EP3236011B2 - Rotor with overhang on rotor blades for a securing element - Google Patents

Description

The invention relates to a rotor for an engine, in particular a gas turbine engine according to the preamble of claim 1.

The EP 2 873 807 A1 and EP 2 860 350 A1 disclose known rotors according to the preamble of claim 1.A generic rotor known, for example, from US 5,256,035 A known rotor has a rotor base part which has fastening slots for rotor blades arranged one behind the other along a circumferential direction around a rotation axis. The individual rotor blades are each held in a form-fitting manner in an associated fastening groove via a blade root. For axial securing with respect to the rotation axis, a one-part or multi-part securing element is provided which is held in a form-fitting manner on at least one of the rotor blades at a radially outer edge and in a form-fitting manner on the rotor base part at a radially inner edge.

In the US 5,256,035 For example, a multi-part securing element is provided which consists of several plate segments and a fastening ring. A radially inner edge of the individual plate segments is positively received in a groove in the rotor base part, so that a radially outwardly extending overhang of the rotor base part engages around the radially inner edge of the plate segments. The fastening ring is in turn received in a groove which is formed on a blade base of a rotor blade. A radially inwardly extending overhang of the blade base engages around the radially outer edge of the fastening ring, which also secures a plate segment which is arranged adjacent to and in the axial direction next to the fastening ring.

However, with regard to the individual overhangs of the multiple rotor blades connected to the rotor base part, undesirable turbulence can arise in the area of two adjacent overhangs during operation of the rotor, particularly in the case of a rapidly rotating and highly loaded rotor, such as that used in a gas turbine engine, for example in the high-pressure compressor or the high-pressure turbine. This can be seen from the Figures 5A , 5B , 5C and 5D which show a section of a rotor known from the prior art.

The rotor comprises a rotor base part in the form of a rotor disk 2 with a plurality of fastening grooves 20 spaced apart from one another along a circumferential direction U. A blade root 32 of a rotor blade 3a, 3b is accommodated in each fastening groove 20. Of the large number of rotor blades that are arranged one behind the other along the circumference of the rotor (for example 20 pieces), Figures 5A , 5B , 5C and 5D only two sections are shown in each case, looking along the rotation axis of the rotor. Each rotor blade 3a, 3b comprises a blade base 31, from which a blade 30 protrudes radially. The blade root 32 extends from the blade base 31 in a radially inward direction ri.

The blade base 31 of a rotor blade 3a or 3b forms an overhang 310 extending radially inwards, i.e. along the radial direction ri pointing towards them. A radially outer edge 43 of a securing plate 4 is encompassed by this overhang 310. Several (at least two) rotor blades 3a and 3b are secured in the axial direction to the rotor base part 2 in the area of the fastening grooves 20 via this securing plate 4. For this purpose, the securing plate 4 is connected not only to the rotor blades 3a and 3b, but also to the rotor base part 2. For a positive connection between the rotor base part 2 and the securing plate 4, a Figures 5A to 5C not shown projection of the rotor base part 2 a radially inner edge 42 of the securing plate 4. The longitudinally extended and circumferentially extending securing plate 4 is thus held both at its radially outer edge 43 and at its radially inner edge 42 and is received in a groove which is formed by a rotor blade 3a, 3b or the rotor base part 2.

As can be seen in particular from the Figure 5A As can be seen, a rotor blade 3a, 3b known from the prior art each forms an overhang 310 for enclosing the radially outer edge 43 of the securing plate 4, which is formed over a total length L along the circumferential direction U as a continuous straight or circular arc-shaped edge 311. Along the circumferential direction U, the respective overhangs 310 of adjacent edges 311 of a pair of rotor blades 3a and 3b arranged adjacent to one another should thus be aligned with one another, so that the radially inner lower edges of these edges 311 lie on a circular path around the axis of rotation M of the rotor.

