Reinforcement and cooling structure of a turbine blade

Abstract

The invention relates to a blade (13, 14) for a turbine (10) which has at least one channel (22) that can be impinged with a coolant fluid. Several turbulators (23) which improve the heat exchange between the wall (19, 20) and the coolant fluid are provided on at least one wall (19, 20) of the channel (22). In addition, the turbulators (23) reinforce the wall (19; 20) and converge. As a result of said reinforcement, the thickness (d) of the wall (19, 20) in the area between the turbulators (23) can be reduced.

Description

[0001] The present invention relates to a blade/vane, in particular a turbine blade/vane, having at least one duct, which is bounded by walls and to which a cooling fluid can be admitted, a plurality of turbulators being provided on at least one wall to improve the heat exchange between the wall and the cooling fluid.

[0002] Such a turbine blade/vane is known, for example, from EP 0 758 932 B1. This known turbine blade/vane has a hollow configuration and four ducts. The ducts are respectively bounded by the two outer walls of the turbine blade/vane and by separating walls and a cooling fluid flows through them for cooling purposes. The outer walls are provided with turbulators in order to improve the heat exchange between the outer walls and the cooling fluid.

[0003] In the known turbine blades/vanes, the turbulators are only used to improve the heat exchange. The loads on the turbine blades/vanes occurring in operation are accepted, almost exclusively, by the outer walls which must, in consequence, have a relatively thick configuration. When the load is increased, the wall thickness of the external walls must be further increased. Due to this increase in the wall thickness, however, the cooling efficiency, and therefore the overall efficiency, are reduced.

[0004] The object of the present invention is, therefore, to make available a blade/vane which permits a higher load-carrying capability without increasing the wall thickness or, alternatively, permits a reduction in the wall thickness for the same load-carrying capability.

[0005] In order to achieve this object, according to the invention, in a blade/vane of the type mentioned at the beginning, provision is made for the turbulators to merge into one another and to be used to reinforce the wall.

[0006] According to the invention and for the first time, the turbulators merge into one another and are used to reinforce the walls. By this means, substantially increased reinforcement is achieved without additional material and without increasing the wall thickness. At the same time, good heat transfer is achieved between the walls and the cooling fluid. There is, therefore, a high cooling efficiency and a high overall efficiency. The reinforcement of the wall does not only occur in the region of an individual turbulator. The connection of the turbulators with one another does, rather, make large-area reinforcement available.

[0007] Advantageous embodiments and developments of the invention are given in the dependent claims. The turbulators have, advantageously, a straight configuration. The use of straight turbulators permits a high level of reinforcement in conjunction with simple manufacture.

[0008] In an advantageous first embodiment, all the turbulators include the same angle with a longitudinal center line of the blade/vane. This provides a symmetrical arrangement of the turbulators, which arrangement can accept the loads uniformly from all directions.

[0009] In an advantageous development, the turbulators include a right angle. As an alternative, an acute or obtuse angle can also be selected.

[0010] According to an advantageous second embodiment, a first group of turbulators includes a first angle with a longitudinal center line of the blade/vane and a second group of turbulators includes a second angle with the longitudinal axis of the blade/vane.

[0011] The two groups of turbulators therefore have different inclinations relative to the longitudinal center line of the blade/vane. The reinforcement of the blade/vane therefore depends on the angle of attack of the load. A specific matching of the reinforcement in different directions can therefore be achieved by the different inclinations.

[0012] The turbulators are advantageously arranged in such a way that they form recesses located adjacent to one another and above one another in the form of polygons, in particular squares, rhombuses or hexagons. The inner surface of the wall is provided with a honeycomb structure. The individual polygons or honeycombs respectively form a closed, highly loadable cross section and mutually support one another. A substantial increase in the reinforcement can be achieved.

[0013] In an advantageous development, the thickness of the wall is reduced, at least in the region between the turbulators. This reduction in the wall thickness is made possible by the fact that the turbulators effect a reinforcement of the wall. The cooling efficiency is further increased by the reduction in the wall thickness. During the casting of the blade/vane, the turbulators can, in this arrangement, be advantageously used as metal feed ducts. The honeycomb structure can therefore be easily manufactured.

[0014] According to an advantageous embodiment, the blade/vane has a plurality of sections provided with different arrangements of turbulators. The reinforcement of the blade can be specifically influenced in the individual sections by these different arrangements. The result is optimum matching to the loads present in the individual section of the blade/vane.

[0015] In an advantageous, first development, the sections are at a distance from one another. This permits a simple transition between different arrangements of turbulators.

