Turbine blade or vane having a stepped and beveled platform edge

Abstract

A turbine blade, including: an airfoil and a platform, which has an upper face on which the airfoil is arranged; and at least one lateral face, the lateral face including a slot for insertion of a sealing strip. The transition between the upper face of the platform and the at least one lateral face includes a stepped portion and a beveled portion is provided.

Claims

1. A turbine blade or vane, which comprises an airfoil, a platform, which has a top surface on which the airfoil is arranged, and at least one lateral face located below the top surface, the at least one lateral face comprising a slot for insertion of a sealing strip, the slot extending along the at least one lateral face, wherein the transition between the top surface of the platform and the at least one lateral face comprises a stepped region and a beveled region.

2. The turbine blade or vane as claimed in claim 1, wherein the turbine blade or vane is a rotor blade or a guide vane.

3. The turbine blade or vane as claimed in claim 1, wherein the at least one lateral face is two lateral surfaces two lateral faces, a front side and a rear side, the stepped region being arranged between the front side and the beveled region, and the beveled region being arranged between the stepped region and the rear side.

4. The turbine blade or vane as claimed in claim 1, wherein the platform comprises a transition region, which is arranged between the stepped region and the beveled region and in which the stepped region merges into the beveled region.

5. The turbine blade or vane as claimed in claim 1, wherein the stepped region comprises a step having a height of between 2 mm and 6 mm and/or a depth of between 0.4 mm and 0.8 mm.

6. The turbine blade or vane as claimed in claim 1, wherein the beveled region is arranged between the rear side of the platform and the airfoil in a longitudinal direction running parallel to the lateral face.

7. The turbine blade or vane as claimed in claim 1, wherein the height of the platform decreases toward the rear side of the platform.

8. A turbine, comprising a turbine blade or vane as claimed in claim 1.

9. The turbine as claimed in claim 8, wherein the turbine is a gas turbine or a steam turbine.

10. A method for producing a turbine blade or vane as claimed in claim 4, wherein the stepped region and/or the beveled region and/or the transition region between the stepped region and the beveled region is formed in the platform by electrical discharge machining.

11. The method as claimed in claim 10, wherein the stepped region and/or the beveled region and/or the transition region between the stepped region and the beveled region is worked out as the slot for the sealing strip is being worked out.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 schematically shows a section through part of a turbine blade or vane.

(3) FIG. 2 schematically shows a partial region of a guide vane in a perspective view;

(4) FIG. 3 schematically shows a partial region of a guide vane in a perspective view and

(5) FIG. 4 schematically shows a gas turbine.

DETAILED DESCRIPTION

(6) FIG. 1 schematically shows a section through part of a turbine blade or vane 1. The turbine blade or vane 1 shown in FIG. 1 can be, for example, a guide vane 117 or a rotor blade 115. FIG. 1 schematically shows part of the platform 2 and part of airfoil 3. The platform 2 comprises a top surface 4, a bottom surface 5, a front side 6, a rear side 7 and two lateral faces 8. The airfoil 3 is arranged on the top side 4 or on the top surface of the platform 2. A blade or vane root 9 adjoins the bottom surface 5 or bottom side of the platform 2.

(7) The lateral face 8 comprises a slot 10 for insertion of a sealing strip. The sealing strip serves to seal off the intermediate space between two adjacent turbine blades or vanes 1.

(8) Both the airfoil 3 and the top surface 4 of the platform 2 are coated with a bond coat and a thermal barrier layer. This is typically done by spraying on the coating material. In order to prevent overspraying of the coating material from the top surface onto the lateral face, the transition from the top surface 4 to the lateral face 8 is configured in the form of a step 11. This has the effect that overspraying of the stepped region 11 is harmless and in particular does not make post-machining of the platform 2 necessary. Moreover, the region of the lateral face 8 beneath the step 11 or recess or notch is effectively protected against undesirable spraying with coating material.

(9) The step 11 has a height h of 4.00.5 mm and a depth t of 0.60.1 mm.

(10) FIGS. 2 and 3 schematically show a partial region of a guide vane 117 in a perspective view. The guide vane 117 comprises an airfoil 3, a platform 2 and a vane root 9. The airfoil 3 is arranged on the platform 2. It comprises a leading edge 16 and a trailing edge 17. The platform 2 comprises two lateral faces 8. A slot 10 for insertion of a sealing ring is arranged on each lateral face 8.

(11) In the main direction of flow 20 of the hot gas, or in a longitudinal direction 21 running parallel to one of the lateral faces 8, the thickness or height d of the platform 2 decreases, preferably continuously, at least from the trailing edge 17 of the airfoil 3 toward the rear side 7 of the platform 2. In FIG. 2, for example, the thickness or height d.sub.1 of the platform 2 downstream of the trailing edge 17 is greater than the thickness or height d.sub.2 of the platform 2 on the rear side 7.

(12) A stepped region 13 and, adjoining the latter, a beveled region 14 are arranged between the front side 6 of the platform 2 and the rear side 7 of the platform 2, along the lateral face 8 above the slot 10 for the sealing ring. The stepped region 13 starts at the front side 6 of the platform 2, and extends as far as downstream of the trailing edge 17 of the airfoil 3, in relation to the longitudinal direction 21. The beveled region 14 extends from the stepped region 13 as far as the rear side 7 of the platform 2.

(13) There is a transition region 15 between the stepped region 13 and the beveled region 14. In the transition region 15, the geometry of the stepped region 13 merges continuously into the geometry of the beveled region 14.

(14) The stepped region 13 preferably has a step 11 having a height of between 2 mm and 6 mm, for example 3.5 mm to 4.5 mm, preferably 4 mm. The step 11 preferably has a depth t of between 0.4 mm and 0.8 mm, for example between 0.5 mm and 0.7 mm, preferably 0.6 mm.

(15) FIG. 4 schematically shows a gas turbine. In the interior, a gas turbine has a rotor with a shaft 107 which is mounted such that it can rotate about an axis of rotation and is also referred to as the turbine rotor. An intake housing 109, a compressor 101, a burner arrangement 15, a turbine 105 and the exhaust gas housing 190 follow one another along the rotor.

(16) The burner arrangement 15 is in communication with a for example annular hot gas duct. There, multiple series-connected turbine stages form the turbine 105. Each turbine stage is formed from blade or vane rings. As seen in the direction of flow of a working medium, in the hot gas duct a row of guide vanes 117 is followed by a row formed from rotor blades 115.

(17) In that context, the guide vanes 117 are secured to an inner housing of a stator, whereas the rotor blades 115 of a row are fitted to the rotor for example by means of a turbine disk. A generator is coupled to the rotor.

(18) While the gas turbine is in operation, the compressor 101 sucks in air through the intake housing 109 and compresses it. The compressed air provided at the turbine-side end of the compressor 101 is passed to the burner arrangements 15, where it is mixed with a fuel. The mix is then burnt in the combustion chamber, forming the working medium. From there, the working medium flows along the hot gas duct past the guide vanes 117 and the rotor blades 115. The working medium is expanded at the rotor blades 115, transferring its momentum, so that the rotor blades 115 drive the rotor and the latter in turn drives the generator coupled to it.

(19) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(20) For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.