However, in practice this is often not the case, as the Figures 5B and 5C Due to permissible tolerances, it can happen that the individual overhangs 310 of adjacent rotor blades 3a, 3b are radially offset from each other. Figures 5B and 5C show an example of an offset g of the two rotor blades 3a and 3b in the area of their overhangs 310. In the variant of the Figure 5B which offsets one (left) blade 3b radially inwards relative to the adjacent (right) blade 3a. In relation to a rotation axis of the rotor about the rotation axis M along the circumferential direction, the one overhang 310 of one blade 3b thus projects into an annular gap flow in the circumferential direction U (offset "into wind"). In the variant of the Figure 5C one (left) blade 3b is offset radially outwards from the other (right) blade 3a (out of wind offset). The edge 311 of the overhang 310 of one blade 3b is thus completely offset from the overhang 310 of the other rotor blade 3a is offset radially outwards.

An offset g that can be observed in practice for both cases is only in the range of 0.2 mm to 0.4 mm for a rotor. However, particularly in the case of fast-rotating rotors for a gas turbine engine, for example in the case of a rotor of a high-pressure turbine or a high-pressure sealer, undesirable turbulence can occur in the area of adjacent blade bases 31 and thus adjacent overhangs 310.

The invention is based on the object of improving a rotor in this respect.

This object is achieved with a rotor of claim 1.

According to the invention, a rotor with a specially designed overhang on at least one rotor blade that is positively connected to the rotor base part is proposed. The overhang has two first and second edge sections along its extension in the circumferential direction, each of which is provided at one end of the overhang in relation to the circumferential direction and is each set back in a radially outward direction relative to at least one further third edge section of the overhang that also encompasses the edge of the securing element, such that the blade root and a lower edge of the overhang can be pushed through the gap in the rotor base part if the securing element is not yet or no longer attached. Overhangs with edge sections that adjoin one another and are each set back radially outwards are provided on at least two rotor blades of the rotor that are arranged adjacent to one another along the circumferential direction. In this way, a radially outward-facing recess of a defined minimum length and minimum height is then formed in the area of the adjoining edge sections of two adjacent rotor blades. At the radial recess, an interruption of a circular path of the edges of the individual overhangs that follow one another along the circumferential direction is thus deliberately provided.

Consequently, the overhang of at least one rotor blade in a rotor according to the invention is withdrawn or set back at a lower edge of the overhang in a radially outward direction such that the overhang at a radially inner lower edge does not have a straight or circular arc-shaped course along the circumferential direction. This includes in particular the formation of an edge section with a radial offset to an adjacent edge section of the same overhang as well as the formation of an edge section whose radial extent decreases continuously in the circumferential direction and thus defines a region of the lower edge of the overhang that runs obliquely to the circumferential direction. Thus, for example, regions that are radially offset from one another and/or run at an angle to one another are formed on a radially inner lower edge of an overhang. A setback is thus defined from the outset, preferably in the region of adjacent overhangs. This can lead to minimizing or avoiding disruptive turbulence in the region of the securing element, particularly with appropriate dimensioning. Furthermore, this makes it possible to reduce weight and simplify the assembly and/or disassembly of a rotor blade. The latter can be achieved by the at least one recessed edge section being designed and arranged along the circumferential direction in such a way that at least part of the overhang can be pushed through the fastening groove in the axial direction when the securing element is not yet or no longer fixed to the rotor base part.

At least one of the first and second radially outwardly recessed edge sections can have a smaller extension in the radially inward direction than an adjacent edge section. The overhang therefore extends less radially inward in the region of the recessed edge section. In one embodiment, at least one of the first and second radially outwardly recessed edge sections is provided at an end of the overhang lying in the circumferential direction. In this way, a defined recess is provided via the recessed edge section in the region where two adjacent rotor blades adjoin one another with their blade bases.

In one embodiment, at least one of the first and second radially outwardly recessed edge sections forms a region on the radially inner lower edge of the overhang, which is at least partially inclined to the circumferential direction. The recessed edge section can therefore not only be designed to step back to an adjacent edge section of the overhang, but can also form a recess that continuously increases or decreases in size in the circumferential direction, at least in sections.

