Turbomachine stage and method for detecting a sealing gap of such a turbomachine stage

Abstract

A turbomachine stage, in particular a turbine stage or compressor stage of a gas turbine, is disclosed. The turbomachine stage has a, in particular conical, housing in which a rotor blade arrangement having a plurality of rotor blades is disposed which have an outer shroud having at least one radial sealing flange. The sealing flange has a recess arrangement having at least one radial recess in which a radial projection is disposed, in particular centrally. A sensor arrangement having at least one capacitive sensor for detecting a radial distance from a circumferential surface of the sealing flange is disposed on the housing.

Claims

1. A turbomachine stage, comprising: a housing; a rotor blade arrangement disposed within the housing, wherein the rotor blade arrangement has an exterior shroud band section with a sealing flange; and a sensor arrangement including a first sensor arranged on the housing, wherein a radial clearance to a circumferential surface of the sealing flange is detectable by the first sensor; wherein the sealing flange has a recess arrangement with a radial recess and a radial projection; wherein the sensor arrangement further includes a second sensor; wherein respective sensing surfaces of the first sensor and the second sensor form equally sized angles in opposite directions with an axis of rotation of the turbomachine stage.

2. The turbomachine stage according to claim 1, wherein the turbomachine stage is a turbine stage or compressor stage of a gas turbine.

3. The turbomachine stage according to claim 1, wherein a circumferential surface of the radial projection is radially depressed in the radial recess.

4. The turbomachine stage according to claim 1, further comprising a processor coupled to the sensor arrangement.

5. A method for determining a seal gap between sealing flange of a rotor blade arrangement and a housing in a turbomachine stage, wherein the sealing flange has a recess arrangement with a radial recess and a radial projection and a sensor arrangement with a first sensor; and a second sensor is arranged on the housing, the method comprising the steps of: detecting a first signal swing of the sensor arrangement as a result of the radial recess and the radial projection of the recess arrangement being detected by the first sensor of the sensor arrangement; and detecting a second signal swing of the sensor arrangement as a result of the radial recess and the radial projection being detected by the second sensor of the sensor arrangement; wherein respective sensing surfaces of the first sensor and the second sensor form equally sized angles in opposite directions with an axis of rotation of the turbomachine stage.

6. The method according to claim 5, further comprising the step of allocating the first signal swing and the second signal swing to a radial distance of the rotor blade arrangement based on a prior calibration.

7. The method according to claim 6, further comprising the step of allocating the first signal swing and the second signal swing to an axial position of the rotor blade arrangement based on a prior calibration.

8. The method according to claim 6, further comprising the step of detecting a rubbing on the housing opposite from the sealing flange.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view in the axial direction of a portion of a turbomachine stage according to an embodiment of the present invention;

(2) FIG. 2 is a portion of the turbomachine stage from FIG. 1 along intersection line II-II in FIG. 1;

(3) FIG. 3A is a signal of a sensor of the turbomachine stage of FIG. 1 for an axial position and a radial distance of the rotor blade arrangement of the turbomachine stage;

(4) FIG. 3B is a signal of the sensor in FIG. 3A of a corresponding representation for another axial position;

(5) FIG. 3C is a signal of the sensor in FIG. 3A of a corresponding representation for another radial distance; and

(6) FIG. 4 is a top view in the radial direction from outside of a portion of a developed view of the turbomachine stage from FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) FIGS. 1, 2 and 4 show, in a view in the axial direction (FIG. 1), a meridian plane (FIG. 2), or a developed top view in the radial direction of a portion of a turbomachine stage according to an embodiment of the present invention. The turbomachine stage can be, for example, a turbine or compressor stage of a gas turbine, preferably of an aircraft engine.

(8) It comprises a rotor blade arrangement having a plurality of rotor blades 1 that are adjacent in the circumferential direction. The rotor blade arrangement is disposed in a conical housing 2.

(9) The rotor blade arrangement comprises a conical outer shroud 1.1 formed of a plurality of outer shroud sections, each of which can be connected to one or more rotor blades.

(10) Disposed radially outside on the outer shroud are two radial sealing flanges 1.2, 1.3 spaced apart from each other in the axial or flow direction (horizontally from left to right in FIGS. 2 and 4), which extend rib-like radially outwardly (see FIGS. 1 and 2) and in the circumferential direction (see FIGS. 1 and 4).

(11) The present invention will be explained in greater detail in the following making reference to the left sealing flange 1.2 in FIGS. 2 and 4; the statements can apply equally to the right sealing flange 1.3 in FIGS. 2 and 4.

(12) The sealing flange 1.2 is formed by a plurality of sealing flange sections, which are configured integrally with the respective outer shroud section, two of which are designated as 1.2′ or 1.2″ in FIG. 1 for better differentiation.

(13) The sealing flange 1.2 comprises a recess arrangement having four radial recesses 4, one of which is depicted in FIG. 1. Each of the similar recesses comprises two opposing flanks (left and right in FIG. 1), which extend substantially in the radial direction. Extending between the flanks is a recess base, which comprises a cylinder ring-shaped circumferential surface, so that the recess 4 is configured to be U-shaped.

(14) Disposed in the recess 4 is a radial projection 4.1, which extends radially outwardly from the recess base and comprises a cylinder ring-shaped circumferential surface. The radial projection 4.1 is disposed, as viewed in the circumferential direction, centrically in the recess 4. The recess 4 with the projection 4.1 disposed therein is configured symmetrically.

(15) Disposed on the housing 2 is a sensor arrangement 3 having six capacitive sensors for detecting a radial distance from a circumferential surface of the sealing flange; FIGS. 1 and 2 depict one sensor and FIG. 4 depicts two sensors 3.1, 3.2.

