FR3057016A1 - METHOD FOR DESIGNING ROTOR MEMBER AND IMPROVED ROTOR ORGAN - Google Patents

Abstract

The invention relates to a method of designing a new rotor member (12) from the design of a reference member (13), wherein each of the new rotor member (14) and the reference (13) comprises an annular web (14, 15) which is centered on a main axis A of said new member (12) or said reference member (13) and which extends in a radial plane with respect to said main axis A and said new member (12) or said reference member (13) has a plurality of orifices (28) made in the fabric (14, 15), which are evenly distributed around the main axis A, characterized in that the method comprises: a first step of determining the axial thickness of the web (14) of the new member (12) with respect to the axial thickness of the web (15) of the reference member (13) which consists in increasing the thickness of the fabric (14) of the new member (12) relative to the axial thickness of the fabric (15). ) of the reference member (13) of a predetermined thickness value, a production step, on a part of one and / or the other of an upstream face (14a) or a downstream face (14b) of the web (14) of the new member (12), a recess (36) which has a bottom located axially, with respect to said main axis A, set back from said upstream face (14a) and / or said associated downstream face (14b). The invention also relates to a rotor member obtained at the end of this process.

Description

DESCRIPTION

TECHNICAL AREA

The invention relates to a method for designing a turbomachine rotor member which is intended to improve the distribution of stresses in the fabric of the member.

The invention also relates to an organ obtained from this process.

PRIOR STATE OF THE ART

An aircraft turbomachine, in particular the parts of the high pressure compressor or of the low pressure turbine of the turbomachine, comprise a plurality of rotor members such as rotor disks, which each extend generally in radial planes with respect to to the main axis of the turbomachine and which are joined to one another.

According to one embodiment, the joining of the members, or of the discs, with one another is effected by bolting an annular flange coming from a member of the rotor onto the fabric of another member of the rotor.

The fabric of the other member therefore has a plurality of holes allowing the passage of screws for bolting.

During the operation of the turbomachine, stresses are exerted on the fabric of the member and these stresses are greater at the level of the orifices formed in the drilled fabric.

In particular, the lifetime of the fabric of the member, at the level of the holes depends on the stress undergone by each drilling, which is oriented tangentially with respect to the main axis of the rotor, of the stress undergone by each drilling, which is oriented radially with respect to the main axis of the rotor and the stress undergone by each drilling, which is oriented in the axial direction, that is to say parallel to the main axis of the rotor.

The tangentially oriented stress is mainly caused by the speed of rotation. The radial stress can be, for example, caused by the rim-bore thermal gradient, a tilting of the part or the architecture of the part.

The object of the invention is to propose a method for designing a rotor member which consists in modifying an existing rotor member, for which the values of the tangential and radial stresses are known.

STATEMENT OF THE INVENTION

The invention provides a method of designing a new rotor member based on the design of a reference member, in which each of the new rotor member and the reference member comprises an annular fabric which is centered on a main axis A of said new member or of said reference member and which extends in a radial plane relative to said main axis A and said new member or said reference member comprises a plurality of orifices made in the fabric, which are regularly distributed around the main axis A, characterized in that the method comprises:

a first step of determining the axial thickness of the fabric of the new member with respect to the axial thickness of the fabric of the reference member which consists in increasing the thickness of the fabric of the new member with respect to the axial thickness of the fabric of the reference member with a predefined excess thickness value, a stage of production, on part of one and / or the other of an upstream face or of a downstream face of the fabric of the new member, a recess which has a bottom located axially, with respect to said main axis A, set back with respect to said upstream face and / or said associated downstream face.

The combination of an increase in the thickness of the fabric with the production of a recess on a part of each upstream or downstream face of the fabric, makes it possible to modify the distribution of the stresses in the fabric, at the orifices of the canvas.

The tangential and radial stresses thus reduced, which consequently increases the life of the organ.

Preferably, the production step consists in producing a recess on a part of the upstream face and / or on a part of the downstream face, each recess being distinct from a plurality of annular parts of said upstream face or of said face. associated downstream, each annular part of which surrounds one of the orifices of the fabric.

