AU2005201225B2

AU2005201225B2 - Turbomachine component having a cooling arrangement

Info

Publication number: AU2005201225B2
Application number: AU2005201225A
Authority: AU
Inventors: Ulrich Rathmann; Ingolf Schulz
Original assignee: Alstom Technology AG
Current assignee: General Electric Technology GmbH
Priority date: 2004-03-23
Filing date: 2005-03-22
Publication date: 2011-09-01
Anticipated expiration: 2025-03-22
Also published as: DE102004014117A1; EP1580414A3; MY147657A; AU2005201225A1; CN1769653A; EP1580414A2; CN100425812C

Abstract

The present invention relates to a turbomachine component (1), in particular a heat shield segment of a gas turbine, said component having a cooling arrangement which has at least one cooling duct for the leadthrough of a cooling medium at or in the component (1) . The component (1) is distinguished in that the cooling duct is formed by a tube (2) having an inside diameter of > 4 mm and fastened to the component (1). With the present component, individual regions of the component can be cooled in a controlled manner, along with a reduced leakage rate of the cooling medium.

Description

AUSTRALIA Patents Act 1990 ALSTOM TECHNOLOGY LTD COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Turbomachine component having a cooling arrangement The following statement is a full description of this invention including the best method of performing it known to us:- 1A Technical field 5 Described embodiments relate to a component of a turbomachine, in particular of a gas turbine, said component having a cooling arrangement which has at least one cooling duct for the leadthrough of a cooling medium at or in the component. 10 Background When turbomachines, in particular gas turbines, are in operation, high temperatures occur which subject individual components of the turbines to severe load. With the development of gas turbines of ever-increasing performance, 15 temperatures are reached which even exceed the melting point of the material of individual turbine components. To prevent damage to these components on account of the high operating temperatures, these have to be constantly cooled during operation. For this purpose, cooling ducts within these turbine components are provided, via which a cooling medium, as a rule sucked-in compressor air, is 20 led past the locations to be cooled. In addition to convective cooling, in which cooling ducts run directly by the regions to be cooled, for example in cooling ducts within a blade leaf, impact cooling and film cooling are also adopted. In impact cooling, the cooling air impacts approximately perpendicularly onto the surface to be cooled, while, in film cooling, it brushes approximately tangentially over the 25 surface and forms a thin cooling air film there. The cooling arrangements formed by the cooling ducts constitute, as a rule, open systems in which the medium flows via bores or orifices from one cavity to another cavity of the same or of another component. This may, 2 however, lead to high leakage rates of the cooling medium owing to the extensive boundary surfaces. One example of components to be cooled is heat shield segments which protect the 5 outer carrier structure of the turbine, for example the carrier for the turbine guide blades, from direct contact with the hot gas. Depending on the alloy material of the heat shield, on the temperatures occurring during operation and on the design, it may or may not be necessary to cool the heat shield. For cooling such a component of the gas turbine, known systems employ the already mentioned cooling 10 arrangements in which the cooling air flows via cavities and connecting orifices, in particular cooling air bores, formed by the components or as a result of the interaction of the components of the turbine plant. In this case, because of the cooling air flowing through, the boundary surfaces of the cavities are also cooled, even if this is not desirable or not desirable in the entire region of the component. 15 Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before 20 the priority date of each claim of this application. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the 25 exclusion of any other element, integer or step, or group of elements, integers or steps. Summary 30 Some embodiments relate to a system of a gas turbine, said system comprising: a heat shield; a cooling arrangement which has at least one cooling duct for the leadthrough of a cooling medium at or in the heat shield; wherein the cooling duct is formed by a tube having an inside diameter 3 between about 70mm and about 4 mm, the tube being fastened to the heat shield and defining a single flow path between one inlet of the tube and one outlet of the tube; wherein at least individual tube portions are designed to be flexible, in order 5 to compensate operationally induced deformations of the component; wherein the tube has at least two curved tube portions, of which a first tube portion lies in a first plane and a second tube portion lies in a second plane, the two planes forming an angle of between 20 and 170'; and wherein the outlet of the tube directs the cooling medium to one or more of: 10 a localised region in or around the heat shield; and a localised region around a blade tip of the gas turbine. Some embodiments relate to a component of a turbomachine, in particular of a gas turbine, for example where the component has a cooling arrangement which allows 15 a more controlled cooling, along with a lower leakage rate. Some embodiments relate to a turbomachine component having a cooling arrangement which has at least one cooling duct for the leadthrough of a cooling medium at or in the component, wherein the cooling duct is formed by a tube 20 having an inside diameter of > 4 mm and fastened to the component. In contrast to known solutions in which cooling ducts are formed as a result of the shaping of the component itself, in particular by means of cavities formed in the component or in interaction with an adjacent component, if appropriate with a 25 corresponding arrangement of webs, the present component comprises separately produced and shaped tubes which are fastened to or in the component. Fastening may in this case take place, for example, by hard soldering, welding or adhesive bonding or by any other suitable mechanical connection. The component itself may, for example, constitute a heat shield segment, but also any other rotating or 30 static turbomachine component to be cooled, in which only a local limited region is to be cooled or the cooling medium is to be lead merely through the component to the cooling arrangement of another component to be cooled, that is to say is to issue into a secondary cooling system.

