GUIDE BLADE ARRANGEMENT FOR A TURBOMACHINE

Abstract

A guide blade arrangement (20) for a turbomachine (1), including a guide blade airfoil (22) and a platform (21). The guide blade airfoil (22) is situated at a side (21.1) of the platform (21) facing the gas channel, an opposite side (21.2) of the platform (21) facing away from the gas channel being contoured at least in one area (30.1, 30.2) with elevations (25) and depressions (26) that follow one another in the circumferential direction (23) in relation to a longitudinal axis (2) of the turbomachine (1), and the elevations (25) and depressions (26) at the side (21.2) facing away from the gas channel being set via a platform thickness (31), taken radially in each case, that is variable in the circumferential direction (23) and that repeatedly increases and decreases with a continuous profile.

Claims

1-14. (canceled)

15. A guide blade arrangement for a turbomachine, the guide blade arrangement comprising: a guide blade airfoil; and a platform having a side facing a gas channel and an opposite side facing away from the gas channel; the guide blade airfoil being situated at the side of the platform facing the gas channel, the opposite side being contoured at least in one area with elevations and depressions following one another in a circumferential direction in relation to a longitudinal axis of the turbomachine, the elevations and depressions at the opposiute side being set via a platform thickness, taken radially in each case, variable in the circumferential direction and repeatedly increasing and decreasing with a continuous profile in the circumferential direction.

16. The guide blade arrangement as recited in claim 15 wherein an amplitude at the elevations and depressions, taken radially in each case, constitutes at least 25% and at most 200% of an average platform thickness formed over the contoured area in the circumferential direction.

17. The guide blade arrangement as recited in claim 15 wherein an amplitude at the elevations and depressions, taken radially in each case, changes over the contoured area in the circumferential direction.

18. The guide blade arrangement as recited in claim 17 wherein the absolute value of the amplitude, based on an average amplitude formed over all elevations and depressions of the contoured area, changes by at least 15% and at most by 100%.

19. The guide blade arrangement as recited in claim 15 wherein the front edge or the rear edge of the guide blade airfoil has a radial overlap with the contoured area so that a radial projection of the front edge or of the rear edge is situated in the contoured area.

20. The guide blade arrangement as recited in claim 15 wherein the side of the platform facing the gas channel has a smooth design, at least in areas.

21. The guide blade arrangement as recited in claim 15 wherein n guide blade airfoils, where n≥2, are situated at the platform.

22. The guide blade arrangement as recited in claim 21 wherein the elevations and depressions in the contoured area follow one another in the circumferential direction with a wavelength whose absolute value deviates by no more than 20% from a circumferential distance between next-closest of the n guide blades in each case.

23. The guide blade arrangement as recited in claim 21 wherein a total number Z.sub.E of elevations following one another in the circumferential direction in the contoured area or a total number Z.sub.V of depressions follow ingone another in the circumferential direction in the contoured area is in a range between n−1 and n+1 so that n−1≤Z.sub.E≤n+1 or n−1≤Z.sub.V≤n+1.

24. The guide blade arrangement as recited in claim 15 wherein the contoured area is situated in a radially open pocket of the platform.

25. The guide blade arrangement as recited in claim 24 wherein the pocket of the platform is circumferentially framed in each case by a lateral web.

26. The guide blade arrangement as recited in claim 24 wherein the pocket of the platform is axially framed by a sealing web, a middle web or an installation web.

27. A turbine module comprising the guide blade arrangement as recited in claim 15.

28. A turbomachine comprising the guide blade arrangement as recited in claim 15.

29. An aircraft engine comprising the turbomachine as recited in claim 28.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention is explained in greater detail below with reference to one exemplary embodiment, it being possible for the individual features, within the scope of the other independent claims besides the main claim, to also be in some other combination that is essential to the present invention, in particular a distinction also not being made between the different claim categories.

[0033] FIG. 1 shows a turbomachine, specifically, a turbofan engine, in an axial section;

[0034] FIG. 2 shows a portion of a guide blade arrangement according to the present invention in a schematic axial view;

[0035] FIG. 3 shows a detailed view of FIG. 2;

[0036] FIG. 4a shows a schematic radial view of the design of an inner platform, without contouring for the sake of clarity;

[0037] FIG. 4b shows a schematic radial view of the design of an outer platform, without contouring for the sake of clarity; and

[0038] FIG. 4c shows a schematic radial view of the design of an alternative outer platform, without contouring for the sake of clarity.

DETAILED DESCRIPTION

[0039] FIG. 1 shows a turbomachine 1, specifically, a turbofan engine, in an axial section. Turbomachine 1 is functionally divided into a compressor 1a, a combustion chamber 1b, and a turbine 1c. Compressor 1a and turbine 1c are each built from multiple stages, and each stage is made up of a guide blade ring and a subsequent rotor blade ring. During operation, the rotor blade rings rotate about longitudinal axis 2 of turbomachine 1. The aspirated air is compressed in compressor 1a, and then combusted with admixed jet fuel in downstream combustion chamber 1b. The hot gas flows through hot gas channel 3 and drives the rotor blade rings, which rotate about longitudinal axis 2.