[0016] According to a second advantageous development, the sections merge into one another. There is a continuous increase in the reinforcement of the blade/vane.

[0017] The blade/vane according to the invention can be configured as a guide vane or as rotor a blade of a turbomachine.

[0018] The invention is described in more detail below using exemplary embodiments, which are diagrammatically represented in the drawing. The same designations are used throughout for similar or functionally identical components. In the drawing:

[0019] FIG. 1 shows a longitudinal section through a turbomachine;

[0020] FIG. 2 shows a perspective, exploded representation of a blade/vane;

[0021] FIG. 3 shows an enlarged representation of the detail X from FIG. 2;

[0022] FIG. 4 shows an end view onto the inner surface of an outer wall of the blade/vane, in a first embodiment;

[0023] FIG. 5 shows a view similar to FIG. 4 in a second embodiment;

[0024] FIG. 6 shows a view similar to FIG. 4 in a third embodiment;

[0025] FIG. 7 shows a diagrammatic representation of a rotor blade; and

[0026] FIG. 8 shows a diagrammatic representation of a guide vane.

[0027] FIG. 1 shows a longitudinal section through a turbomachine in the form of a turbine 10 with a casing 11 and a rotor 12. The casing 11 is provided with guide vanes 13 and the rotor 12 is provided with rotor blades 14. In operation, fluid flows through the turbine 10 in the arrow direction 15, which fluid flows along the guide vanes 13 and rotor blades 14 and sets the rotor 12 into rotation about a center line 16.

[0028] In many applications, the temperature of the fluid is relatively high, particularly in the region of the first blading row (shown on the left in FIG. 1). For this reason, cooling is provided for the guide vanes 13 and rotor blades 14. The flow of the cooling fluid is diagrammatically indicated by the arrows 17, 18. Air, in particular, can be used as the cooling fluid.

[0029] FIG. 2 shows, diagrammatically, an exploded representation of a guide vane 13. The guide vane 13 has curved outer walls, 19, 20. The internal space located between the outer walls 19, 20 is subdivided into a total of three ducts 22 by means of two separating walls 21. In operation, a cooling fluid is admitted to the ducts 22.

[0030] In order to improve the heat exchange between the outer walls 19, 20 and the cooling fluid, the outer walls 19, 20 are provided with a plurality of turbulators 23. For reasons of drawing representation, the turbulators 23 in FIG. 2 are represented in an extremely simplified manner. It can, however, be seen that the turbulators 23 merge into one another and form a honeycomb structure. This honeycomb structure produces reinforcement of the outer walls 19, 20.

[0031] FIG. 3 shows an enlarged representation of the detail X from FIG. 2. The turbulators 23 have a straight configuration and merge into one another. In the exemplary embodiment represented, each recess 24 is bounded by four turbulators. The wall thickness d of the outer wall 19 is continually reduced, starting from the turbulators 23, as far as the center of the recess 24. This reduction in the wall thickness d is made possible because the turbulators 23 support one another and, by this means, substantially increase the reinforcement of the guide vane 13. At the same time, the turbulators 23 act as an impact protection.

[0032] Because of the reduced wall thickness d, the cooling efficiency is increased. In consequence, less cooling fluid is required so that a higher overall efficiency of the turbine 10 can be achieved.

[0033] The turbulators 23 have an approximately triangular configuration in cross section and taper, starting from the outer wall 19. During the casting of the guide vane 13, therefore, they can be used as metal feed ducts. The guide vane 13 according to the invention is, therefore, easy to manufacture.

[0034] FIGS. 4 to 6 show a diagrammatic end view onto the inside of the outer wall 19, in three different embodiments. In the embodiment of FIG. 4, all the turbulators 23a, 23b include the same angle &agr;, &bgr;, with a center line 25 of the guide vane 13. The turbulators 23a, 2b include, between them, a right angle 26. The recesses 24 bounded by the turbulators 23a, 23b therefore form squares.

[0035] A turbulator 23a, 23b extends between two contact points 31 in each case. In the region of the contact points 31, the turbulators 23a, 23b merge into one another. The use of straight turbulators 23a, 23b simplifies the manufacture. In addition, increased reinforcement is produced.

[0036] In the embodiment of FIG. 5, a first group of turbulators 23a includes a first angle &agr; with the longitudinal center line 25, whereas a second group of turbulators 23b includes a second angle &bgr; with the longitudinal axis 25. In this embodiment, the angle 26 between the turbulators is greater than 90°. The result, correspondingly, is a recess 24 in the form of a rhombus. The different inclination of the turbulators 23a, 23b relative to the longitudinal axis, results in a different reinforcement of the guide vane 13, depending on the direction of the load.