Preferably, the determination step consists in increasing the axial thickness of the fabric only at the level of a plurality of annular parts, each annular part of which surrounds one of the orifices of the fabric.

Preferably, the production step consists in producing a recess on a part of the upstream face and / or on a part of the downstream face, which is distinct from the annular parts of said upstream face or of said associated downstream face, surrounding the canvas holes.

Preferably, that the ratio between the value of the additional thickness is between 0% and 50% of the thickness of the fabric of the reference member and the value of the additional thickness is preferably equal to 1.5 millimeters .

Preferably, the depth of the recess produced in one and / or the other of the upstream face and of the downstream face is between 120% and 180% of the value of the additional thickness at each of the upstream face and of the downstream face.

The invention also provides a rotor member designed using a method according to the invention, which comprises an annular fabric which is centered on a main axis A of said member and a radially central hub and located at the internal radial end of the fabric and which extends in a radial plane with respect to said main axis A and which comprises a plurality of orifices which are produced in the fabric and which are distributed regularly around the main axis A, characterized in that the fabric has an upstream face and a downstream face in at least one of which a recess is produced.

Preferably, each of the upstream face and the downstream face of the fabric and the depth of the recess which is produced on the upstream face is different from the depth of the recess produced on the downstream face.

Preferably, the depth of the indentation made in the upstream face is 1.2 millimeters and the depth of the indentation made in the downstream face is 1.3 millimeters.

Preferably, each recess extends over a part of the upstream face and / or over a part of the downstream face, the rest of said upstream face and / or the rest of the downstream face protruding axially relative to the bottom of the recess associated therewith and being produced in a plurality of parts, each part of which is associated with an orifice and encircles each orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended figures among which:

Figure 1 is a schematic representation in section along an axial plane of a bladed part of a turbomachine comprising at least one rotor member produced according to the invention;

Figure 2 is a schematic representation on a larger scale of a portion of a rotor member such as one of the members shown in Figure 1, showing the angular sectors for defining the radial and tangential stresses;

Figure 3 is a sectional view of a reference member used for the design of the new rotor member according to the method;

Figure 4 is a sectional view of an intermediate element obtained at the end of the first step of the method;

Figure 5 is a schematic perspective representation of the rotor member obtained at the end of the method according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

In the description which follows, the direction from upstream to downstream will be used as being the direction of flow of the gases in the turbomachine and which is here the orientation from left to right in FIG. 1.

FIG. 1 shows a part of a turbomachine rotor which carries the moving blades of a component of the turbine. This part, also called bladed part, is, for example, that of a low pressure turbine of a turbomachine and it comprises in particular several rotor members 12 each of which corresponds to one stage of the turbine 10. It will be understood that the invention is not limited to the rotor members of the low pressure turbine 10 and that the description of the invention which follows may relate to any other bladed part of the rotor of the turbomachine, which belongs for example to the high pressure turbine, the compressor low pressure or the high pressure compressor.

Each rotor member 12 is coaxial with the main axis A of the turbomachine and it comprises an annular radial fabric 14, a hub 16 radially central and located at the internal radial end of the fabric 14 and a rim 18 located at the external radial end of the canvas 4.

In the embodiment shown in the figures, the rim 18 of the rotor member 12 is shaped to support the blades 20 of the stage of the turbine 10, it has for this purpose a plurality of grooves which are formed in its edge peripheral, and which receive feet from the blades 20.

All the members 12 of the part 10 of the rotor, which is here the low pressure turbine 10, are integral with each other in rotation about the main axis A of the turbomachine.

For this, certain members 12 comprise an annular flange 24 which extends axially in the direction of an adjacent member 12. The free axial end of the flange 24 consists of an annular flange 26 which is fixed to the fabric 14 of the adjacent member.

According to the embodiment shown in Figure 1, with reference to an order of the organs 12 going from upstream to downstream, which will be the axial orientation going from left to right, the first member 12, c 'is to say that which is located most left, has a flange 24 extending axially downstream to the second member; the second member 12 comprises a flange 24 extending axially downstream to the third member 12 and the fourth member 12 comprises a flange 24 extending axially upstream to the third member 12.

