Blade for a turbomachine

Abstract

The invention relates to a blade (1) for a turbomachine, in particular for a stationary gas turbine, comprising at least one blade platform (3) and an airfoil (4) which extends from the at least one blade platform (3) in a radial direction (R) and has an outer wall which defines a front leading edge (6), a rear trailing edge (7), a suction side (8) and a pressure side (9), wherein the airfoil (4) is provided with at least one specifically designed cavity (11) through which a cooling fluid is conducted during operation of the turbomachine. The invention also relates to a casting core (10) for producing such a blade (1).

Description

[0001] 2024PF00753 1

[0002] Description

[0003] Blade for a turbomachine

[0004] The invention relates to a blade for a turbomachine, in particular for a stationary gas turbine, comprising at least one blade platform and a blade extending radially from the at least one blade platform, the blade having an outer wall defining a leading edge, a trailing edge, a suction side, and a pressure side, wherein the blade is provided with at least one cavity through which a cooling fluid is passed during operation of the turbomachine. The invention further relates to a casting core configured for manufacturing such a blade.

[0005] Turbomachinery, for example in the form of stationary gas turbines, is known in the art in a wide variety of configurations. It serves to convert the thermal energy and flow energy of a hot gas into mechanical rotational energy. In the turbine section of the turbomachine, the hot gas is guided through an annular flow channel, internally bounded by a rotor. The turbine section has several turbine stages in the direction of flow, each comprising a stationary guide vane ring and a rotor blade ring attached to the rotor. The guide vanes projecting into the flow channel serve to direct the hot gas flow at the most favorable angle possible onto the downstream rotor blades, which also project into the flow channel, in order to impart the greatest possible force to the rotor blades, thus setting the rotor in motion.The rotational energy of the rotor can then be converted into electrical energy, for example, using a generator. 2024PF00753 2.

[0006] The thermodynamic efficiency of a gas turbine increases with rising turbine inlet temperature of the hot gas. However, the hot gas temperature is limited, among other things, by the thermal stress capacity of the components arranged in the flow channel. One way to achieve the highest possible hot gas inlet temperature is to cool thermally stressed components, such as the guide vanes and rotor blades. The aim is to keep the required cooling fluid mass flow rate as low as possible.

[0007] Rotor blades typically comprise a single blade platform and a blade extending radially from the at least one blade platform, with an outer wall defining a leading edge, a trailing edge, a suction side, and a pressure side, where the terms "front" and "back" refer to the flow direction of the hot gas stream during operation of the turbomachine. Guide blades comprise another blade platform on the opposite side of the blade. The blade of cooled blades is provided with at least one cavity through which a cooling fluid is passed during operation of the turbomachine.In many well-known blade designs, the cavity is designed to meander, so that the cooling fluid is guided radially through the blade from the leading edge to the trailing edge, with each deflection of 180°, and then discharged from the blade through cooling fluid outlet openings provided at the trailing edge.

[0008] However, meandering cavities lead to a strong variation in local flow velocities of the cooling fluid due to the 180° deflections, which is not desirable with regard to uniform cooling of the blade. 2024PF00753 3

[0009] This is desirable. Furthermore, the temperature of the cooling fluid increases depending on the distance traveled within the blade. Consequently, downstream areas of the blade are cooled significantly less effectively than upstream areas. This makes it difficult to address so-called hotspots in downstream areas. Another disadvantage is that meandering cavities are difficult to produce using casting techniques.

[0010] Starting from this state of the art, it is an object of the present invention to create a paddle blade of the type mentioned above with an alternative structure, as well as a casting core for the production of such a paddle blade.