It has been shown that for certain applications and in particular speeds of the rotor, a certain minimum size for the radially outwardly directed recess of the edge section of a rotor blade overhang is advantageous in order to reduce turbulence. In this context, one embodiment provides that the at least one radially outwardly recessed edge section extends with a length along the circumferential direction of the rotor that corresponds to at least three times, in one variant at least four times, a height with which the radially outwardly recessed edge section is (at least) recessed relative to an adjacent edge section of the overhang. With a minimum height b, with which the at least one edge section is recessed radially outwards relative to an adjacent edge section of the overhang, i.e. radially in an outward direction, and a length a, with which the at least one recessed edge section extends along the circumferential direction, this consequently means that: a ≥ 3b.

Alternatively or additionally, the at least one edge section which is set back radially outwards is set back by at least a height of 0.5 mm, in particular by at least a height of 0.8 mm or 1 mm, relative to an adjacent edge section of the rotor blade overhang. A recess is thus formed in the recessed edge section which, when two adjacent rotor blades are nominally aligned, has a maximum depth of at least 0.5 mm, 0.8 mm or 1 mm.

In one variant, the overhang of a rotor blade of the rotor can have two edge sections, namely a first and a second edge section, which are each set back in a radially outward direction relative to at least one further third edge section of the overhang, which also encompasses the edge of the securing element. The first edge section and the second edge section are thus spatially separated from one another along the circumferential direction and spaced apart from one another, but are each set back radially outward relative to at least one third edge section of the rotor blade overhang.

The two recessed edge sections can be recessed to different degrees and/or extend along the circumferential direction with different lengths. The overhang of a rotor blade can thus be designed asymmetrically with respect to a radial direction. This enables, for example, a direction-of-rotation optimized design of a recess formed by two edge sections of two adjacent rotor blades that are adjacent to one another and each recessed radially outwards.

In particular with regard to such a variant, it can be provided that the first and second radially outwardly recessed edge sections of a rotor blade are provided at ends of the associated overhang (and a blade base of the associated rotor blade) that are spaced apart from one another along the circumferential direction. Along the circumference of the rotor, a second edge section of a (first) rotor blade overhang and a first edge section of another (second) rotor blade overhang thus adjoin one another in the case of adjacent rotor blades and adjacent blade bases.

In one variant, at least one of the first and second edge sections that are set back radially outwards is set back relative to the adjacent third edge section of the rotor blade overhang by at least the sum of the shape and position tolerances of this third edge section. A set-back first or second edge section thus forms a recess that, when two adjacent rotor blades are nominally aligned, has a maximum (radial) depth of at least the sum of the shape and position tolerances of the third edge section. The shape and position tolerances are used to specify a nominal position of the third edge section with respect to the associated fastening groove and/or with respect to an overhang of an adjacent rotor blade of the rotor.

A recess defined in the area of the blade bases of two adjacent rotor blades is, for example, elliptical, trapezoidal or triangular in a view along the axis of rotation.

Overhangs with adjacent edge sections that are each set back radially outwards can be provided on each pair of adjacent rotor blades along the circumferential direction of the rotor, so that a radially outward-facing recess of a defined minimum length and minimum height is formed along the circumferential direction in the area of adjacent edge sections of two adjacent rotor blades. In this variant, the formation of a recess is therefore not limited to individual pairs of rotor blades, but is provided throughout every area of two adjacent rotor blades.

At least one of the first and second radially outwardly recessed edge sections can be produced, for example, by mechanical material removal. This includes production by a machining manufacturing process, such as grinding or milling. In such a variant, material can therefore be removed in a targeted manner, for example ground off, from the overhang of a rotor blade base in order to ensure that a radially inner lower edge of the overhang no longer has a straight line.

Alternatively, an edge section that is set back radially outwards can be produced by thermal material removal. For example, in this context it can be provided that the production takes place by means of erosion. This includes production by spark erosion, whereby a set-back edge section can also be produced subsequently on an overhang made of high-strength material in a comparatively simple manner. In this case it can be provided that the (thermal) material removal on the overhang to produce a set-back edge section takes place in one operation with the production of certain functional areas on a rotor blade. For example, it is usual for a functional area, such as a damper pocket or a blade base area provided with at least one recess to reduce weight, to be produced on a rotor blade in the area of the blade base by erosion. In In such a working step, the overhang of a rotor blade can then also be machined accordingly in order to provide an edge section that is recessed radially outwards.

