Turbine blade and gas turbine with such a turbine blade

[0001] The invention relates to a turbine blade with a tongue arranged along the blade axis and to a platform area which has a platform on the blade root which extends across the blade axis. The invention furthermore extends to a gas turbine with a flow channel with an annular cross-section to a working medium, a second stage of blades, arranged along the axis behind the first step of the blades, wherein one step of the blades has a number of ring-shaped radially-entering vents. the turbine.

[0002] In a gas turbine of this kind, in the flow channel, after being supplied with a hot gas, temperatures are present which may lie in the region between 1000 ° C and 1400 ° C. The turbine blade platform forms a number of such turbine blades in a single stage of the blade portion of the jet channel for the gas flow flowing through the gas turbine as a result of the annular system, which thus drives an axial turbine rotor through the turbine blades. Such a strong thermal load of the flow channel constraints created by the platform is counteracted so that the platform is cooled at the back, i.e. from underneath the foot platform of the turbine blade. For this purpose, the foot and the platform area are usually provided with a suitable drainage system to supply the cooling medium.

[⁰⁰⁰3] ZD^{E 2 628 807} AND¹ in^sn^ikand the impact walking system^go turbine blades of the kind mentioned at the outset. In DE 2 628

807 A1 in order to cool the platform against the side of the platform opposite to the hot exhaust gases, i.e. behind the platform, i.e.

a perforated wall element is placed between the base of the blade and the platform. Through the openings of the wall element, the cooling air at relatively high pressure encounters the side of the platform which is opposite to the hot exhaust gases, thereby achieving effective impact cooling.

[0004] EP 1 073 827 B1 discloses a new road in the design of the platform area of ​​cast turbine blades. The platform area is shaped as a double platform with two opposite platform walls. As a result, it is achieved that the flow wall of the platform, which is directly exposed to the flow channel and thus to the hot exhaust gases, can be thin. The embodiment with two walls of the platform carries a division of functions for the walls of the platform. The flow wall of the platform, which limits the flow channel, is in fact responsible for the canalization of hot exhaust gases. The opposite side of the platform, which is not covered by hot exhaust gases, receives the load from the blade blade. This division of functions enables such a thin construction of the boundary wall of the platform that limits the flow channel,

[0005] In the embodiment of the turbine blade of the kind mentioned at the beginning in a tightly sealed manner between the platforms adjacent to each other turbine blades of the same degree of blades or neighboring vanes placed behind the other vane steps, sealing means are necessary to prevent undesired and excessive flow of cooling agent into the duct flow-through with hot exhaust. The means required for sealing can lead to difficult situations in terms of design and technique of cooling in the thermally loaded platform wall and represent an increased failure potential of the turbine blade, i.e. the gas turbine.

[0006] Usually, the sealing of such partial gaps is achieved by the assembly of special sealing elements. On the one hand, they must be flexible enough to permit simultaneous movements of neighboring parts relative to each other, in particular adjacent turbine blades and their platforms, and on the other hand they must nevertheless retain a sealing effect. The assembly of such sealing elements leads to the creation of geometrically and structurally complicated construction elements. As a result, special cooling means are necessary to be able to sufficiently cool the hard-to-reach edge areas of the platform. Another turbine blade according to the prior art is known from FR 2831207. It would be desirable to make it as simple as possible,

[0007] An invention is now underway which aims to propose a turbine blade with a platform that at the same time has a simple structure and at the same time satisfies the geometrical and structural requirements and cooling techniques within the gas turbine flow channel limitation. In addition, the sealing of partial gaps between adjacent turbine blades should be particularly simple and cheap.

[0008] With reference to the turbine blade, the object of the invention is solved by the turbine blade mentioned at the outset, in which the platform according to the invention is at least partly formed by a first elastic blade element that is firmly fixed on the blade blade, which is tightly applied to the blade. to the middle stop placed on the adjacent turbine blade.

[0009] The invention is based on the belief that the use of a non-load-bearing platform as a restriction of the hot gas-powered flow channel of a gas turbine is generally suitable for cooling the platform as effectively as possible and thus reducing the flow channel. In addition, the essential observation of the invention lies in the fact that it is possible to give the platform itself an increased sealing effect, namely that the platform has such a thin wall that it is formed from a blade adjacent to the tongue, a resiliently flexible sheet element.

