EP4134523A2 - Blade base receptacle for receiving a blade - Google Patents

Abstract

The present invention relates to a blade root mount (20) for receiving a blade root (21) of a moving blade (4.2) of a turbomachine (1), which blade root mount (20) has a supporting flank (25) for radially form-fitting contact with the blade root (21), which faces at least partially radially inwards in relation to an axis of rotation (2), the supporting flank (25) being provided with a bulge (40) which, viewed in a perpendicular section, has an at least partially convex shape (41), and also in a section parallel to the axis has an at least partially convex shape (51).

Description

technical field

The present invention relates to a blade root receptacle for receiving a blade root of a rotating blade of a turbomachine.

State of the art

A turbomachine is functionally divided into compressor, combustion chamber and turbine, whereby in the case of an aircraft engine, intake air is compressed in the compressor and burned in the downstream combustion chamber with added kerosene. The resulting hot gas, a mixture of combustion gas and air, flows through the downstream turbine and is expanded in the process. As a rule, the turbine and the compressor are each constructed in multiple stages, with each stage comprising a ring of guide vanes and a rotor blade ring. Each blade ring is made up of a plurality of peripherally consecutive blades around which the compressor gas or the hot gas flows, depending on the application.

In this case, a rotor blade ring can have, for example, a rotor disk on which the rotor blades are successively mounted circumferentially in a form-fitting manner. For this purpose, the rotor disk can be provided with a blade root receptacle at different circulation positions, namely an axially extending profile groove. A blade root can be inserted into each profile groove, the outer wall surface of which then forms a form fit with the flanks of the blade root receptacle that delimit the profile groove. Because of this profiling, the rotor blade is held in a form-fitting manner in the radial direction, in particular against the centrifugal forces during operation.

Presentation of the invention

The present invention is based on the technical problem of specifying a particularly advantageous blade root receptacle.

• in einem achssenkrechten Schnitt betrachtet eine zumindest abschnittsweise konvexe Form hat, und auch
• in einem achsparallelen Schnitt betrachtet eine zumindest abschnittsweise konvexe Form hat.

According to the invention, this is achieved with the blade root receptacle according to claim 1 . In this case, at least one bearing flank, against which the blade root is pressed during operation, is provided with a bulge that

• has a shape that is at least partially convex when viewed in a perpendicular section, and also
• viewed in a section parallel to the axis, has a shape that is at least partially convex.

The bulge or convex shape is not only related to the circumferential or radial extension of the supporting flank (perpendicular section), but also in terms of its longitudinal extension, ie in the axial direction (paraxial section). This convexity or crowning, which is formed in two directions, can e.g. B. be advantageous in terms of structural mechanics, for example, as a result, enable a more uniform load transfer between the blade root and the supporting flank. Compared to a plan supporting flank, in which z. B. can result in different contact areas due to production, can with the convex training z. B. a reproducible contact surface can be created.

In some configurations, smaller tolerances can only be provided locally in the area of the bulges and/or the influence of deviations outside of the bulges can be reduced.

Preferred refinements of the invention can be found in the dependent claims and in the entire disclosure, with the description of the features not always making a distinction in detail between aspects of the device and aspects of the method or use; at least implicitly, the disclosure is to be read with regard to all categories of claims. Furthermore, it is always aimed at both the blade root mount itself and a blade arrangement with a corresponding blade root mount and a moving blade, as well as a rotor disk with a plurality of blade root mounts.

The terms "axial", "radial" and "circumferential", as well as the associated directions (axial direction, etc.), refer to the axis of rotation around which the blade root receptacle with the rotor blade, and in particular the disk or the rotor blade ring, rotate during operation . This typically coincides with a longitudinal axis of the turbomachine, ie for example the aircraft engine. The perpendicular section is perpendicular to the axis of rotation; the axially parallel sectional plane is parallel thereto, and it can in particular be perpendicular to the supporting flank.

The bearing flank is "facing radially inwards at least in part", so a surface normal on the bearing flank has at least one radial component directed inwards. Depending on the specific configuration, it can also have a circulation component, ie lie at an angle. Viewed in the perpendicular section, the support flank can extend, for example, between a concave curved section, which leads radially inward into a radially inner free flank or the groove base, and a convex curvature, which leads into a radially outer free flank or, for example, the disk circumference. Overall, the blade root receptacle can form a so-called fir tree profile, for example, but this is only one possibility.