The third member 12 does not have a flange 24 and receives two flanges 26 located axially on either side of this third member 12.

It will be understood that the invention is not limited to this distribution of the flanges 24 and that any variant may be concerned with the present invention.

In the description which follows, reference will be made to one of the members 12 on which the flange 26 of a flange 24 is mounted, that is to say here one of the second or third member 12.

The attachment of each flange 26 with the fabric 14 which is associated with it is carried out by bolting, that is to say by a plurality of sets of screws 32 and nuts 34 which tighten the flange (s) 26 on the fabric 14. The fabric 14 comprises for this purpose a plurality of orifices 28 passing through the fabric 14 and which are arranged to be aligned with associated orifices 30 formed in the flanges 26.

In the case, here, of the third member 12, on which the flange 26 from the second member 12 and the flange 26 from the fourth member 12 are fixed, each orifice 28 of the fabric 14 is aligned with an orifice 30 of the flange 26 coming from the second member 12 and with an orifice 30 of the flange 26 coming from the fourth member

12.

Each flange 26 of the first, second or fourth member 12 is in contact with an upstream face 14a or a downstream face 14b of the fabric 14 of the second or third member 12.

Each of the upstream face 14a or the downstream face 14b extends in a radial plane relative to the main axis A of the member 12, that is to say a plane perpendicular to the main axis A of organ 12.

Each flange 26 has a radial face which comes into contact and is clamped against the upstream face 14a or against the downstream face 14b of the fabric 14 by the bolts 32, 34.

During the operation of the turbomachine, the speed of rotation of the rotor and the high temperature prevailing in the turbomachine create stresses in the fabric 14 which are in particular concentrated at the level of the orifices 28.

These constraints each comprise three components oriented tangentially, radially or axially, relative to the main axis 1 of the rotor.

Referring to FIG. 2, for each orifice 28 of the fabric 14, four angular sectors are defined centered on the center of the orifice 28.

These angular sectors obtained by the intersection of two straight lines B perpendicular to each other and inclined at 45 degrees relative to a radial straight line relative to the main axis of the rotor passing through the center of the orifice 28.

In the description which follows, for each orifice 28, the tangential stresses are defined as being the stresses in the wall of the orifice 28 which are located in the two angular sectors opposite to each other and including the radial straight line defined above. The radial stresses are also defined as the stresses in the wall of the orifice 28 which are located in the other two angular sectors. Finally, the axial stresses are defined as being the stresses in the wall of the orifice 28 which are oriented parallel to the main axis A of the rotor.

The purpose of the method according to the invention is to design an improved rotor member from an existing rotor member.

FIG. 3 shows a reference rotor member 13 which is intended to be improved by the method which will be described later. In the following description, this rotor member 13 will be called the reference member

This reference member 13 comprises a fabric 15 which has a predefined axial dimension, or thickness, the upstream face 15a and the downstream face 15b each extending in a radial plane relative to the main axis A of the rotor 10 and each of which upstream face 15a and downstream face 15b is planar.

According to a first step of the method, a first modification of the fabric 15 of the reference member 13 is carried out, by modifying the thickness of the fabric

15.

According to this first step, the thickness of the fabric of the new member is determined, by adding a predefined value of fabric thickness to the thickness of the fabric 15 of the reference member 13.

Thus, as can be seen in FIG. 4, the intermediate product obtained at the end of this first step comprises a fabric 14 whose thickness is greater than the thickness of the fabric 15 of the reference member 13.

At the end of this first step, the other characteristics of the fabric 15 are unchanged, in particular the characteristic that the upstream face 14a and the downstream face 14b of the fabric 14 of the intermediate product are flat.

Preferably, the value of the total excess thickness of the fabric is between 0% and 50% of the thickness of the fabric 15 of the reference member 13. According to an exemplary embodiment, the value of the total excess thickness of the fabric is equal to 21% of the thickness of the fabric 15 of the reference member, or 1.6 millimeters when the thickness of the reference fabric is 7.2 millimeters.

This increase in the thickness of the fabric has the consequence that the value of the radial stress decreases sharply and that the value of the tangential stress decreases less significantly.