[0010] As a result, the platform as a limiting part of the hot-gas-fired passageway fulfills all the cooling and sealing requirements. Thanks to the blade attached to the blade, the elastic-elastic sheet element as such is elastic enough to allow simultaneous movements of the blade blades and other parts with respect to each other, while still retaining the sealing effect. Thanks to this, a special sealing element becomes unnecessary. This simplifies the execution and cooling of the flow channel limitation.

According to the invention, the first elastic-elastic sheet element is in the form of a non-load-bearing platform wall which at least partially limits the heat supplied by the hot exhaust gas passage. The supporting platform wall, as provided in EP 1 073 827 B1, which would be positioned after the first elastic-elastic sheet element, can largely be omitted. The platform thus consists of a first elastic-elastic sheet metal element attached at least partially to the blade shoulder.

[0012] The sealing element needed to date between adjacent turbine blades may be dispensed with, since the first resilient-elastic sheet element of one turbine blade adheres tightly to the other of the adjacent turbine blades.

[0013] The advantages still remain regarding the cooling and sealing action of the first resilient- elastic sheet metal element for the platform and thus the restriction of the flow channel.

[0014] Preferred embodiments of the invention result from the dependent claims and specify in detail the advantageous possibilities, in particular the development of the platform in terms of the above task.

According to a particularly advantageous embodiment of the invention, it is provided that the plate is formed by a first blade attached to the first stop, a resilient-elastic sheet element and a resilient-elastic element attached to the other side of the blade blade. from sheet metal. There are therefore two sheet metal elements that form the platform, i.e. extend both sides of the blade blade on both sides of the blade shoulder.

[0016] Deliberately adhering to the blade blade, the second sheet metal element assumes the function of the first non-holding blade of the platform wall blade, and the platform wall further has a second wall holding the blade tongue. In this embodiment, between the first non-loadbearing platform wall of the second sheet metal element and the second thicker load-bearing wall of the platform, a suitable cooling space for supplying the cooling medium is created as a particularly supporting structure.

[0017] According to a further embodiment of the invention, each stop can be in the form of a groove or edge. This enables a particularly reliable and advantageous in terms of flow technique to fasten the element from the sheet metal to the foot of the blade blade.

In a preferred embodiment of the invention, it has been advantageous that the sheet elements, and in particular the first, are held at the next stop of the adjacent turbine blade. Preferably, this further stop can be in the form of a support. For example, such a support may be in the form of a step formed between the foot of the blade and the blade root of the blade. The first sheet metal element of the first turbine blade seals tightly against the support of the adjacent turbine blade. The second sheet metal element may preferably act as a support arranged on the same turbine blade or, additionally or alternatively, it may be welded to a step.

[0019] Preferably, the first resilient-elastic sheet member abuts loosely to the next stop of an adjacent turbine blade in the relaxed state. In this case, the further explanation of a sufficiently fastening of the sheet metal part results from the movement or flow-technical connection of the turbine blade in the working condition of the gas turbine.

[0020] The sealing action of the first elastically elastic sheet element at the next stop can be further improved when the first resilient-elastic sheet element adheres to the next stop with self-generated pre-stress.

[0021] In order to solve the problem, the invention further leads to the gas turbine mentioned at the outset, wherein one degree of blades has a number of annularly arranged radial blades that enter radially into the flow channel, the turbine blade according to the invention being of the type mentioned above.

Preferred embodiments of the gas turbine result from the further dependent claims and specify in detail the advantageous possibilities, in particular regarding the design of the flow channel constraint and the operating principles of the turbine blade within the restriction of the flow channel within the meaning of the above task.