3A With the present component, the controlled cooling of only part of this component or the transport of the cooling medium, without the cooling of the component, into 4 a secondary cooling system becomes possible. Extensive boundary surfaces for leading the cooling medium are in this case avoided, thus resulting in a leakage rate which is reduced, as compared with known solutions. It is precisely heat shield segments, additionally possessing mechanical functions, for example for fastening 5 the guide blades, which also have an appreciable radial extent. The temperature gradients caused due to large-area contact with the cooling medium are very high and lead to undesirably pronounced thermal deformations of this part. Owing to the configuration of such a heat shield according to described embodiments, it is possible to lead the cooling medium solely to those surfaces to be cooled which are 10 near the hot gas path, without the regions of the heat shield which lie further outward radially being cooled appreciably. In a preferred refinement, the one or more tubes of the cooling arrangement are designed to be at least partially flexible or elastic, so that thermally induced 15 fluctuations in expansion of the component can be followed or compensated. Several possibilities are appropriate for this purpose. Thus, the tubes may have a multiply curved or coiled shape, in particular also run helically or spirally. Furthermore, individual portions of the tubes may form bellows, so that flexibility in a predominantly axial direction of the tubes is achieved. In a further refinement, 20 locations of connection of the tubes to the component may be connected to sliding joints, in particular at locations where the tubes are led through a wall of the component. Such a leadthrough may also be provided with an additional seal. Furthermore, it is possible to assemble the tubes in a component from a plurality of tube parts. In this case, it is also possible for sliding joints to be used as a 25 connection between individual tube parts. The component on one side and the tube or tubes of the cooling arrangement on the other side may be produced independently of one another by means of different techniques, for example by casting, by cutting shaping, by semicold or 30 coldforming or by similar known techniques. In the case of tubes composed of individual sections, these can likewise be connected to one another via conventional techniques, such as, for example, hard soldering, welding or other mechanical connection techniques.