On the other hand, this modification of the thickness of the fabric 14 has, as a consequence, a modification of the connection radius 60 between the external radial end of the fabric 14 and the rim 18 of the member 12.

In this case, due to the increase in the thickness of the fabric 14, the stresses at this connection radius are increased and therefore the lifetime of the member is reduced compared to the member of reference 13.

Also, the increase in the thickness of the fabric 14 increases the amount of material necessary to produce the member 12, which therefore increases the mass and the production cost of the member 12.

To solve these problems, the method comprises a second step consisting in producing a recess 36 on each of the upstream face 14a and of the downstream face 14b of the intermediate part.

This recess 36 consists of a removal of material which extends over a part of the upstream face 14a and over a part of the downstream face 14b.

According to an alternative embodiment, the recess is produced on only one of the upstream face 14a or of the downstream face 14b of the fabric 14.

By making such a recess 36, the value of the tangential stress in each orifice 28 decreases sharply compared to the tangential stress obtained at the end of the first step. On the other hand, the value of the radial stress in each orifice 28 decreases slightly compared to the value of the radial stress obtained at the end of the first step.

Thus, the value of the total stress at each orifice 28, calculated according to the Von Mises criterion, decreases at the end of the first step and it also decreases at the end of the second step.

As a result, the life in the fabric 14 is increased by the method according to the invention.

The parts of the upstream face 14a and / or the part of the downstream face 14b on which there is no removal of material, that is to say the zones in which the recess does not extend are at least situated around the orifices 28.

Preferably, each of these remaining parts 62 of the upstream face 14a and / or of the downstream face 14b is associated with an orifice 28. Each part 62 is also of annular shape and is coaxial with the orifice 28 which is associated with it .

An exemplary embodiment shown in FIG. 5 shows that the recess 36 extends over the whole of the upstream face 14a and of the downstream face 14b of the fabric with the exception only of these annular parts 62.

It will be understood that the invention is not limited to this embodiment shown in Figure 5 and that another part of each of the upstream face 14a and / or the downstream face 14b of the fabric 14 may not include the recess, in addition to the annular parts 62 mentioned above.

The bottom 38 of the recess 36 which is produced on the upstream face 14a is thus located axially set back downstream relative to the upstream face 14a.

Similarly, the bottom of the recess 36 which is produced on the downstream face 14b is located axially set back upstream relative to the downstream face 14b.

Preferably, the depth of the recess 36 produced on the upstream face 14a of the fabric 14 is different from the depth of the recess 36 produced in the downstream face 14b of the fabric 14 when each of the upstream face 14a and the downstream face 14b of the fabric 14 has a recess 36.

According to an alternative embodiment, the depth of the recess 36 produced on the upstream face 14a of the fabric 14 is equal to the depth of the recess 36 produced in the downstream face 14b of the fabric 14

In addition, the depth of each recess 36 is preferably greater than the value of the additional thickness at each upstream or downstream face of the fabric.

According to a preferred embodiment, the depth of each recess is between 120% and 180% of the value of the additional thickness at each of the upstream 14a or downstream 14b faces of the fabric 14.

Referring to the example described above, for which the value of the total excess thickness of the fabric 14 relative to the thickness of the fabric 15 of the reference member 13 is 1.6 millimeters, the value of the extra thickness at each face 14a, 14b of the fabric 14 is 0.8 millimeters.

According to this example, the depth of the recess 36 produced in the upstream face 14a is here 150% of the value of the additional thickness, that is to say 1.2 millimeters and the depth of the recess produced in the downstream face 14b is 163% of the value of the extra thickness, ie 1.3 millimeter.

The difference in depth of the recess 36 produced on the upstream face 14a relative to the recess 36 produced on the downstream face 14b of the fabric 14 makes it possible to modify the axial distribution of the stresses so that they are located substantially at the axial center of the fabric 14.

According to an alternative embodiment of the method, the first step consists in increasing the thickness of the fabric on the upstream face 14a and on the downstream face 14b only at the level of the annular parts surrounding the orifices and the second step consists in making a recess on the rest of the upstream face 14a and on the rest of the downstream face 14b.