In principle, the at least one securing element can be provided for the axial securing of at least two rotor blades. In this case, a securing element, preferably in the form of a plate, is then encompassed at one (radially outer) edge by the overhangs of at least two rotor blades.

The attached figures illustrate exemplary possible embodiments of the invention.

Figur 1A

ausschnittsweise einen erfindungsgemäß ausgestalteten Rotor mit Blick entlang einer Rotationsachse des Rotors auf zwei abschnittsweise radial nach außen zurückgenommene Überhänge zweier benachbarter Laufschaufeln des Rotors;

Figur 1B

in mit der Figur 1A übereinstimmender Ansicht einen radialen Versatz zwischen zwei Schaufelbasen der benachbarten Laufschaufeln gegenüber der in der Figur 1A dargestellten nominellen Ausrichtung der beiden Laufschaufeln zueinander;

Figur 1C

in mit der Figur 1A übereinstimmender Ansicht den Rotor unter teilweiser Ausblendung eines Sicherungselements zur Veranschaulichung eines Schaufelhalses einer Laufschaufel, der in eine Befestigungsnut eingeschoben ist;

Figur 1D

eine Laufschaufel in Einzeldarstellung;

Figur 2A

in mit den Figuren 1A und 1B übereinstimmender Ansicht eine weitere Ausführungsvariante mit geometrisch unterschiedlich ausgestalteten zurückgenommenen Randabschnitten an zwei Überhängen zweier Laufschaufeln;

Figur 2B

in mit der Figur 1C übereinstimmender Ansicht den Rotor der Figur 2A;

Figur 3

eine Schnittdarstellung längs der Rotationsachse eines erfindungsgemäß ausgestalteten Rotor im eingebauten Zustand in ein Gasturbinentriebwerk;

Figur 4

ausschnittsweise eine entlang einer Schnittlinie parallel zur Rotationsachse des Rotors gewonnene Schnittdarstellung des Rotors;

Figuren 5A - 5D

jeweils ausschnittsweise ein aus dem Stand der Technik bekannter Rotor mit zwei benachbarten Laufschaufeln, deren Überhänge mit einem geradlinig verlaufenden Rand und damit nominell miteinander fluchtenden Unterkanten (Figur 5A) sowie gegebenenfalls toleranzbedingt zueinander versetzten Unterkanten (Figuren 5B und 5C) sowie unter teilweiser Ausblendung eines Sicherungselements (Figur 5D) dargestellt sind;

Figur 6

in Schnittdarstellung schematisch ein Gasturbinentriebwerk, in dem ein erfindungsgemäßer Rotor Verwendung findet.

They show:

Figure 1A

a detail of a rotor designed according to the invention with a view along a rotation axis of the rotor onto two overhangs of two adjacent rotor blades of the rotor which are partially radially recessed outwards;

Figure 1B

in with the Figure 1A consistent view a radial offset between two blade bases of the adjacent rotor blades compared to the Figure 1A shown nominal alignment of the two blades to each other;

Figure 1C

in with the Figure 1A a corresponding view of the rotor with a securing element partially hidden to illustrate a blade neck of a rotor blade which is inserted into a fastening groove;

Figure 1D

a rotor blade in individual representation;

Figure 2A

in with the Figures 1A and 1B In the same view, another variant with geometrically differently designed recessed edge sections on two overhangs of two rotor blades;

Figure 2B

in with the Figure 1C consistent view of the rotor of the Figure 2A ;

Figure 3

a sectional view along the axis of rotation of a rotor designed according to the invention in the installed state in a gas turbine engine;

Figure 4

a partial sectional view of the rotor taken along a cutting line parallel to the axis of rotation of the rotor;

Figures 5A - 5D

each section of a rotor known from the state of the art with two adjacent blades, the overhangs of which have a straight edge and thus nominally aligned lower edges ( Figure 5A ) and, if necessary, offset lower edges due to tolerances ( Figures 5B and 5C ) and partially hiding a security element ( Figure 5D ) are shown;

Figure 6

in sectional view schematically a gas turbine engine in which a rotor according to the invention is used.