[0011] To solve this problem, the present invention provides a blade for a turbomachine, in particular for a stationary gas turbine, comprising at least one blade platform and a blade extending radially from the at least one blade platform, with an outer wall defining a leading edge, a trailing edge, a suction side and a pressure side, wherein the blade is provided with at least one cavity through which a cooling fluid is passed during operation of the turbomachine, characterized in that the at least one cavity comprises at least one centrally arranged, radially extending, elongated first cavity section, which is provided with a cooling fluid supply opening, and several radially extending sections arranged circumferentially around the at least one first cavity section.elongated second cavity sections, each connected via several radially spaced connecting channels with 2024PF00753 4,

[0012] The at least one first cavity section is connected in such a way that it is supplied with the cooling fluid via this first cavity section. In the blade design according to the invention, all second cavity sections are supplied with the cooling fluid via the at least one centrally arranged first cavity section, which serves as a high-pressure cooling fluid reservoir. By appropriately selecting the position and flow cross-section of the individual connecting channels, the fresh cooling fluid can thus be supplied to the second cavity sections as needed, depending on the local heat load of the blade, particularly also at positions further downstream. In this way, a very homogeneous temperature distribution across the blade and thus very effective cooling can be achieved during operation, which has a positive effect on the blade service life.Another advantage is that the casting core for manufacturing a shovel according to the invention can be produced relatively easily.

[0013] The second cavity sections preferably have an essentially square cross-section with rounded corners.

[0014] According to one embodiment of the present invention, at least seven second cavity sections are provided, which results in a very good distribution of cooling fluid within the blade.

[0015] Preferably, the connecting channels, considering the blade in cross-section, each open into the second cavity sections in such a way that the cooling fluid introduced into the second cavity sections via the connecting channels is subjected to a swirl in the circumferential direction of the second cavity sections, thereby increasing the cooling effect.

[0016] efficiency is improved. In particular, the connecting channels open into the second cavity sections at a position that is offset relative to the center of the cross-section of the corresponding second cavity section in the direction of the circumferential wall of the second cavity section and is chosen such that the cooling fluid enters the corresponding second cavity section parallel to the circumferential wall.

[0017] Advantageously, the circumferential walls of the second cavity sections are provided with flow contours extending in the direction of swirl. Such flow contours, which can be provided in particular in the form of projections or depressions, serve to increase the surface area of ​​the second cavity sections and to maintain the swirl as the cooling fluid moves downstream along the second cavity sections.

[0018] According to one embodiment of the present invention, the second cavity sections, viewed in longitudinal section of the blade, have a cross-section that widens conically with increasing distance from the at least one blade platform, wherein the connecting channels extending from the at least one blade platform are arranged radially, in particular at uniform intervals, and / or have a uniform flow cross-section. In this embodiment, the at least one first cavity section, viewed in longitudinal section of the blade, can have a cross-section that tapers conically with increasing distance from the at least one blade platform.

[0019] According to a further embodiment of the present invention, the second cavity sections, considering the blade in longitudinal section, have a cross-section which is at least substantially constant starting from the at least one blade platform, wherein the 2024PF00753 6

[0020] Connecting channels extending radially from the at least one blade platform are arranged, particularly at increasing intervals, wherein the flow cross-sections of the connecting channels preferably increase in the radial direction extending from the at least one blade platform. In this embodiment, the at least one first cavity section, considering the blade in longitudinal section, can have a cross-section that is at least substantially constant extending from the at least one blade platform.

[0021] Preferably, the second cavity sections open into a third cavity section located on the opposite side of the blade from the cooling fluid supply opening. This third cavity section extends in a front-to-back direction and directs the cooling fluid towards the trailing edge. The cross-section of the third cavity section can widen towards the trailing edge, particularly conically, in the manner of a diffuser.

[0022] Advantageously, the third cavity section has cooling fluid outlet openings, which in the case of a rotor blade are designed in such a way that they release the cooling fluid from the blade in the direction of the blade tip.

[0023] Preferably, a fourth cavity section extending radially towards the at least one blade platform is connected to an end of the third cavity section pointing towards the downstream edge. Several cooling fluid discharge channels, spaced apart from one another in a radial direction, branch off from this fourth cavity section. These channels extend in the front-to-back direction towards the downstream edge and form cooling fluid outlet openings there. Instead of the cooling fluid discharge channels, the fourth cavity section can also contain a 2024PF00753 7

[0024] so-called pin-fin arrays, through which the cooling fluid is released from the blade towards the trailing edge.