The depth of this recess 36 is defined to obtain an axial offset between the bottom of the recess 36 and the free axial end of each annular part, equal to the value of the depth of the recess 36 which has been described above, in relation to the first embodiment of the method.

That is to say that there is an axial offset of 1.2 millimeters at the upstream face 14a and 1.3 millimeters at the downstream face 14b.

The rotor member obtained at the end of a process according to one or other of the two variants which have just been described previously comprises, as can be seen in FIG. 5, an annular fabric 14 in which holes 28 are made.

This fabric 14 has an upstream face 14a and a downstream face 14b which are oriented respectively upstream and downstream, along the main axis A of the member 12.

According to a preferred embodiment, each of the upstream face 14a and the downstream face 14b has a recess 36 produced in only part of the surface of said face.

The depth of the recess 36 produced in the upstream face 14a is preferably equal to 1.2 millimeters and the depth of the recess produced in the downstream face 14b is preferably equal to 1.3 millimeters.

According to an alternative embodiment, only one of the upstream face 14a or of the downstream face 14b has a recess 36.

Each recess 36 extends over only part of the upstream face 14a or of the downstream face 14b, respectively, and the part of the upstream face 14a or of the downstream face 14b over which the recess 36 does not extend is associated with each of the orifices 28 of the fabric 14.

Thus, the rest of the upstream face 14a and / or of the downstream face 14b is in several parts 62, each part 62 of which is associated with an orifice 28 in the canvas4.

Each part 62 is coaxial with the hole 28 which is associated with it and is crossed by it. The part 62 is therefore of annular main shape.

Each part 62 of the upstream face 14a projects axially upstream relative to the bottom of the recess produced in the upstream face 14a and each part 62 of the downstream face 14b projects axially downstream relative to the bottom of the recess produced in the downstream face 14b.

Compared to a reference member 13, the axial distance between the parts 62 of the upstream face 14a and the parts 62 of the downstream face 14b of the fabric is greater than the axial thickness of the fabric 15 of the reference member , the value of the additional thickness corresponding to the difference between these two dimensions is equal to a predefined value which is here between 0% and 50% of the thickness of the fabric 15 of the reference member 13.

Thus, according to the example of embodiment mentioned above, with reference to the method for producing the member 12, the value of the additional thickness is equal to 21% of the thickness of the fabric 15 of the reference member, ie 1 , 6 millimeter when the thickness of the reference fabric is 7.2 millimeters.

In addition, the axial distance between each part 62 of the upstream face 14a and / or of the downstream face 14b and the bottom of the recess 36 produced in the associated face 14a, 14b is preferably between 120% and 180% of the value of the additional thickness at the level of said upstream face 14a or downstream 14b of the fabric 14.

Referring to the example described above, for which the value of the additional thickness is 1.6 millimeters, the value of the additional thickness at each face 14a, 14b of the fabric 14 is 0.8 millimeters.

According to this example, the axial distance between each part 62 of the upstream face 14a and the bottom of the associated recess 36 is here 150% of the value of the additional thickness, that is to say 1.2 millimeters, and the axial distance between each part 62 of the downstream face 14b and the bottom of the associated recess 36 is 163% of the value of the additional thickness, or 1.3 millimeters.

Despite the fact that the general thickness of the fabric 14 of the member 12 is greater than the thickness of the reference member 13, the total mass of the member 12 is slightly greater than the mass of the member reference, thanks to the presence of the recess (s).

Indeed, the sum of the depths of the recesses 36 made on the two faces 14a, 14b of the fabric 14 is greater than the excess thickness of the fabric 14 relative to the fabric 15 of the reference member. This greatly limits the addition of material to the canvas.

In the description of the process which has been made, as well as of the member 12 obtained from this process, reference is made to a recess 36 produced in each of the two faces 14a, 14b of the fabric 14. And that the additional thickness is distributed over these same two faces 14a, 14b of the fabric 14.

It will be understood that the invention is not limited to this embodiment, and that the additional thickness can also be formed on a single face 14a, 14b of the fabric.