The Figure 6 illustrates schematically and in cross-section a (gas turbine) engine T in which the individual engine components are arranged one behind the other along a central axis or axis of rotation M. At an inlet or intake E of the engine T, air is sucked in along an inlet direction E by means of a fan F. This fan F is driven by a shaft which is set in rotation by a turbine TT. The turbine TT is connected to a compressor V which, for example, has a low-pressure compressor 11 and a high-pressure compressor 12, and possibly also a medium-pressure compressor. The fan F supplies air to the compressor V on the one hand and to a bypass channel B on the other hand to generate the thrust. The air conveyed via the compressor V finally reaches a combustion chamber section BK in which the drive energy for driving the turbine TT is generated. The turbine TT has a high-pressure turbine 13, a medium-pressure turbine 14 and a low-pressure turbine 15 for this purpose. The turbine TT uses the energy released during combustion to drive the fan F, which then generates the required thrust using the air fed into the bypass channel B. The air leaves the bypass channel B in the area of an outlet A at the end of the engine T, where the exhaust gases from the turbine TT flow out. The outlet A usually has a thrust nozzle.

In particular in the area of the high pressure turbine 13, at least one rotor comes into contact with the Figures 5A to 5D The configuration shown is used. The rotor is arranged and mounted so that it can rotate around the central axis or rotation axis M, that the individual the circumferential direction U for axially securing the rotor blades 3a, 3b, securing plates 4 are arranged on a downstream end face of the rotor 2. The individual securing elements 4 thus face an annular space 5 which is formed in the area of the blade roots 32 of the individual rotor blades 3a, 3b between the rotor and a guide vane arrangement 6. The flow arising in this annular space 5 can - as explained in the introduction - be undesirably swirled in a configuration of the overhangs 310 of the blade bases 31 used to connect the rotor blades 3a, 3b and a securing element 4 if individual overhangs 310 are offset from one another due to tolerances. Then individual overhangs 31 protrude completely into the flow path defined in a circular ring around the axis of rotation along the securing plates 4 or are set back radially outwards for this purpose (see Figures 5B and 5C ).

An improvement can be achieved here with the solution according to the invention. According to this, an overhang 310, which is provided for a positive connection with a radially outer edge 43 of a multi-part or one-part securing element, such as a securing plate 4, is designed with an edge section of defined geometry and size that is set back in the radially outer direction ra. With the solution according to the invention, even with the nominal arrangement of the individual rotor blades 3a, 3b relative to one another, it can be ruled out that a straight or circular arc-shaped course of the radially inner lower edges of the overhangs 310, which follow one another along the circumferential direction U, is present on each pair of adjacent rotor blades 3a, 3b. Rather, at least one defined radial recess is provided from the outset, which influences the flow as little as possible, but in any case predictably. Preferably, several recesses distributed along the circumferential direction U are provided, in particular on each pair of blade bases 31 arranged adjacent to one another.

In the version of the Figures 1A to 1C For example, an overhang 310 of a blade base 31 of each rotor blade 3a, 3b fixed to the rotor base part 2 has two radially outwardly recessed edge sections 311a and 311c. These two radially recessed edge sections 311a and 311c have a smaller extension in the radially inward direction ri than a third edge section 311b formed between them. The length of the third edge section 311b along the circumferential direction U can be at least twice the shape and position tolerances of a gap between the axial securing elements 4 and/or at least half of a minimum width d of a blade neck 320 of the blade root 32 of a rotor blade 3a or 3b inserted into the associated fastening groove 20 (cf. the individual illustration of a rotor blade 3a of the Figure 1D ). The length of the third edge portion 311b along the circumferential direction U amounts to less than 60%, possibly less than 50% or even less than 35% of the total length L of an overhang 310 along the circumferential direction U.

A recessed edge section 311a or 311c is provided at each of the ends of an overhang 310 that are spaced apart from one another along the circumferential direction U. The edge sections 311a and 311c extend with different lengths a1 and a2 in the circumferential direction U. Both recessed edge sections 311a and 311c also form a region of the lower edge of the overhang 310 that runs at an angle to the circumferential direction U. Each recessed edge section 311a, 311c runs from the middle, third edge section 311b at an angle outwards towards the respective end, so that a radial extension of the respective recessed edge section 311a or 311c decreases steadily towards the respective lateral edge of the overhang 310.

