl), namely:

[0142] - measure by probing with a coordinate measuring machine (CMM) the second passage section sp2, and

[0143] - calculate the actual total ventilation section of the cells 19 of the second series S2.

[0144] Thanks to the method of the invention, during sub-step (b6), the ventilation section total St of disc 14 is equal to the target value.

[0145] Thus, the invention makes it possible to dispense with a movable ring secured to the turbine rotor disc to calibrate the air in the ventilation circuit. The configuration of the turbine rotor is therefore simplified, the turbine rotor is lighter and less bulky.

[0146] Furthermore, thanks to the series combination of cells, advantageously produced by two separate machining processes, it is possible to achieve the total ventilation section St, and this quickly. The disc according to the invention can be produced on an industrial scale.

[0147] The invention has been described in relation to the low pressure turbine 6, but applies in the same way to the high pressure turbine 7.

Claims

Claims

1. Turbine (6, 7) for an aircraft turbomachine (1), comprising: - a disc (14) comprising an annular body (18) having a longitudinal axis (X) and cells (19) regularly distributed on an external periphery (18a) of the annular body (18), the cells (19) being distributed into a first series (S1) of cells (19) and a second series (S2) of cells (19), the cells (19) of the first series (S1) having a first predetermined cross-section (S1'), and the cells (19) of the second series (S2) having a second predetermined cross-section (S2') which is different from the first cross-section (S1'), - blades (15) extending radially from the disc (14) and each comprising a blade (17) and a root (16) connected to the blade (17), each cell (19) receiving the foot (16) of one of the blades (15),each cell (19) of the first series (SI) defining respectively with the foot (16) that it receives a first ventilation air passage (25a) having a first predetermined passage section (spl), and each cell (19) of the second series (S2) defining respectively with the foot (16) that it receives a second ventilation air passage (25b) having a second predetermined passage section (sp2) and different from the first passage section (sp2), the sum of the first and second passage sections (spl, sp2) defining a total ventilation section (St) of the disc (14) corresponding to a target value.,

2. Turbomachine (1) for an aircraft, comprising from upstream to downstream, a compressor (4), a combustion chamber (5), and a turbine (6, 7) according to the preceding claim, the turbomachine (1) further comprising a ventilation circuit (1e) configured to convey air from the compressor (4) to the first and second air passages (25a, 25b) for ventilation of the cells (19) of the disk (14) according to a flow rate calibrated by the total ventilation section (St).

3. A method of manufacturing a disc (14) for a turbine (6, 7) of an aircraft turbomachine (1), the method comprising the following steps: (a) providing an annular body (18) having a longitudinal axis (X), (b) machining cells (19) in the annular body (18), the cells (19) being regularly distributed over an external periphery (18a) of the annular body (18) and each being intended to receive a root (16) of a blade (15), the cells (19) being distributed in a first series (SI) of cells (19) and a second series (S2) of cells (19), the method being characterized in that step (b) comprises the following chronological sub-steps: (b0) machining the first series (SI) of cells (19), each cell (19) of the first series (SI) having a first predetermined cross-section (si'), (bl) determining an actual total ventilation section of the cells (19) of the first series (SI), the actual total ventilation section being the sum of first passage sections (spl) of the cells (19) of the first series (SI), the first passage section (spl) being the section of a first ventilation air passage (25a) delimited respectively by a cell (19) of the first series (SI) and the foot (16) which is intended to receive, (b2) comparing the actual total ventilation section with a target total ventilation section of the disc (14), (b4) machine the second series (S2) of cells (19),each cell (19) of the second series (S2) having a second predetermined cross-section (s2') different from the first cross-section (si') so as to achieve a total ventilation section (St) of the disc corresponding to the target total ventilation section, the total ventilation section (St) corresponding to the sum of the actual total ventilation section of the cells (19) of the first series (SI) and the actual total ventilation section of the cells (19) of the second series (S2).,

4. Method according to the preceding claim, characterized in that sub-step (b4) is carried out by electro-erosion.

5. Method according to any one of claims 3 to 4, characterized in that sub-step (b0) is carried out by broaching or milling.

6. Method according to any one of claims 3 to 5, characterized in that sub-step (bl) comprises the following steps: (b 10) measuring by probing with a three-dimensional measuring machine the first passage section (spl) of each cell (19) of the first series (SI), and (bl 1) deducing the actual total ventilation section of the cells (19) of the first series (SI).

7. Method according to any one of claims 3 to 6, characterized in that the sub-step (b4) is carried out by grinding a plurality of cells (19) of the first series (S1) so as to form the second series (S2) of cells (19).

8. Method according to any one of claims 3 to 6, characterized in that the sub-step (b4) is carried out by machining new cells (19) in the annular body (18) so as to form the second series (S2) of cells (19).

9. Method according to any one of claims 3 to 8, characterized in that step (b) further comprises the following sub-steps: (b5) determining the actual total ventilation section of the second series of cells, (b6) calculating the total ventilation section (St) of the disc (14).

10. Method according to any one of claims 3 to 9, characterized in that it comprises, between sub-steps (b2) and (b4), the following sub-step: (b3) calculating a return passage section (Sr), the return passage section (Sr) being the difference between the target total ventilation section and the actual total ventilation section measured in step (bl), and calculating the distribution of the return passage section (Sr) per cell (19) of the second series (S2).

Images