Likewise, independently of the distribution of the additional thickness on one and / or the other of the two faces 14a, 14b of the fabric 14, the second step may consider in making a recess on one of the two faces 14a, 14b of the canvas, or on both sides.

The member 12 thus obtained thus comprising a single recess produced on a single face 14a, 14b, or else recesses 36 produced on each of the two faces 14a, 14b of the fabric 14.

Claims (10)

1. Method for designing a new rotor member (12) from the design of a reference member (13), in which each of the new rotor member (12) and the reference member (13 ) comprises an annular fabric (14,15) which is centered on a main axis A of said new member (12) or of said reference member (13) and which extends in a radial plane relative to said main axis A and said new member (12) or said reference member (13) comprises a plurality of orifices (28) made in the fabric (14, 15), which are distributed regularly around the main axis A, characterized in that the method includes: a first step of determining the axial thickness of the fabric (14) of the new member (12) relative to the axial thickness of the fabric (15) of the reference member (13) which consists in increasing the thickness of the fabric (14) of the new member (12) with respect to the axial thickness of the fabric (15) of the reference member (13) by a predefined excess thickness value, a step of realization, on a part of one and / or the other of an upstream face (14a) or of a downstream face (14b) of the fabric (14) of the new member (12), of a recess (36) which comprises a bottom located axially, with respect to said main axis A, set back with respect to said upstream face (14a) and / or said associated downstream face (14b). 2. Method according to claim 1, characterized in that the production step consists in producing a recess (36) on a part of the upstream face (14a) and / or on a part of the downstream face (14b), each recess being distinct from a plurality of annular parts (62) of said upstream face (14a) or of said associated downstream face (14b), each annular part (62) surrounding one of the orifices (28) of the fabric (14) . 3. Method according to the preceding claim, characterized in that the determining step consists in increasing the axial thickness of the fabric (14) only at the level of a plurality of annular parts (62) each annular part of which surrounds one of the holes (28) of the fabric (14). 4. Method according to the preceding claim, characterized in that the production step consists in producing a recess (36) on a part of the upstream face (14a) and / or on a part of the downstream face (14b), which is distinct from the annular parts (62) of said upstream face (14a) or of said associated downstream face (14b), surrounding the orifices (28) of the fabric (14). 5. Method according to the preceding claim, characterized in that the value of the additional thickness is between 0% and 50% of the thickness of the fabric (15) of the reference member (13) and the value of the additional thickness is preferably equal to 1.6 millimeters. 6. Method according to the preceding claim, characterized in that the depth of the recess (36) produced in one and / or the other of the upstream face (14a) and of the downstream face (14b) is between 120% and 180% of the value of the additional thickness at each of the upstream face (14a) and the downstream face (14b). 7. rotor member (12) designed from a method according to any one of the preceding claims, which comprises an annular cloth (14) which is centered on a main axis A of said member (12) and a hub (16 ) radially central and located at the internal radial end of the fabric (14) and which extends in a radial plane relative to said main axis A and which comprises a plurality of orifices (28) which are made in the fabric ( 14) and which are distributed regularly around the main axis A, characterized in that the fabric (14) has an upstream face (14a) and a downstream face (14b) in at least one of which a recess (36) is realised. 8. rotor member (12) according to the preceding claim, characterized in that each of the upstream face (14a) and the downstream face (14b) of the fabric (14) has a recess (36) and in that the depth of the recess (36) which is produced on the upstream face (14a) is different from the depth of the recess (36) produced on the downstream face (14b). 9. rotor member (12) according to claim 7 or 8, characterized in that the depth of the recess (36) produced in the upstream face (14a) is 1.2 millimeters and the depth of the recess (36) produced in the downstream face (14b) is 1.3 millimeter. 10. rotor member (12) according to any one of claims 7 to 10 9, characterized in that each recess (36) extends over a part of the upstream face (14a) and / or over a part of the downstream face (14b), the rest of said upstream face (14a) and / or the rest of the downstream face (14b) projecting axially relative to the bottom of the recess (36) associated therewith and being produced in a plurality of parts each part of which is associated with an orifice (28) and encircles each orifice ( 28). S. 59717 1/3 < ι O I