[0025] Advantageously, the third cavity section and / or the fourth cavity section are connected to the first cavity section via connecting channels so that fresh cooling fluid can also be supplied to them.

[0026] To solve the aforementioned problem, the present invention further provides a casting core designed for the production of a shovel according to the invention.

[0027] Further features and advantages of the present invention will become clear from the following description with reference to the accompanying drawing. Therein is

[0028] Figure 1 shows a schematic perspective view of a running blade according to one embodiment of the present invention;

[0029] Figure 2 shows a schematic perspective view of a casting core for the production of the running blade shown in Figure 1;

[0030] Figure 3 shows a schematic sectional view along line III-III in Figure 2;

[0031] Figure 4 shows a schematic sectional view along line IV-IV in Figure 3 and

[0032] Figure 5 is a schematic sectional view analogous to Figure 4 according to a variant of the invention.

[0033] The blade 1 shown in Figure 1, which in this case is a rotor blade of a stationary gas turbine 2024PF00753 8

[0034] The assembly comprises a blade root 2, a blade platform 3, and a blade 4 extending radially outward from the blade platform 3, with a blade tip 5. The blade 4 has an outer wall that defines a leading edge 6, a trailing edge 7, a suction side 8, and a pressure side 9. It should be noted that the blade 1 can also be a guide vane. The type of turbomachine in which the blade 1 is used can also vary.

[0035] To cool the blade 1, the blade 4, as shown in Figures 2 to 4 with reference to the casting core 10 shown therein, is provided with at least one cavity 11 through which a cooling fluid is passed during the operation of the turbomachine.The cavity 11 comprises a centrally arranged, radially extending, elongated first cavity section 12, radially extending, elongated second cavity sections 13 distributed around the first cavity section 12, which are fluidically connected to the first cavity section 12 via connecting channels 14, a third cavity section 15 extending in a front-back direction along the blade tip 5, into which the second cavity sections 13 open, and a fourth cavity section 16 extending radially from the third cavity section 15 towards the blade platform 3.

[0036] The first cavity section 12 is provided at its lower end with a cooling fluid supply opening 17, through which a cooling fluid is supplied to the blade 1 from the outside during operation. 2024PF00753 9

[0037] The connecting channels 14, each extending at least substantially in the front-to-back plane, are arranged at a distance from one another in the radial direction R and connected to the first cavity section 12 such that they are supplied with the cooling fluid via the first cavity section 12. The number of connecting channels 14, the distances between them, and their respective flow cross-sections are selected depending on the cooling requirements. In particular, the number of connecting channels 14, the distances between them, and their respective flow cross-sections should be selected such that maximum pressure is maintained in the second cavity sections 13 while maximizing heat transfer.Figure 4 shows a variant in which the second cavity sections 13, viewed in longitudinal section of the blade, each have cross-sections that widen conically with increasing distance from the at least one blade platform 3. In this variant, the connecting channels 14 extending radially from the blade platform 3 are preferably arranged at uniform intervals and, in particular, have a uniform flow cross-section. The first cavity section 12, viewed in longitudinal section of the blade 4, has, in the illustrated embodiment, a cross-section that tapers conically with increasing distance from the at least one blade platform 3, although this is not mandatory.Figure 5 shows another variant in which the second cavity sections 13, viewed in longitudinal section from the blade 4, have a cross-section that is at least substantially constant starting from the at least one blade platform 3. The connecting channels 14 are arranged here at increasing intervals in the radial direction R starting from the blade platform 3, with the flow cross-sections of the connecting channels 14 in the radial direction R starting from the at least one 2024PF00753 10.

[0038] The blade platform 3 is preferably larger. Here, the first cavity section 12, viewed in longitudinal section as the blade 4, can also have a cross-section that is at least substantially constant starting from the at least one blade platform 3. As shown in Figure 3, the connecting channels 14 open, viewed in cross-section as the blade 4, into the second cavity sections 13 near their circumferential wall in such a way that the cooling fluid introduced into the second cavity sections 13 via the connecting channels 14 is subjected to a swirl 18 directed in the circumferential direction of the second cavity sections 13.In particular, the connecting channels 14 open into the second cavity sections 13 at a position which is offset in the direction of the circumferential wall of the second cavity section 13 with respect to the center of the cross-section of the corresponding second cavity section 13 and is selected such that the cooling fluid enters the corresponding second cavity section 13 parallel to the circumferential wall.