[0023] In the first embodiment, the turbine blade is a rotating blade. Such a rotating blade is mounted on an axially running turbine rotor and rotates during operation of the gas turbine together with the turbine rotor. In the centrifuging mode, the turbine blades in the form of a vane rotating on the turbine rotor generate a centrifugal force acting from the blade root of the blade towards the blade blade. In this embodiment, it is provided that the first resilient elastic sheet element achieves a sufficient sealing effect between two adjacent sheet metal elements of two adjacent rotating blades. Due to the centrifugal force, the first elastic-elastic element from the sheet metal of the first rotor blade is pressed against the next stop of the second rotor blade and consequently adheres to the attachment under the effect of the centrifugal force. Thus, even in the case where the first resilient-elastic element rests in the rest condition loosely to the next stop, then the centrifugal force ensures that the elastically elastic sheet element in the working condition adheres tightly to the rotating blade. During operation of the rotating gas turbine blade, the first elastic-elastic element from the sheet metal therefore also has the function of a sealing element. Preferably, the contact surface of the first resilient elastic sheet element at the subsequent stop of an adjacent rotating blade in the form of a support acts as a sealing thrust bearing for the first sheet metal element. The penetration of the hot exhaust gases flowing through the turbine through the gap formed up to now by the two platforms of neighboring rotor blades can be prevented by effective sealing, likewise undesired leakage of the coolant through the gap into the hot exhaust chamber.

[0024] According to an alternative embodiment of the gas turbine, the turbine blade is provided as a guide vane on the periphery turbine body. During the operation of the turbine blade in the form of a guide blade on the turbine body, the coolant generates a pressure drop from the blade root of the blade towards the blade blade. The alternative embodiment provides that the first resilient elastic sheet element of the first guide vane is pressed by a pressure drop to the further stop of the second guide vane, thereby being clamped. The pressure drop is thus produced such that the first elastic-elastic sheet element is powered from the back by the coolant and thus pressed against the further stop. For the vane guide the pressure drop is large enough thus, it suffices not only to press the first elastically elastic sheet element against the next stop, but also, during the operation of the guide blade, the first resilient-elastic sheet element functions as a sealing element. The contact surfaces of the first sheet metal element act on the limiting surface explained above as sufficient sealing surfaces, and the stop as the support bearing for the first resilient sheet metal part.

In a gas turbine embodiment, it is advantageous that a restriction is formed between the first turbine blade and the neighboring second turbine blade of the same degree of blades from the first elastic-elastic sheet element of the first turbine blade and from the second sheet metal member of the second turbine blade. flow channel, which is continuous. Within the degree of the blades, a continuous radial restriction of the flow channel is thus preferably formed.

[0026] In a further embodiment of the gas turbine, it is furthermore advantageous that between the first turbine blade of the first stage of the vanes and adjacent to the first turbine blade axially with respect to the rotor, the second vanes of the second degree turbine vanes from the first elastic-elastic element from the first sheet the turbine blades and the second sheet metal element of the second turbine blade, a flow channel limitation is established, which is continuous. In this way, a continuous axial restriction of the flow channel is preferably formed. Preferably, the degrees of the blades are the degrees of guide vanes, and for the turbine blades, the guide vanes.

[0027] Due to the aforementioned types of continuous limitation, it is unnecessary to require sealing in the case of typical gas turbine flow channel constraints, partial gaps and additional sealing elements then required. The problems occurring in connection with the sealing elements are completely eliminated by the continuous restriction of the flow channel by means of the first elastic-elastic and the second sheet-metal element.

[0028] In this case, it is expedient to provide a first elastic sheet element placed on the turbine blade and a second sheet metal element placed on the second turbine blade that is held together at the next stop of the first turbine blade. Details are explained in connection with the drawing.

[0029] A particularly preferred embodiment of the invention is described below on the basis of the drawing. It is not intended to present an example of execution while maintaining a scale, but where it is useful to explain, this figure is rather in schematic and / or slightly distorted form. With reference to the supplementation of knowledge resulting directly from the drawing reference is made to the relevant state of the art. In particular, the picture shows:

1 a particularly preferred embodiment of a gas turbine with a flow channel and a preferred embodiment of a steering and swirling bluff in schematic and cross-sectional form;

2 a platform area of ​​a particularly preferred embodiment of the first blade of the first stage of the blades and an axially second blade, the second blade of the second stage of the blades, in a perspective view.

[0030] FIG. 1 shows a gas turbine 1 with a flow channel 5 with an annular cross-section 5 extending along the axis 3 for a working medium M. A number of blade stages are arranged in the flow channel 5. In particular, the second stage 9 of the blades is arranged after the first step 7 of the blades along the axis 3. In addition, after the first stage 11 of the rotor blades there is a second stage 13 of the rotating blades. The rotor vanes 7, 9 have a number of guide vanes 21, arranged annually on the periphery turbine body 15 and extending radially into the flow channel 5. The rotor vanes 11, 13 have a number of rings arranged on the axial rotor 19 of the turbine, incoming radially in the flow channel 5 rotating blades 23. The flow of the working medium M is produced in the form of hot flue gas through the burner 17. According to the annular section of the flow channel 5, a number of such burners 17 are arranged in a not shown in cross section FIG. 1, the annular space around the axis 3.