Here, the individual edge sections 311a and 311c are each set back up to a height b1 or b2 relative to the middle edge section 311b. This height b1 or b2 is in the present case greater than 0.8 mm and amounts to approximately 1 mm. The extension in the circumferential direction U of the respective set-back edge section 311a, 311c is in turn measured as a - preferably integer - multiple of this height b1 or b2. In the present case, a length a1, a2 corresponds to at least three times a height b1 or b2 of the respective set-back edge section 311a, 311c.

The heights b1 and b2 of the recessed edge sections 311a and 311c are dimensioned such that in the area of adjacent rotor blades 3a, 3b and thus adjacent blade bases 31, a radial recess 33 is formed in the course of the lower edges of several securing plates 4 that follow one another in the circumferential direction U by two recessed edge sections 311c and 311a that run obliquely towards one another. This radial recess 33 is dimensioned over the recessed edge sections 311c and 311a of the individual rotor blades 3a and 3b such that even with a tolerance-related maximum radial offset g of two rotor blades 3a and 3b, a radial depth of the respective recess 33 is greater than the offset g and preferably corresponds to a multiple of the offset g. This means that a (relevant) flow influence due to the offset g is excluded or minimal (compare Figure 1B ).

The recessed edge sections 311a and 311c of course still provide a sufficient extension of the overhang 310 in the radially inner direction ri, so that a groove 3100 for the encompassed radially outer edge 43 of the securing plate 4 is also present in the region of a recessed edge section 311a or 311c. The radially inner edge 42 of a securing plate 4 is in a groove 2100 of the rotor base part 2, which is formed by a projection 210 protruding in the radially outer direction ra. In this way, the securing plate 4 ensures that the individual rotor blades 3a, 3b are axially secured to the rotor base part 2 in the region of their respective blade root 32, which is at least partially covered by a securing plate 4 (see also Figure 3 ).

In contrast to the state-of-the-art solution according to the Figures 5A to 5D (see especially Figure 5D ) the recessed edge sections 311a and 311c also ensure that the overhang 310 extends further radially inwards with the edge section 311b lying between them along the circumferential direction U only in the area in which the fastening groove 20 is located. The edge section 311b which projects further radially inwards is thus dimensioned such that the blade root 32 can be pushed in the axial direction through the fastening groove 20 and the gap defined thereby between two webs 22 of the rotor base part 2 if the securing plate 4 is not yet or no longer attached. This is possible with an overhang of constant radial extension in accordance with the Figure 5D not possible. Here, the blade root 32 is blocked from being pushed through a fastening groove 20 by the overhang 310. The overhang 310 cannot be pushed over the opposing webs 22 of the rotor base part 2, which laterally border a fastening groove 20. For complete axial displacement through the fastening groove 30, the radial extent of the blade root 32 and thus the length of a blade neck 320 would have to be increased so that a lower edge of the overhang 310 runs radially further out than the end of the webs 22. However, this would entail an increase in the weight of a rotor blade 3a, 3b. In contrast, the additional assembly advantage can be achieved in the illustrated embodiment of a solution according to the invention without a weight disadvantage.

In the case of the Figures 2A and 2B The shape of the recessed edge sections 311a and 311c differs from the variant of the Figures 1A to 1C varies. An overhang 310 on a blade base 31 is profiled so that the two edge sections 311a and 311b of a rotor blade 3a or 3b, which are spaced apart from one another along the circumferential direction U, are designed to be radially recessed in the radially outer direction ra relative to the middle, third edge section 311b of the overhang 310 of the respective rotor blade 3a or 3b. The individual recessed edge sections 311a and 311c each have regions of constant radial extension along the circumferential direction U. In other words, each of the recessed edge sections 311a, 311c of a rotor blade of the Figures 2A and 2B at least one region in which a height of the respective recessed edge portion 311a, 311c does not decrease in the circumferential direction U or opposite thereto.

In particular, this ensures that a recess 33 defined in the area of the blade bases 31 of two adjacent blades 3a, 3b in the view along the axis of rotation of the Figure 2 is trapezoidal, while the recess 33 in the variant of the Figures 1A to 1C is triangular. If the lower edges of the recessed edge sections 311a, 311c are more rounded, an elliptical recess can also be formed in a possible further development.