(16) When a recess 4 travels over a sensor the radial distance changes: it increases to begin with as soon as the sensor detects the recess base. Then the radial distance decreases when the sensor detects the projection. Then it increases again as soon as the sensor detects the recess base on the opposite side of the projection in the circumferential direction. Then the radial distance decreases again to the initial value when the sensor detects the circumferential surface of the sealing flange next to the recess.

(17) Therefore, when a recess rotates past a sensor, a generally W-like signal progression with four alternating, opposite-direction signal swings is produced. FIG. 3A depicts such a signal progression for the two adjacent sensors 3.1, 3.2 when the same recess 4 successively rotates past the sensors 3.1, 3.2. In the process, the abscissa φ can depict an angle of rotation of the rotor wheel arrangement or the time in equal measure, because both are mutually transferable via the rotational speed of the rotor wheel arrangement.

(18) A processing means 5 is used to detect the signal swings of the sensor arrangement as a result of a detection of the recesses of the recess arrangement and the projections thereof by means of the sensors of the sensor arrangement.

(19) The signal swings d, which are yielded as a result of the distance change between the recess base and the projection and between the projection and the recess base, are allocated to a radial distance of the rotor blade arrangement based on a previous calibration. FIG. 3C depicts the signal progression of FIG. 3A for another radial distance between the rotor blade arrangement 1 and the sensor arrangement 3 or housing 2. One can see that the signal swings d′ differ in the case of these different radial distances. Correspondingly, the signal swing d or d′ can be respectively allocated to a specific radial distance based on a previous calibration radial distance.

(20) The sensors of the sensor arrangement and the detection surfaces thereof form, with an axis of rotation of the turbomachine stage, angles ±α of equal amounts of ± 15° in opposite directions (see FIG. 4).

(21) Because of these detection surfaces that are slanted with respect to the axis of rotation of the turbomachine, it is possible to detect an axial position of the rotor blade arrangement. FIG. 3B depicts the signal progression of FIG. 3A for another axial position of the rotor blade arrangement 1. First the signal swings d of the sensor arrangement are detected as a result of a detection of a recess of the recess arrangement and of the projection in this recess by means of a sensor 3.1 of the sensor arrangement (on the left in FIGS. 3A and 3B).

(22) By further rotating the rotor towards a further sensor 3.2, further signal swings (on the right in FIGS. 3A and 3B) of the sensor arrangement are detected as a result of a detection of this recess and of the projection in this recess by means of a further sensor 3.2 of the sensor arrangement. The time-related distance or rotation angle distance of these signal swings, indicated in FIGS. 3A and 3B by the distance T or T′ of the middle peaks, can then be allocated in the processing means 5 based on a previous calibration to an axial position of the rotor blade arrangement.

(23) FIG. 4 shows that, in the case of the detection surfaces of the sensors 3.1, 3.2 that are converging from left to right, the distance of the signal swings decreases the farther the sealing flange is displaced from left to right.

(24) Just as explained in the foregoing relating to the signal between the recess base 4 and the projection 4.1 or the projection 4.1 and the recess base 4, a signal swing D or D′ (see FIGS. 3A and 3C) is also produced when a recess enters or exits the detection surface of a sensor. The sensor is used in the processing means 5 to detect an abrasion of the sealing flange 1.2: the greater the abrasion, the smaller the signal swing D or D′. Accordingly, signal swings of the sensor arrangement can be detected as a result of a detection of a recess of the recess arrangement and of a circumferential surface of the sealing flange adjacent to the recess, in particular upstream or downstream in the rotational direction, by means of a sensor of the sensor arrangement and the signal swings can be allocated to an abrasion of the sealing flange based on a previous calibration.

(25) The sealing gap between the sealing flange and the housing, in particular an abradable lining of the housing, can, along with the radial distance of the sealing flange from a housing-mounted sensor and a possible abrasion of the sealing flange, also be a function of a worn area 2.1 on the housing, as indicated in FIG. 2. Accordingly, a worn area of the housing 2 opposite from the sealing flange, in particular of an abradable lining of the housing opposite from the sealing flange, can be detected and be taken into consideration by the processing means 5 in the detection of the sealing gap, in particular for a detected radial distance, and be added to an abrasion of the sealing flange.

(26) FIG. 1 shows that the circumferential surface of the radial projection 4.1 is lowered radially in the recess 4 and that the recess 4 and the projection 4.1 extend symmetrically over the contact surface of two adjacent rotor blades. For this, the sealing flanges 1.2′, 1.2″ of two adjacent outer shroud sections are lowered radially with respect to the sealing flange 1.2 of the further outer shroud sections following it (see FIG. 1), so that the recess 4 extends over both complete outer shroud sections 1.2′, 1.2″. The radial projection 4.1 is disposed on the facing contact surfaces of the adjacent outer shroud sections 1.2′, 1.2″.

(27) Although exemplary embodiments were explained in the previous description, it should be noted that a plurality of modifications are possible. It should also be noted that the exemplary embodiments are merely examples, which should not restrict the protective scope, the applications and construction in any manner. On the contrary, the foregoing description provides a person skilled in the art with a guideline for implementing at least one exemplary embodiment, wherein various modifications, in particular with respect to the function and arrangement of the described components, can be undertaken without leaving the protective scope, as yielded by the claims and these equivalent combination of features.

LIST OF REFERENCE CHARACTERS:

(28) 1 Rotor blade (arrangement)

(29) 1.1 Outer shroud (section)

(30) 1.2, 1.3 Sealing flange

(31) 1.2′, 1.2″ Sealing flange section

(32) 2 Housing

(33) 2.1 Worn area

(34) 3 Sensor arrangement

(35) 3.1, 3.2 (Detection surface of a) sensor

(36) 4 Recess

(37) 4.1 Radial projection

(38) 5 Processing means

(39) As also discussed above, the foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.