Regardless of these details, the blade root, in particular a bulge thereof that is essentially complementary to the blade root receptacle, is pressed against the support flank during operation. Overall, the blade root receptacle can also have more than one bearing flank, for example a further bearing flank offset in the direction of rotation and/or one or more bearing flanks radially inside or outside. Overall, more than one bearing flank can then also be formed with a bulge; a corresponding design of all bearing flanks of the blade root receptacle or only a subset thereof is possible. In general, "a" and "an" are to be read in the context of this disclosure as indefinite articles and thus always as "at least one" or "at least one", so there can also be several configurations, for example in the supporting flank or a respective supporting flank give, see below in detail.

In general, the convex curvature can also extend axially over the entire support flank. In a preferred embodiment, it goes in the paraxial Viewed in section, however, in the direction of a first axial end of the supporting flank into a concave profile, ie the profile between the first end and the convex curvature is concave at least in sections. The transition from the convex to the concave profile can be spaced, for example, by at least 5% of an axial length of the support flank from the first axial end, with further possible lower limits of, for example, at least 10% or 15% (and theoretical upper limits of 70% , 50% or 30%). A certain distance between the convex shape and the (first) axial end of the supporting flank can be advantageous in terms of structural mechanics, for example.

In a preferred embodiment, the support flank runs straight into the first end, adjoining the concave profile in the direction of the first axial end, viewed in the axially parallel section. The straight section can in particular lie parallel to the axis. In general, the “first end” can be located axially in front or axially behind in relation to the arrangement in the turbomachine, ie upstream or downstream.

According to a preferred embodiment, the convex shape, viewed in the axially parallel section, also transitions into a concave profile in the direction of a second axial end, which is axially opposite to the first, ie a concave profile adjoins the convex shape axially on both sides. Depending on the position of the bulge, the concave profile can also be followed by a straight line in the direction of the second axial end, which runs into the second end of the supporting flank, in particular parallel to the axis (alternatively, however, another bulge can also follow, see below in detail).

A further preferred embodiment relates to the profile of the support flank in the section perpendicular to the axis, namely in this section the convex shape changes into a concave profile, preferably on both sides. The latter means that in relation to a width direction of the supporting flank, in which its width is taken in the axially perpendicular section (and which, depending on the orientation of the supporting flank, has a circumferential and possibly a radial component), on both sides a concave course to the convex shape connects. In terms of the width orientation, the concave course can be followed by a rectilinear course, to one or to both sides.

In a preferred embodiment, a further bulge is formed in the supporting flank, that is to say there are a total of at least two bulges in the supporting flank. The further bulge can also have a convex shape when viewed both in a section perpendicular to the axis and in a section parallel to the axis. In a preferred embodiment, the (first) and the further bulge are offset from one another in the axial direction; alternatively or additionally, they can be offset from one another in the width direction of the supporting flank. In the latter case, they can be offset with a rotating component and, depending on the orientation of the support flank (see above), with a radial component.

In general, a large number of bulges can also be formed in the supporting flank, with possible upper limits being, for example, at most 30, 20 or 10 bulges, but in principle an even larger number is also possible. According to a preferred embodiment, however, exactly three bulges are provided in the supporting flank, which together form a reproducible abutment for the associated surface or flank of the blade root. The three bulges are therefore preferably offset in the bearing flank in such a way that they define a plane with one another (that is to say they do not lie on a common straight line).

In some configurations, the number of bulges on one or each supporting flank of the blade root receptacle is in the range from 1 to 10 per supporting flank, preferably 2 to 7 per supporting flank, in particular 3 to 4 per supporting flank.

In some configurations, the bulge (40), in particular each of the bulges, has a profile with a continuously differentiable course in each section perpendicular to the support flank through the bulge. In other words, the progression in these configurations is soft and free of jags, cracks and/or edges. This enables a defined, to a certain extent areal and stress-technically particularly advantageous system.

In some configurations, the ratio H/D of the height H of the bulge to the smallest transverse dimension D of the bulge within the support flank is in the range of 1:2 to 1:500, in particular for each of the bulges 1:10 to 1:200 or 1:100 to 1:500. This enables a particularly advantageous system in terms of voltage.