The guide vane 21 and the rotor blade 23 are schematically depicted in FIG 1. The guide vane 21 has a top 27, a tongue 29 and a platform area 31 arranged along an axis 25. The platform area 31 has a platform 33 extending transverse to the blade axis 25 and a blade foot 35.

[0032] The rotor blade 23 has a tip 37, a tongue 39 disposed along the axis, and a platform area 41. The platform area 41 has a platform 43 extending transverse to the blade axis 45 and a blade foot 47.

[0033] The platform 33 of the guide vane 21 and the platform 43 of the rotor blade 23 form individual restriction parts 49, 51 of the flow channel 5 for the working medium M that flows through the gas turbine 1. The peripheral limit 49 is part of the peripheral turbine body 15. The rotor limit 51 is here part of the turbine rotor 19 rotating in the operating state of the gas turbine 1.

[0034] As schematically indicated in FIG 1 and shown in detail in FIG 2, the platform 33 of the guide vane 21 and the platform 43 of the rotor blade 23 are formed by sheet elements attached to the blade 29, 39 of the spatula.

[0035] FIG. 2 shows platform area 61 instead of platform area 31, 41. The first turbine blade 63 shown in FIG. 2 and the second turbine blade 65 are shown instead of the first guide vane 21 of the first step 7 of the guide vanes and axially positioned directly behind it, the second guide vane 21 of the second stage 9 of the guide vanes. The first turbine blade 63 and the second turbine blade 65 are also shown, instead of the first rotor blade 23 shown in FIG. 1, of the first rotor blade 11 and axially immediately behind it, the second rotor blade 23 of the second stage 13 of the rotor vanes. In the case of the turbine blades 63, 65, however, it is advantageous for guide vanes.

The first turbine blade 63 has a wiper blade 69 shown. A second turbine blade 65 is shown in a ruptured tongue 67. In the case of the first turbine blade 63 and the second turbine blade 65 in the area 61 of the platform on the foot 67, 69 of the blade blade a platform 71 is formed that extends transversely to the blade axes 73, 75. Here, the platform 71 is formed first by the first elastic element 79 shown at the first blade 63, and secondly by the second blade member 77 shown at the second blade 65. The first elastic-elastic element 79 of sheet metal is fixed on the first stop 83 on one side of the blade blade 69, which side is shown at the first turbine blade 63. A second elastic-elastic element 77 of sheet metal is mounted on the second stop 81 on the other side of the blade pad 67, which side is shown at the second turbine blade 65. The fixing can take place, for example, by welding / welding or soldering, and is also airtight. The first stop 83 and the second stop 81 are hereby made in the form of a groove, into which the first elastic-elastic element 79 of sheet metal and the second sheet 77, respectively, extend with the edge ending on the blade blade 69 or the blade blade 67. The second elastic-elastic element 77 of the sheet is further held on a further stop 85 of the second turbine blade 65. In the present embodiment, the second sheet-metal element 77 is attached to the stop 85. Alternatively, or additionally, the second sheet metal body 77 could also act as a distal stop 85. The last embodiment relates to a first elastomeric sheet metal body 79 of the first turbine blade 63 which, together with the second sheet metal element 77, is attached to the distal stop 85 of the second turbine blade 67. For this purpose, the first elastic-elastic element 79 of the sheet loosely follows the next stop 85. The next stop 85 for holding the second sheet 77 from the sheet and the first elastic-elastic sheet element 79 is formed in the form of a support, thus forming on its the side facing the first resilient elastic element 79 of the sheet metal sealing surface, which serves as a thrust bearing for the first elastic-elastic sheet element 79.