[0039] The cross-sections of the second cavity section are essentially square with rounded corners. The circumferential walls of the second cavity sections 13 are provided with flow contours 19 extending in the swirl direction. These contours serve to increase the surface area of ​​the second cavity sections 13 and to maintain the swirl generated by the circumferential introduction of the cooling fluid as the cooling fluid flows through the second cavity sections 13. The swirl increases the residence time of the cooling fluid within the second cavity sections 13, thereby achieving optimal cooling.

[0040] The third cavity section 15 may, although not shown here, have cooling fluid outlet openings through which cooling fluid flows over the blade tip 52024PF00753 11

[0041] from the blade 4. Furthermore, the cross-section of the third cavity section can widen towards the trailing edge in the manner of a diffuser, in particular conically.

[0042] From the fourth cavity section 16, several cooling fluid discharge channels 20 branch off in the radial direction R at intervals from each other, extending in the front-back direction to the outflow edge 7 and forming cooling fluid outlet openings 21 there, through which the cooling fluid is discharged from the blade 4.

[0043] In principle, although not shown here, it is possible to provide an additional fifth cavity section, which connects to the lower end of the fourth cavity section 16 and extends radially R back towards the blade tip 5. In the case of such a fifth cavity section, the aforementioned cooling fluid discharge channels 20 branch off from this fifth cavity section, which is located immediately adjacent to the trailing edge 7. It is also possible to provide a pin-fin array instead of the cooling fluid discharge channels 20, through which the cooling fluid is discharged from the blade 4 towards the trailing edge 7.

[0044] The third cavity section 15 and / or the fourth cavity section 16 and / or the fifth cavity section can be connected to the first cavity section 12 via connecting channels in order to supply it with fresh cooling fluid, although this is not the case here.

[0045] During operation in the turbomachine, as shown in Figures 2 and 3, a cooling fluid, for example in the form of cooling air, is introduced into the central first cavity section 12 in the direction of arrow 22. This forms a pressurized cooling fluid reservoir from which the cooling fluid flows via the 2024PF00753 12

[0046] The cooling fluid is distributed to the second cavity sections 13 via connecting channels 14 as required, as indicated by arrows 23. The cooling fluid is supplied to the second cavity sections in the radial direction R at various heights, ensuring that even downstream positions of the second cavity sections 13 are supplied with fresh cooling fluid according to their cooling requirements. The cooling fluid flows through the second cavity sections in the direction of arrows 24, ideally with maximum cooling capacity and minimal pressure loss, then enters the third cavity section 15 and is guided along the blade tip 5 in the direction of arrow 25 to the fourth cavity section 16.In the fourth cavity section 16, the cooling fluid flows radially in direction R in the direction of arrow 26 back towards the blade platform 3 and is distributed onto the individual cooling fluid discharge channels 20, in which it is discharged in the direction of arrows 27 to the outflow edge 6 and through the cooling fluid outlet openings 21 from the blade 4.

[0047] The blade design according to the invention is advantageous in that all second cavity sections 13 are supplied with the cooling fluid via the centrally arranged first cavity section 12. By appropriately selecting the position and flow cross-section of the individual connecting channels 14, the fresh cooling fluid can thus be supplied to the second cavity sections 13 as required, depending on the local heat load of the blade 1, particularly also at positions further downstream. Since the conventional meandering cavity design is replaced according to the invention by a plurality of second cavity sections, which are supplied with cooling fluid via the at least one central first cavity section and are subjected to a swirl, a very homogeneous temperature distribution over the blade can be achieved during operation.

[0048] A very effective cooling system can be implemented, which has a positive effect on the blade service life. The cooling fluid requirement can also be reduced. A further advantage is that the casting core 10 for manufacturing a blade 1 according to the invention can be produced relatively easily. It should be noted that the blade 1 and / or the casting core 10 according to the invention can, of course, also be manufactured additively.