The invention also relates to a blade arrangement with a blade root receptacle disclosed in the present case and a moving blade, the blade root of which is arranged in the blade root receptacle. The blade root lies against the support flank, during operation it is pressed against it by centrifugal force.

Furthermore, the invention relates to a rotor disk for a rotor blade ring of a turbomachine, in particular an aircraft engine. The rotor disk, which can have a ring shape overall, for example, has a plurality of blade root receptacles distributed circumferentially, each of which is preferably designed with a supporting flank according to the present disclosure.

Furthermore, the invention relates to a method for producing a blade root receptacle disclosed in the present case or the blade arrangement or rotor disk, the support flank being machined from a solid material by removing material. This is preferably done by electrochemical removal (Electro Chemical Machining , ECM), with which the desired surface contour can be achieved particularly well.

Brief description of the drawings

The invention is explained in more detail below using an exemplary embodiment, with the individual features within the framework of the independent claims also being able to be essential to the invention in a different combination and no distinction being made in detail between the different claim categories.

Figur 1

eine Strömungsmaschine, nämlich ein Mantelstromtriebwerk in einem Axi-alschnitt;

Figur 2

eine Schaufelfußaufnahme in einer schematischen Axialansicht;

Figur 3

eine Tragflanke der Schaufelfußaufnahme gemäß Figur 2 in einem achssenrechten Schnitt;

Figur 4

die Tragflanke gemäß Figur 3 in einem achsparallelen Schnitt;

Figur 5

eine alternativ gestaltete Tragflanke in einer schematischen Aufsicht.

In detail shows

figure 1

a turbomachine, namely a turbofan engine in an axial section;

figure 2

a blade root recording in a schematic axial view;

figure 3

a supporting flank of the blade root recording according to figure 2 in an axial section;

figure 4

the bearing flank according to figure 3 in an axially parallel section;

figure 5

an alternatively designed support flank in a schematic plan view.

Preferred embodiment of the invention

figure 1 shows a turbomachine 1, specifically a turbofan engine, in an axial section. The turbomachine 1 is functionally divided into a compressor 1a, a combustion chamber 1b and a turbine 1c. Both the compressor 1a and the turbine 1c are each constructed of multiple stages. Each of the stages consists of a vane ring and a rotor blade ring. For the sake of clarity, for the turbine 1c only one of the stages of the guide blade ring 3 and the associated rotor blade ring 4 are referenced with reference symbols. The intake air is compressed in the compressor 1a and then burned in the downstream combustion chamber 1b with added kerosene. The hot gas flows through the hot gas duct and drives the moving blade rings, which rotate about the axis of rotation 2 . The rotor blade ring 4 comprises a rotor disk 4.1, in which a plurality of rotor blades 4.2 are used, distributed circumferentially.

figure 2 shows a section of the running disk 4.1 in an axial view, ie looking at it along the axis of rotation 2. A blade root receptacle 20 is provided in the running disk 4.1, which is introduced in the form of a profiled groove which penetrates the running disk 4.1 axially. A blade root 21 , indicated here only schematically, of the respective rotor blade 4 . In operation, it is pressed against bearing flanks 25 of the blade root receptacle, one of which is referenced here with a reference number and will be discussed in further detail.

The supporting flank 25 extends between a convex curvature section 26 and a concave curvature section 27, as shown in FIG figure 2 is to recognize their width 28. Perpendicular thereto, ie in the axial direction 32, the supporting flank 25 has its longitudinal extension. In the present case, it is oriented in such a way that it partially runs in the radial direction 22 and also in the circumferential direction 33 .

figure 3 shows the supporting flank 25 in a detailed view, namely in a section perpendicular to the axial direction 32 . This reveals a bulge 40 which has a convex shape 41 . The convex shape 41 merges into a concave profile 42 on both sides.

figure 4 shows the bulge 40 in a sectional plane perpendicular thereto, namely an axis-parallel section AA (cf figure 2 to the position of the cutting plane). The bulge 40 also has a convex shape 51 in this section, which in the present example transitions first into a concave profile 52 and then into a straight line 53 both in the direction of a first axial end 61 and in the direction of a second axial end 62 . In relation to an axial length 55 of the support flank 25, a transition 56 between convex/concave extension is about 30% away from the first axial end 61 in this example (which applies in mirror image to the other transition and the second axial end 62).