[0040] FIG. 2 shows a portion of a guide blade arrangement 20 according to the present invention, in particular a platform 21 including multiple guide blade airfoils 22, namely, guide blade airfoils 22.1, 22.2 through 22.n (in the present case, n=6). Guide blade arrangement 20 is combined as a segment with further structurally identical guide blade arrangements (not illustrated), which then, following one another in a circumferential direction 23, jointly form a guide blade ring. In the case of turbine 1c, guide blades 22 are then situated in hot gas channel 3, and the combustion gas or hot gas flows around them during operation.

[0041] Guide blades 22 are situated at a side 21.1 of platform 21 facing the gas channel, and radially opposite side 21.2 facing away from the gas channel is contoured. The radially opposite side is formed with elevations 25 and depressions 26, which follow one another in an undulating manner in circumferential direction 23. As described in detail in the introduction to the description, via this contouring at side 21.2 of platform 21 facing away from the gas channel, the mechanical stress level at the opposite side, specifically, at the transition between platform 21 and guide blade airfoils 22, may be reduced.

[0042] As is apparent from FIG. 2 and in particular the detailed view according to FIG. 3, side 21.1 of platform 21 facing the gas channel is not complementarily contoured (in the present case, it has a smooth design). Accordingly, in a contoured area 30 of platform 21, a platform thickness 31 repeatedly increases and decreases in circumferential direction 23. In the present case, platform thickness 31 is greater in the area of elevations 25 and is lesser for depressions 26.

[0043] Based on an average platform thickness 35 that is formed as an average value over area 30, an amplitude 36 of the elevations and depressions is between approximately 50% and 100%. Amplitude 36 also changes over contoured area 30; in the present case, it decreases in circumferential direction 23. Based on an average amplitude that is formed over elevations 25 and depressions 26 of contoured area 30, this results in a variation between 30% and 50%. In circumferential direction 23, elevations 25 and depressions 26 follow one another with a wavelength 38 that corresponds approximately to a circumferential distance 39 between guide blade airfoils 22. The number of elevations 25 corresponds approximately (±1) to the number of guide blade airfoils 22; the same applies for the number of depressions 26.

[0044] FIG. 4a shows a platform 21, specifically, an inner platform 41, in a radial view. The viewing direction is radial from the inside to the outside; guide blade airfoils 22 situated at the opposite side (behind the plane of the drawing) are illustrated as dashed lines for purposes of orientation. Their front edges 22a as well as their rear edges 22b (shown only for one guide blade airfoil 22 for the sake of clarity) are apparent. Two contoured areas 30.1, 30.2 according to the above description are formed at inner platform 41, i.e., are formed with elevations and depressions (not shown in FIG. 4a for the sake of clarity). Areas 30.1, 30.2 are formed in so-called pockets 44.1, 44.2 of platform 21, which are framed by lateral webs 45 in circumferential direction 23 (also cf. FIG. 2 for purposes of illustration). Pockets 44.1, 44.2 are axially framed by sealing webs 46; there is also a middle web 47 situated axially between same.

[0045] FIG. 4b likewise shows a platform 21, namely, an outer platform 51. This platform, based on the illustration according to FIG. 2, would be situated radially oppositely, but is not illustrated there for the sake of clarity. Outer platform 51 is also framed with contoured areas 30.1, 30.2 (the contouring is not shown in FIG. 4b), in which the radial projections of front edges 22a and rear edges 22b of guide blade airfoils 22 fall. Contoured area 30.1 is once again a radially open pocket 54.1 (in the present case, radially outwardly open). This pocket is framed by lateral webs 45 in circumferential direction 23, and is axially delimited by sealing web 46 and an installation web 57 with guide blade hooks. A further pocket 54.2, which likewise may, but does not have to, be designed as a contoured area is formed between installation webs 57.

[0046] FIG. 4c likewise shows an outer platform 51; in contrast to FIG. 4b, contoured area 30.1 is not situated in a pocket 54.1 that is delimited axially to the front and to the side by lateral webs 45.

LIST OF REFERENCE NUMERALS

[0047] 1 turbomachine [0048] 1a compressor [0049] 1b combustion chamber [0050] 1c turbine [0051] 2 longitudinal axis [0052] 3 hot gas channel [0053] 20 guide blade arrangement [0054] 21 platform [0055] 21.1 side facing the gas channel [0056] 21.2 side facing away from the gas channel [0057] 22 guide blade airfoils [0058] 22a front edge [0059] 22b rear edge [0060] 22.1, 22.2 through 22.n guide blade airfoils [0061] 23 circumferential direction [0062] 25 elevations [0063] 26 depressions [0064] 30 contoured area [0065] 30.1, 30.2 contoured areas [0066] 31 platform thickness [0067] 35 average platform thickness [0068] 36 amplitude [0069] 38 wavelength [0070] 39 circumferential distance [0071] 41 inner platform [0072] 44.1, 44.2 pockets [0073] 45 lateral web [0074] 46 sealing web [0075] 47 middle web [0076] 51 outer platform [0077] 54.1, 54.2 pockets [0078] 57 installation web