Rotating blade having a rib arrangement with a coating

Abstract

The present invention relates to a rotating blade (5), in particular for a compressor or turbine stage of a gas turbine, having a radially outer rib arrangement with at least one rib (2), onto which a coating (3) is disposed, whereby, in a meridian section, the coating (3) has an outer contour (3.1), which extends axially outwardly in the radial direction.

Claims

1. A rotating blade for a compressor or turbine stage of a gas turbine, comprising a radially outer rib arrangement with at least one rib, having a radially outer end face and adjacent flanks, onto which a coating is disposed on the radially outer end face and a portion of the flanks wherein, in a meridian section, the coating has an outer contour, which extends outwardly in the radial direction and is broader in the axial direction as a radial distance increases.

2. The rotating blade according to claim 1, wherein the rib arrangement has two or more ribs disposed behind one another in the axial direction, whereby a coating is disposed on each of at least two adjacent ribs, and whereby at least one gap between flanks of the adjacent coatings facing one another corresponds at most to an axial width of the radially outer end face of one of the two adjacent ribs up to about 75% of the axial width.

3. The rotating blade according to claim 1, wherein at least one rib of the rib arrangement is inclined in the peripheral direction (U) by an angle (α) not equal to 0° , but which is smaller than 10° in magnitude.

4. The rotating blade according to claim 1, wherein at least two ribs of the rib arrangement have radially outer end faces in radial direction (R), which, at least substantially, lie at the same radial height, and, proceeding from the end face, are of inwardly different heights, in the radial direction.

5. The rotating blade according to claim 1, wherein at least two ribs of the rib arrangement, in radial direction (R), have radially outer end faces that lie at different radial heights, whereby the ribs are of different heights in the radial direction.

6. The rotating blade according to claim 1, wherein the rib arrangement is disposed on a shroud, which is oblique in the axial direction of the rotating blade.

7. The rotating blade according to claim 1, wherein the coating has a greater hardness than the rib on which it is disposed.

8. The rotating blade according to claim 1, wherein at least one rotating blade is configured as a rotating blade in gas turbine turbomachine.

9. A method for coating at least one rib of a radially outer rib arrangement of a rotating blade, comprising the steps of: providing a rib arrangement; and spraying a coating material onto the rib arrangement from two opposite spraying directions (S.sub.1, S.sub.2).

10. The method according to claim 9, wherein the spraying directions are inclined toward the radial direction (R) by spraying angles (β.sub.1, β.sub.2) that are particularly the same in magnitude.

11. The method according to claim 9, wherein an angle of spraying direction (β.sub.1, β.sub.2) is between about 20° and about 70° in magnitude.

12. The method according to claim 9, wherein the coating material is sprayed on thermally, in a technique selected from the group consisting of plasma-sprayed, flame-sprayed, high-speed flame-sprayed, detonation-sprayed, cold-gas-sprayed, arc-sprayed, laser-sprayed and combinations thereof.

13. The method according to claim 9 wherein the coating is post-processed after it has been sprayed on.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) These and other features, aspects, and advantages of the rotating blade will become better understood with reference to the following description, appended claims, and accompanying drawings where:

(2) FIG. 1: the shroud of a rotating blade according to an embodiment of the present invention in a top view counter to a radial direction;

(3) FIG. 2: an enlarged excerpt of FIG. 3 or 4;

(4) FIG. 3: a meridian section of a gas turbine stage according to an embodiment of the present invention; and

(5) FIG. 4: a meridian section of a gas turbine stage according to another embodiment of the present invention.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

(6) FIG. 3 shows a meridian section of a gas turbine stage according to an embodiment of the present invention, having a rotating blade 5, on whose oblique shroud 1 is disposed a rib arrangement with five ribs 2 disposed one behind the other in the axial direction. A honeycomb-shaped sealing surface 4 is disposed radially opposite the rib arrangement 2. In the otherwise corresponding embodiment of FIG. 4, a sealing surface 4′ with one or two (dashes) counter-rib(s) is provided instead of the honeycomb-shaped sealing surface.

(7) FIG. 2 shows an enlargement of the excerpt of shroud 1 with the rib arrangement. As can be especially seen, on each of the radially outer end faces of ribs 2, which lie at the same radial height so that the ribs have different heights due to the oblique shroud 1, there is disposed a coating 3.

(8) This coating 3 is introduced by means of sequential plasma spraying, first in a first spraying direction S.sub.1, and subsequently in an opposite or mirror-symmetrical second spraying direction S.sub.2, as indicated by arrows in FIG. 2. The two spraying directions are inclined toward radial direction R, in which ribs 2 extend, by an angle β.sub.1=−β.sub.2=45°.

(9) In this way, coatings 3 that have an outer contour that extends outwardly in the radial direction result on ribs 2, as shown in the meridian section of FIG. 2. In other words, with increasing radial distance from an axis of rotation of the gas turbine (from bottom to top in FIG. 2), the axial distance (horizontal in FIG. 2) increases between outer flanks 3.1 of the outer contour of a coating 3; the coating will be broader radially outwardly in the axial direction. Correspondingly, a gap s between the outer flanks of adjacent coatings is reduced and radially outwardly amounts to only approximately 75% of the axial width b of the radially outer end face of the wider of the two adjacent ribs 2 (left in FIG. 2).

(10) A substantially planar end surface of coatings 3 can be presented by superimposing the oppositely-directed two spraying directions S.sub.1, S.sub.2. Likewise, the coating, in particular its radially outer end face (top in FIG. 2) can be post-processed, ground in particular, after it has been sprayed on.

(11) It can be recognized particularly in FIG. 2 that an extensive sealing surface, particularly sealed to fluids, is made available by coatings 3 that widen in the radial direction outwardly or with increasing radial distance from the axis of rotation, the weight of the rib arrangement remaining advantageously small due to the intermediate spaces between the ribs.

(12) As can be recognized in FIG. 1, ribs 2 are inclined toward the peripheral direction U by an angle α that amounts to 2° in the example of embodiment. The peripheral direction U as well as a radial direction R are indicated in the figures for illustration, whereby FIGS. 2 to 4 can each represent a section horizontal to the drawing plane of FIG. 1; an axial direction thus runs horizontally from left to right in all figures. The sprayed layer is thus not shown.