[0037] Good matching to different boundary conditions is therefore achieved.

[0038] In the embodiment of FIG. 6, six turbulators 23 form a recess 24 in the form of a hexagon in each case. The result is a honeycomb structure which substantially increases the reinforcement of the guide vane 13.

[0039] Other appropriate arrangements of turbulators 23 can, of course, be used. The turbulators 23 are advantageously arranged in such a way that the recesses 24 represented in FIGS. 4 to 6 are produced. In the end view, these recesses 24 have a closed cross section and, therefore, a high level of reinforcement. As an alternative, the turbulators 23 can also be arranged in the form of a V or X.

[0040] The turbulators 23 can also, of course, be provided in the case of a rotor blade 14. FIG. 7 shows, diagrammatically, such a rotor blade 14, which has a plurality of sections 28, 29, 30 provided with different arrangements of turbulators 23. The arrangement of the section 28 corresponds, in this case, to the representation of FIG. 4, whereas the sections 29, 30 correspond to the configurations of FIGS. 5 and 6. The individual sections 28, 29, 30 are at a distance from one another. Cross-sectional and shape changes of the rotor blade 14 can be undertaken, with little manufacturing outlay, in the region between the sections 28, 29, 30. In order to achieve the necessary reinforcement, the wall thickness d of the outer walls 19, 20 is correspondingly increased in these transition regions. The use of different arrangements of turbulators 23 permits the reinforcement of the blade 14 to be specifically influenced in the individual sections 28, 29, 30. The result is, therefore, optimum matching to different boundary conditions along the longitudinal center line 25.

[0041] The sections 28, 29, 30 can also merge into one another, as is diagrammatically represented using a guide vane 13 in FIG. 8. In this case, the turbulators 23 of the individual sections 28, 29, 30 merge into one another at contact points (not represented in any more detail). The result, therefore, is a continuous reinforcement of the guide vane 13 along its longitudinal center line 25.

[0042] The present invention permits an increase in the reinforcement by means of a specific arrangement of the turbulators provided to improve the heat exchange. For the same load, the wall thickness d of the outer walls 19, 20 can be reduced. The cooling efficiency is increased by this reduction in the wall thickness so that this results in, overall, a higher overall efficiency of the turbine 10.

Claims

1. A blade/vane, in particular a turbine blade/vane (13; 14), having at least one duct (22), which is bounded by walls (19, 20, 21) and to which a cooling fluid can be admitted, a plurality of turbulators (23) being provided on at least one wall (19; 20) to improve the heat exchange between the wall (19; 20) and the cooling fluid, characterized in that the turbulators (23) merge into one another and are used to reinforce the wall (19; 20).

2. The blade/vane as claimed in claim 1, characterized in that the turbulators (23) have a straight configuration.

3. The blade/vane as claimed in claim 2, characterized in that all the turbulators (23a, 23b) include the same angle (&agr;, &bgr;) with a longitudinal center line (25) of the blade/vane (13; 14).

4. The blade/vane as claimed in claim 2 or 3, characterized in that the turbulators (23a, 23b) include a right angle (26).

5. The blade/vane as claimed in claim 2, characterized in that a first group of turbulators (23a) includes a first angle (&agr;) with a longitudinal center line (25) of the blade/vane (13; 14) and a second group of turbulators (23b) includes a second angle (&bgr;) with the longitudinal center line (25) of the blade/vane (13; 14).

6. The blade/vane as claimed in one of claims 2 to 5, characterized in that the turbulators (23) are arranged in such a way that they form recesses located adjacent to one another and above one another in the form of polygons, in particular squares, rhombuses or hexagons.

7. The blade/vane as claimed in one of claims 1 to 6, characterized in that the wall thickness (d) of the wall (19; 20) is reduced, at least in the region between the turbulators (23).

8. The blade/vane as claimed in one of claims 1 to 7, characterized in that the blade/vane (13; 14) has a plurality of sections (28, 29, 30) provided with different arrangements of turbulators (23).

9. The blade/vane as claimed in claim 8, characterized in that the sections (28, 29, 30) are at a distance from one another.

10. The blade/vane as claimed in claim 8, characterized in that the sections (28, 29, 30) merge into one another.

11. The blade/vane as claimed in one of claims 1 to 10, characterized in that the blade is configured as a guide vane (13) or as a rotor blade (14) of a turbomachine (10).