5 Individual tubes may in this case vary in their inside diameter over the tube length, depending on requirements. The cross-sectional shape of the inside diameter may also be suitably optimized. Thus, the tubes may have a circular inner cross section, for example, in rectilinear portions, while they have an elliptical or ellipse-like 5 design in curved regions. A secondary cooling system to which the tubes lead the cooling medium may, of course, employ the most diverse possible known cooling techniques, that is to say convective cooling, impact cooling or film cooling. It may be formed in the 10 component itself in a known way or else in or on an adjacent component. Brief description of the drawings Embodiments are explained once again in more detail below, by way of example, 15 in conjunction with the drawings in which: fig. I shows a first example of embodiments of the component having the cooling arrangement; 20 fig. 2 shows alternative embodiments of the component for the purpose of cooling the blade cover band; fig. 3 shows a second example of embodiments of the component having the cooling arrangement; 25 fig. 4 shows an example of the shape of a cooling tube used; fig. 5 shows the tube of fig. 4 in three different views; 30 fig. 6 shows an example of the cross section of the tube in a curve. Detailed Description Figure 1 shows a first example of an embodiment of the present components 6 having the cooling arrangement. The cooling arrangement is composed, in this example, of a multiply bent tube 2 which is fastened at its first end to an inlet orifice 4 of the component, a heat shield 1, and which conducts the cooling air to a region of the component I which lies on the hot gas path of the turbine. The path 5 of the cooling air is indicated by the arrows illustrated in the figure. The cooling air emerges via the orifices 3 in the component 1 into the hot gas path and cools this region of the component on the outside. In a conventional construction of a turbine, of course, a plurality of these tubes are arranged in the heat shield 1 so as to be distributed over the circumference of the hot gas path. 10 Owing to the closed routing of the cooling air in the tube 2, the remaining parts of the component 1 are not cooled, so that markedly lower temperature gradients occur in the component in the radial direction. Since the cooling air also does not occupy the entire inner space of the components 1, the leakage rates are markedly 15 reduced, as compared with an embodiment of this type. In the present example, the tube 2 is connected to the component I via a hard-soldered sleeve 9 in the inlet orifice 4. The seals 5, into which blade leaf tips of the turbine engage during operation, can also be seen at that region of the component I which lies on the hot gas path. 20 This is illustrated in figure 2 which shows part of a blade leaf 6 for the turbine in engagement with the seals 5. In this example, the heat shield I is not cooled or is only insignificantly cooled. Instead, the tube 2 is utilized in order to employ the cooling air directly for cooling the tip of the blade leaf 6. This -7 is illustrated by the arrow which can be seen in the figure which indicates the cooling air which emerges from the tube 2 and impinges onto the tip of the blade leaf 6. 5 Figure 3 shows a further example of an embodiment of the present component, in which the tube 2 has, in the upper region, a portion which is designed as a bellows 7 and which allows an axial expansion of the tube 2. 10 This axial expansion may be necessary in order to follow or compensate a different expansion of the component 1 caused in the same direction on account of temperature fluctuations. The figure also illustrates, furthermore, a possibility of expansion in the radial 15 direction, which is implemented by means of a sliding joint 8 (slip joint), by means of which the outlet end of the tube 2 is connected to the component 1. In this embodiment, a reduction in the cross section of the tube 2 brought about by the sliding joint 8 can be 20 seen, this reduction leading to higher outflow velocities of the cooling air from the tube 2. In the present examples, the tube 2 has a doubly curved shape, as can be seen in figure 4. As a result of this 25 doubly curved shape, in which, in this example, the curves lie in two planes perpendicular to one another, some flexibility of the tube 2 is likewise achieved. The basic possibilities for the configuration of a doubly curved shape of this type are illustrated by 30 means of figure 5 which shows a tube 2 of the type with corresponding dimensions in three different. views. The following ranges can be selected, as a function of the outside diameter D, for the dimensions which can be seen in figure 5: X1 = 0.2 - 50D, X2 = 0.2 - 70D, Y1 = 35 0.2 - 90D, R1 = 0.5 - 10D, R2 = 0.5 - 10D, al = 24 1700, a = 20 - 1700 and a3 > 100. These dimensions are in this case selected according to the shape of the component 1 and to the desired routing of the cooling -8 air in the component. The inside diameter of the tube in this case moves in an order to magnitude of > 4 mm to preferably a maximum of 70 mm. The wall thickness may in this case be selected as desired. 5 Finally, figure 6 shows, by way of example, a cross section of the tube 2, such as may be selected in a curve. In principle, the ratio between the diameter D2 and the diameter D1 of the tube 2 can be varied within 10 the ranges D1/D2 = 0.4 - 1.6 as a 'function of the respective tube portion.

.9 List of reference symbols 1 Heat shield 2 Tube 5 3 Orifices 4 Inlet orifice 5 Seals 6 Blade leaf 7 Bellows 10 8 Sliding coupling 9 Sleeve

Claims

1. A system of a gas turbine, said system comprising: a heat shield; 5 a cooling arrangement which has at least one cooling duct for the leadthrough of a cooling medium at or in the heat shield; wherein the cooling duct is formed by a tube having an inside diameter between about 70mm and about 4 mm, the tube being fastened to the heat shield and defining a single flow path between one inlet of the tube and one outlet of the tube; 10 wherein at least individual tube portions are designed to be flexible, in order to compensate operationally induced deformations of the component; wherein the tube has at least two curved tube portions, of which a first tube portion lies in a first plane and a second tube portion lies in a second plane, the two planes forming an angle of between 2' and 1700; and 15 wherein the outlet of the tube directs the cooling medium to one or more of: a localised region in or around the heat shield; and a localised region around a blade tip of the gas turbine.

2. The system as claimed in claim 1, wherein the tube is soldered, welded or 20 adhesively bonded to the heat shield.

3. The system as claimed in claim 1 or claim 2, wherein the tube runs helically or spirally in order to compensate operationally induced deformations of the heat shield. 25

4. The system as claimed in any one of claims 1 to 3, wherein one or more tube portions form a bellows in order to compensate operationally induced deformations of the heat shield.

5. The system as claimed in any one of claims I to 4, wherein one or more tube 30 portions are connected to one another or to the component via a sliding joint in order to compensate operationally induced deformations of the heat shield. l1

6. The system as claimed in any one of claims 1 to 5, wherein curved tube portions have a predominantly elliptical inner cross section and straight tube portions have a predominantly circular inner cross section. 5

7. The system as claimed in any one of claims I to 6, wherein the first and second planes form an angle of between 80' and 100'.

8. The system as claimed in any one of claims I to 7, wherein the first tube portion has a curvature of 1700 to 190' and the second tube portion has a curvature of 800 to 10 100 .

9. The system as claimed in any one of claims 1 to 8, wherein a plurality of the tubes are fastened to the heat shield. 15

10. The system as claimed in any one of claims I to 9, wherein the tube or tubes lead into a secondary cooling system.

11. A system substantially as hereinbefore described with reference to the drawings.