A machining process or thermal material removal may be used to produce the recessed edge sections 311a, 311c on a rotor blade 3a or 3b. For example, the recessed edge sections 311a and 311c in the embodiment of the Figures 1A to 1C can be produced relatively easily by grinding. A profiled version according to the variant of the Figures 2A and 2B can be produced, for example, by erosion. The production of the recessed edge sections 311a and 311c can be carried out in one operation with damper pockets (not shown here) or other functional areas on the rotor blades 3a, 3b, which are usually also produced by erosion.

Based on the Figure 2B is in accordance with the Figure 1C still partially hiding the securing plate 4, it is illustrated that even in this embodiment variant, due to the recessed edge sections 311a and 311c, the overhang 310 does not block the blade root 32 from being pushed through in the axial direction through a fastening groove 20. The (middle) edge section 311b, which projects further radially inwards, is dimensioned such that it fits through the gap defined between two webs 22 of the rotor base part 2 at the upper end of the fastening groove 20.

Based on the partial representation of a longitudinal section according to the Figure 4 The design of the securing plate 4 is shown separately. The securing plate 4 has a central region 40 located between the radially inner and radially outer edges 42 and 43. From the Figure 4 It is particularly evident how a radially outer edge 43 of the securing plate 4 is received in the groove 3100 of the blade base 31 of a rotor blade 3b and is encompassed by the radially inwardly extending overhang 310, while the central region 40 extends outside the groove 3100 along the blade root 32.

list of reference symbols

T

gas turbine engine

11

low-pressure compressor

12

high-pressure compressor

13

high-pressure turbine

14

medium-pressure turbine

15

low-pressure turbine

2

rotor base part

20

mounting groove

210

supernatant

2100

Nut

22

web

30

blade

31

blade base

310

overhang

3100

Nut

311

edge

311a, 311b, 311c

edge section

32

blade root

320

shovel neck

33

radial recess

3a, 3b

blade

4

locking plate (locking element)

40

middle range

42

inner edge

43

outer edge

5

annular gap

6

guide vane arrangement

A

outlet

a1, a2

length

B

bypass channel

BK

combustion chamber section

b1, b2

Height

c

Width

d

Minimum width of the blade neck

E

intake

F

fan

G

offset

L

total length

M

central axis / axis of rotation

R

entry direction

ra, ri

radial direction

TT

turbine

U

circumferential direction

V

compressor

Claims (12)

1. Rotor for an engine (T), comprising

   - a rotor base part (2) which has fastening grooves (20) for rotor blades (3a, 3b), said fastening grooves being arranged in succession along a circumferential direction (U) about an axis of rotation (M),

   - a plurality of rotor blades (3a, 3b) which are each held in an associated fastening groove (20) in a positively locking manner by way of a blade root (32), and

   - at least one securing element (4) for axially securing, in relation to the axis of rotation (M), at least one of the rotor blades (3a, 3b) to the rotor base part (2),

   wherein the at least one securing element (4) has two peripheries (42, 43) which are spaced apart radially from one another and by way of which the securing element (4) is held, on the one hand, on the rotor base part (2) and, on the other hand, on the at least one rotor blade (3a, 3b) in a positively locking manner, and for the positively locking engagement with the rotor blade (3a, 3b), the one periphery (43) of the securing element (4) is encompassed at least in one region by an overhang (310) of the rotor blade (3a, 3b), said overhang for this purpose extending, with respect to the axis of rotation (M), radially inwardly over the one periphery (43) of the securing element (4) and along the circumferential direction (U),

   wherein a respective gap between two webs (22) of the rotor base part (2) is defined by a fastening groove (20), and

   wherein the overhang (310) has, along its extent in the circumferential direction (U), at least one peripheral portion (311a, 311c) which engages around the periphery (43) of the securing element (4) and which is set back, at a radially inner lower edge of the overhang (310), in a radially outwardly pointing direction (ra) in relation to at least one further peripheral portion (311b) of the overhang (310), said further peripheral portion likewise engaging around the periphery (43) of the securing element (4),

