BLADE OF A TURBOMACHINE HAVING BLADE ROOT THERMAL INSULATION

Abstract

Disclosed is an arrangement for fastening a blade root of a blade of a turbomachine in a blade root receptacle, with a blade having a blade root of a first material and with a blade root receptacle of a second material, wherein a thermal barrier layer is arranged between the blade root and the blade root receptacle. Further disclosed is a blade having a blade root with a thermal barrier layer and also a method for operating a turbomachine, in which a blade having a blade root is received in a blade root receptacle and a blade root temperature which is above the blade root receptacle temperature is set.

Claims

1. An arrangement for fastening a blade root of a blade of a turbomachine in a blade root receptacle, wherein the blade comprises a blade root of a first material and the blade root receptacle is formed of a second material, and a thermal barrier layer is arranged between the blade root and the blade root receptacle.

2. The arrangement of claim 1, wherein the thermal barrier layer has a lower thermal conductivity than that of the first material of the blade root and the second material of the blade root receptacle.

3. The arrangement of claim 1, wherein the thermal barrier layer is formed from a ceramic material or comprises ceramic material.

4. The arrangement of claim 1, wherein the thermal conductivity of the thermal barrier layer is not higher than 50 W/mK.

5. The arrangement of claim 1, wherein the thermal conductivity of the thermal barrier layer is not higher than 25 W/mK.

6. The arrangement of claim 1, wherein the thermal conductivity of the thermal barrier layer is not higher than 1 W/mK.

7. The arrangement of claim 1, wherein the thermal barrier layer is coated onto the blade root and/or a boundary wall of the blade root receptacle.

8. The arrangement as claimed in claim 7, wherein a ductile layer is deposited on the thermal barrier layer, a ductility of the ductile layer being greater than a ductility of the thermal barrier layer.

9. The arrangement as claimed in claim 8, wherein the ductile layer is formed from metallic material and/or a material of the ductile layer has an elongation at break of more than 5%.

10. The arrangement as claimed in claim 9, wherein the material of the ductile layer has an elongation at break of more than 10%.

11. A blade for a turbomachine having a blade root to be received in a blade root receptacle, wherein the blade root comprises a thermal barrier layer.

12. The blade of claim 11, wherein the thermal barrier layer has a lower thermal conductivity than that of a material of the blade root.

13. The blade of claim 11, wherein the thermal barrier layer is formed from ceramic material or comprises ceramic material.

14. The blade of claim 11, wherein a thermal conductivity of the thermal barrier layer is not higher than 50 W/mK.

15. The blade of claim 11, wherein a thermal conductivity of the thermal barrier layer is not higher than 25 W/mK.

16. The blade of claim 11, wherein a ductile layer is present on the thermal barrier layer, a ductility of the ductile layer being greater than a ductility of the thermal barrier layer.

17. The blade as claimed in claim 16, wherein the ductile layer is formed from a metallic material and/or the material of the ductile layer has an elongation at break of more than 5%.

18. A method for operating a turbomachine, wherein the method comprises using a blade having a blade root received in a blade root receptacle and setting a blade root temperature which is above a blade root receptacle temperature.

19. The method of claim 18, wherein a thermal barrier layer is arranged between the blade root and the blade root receptacle, and a temperature difference during operation of the turbomachine between a side of the thermal barrier layer on the blade root and a side of the thermal barrier layer on the blade root receptacle is at least 25° C.

20. The method of claim 18, wherein the blade root temperature during operation of the turbomachine is selected in such a way that a limit value of a ductility of a material from which the blade root is formed is exceeded and/or wherein the blade root receptacle temperature is selected in such a way that a limit value of a strength of a material of the blade root receptacle is exceeded and/or a limit value of a creep rate and/or of an oxidation or corrosion rate of a material of the blade root receptacle is undershot.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings show, purely schematically, in

[0037] FIG. 1 a perspective illustration of a blade of a turbomachine, and in

[0038] FIG. 2 a sectional view through a root region of a further blade of a turbomachine.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0039] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

[0040] FIG. 1 shows a schematic example of a blade 1 of a turbomachine, such as for example a gas turbine or an aero engine. The blade 1 shown in FIG. 1 can be arranged, for example, as a rotor blade on a rotor of a turbomachine, wherein the root 2 of the blade 1 is received in a corresponding blade root receptacle (not shown) of a rotor disk or the like. In the case of the blade 1 shown in FIG. 1, the region of the blade root 2 which is received in a blade root receptacle is separated from the airfoil 3 by an inner shroud. However, the invention can also be used for other types of blades with different blade shapes, with or without inner and outer shrouds, and also different blade root shapes.