figure 5 shows a supporting flank 25 in a schematic top view, in which, in addition to the (first) bulge 40, a further bulge 70 is provided, which is offset axially and also circumferentially or radially with respect to the first bulge 40. A total of three bulges 71 are provided in the support flank 25, which together form a defined contact surface. <b>REFERENCE LIST</b> flow machine 1 compressor 1a combustion chamber 1b turbine 1c axis of rotation/longitudinal axis 2 vane ring 3 blade ring 4 running disc 4.1 Multiple blades 4.2 blade root mount 20 blade root 21 radial direction 22 supporting flanks 25 Convex curvature section 26 Concave curvature section 27 width 28 axial direction 32 direction of circulation 33 First bulge 40 convex shape 41 Axis-parallel cut aa convex shape 51 concave profile 52 Straight course 53 axial length 55 crossing 56 First axial end 61 Second axial end 62 More bulge 70 Three bulges 71

Claims (15)

Blade root receptacle (20) for receiving a blade root (21) of a moving blade (4.2) of a turbomachine (1), which blade root receptacle (20) has a support flank (25) for radially form-fitting contact with the blade root (21), which faces at least partially radially inwards in relation to an axis of rotation (2), wherein the support flank (25) is provided with a bulge (40) which - has a shape (41) that is at least partially convex when viewed in a perpendicular section, and also - Viewed in a section parallel to the axis, has a shape (51) that is convex at least in sections. Blade root receptacle (20) according to Claim 1, in which, viewed in the axially parallel section, the convex shape (51) changes into a concave profile (52) in the direction of a first axial end (61) of the supporting flank (25). Blade root receptacle (20) according to Claim 2, in which, viewed in the axially parallel section, a transition (56) between the convex shape (51) and the concave profile (52) by at least 5% of an axial length (55) of the supporting flank (25) of the first axial end (61) is spaced. Blade root receptacle (20) according to Claim 3, in which, viewed in the axially parallel section, the supporting flank (25) runs straight into the first end (61). Blade root receptacle (20) according to one of Claims 2 to 4, in which, viewed in the axially parallel section, the convex shape (51) also changes in the direction of a second axial end (62) of the support flank (25) opposite the first (61) into a concave Profile (52) transitions. Blade root receptacle (20) according to one of the preceding claims, in which, viewed in the perpendicular section, the convex shape (41) changes into a concave profile (42). Blade root receptacle (20) according to one of the preceding claims, in which a further bulge (40) is additionally formed in the supporting flank (25) or a plurality of further bulges (40) are formed. Blade root receptacle (20) according to one of the preceding claims, in which the, in particular each of the bulges (40) has a profile with a continuously differentiable course in each section perpendicular to the bearing flank through the bulge. Blade root receptacle (20) according to one of the preceding claims, in which for the, in particular for each of the bulges (40), the ratio H/D of height H to the smallest transverse dimension D is in the range from 1:2 to 1:500, in particular 1:10 to 1:200 or 1:100 to 1:500. Blade root receptacle (20) according to one of Claims 7 to 9, in which the bulges (40, 70) are offset axially with respect to one another. Blade root receptacle (20) according to one of Claims 7 to 10, in which the bulges (40, 70) are offset with respect to one another with a radial and/or a rotating component. Blade root receptacle (20) according to one of Claims 7 to 11, in which a total of three bulges (71) are formed in the supporting flank (25). Blade arrangement with a blade root mount (20) according to one of the preceding claims and moving blade (4.2), the blade root (21) of which is arranged in the blade root mount (20) and bears against the support flank (25). Rotor disk (4.1) for a rotor blade ring (4) of a turbomachine (1), with a plurality of blade root receptacles (20) according to one of Claims 1 to 12. Method for producing a blade root mount (20) according to one of Claims 1 to 12, a blade arrangement according to Claim 13 or a running disk (4.1) according to Claim 14, in which at least the supporting flank (25) of the blade root mount (20) is electrochemically removed from a solid material is worked out.

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