   characterized in that

   the overhang (310) has two, first and second, peripheral portions (311a, 311c) which are each provided at an end of the overhang (310) in relation to the circumferential direction (U) and are each set back in the radially outwardly pointing direction (ra) in relation to at least one further third peripheral portion (311b) of the overhang (310), said further peripheral portion likewise engaging around the periphery (43) of the securing element (4), in such a way that the blade root (32) and a lower edge of the overhang (310) can be pushed through the gaps in the rotor base part (2) when the securing element (4) is not yet attached or is no longer attached, and

   overhangs with mutually adjoining and in each case radially outwardly set-back peripheral portions (311a, 311c) are provided on at least two rotor blades (3a, 3b) of the rotor which are arranged adjacent to one another along the circumferential direction (U), such that a radially outwardly directed recess (33) of defined minimum length and minimum height is formed in the region of the mutually adjoining peripheral portions (311a, 311c) of the two adjacent rotor blades (3a, 3b).
2. Rotor according to Claim 1, characterized in that at least one of the first and second radially outwardly set-back peripheral portions (311a, 311c) has a smaller extent in the radially inwardly pointing direction (ri).
3. Rotor according to Claim 1 or 2, characterized in that at least one of the first and second radially outwardly set-back peripheral portions (311a, 311c) forms, at the radially inner lower edge, a region that runs in an at least partially inclined manner with respect to the circumferential direction (U).
4. Rotor according to one of the preceding claims, characterized in that at least one of the first and second radially outwardly set-back peripheral portions (311a, 311c) extends, along the circumferential direction (U), with a length (a1, a2) that corresponds to at least three times a height (b1, b2) by which the radially outwardly set-back peripheral portion (311a, 311c) is maximally set back in relation to the adjoining third peripheral portion (311b) of the overhang (310).
5. Rotor according to one of the preceding claims, characterized in that at least one of the first and second radially outwardly set-back peripheral portions (311a, 311c) is set back in relation to the adjoining third peripheral portion (311b) of the overhang (310) at least by a height (b1, b2) of 0.5 mm, in particular at least by a height (b1, b2) of 0.8 mm or 1 mm.
6. Rotor according to one of the preceding claims, characterized in that the two set-back peripheral portions (311a, 311c) are set back to differing extents and/or extend along the circumferential direction (U) with differing lengths (a1, a2).
7. Rotor according to one of the preceding claims, characterized in that the first and second radially outwardly set-back peripheral portions (311a, 311c) are provided at ends of the overhang (310) which are spaced apart from one another along the circumferential direction (U).
8. Rotor according to one of the preceding claims, characterized in that one of the first and second radially outwardly set-back peripheral portions (311a, 311c) are set back in relation to the adjoining third peripheral portion (311b) of the overhang (310) at least by the sum of predefined dimensional and positional tolerances of this third peripheral portion (311b), wherein the dimensional and positional tolerances predefine a nominal position of the third peripheral portion (311b) with respect to the associated fastening groove (20) and/or with respect to an overhang (310) of an adjacent rotor blade (3b, 3a).
9. Rotor according to one of the preceding claims, characterized in that the recess (33) is elliptical, trapezoidal or triangular in a view along the axis of rotation (M).
10. Rotor according to one of the preceding claims, characterized in that overhangs with mutually adjoining and in each case radially outwardly set-back peripheral portions (311a, 311c) are provided along the circumferential direction (U) at each pair of mutually adjacently arranged rotor blades (3a, 3b), such that a respective radially outwardly directed recess (33) of defined minimum length and minimum height is formed along the circumferential direction (U) in the region of mutually adjoining peripheral portions (311a, 311c) of two adjacent rotor blades (3a, 3b).
11. Rotor according to one of the preceding claims, characterized in that the at least one radially outwardly set-back peripheral portion (311a, 311c) is produced by mechanical or thermal abrasion of material.
12. Rotor according to one of the preceding claims, characterized in that the at least one securing element (4) is provided for axially securing at least two rotor blades (3a, 3b), and the one periphery (43) of the securing element (4) is thus encompassed by overhangs (310) of at least two rotor blades (3a, 3b).

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