[0041] FIG. 2 shows a section through a comparable blade having a differently shaped blade root 2, with the blade root receptacle 7 of a rotor disk 6 additionally being shown in the sectional view.

[0042] The sectional illustration in FIG. 2 shows the structure according to the invention of the blade root having a thermal barrier layer 4, which is provided at least over the entire surface region of the blade root 2 which can come into contact with the inner wall region of the blade root receptacle 7.

[0043] In addition to the thermal barrier layer 4, a ductile layer 5 is applied to the thermal barrier layer 4 in the exemplary embodiment of FIG. 2. As is shown in the right-hand part of the blade root 2 of FIG. 2, the ductile layer 5 can be applied merely over partial regions of the thermal barrier layer 4, such that, in the remaining regions, in which no ductile layer 5 is provided, a gap 8 can be formed between the boundary wall of the blade root receptacle 7 and the thermal barrier layer 4 of the blade root 2. As an alternative, as is shown in the left-hand part of the blade root 2 of FIG. 2, however, the ductile layer 5 can also be applied substantially over the entire region of the thermal barrier layer 4. The left-hand part and the right-hand part of FIG. 2 therefore show two different embodiments with respect to the ductile layer 5.

[0044] According to the invention, the thermal harrier layer 4, which is arranged on the blade root 2 in the exemplary embodiment shown, but, in other exemplary embodiments, could also be arranged on the boundary wall of the blade root receptacle 7, is used to set a temperature gradient from the blade root 2 to the boundary wall of the blade root receptacle 7 or the disk or rotor material in which the blade root receptacle 7 is formed. The thermal barrier layer 4 makes it possible to set a higher temperature in the blade root 2, during operation of the turbomachine, than in the rotor disk 6 or the rotor. It is thereby possible to provide a material optimized for higher operating temperatures for the blade root 2, while a material optimized for a lower operating temperature can be used for the rotor disk 6. Correspondingly, the cooling of the blade root can also be reduced without having to fear that the material of the rotor disk 6 will be overheated.

[0045] By way of example, the rotor disk 6 could be formed from a nickel base material, while the blade or the blade root 2 could be formed from a nickel base superalloy having a higher use temperature or from another material having a higher use temperature, such that a temperature difference between the operating temperature of the blade root 2 and the operating temperature of the rotor disk 6 in the order of magnitude of 50° C. to 100° C. or higher can be set via the thermal barrier layer 4, in order to be able to correspondingly utilize the potential of the different materials of rotor disk 6 and blade 1.

[0046] Corresponding materials having a low thermal conductivity are suitable as the thermal barrier layer, such as for example ceramic thermal barrier layers or thermal barrier layers containing ceramic proportions. By way of example, materials consisting of or comprising aluminum oxide and/or zirconium oxide could be used.

[0047] The ductile layer 5, which can be formed from a suitable ductile material, such as for example a metallic material having a sufficiently high elongation at break, serves substantially for protecting the thermal barrier layer by the avoidance of stress peaks, which might arise in particular in the event of point or linear contact between the blade root 2 or the thermal barrier layer 4 arranged thereon and the blade root receptacle 7. By virtue of a ductile layer 5, possible manufacturing inaccuracies which could lead to such stress peaks can be compensated for in a simple manner, and the thermal harrier layer can he protected from instances of mechanical overloading. In addition, the ductile layer 5 can furthermore perform additional functions, such as for example with respect to the avoidance of frictional wear or the like.

[0048] Although the present invention has been described in detail on the basis of the exemplary embodiments, it is obvious to a person skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features can be omitted or different combinations of features can be implemented, without departing from the scope of protection of the accompanying claims. The disclosure of the present invention additionally includes all combinations of the individual features presented.

LIST OF REFERENCE NUMERALS

[0049] 1 Blade [0050] 2 Blade root [0051] 3 Airfoil [0052] 4 Thermal barrier layer [0053] 5 Ductile layer [0054] 6 Rotor disk [0055] 7 Blade root receptacle [0056] 8 Gap