[0037] In the above-described manner, between the first turbine blade 63 and the second turbine blade 65 from the first elastic-elastic member 79 from the sheet of the first turbine blade 63 and from the second sheet metal member 77 from the second turbine blade 65, a restriction 87 of the flow channel 5 is formed, the restriction 87 is continuous. In this way, the use of a thin-wall non-load-bearing platform 71 to form a restriction 87 in the form of a second sheet metal element 77 and a first elastic sheet spring 79 allows simultaneous operation of the sheet metal elements 77, 79 as a sealing element. A sealing element of this type is at the same time flexible enough to allow the first turbine blade 63 and the second turbine blade 65 to move adjacent to each other, and yet it has sufficient sealing effect. This saves on one sealing element that would previously be necessary in mutually opposing platforms for sealing partial gaps. In this way, potentially endangered structurally and thermally disadvantageous structures for fastening such a sealing element are avoided.

[0038] In the embodiment shown here, the platform 71 on its rear side 89 largely does not require a supporting structure or supporting walls. On the back side 89, a first cooling space 93 and a second cooling space 91 are formed which allow optimal cooling of the platform 71 in the area between the second turbine blade 65 and the first turbine blade 63. In this way, the construction of the platform edge otherwise having a complicated structure can be made in a simpler and more thermally insensitive manner with respect to the further stop 85. In order to assist cooling in the cooling spaces 91, 93 the feathers 67, 69 of the turbine blades 65, 63 coming out of the bearing beams 95, 97 are made in a shape-optimized manner continued to the blade foot 35, 47 in FIG. 1.

[0039] In dependence on the mode of operation of the first turbine blade 63 and the second turbine blade 65, preferably in the embodiment of the guide blade 1 or possibly also in the form of the rotor blade shown in FIG 1, it comes to a predetermined restriction 85, for sealing operation of the second sheet metal element 77 and the first elastic-elastic sheet element 79. During centrifugation of the turbine blade 65, 63 in the form of a rotor blade 23 on the turbine rotor 19, centrifugal force is produced due to rotation, acting from the blade root 67, 69 in the direction of the blade tongue 67, 69. There is also a drop in pressure, as in the case of the guide blade 21. It is also possible that the first elastic-elastic element 79 from the sheet adheres tightly to the distal stop 85 by means of a pre-stress produced by the first elastic-elastic element 79 from the sheet. In this way, the pressure force generated by the pressure drop can be increased.

During operation, the turbine blade 65, 63 in the form of the guide vanes 21 shown in FIG. 1 on the peripheral turbine body 15 from the rear 89 of the platform 71 is produced by the coolant pressure drop from the blade root 67, 69 in the direction of 99 feathers 67, 69 shoulders. The direction 99 of both the above-mentioned centrifugal force for the rotor blade 23, as well as the pressure drop direction 99 for the guide vane 21 is marked in FIG. 2 by means of an arrow. Depending on the embodiment of the turbine blade 67, 69 as the rotor blade 23 or the guide vane 21, the platform form 71 in the form of elastically flexible elements 77, 79 is pressed by a centrifugal force or a pressure drop to the next stop 85. Thus forming the platform 71 the elements 77, 79 made of sheet metal are fixed by centrifugal force or pressure,

[0041] In summary, to constrain as simple as possible the restriction 87 of the flow channel 5 of the gas turbine 1 in the turbine blade 63, 65 with the feathers 67, 69 along the axis 73, 75 and with the platform area 61 which is placed on the foot of the tongue 67, 69 the blade platform 71, which extends transversely to the blade axes 73, 75, it is proposed that the platform 71 is formed by a sheet metal element 77, 79 attached to the blade 67, 69. The result is also a gas turbine 1 with a flow channel 5 with an annular cross section along the axis 3 of the gas turbine 1, for the working medium M, with the second stage 9, 13 of the blades arranged along the axis 3 behind the first stage 7, 11 of the blades. 7, 9, 11, 13 blades has a number of rings arranged,

List of references [0042] Axis flow channel

7, 9 11, 13 degree of blades directing the degree of blades rotating the gas turbine

9105PL00

ΕΡ 1 706 593 B1 turbine body burner turbine rotor vane guide vane rotating vane axis vane top blade 39 vane blade platform area platform foot vane limitation platform area 65 turbine blade feather vanes platform 75 axle blade sheet element stop limitation limitation back side cooling space supporting structure direction of the working medium

SIEMENS AKTIENGESELLSCHAFT

Proxy:

84P29105PL00

EP 1 706 593 B1