[0049] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention.

[0050] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

2024PF00753 14 Patentansprüche 1. A blade (1) for a turbomachine, in particular for a stationary gas turbine, comprising at least one blade platform (3) and a blade (4) extending radially (R) from the at least one blade platform (3) with an outer wall defining a leading edge (6), a trailing edge (7), a suction side (8) and a pressure side (9), wherein the blade (4) is provided with at least one cavity (11) through which a cooling fluid is passed during operation of the turbomachine, characterized in that the at least one cavity (11) comprises at least one centrally arranged, radially (R) extending, elongated first cavity section (12) which is provided with a cooling fluid supply opening (17), and several cavities surrounding the at least one first cavity section (12). ) distributed,having elongated second cavity sections (13) extending in the radial direction (R), each of which is connected to the at least one first cavity section (12) via several connecting channels (14) arranged at intervals in the radial direction (R) such that they are supplied with the cooling fluid supplied to the at least one first cavity section (12) via the at least one first cavity section (12).

2. Shovel ( 1 ) according to claim 1 , characterized in that at least seven second cavity sections ( 13 ) are provided .

3. Blade (1) according to claim 1 or 2, characterized in that the connecting channels (14), considering the blade (4) in cross-section, each open into the second cavity sections (13) such that the cooling fluid introduced into the second cavity sections (13) via the connecting channels (14) is given a swirl (18) 2024PF00753 15 is acted upon in the circumferential direction of the second cavity sections ( 13).

4. Blade ( 1 ) according to claim 3, characterized in that the circumferential walls of the second cavity sections ( 13) are provided with flow contours ( 18 ) extending in the direction of the swirl.

5. Blade ( 1 ) according to one of the preceding claims, characterized in that the second cavity sections ( 13) , considering the blade (4 ) in longitudinal section, have a cross-section which widens conically with increasing distance from the at least one blade platform (3), and that the connecting channels ( 14 ) starting from the at least one blade platform (3) in radial direction (R) are arranged in particular at uniform intervals and / or have a uniform flow cross-section.

6. Blade ( 1 ) according to one of claims 1 to 4, characterized in that the second cavity sections ( 13 ) have a cross-section which is at least substantially constant starting from the at least one blade platform (3), wherein the connecting channels ( 14 ) are arranged in the radial direction (R) starting from the at least one blade platform (3) in particular at increasing intervals, wherein the flow cross-sections of the connecting channels ( 14 ) preferably increase in the radial direction (R) starting from the at least one blade platform (3).

7. Blade ( 1 ) according to one of the preceding claims, characterized in that the second cavity sections ( 13 ) are arranged in a blade side opposite the cooling fluid supply opening ( 17 ), extending in 2024PF00753 16 the third cavity section ( 15) extending in the front-to-back direction, which directs the cooling fluid towards the outflow edge (7 ).

8. Blade ( 1 ) according to claim 7, characterized in that the third cavity section ( 15) has cooling fluid outlet openings .

9. Blade ( 1 ) according to claim 7 or 8, characterized in that a fourth cavity section ( 16) extending radially in the direction of the at least one blade platform (3) is connected to an end of the third cavity section ( 15) pointing towards the outflow edge (7 ), from which several cooling fluid discharge channels (20) arranged at intervals in the radial direction (R) branch off, extending in the front-back direction towards the outflow edge (7 ) and forming cooling fluid outlet openings (21 ) there.

10. Blade ( 1 ) according to claim 7 or 8, characterized in that a fourth cavity section ( 16) extending radially in the direction of the at least one blade platform (3) is connected to an end of the third cavity section ( 15) pointing towards the outflow edge (7 ) and comprising a pin-fin array .

11. Shovel ( 1 ) according to one of claims 7 to 10, characterized in that the third cavity section ( 15) and / or the fourth cavity section ( 16) are connected to the first cavity section ( 12 ) via connecting channels.

12. Casting core ( 10) , which is designed for the production of a shovel ( 1 ) according to one of the preceding claims .

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