Sealing arrangement, in particular for the blade segments of gas turbines
In a sealing arrangement, in particular for the blade segments of gas turbines, two bodies, with two end faces which extend along a longitudinal axis, adjoin one another while forming a gap, the width of which can vary between zero and a maximum width. The gap is covered by a sealing strip which lies transversely to the gap, extends along the longitudinal axis and is mounted with clearance in two opposite grooves of a predetermined depth. In such a sealing arrangement, an increased maximum width of the gap is made possible by the sealing strip having a basic width transversely to the longitudinal axis, this basic width being less than or equal to twice the depth of the grooves, and by the sealing strip having additional means which prevent the sealing strip from slipping out of the grooves if the sum of the maximum width of the gap and the depth of the grooves is greater than or equal to the basic width of the sealing strip.
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This application is a continuation application under 35 U.S.C. §120 of International Application No. PCT/CH2003/000124, filed Feb. 19, 2003, designating the United States, the contents of which are incorporated herein by reference.
TECHNICAL FIELDThe present invention relates to the field of thermal machines. It relates to a sealing arrangement, in particular for the blade segments of a gas turbine, according to the preamble of claim 1.
Such a sealing arrangement has been disclosed, for example, by publication EP-A2-0 896 128.
PRIOR ART Turbine stages of gas turbines comprise rows of guide blades (stator) and moving blades (rotor). These rows are each composed of a certain number of blade segments. Such a guide blade segment is reproduced in
Provided at the end faces of the shroud segments 12, 13 are outer and inner shroud seals 14 and 15, respectively, which run in the direction of a longitudinal axis 26 and serve to seal off the intermediate spaces (gaps) between adjacent shroud segments. The cross section through such a known sealing arrangement along the plane A-A in
On account of the thermal expansion during operation, the adjacent segments must be designed with a nominal clearance in the cold state in order to be able to absorb the thermal expansion. Superimposed on the nominal clearance are tolerances which result from the type of circumferential fastening of the segments. A clearance in the form of a gap 18 is obtained overall, the width of which can assume values of between 0 and a maximum width (maximum clearance) X (see
S≦2·T (1)
If condition (1) is met, the sealing strip 19 is not loaded in the transverse direction even when the clearance or the width of the gap 18 is zero (see the illustration in
S−T≧X (2)
If condition (2) is met, the situation shown in
A disadvantage with this type of dimensioning is that the depth T of the grooves 16, 17 and the width S of the sealing strip 19 can become very large depending on the maximum width X of the gap 18 or the maximum clearance. However, the depth T of the grooves 16, 17 and the width of the seal may be limited by the production process, the predetermined geometry or the cooling requirements of the end faces 24, 25 of the segments. In these cases, a compromise has to be found or another sealing method has to be used.
SUMMARY OF THE INVENTIONIt is therefore the object of the invention to specify a sealing arrangement which can be used in particular for the blade segments of gas turbines and which avoids the disadvantages of the known sealing arrangements and is characterized in particular by the fact that a larger maximum clearance can be reliably absorbed between the adjoining bodies or segments with comparatively little effort.
This object is achieved by all the features of claim 1 in their entirety. The essence of the invention, starting from the conventional form of the sealing strip, is to provide additional means on the sealing strip which prevent the sealing strip from slipping out of the grooves if the sum of the maximum width of the gap and the depth of the grooves is greater than or equal to the basic width of the sealing strip.
A preferred configuration of the invention is characterized by the fact that the additional means comprise lugs which are arranged in a distributed manner on the longitudinal sides of the sealing strip, are defined in the direction of the longitudinal axis and locally increase the width of the sealing strip beyond the basic width by a predetermined additional width. On the one hand, the lugs, with their additional width, increase the maximum clearance which can safely be bridged by the sealing strip. On the other hand, the lugs can yield locally by bending up if transverse forces act on the sealing strip at zero clearance.
At least two lugs are preferably arranged on a longitudinal side of the sealing strip in such a way as to be distributed over the longitudinal side. In particular, the at least two lugs are arranged on the ends of the longitudinal side. This results in a stable and predetermined position of the sealing strip in the grooves at all times.
Especially favorable is a geometry in which the lugs are arranged in pairs opposite one another on the two longitudinal sides of the sealing strip.
The lugs are preferably integrally formed on the sealing strip and have the same width as the sealing strip.
In this case, the lugs may lie in the plane of the sealing strip in the initial state. However, they may also be bent out of the plane of the sealing strip in the initial state.
The sealing arrangement is especially space-saving and exerts less stress on the sealing strip if, according to another configuration, in order to accommodate the lugs, deeper pockets are formed at the corresponding locations of the grooves.
In the simplest case, the walls of the grooves may be oriented perpendicularly to the gap.
However, it is also conceivable for the walls of the grooves to be oriented obliquely relative to the gap on one side or on both sides in such a way that the grooves have a V-shaped cross-sectional profile.
Further embodiments follow from the dependent claims.
BRIEF EXPLANATION OF THE FIGURESThe invention is to be explained in more detail below with reference to exemplary embodiments in connection with the drawing, in which:
A preferred exemplary embodiment of the sealing arrangement according to the invention is reproduced in
S+2·S1−T≧X (3)
It follows directly from condition (3) that, compared with the known sealing arrangement (see condition (2)), at constant values of S and T, greater values of X can be tolerated without the sealing arrangement or the sealing strip 20 being put at risk. If the lugs 21 (at zero clearance) are first of all bent upward (or downward), the additional width of the sealing strip 20 is certainly largely lost and thus the ability to absorb a larger maximum clearance X without problems is also largely lost, but the sealing strip 20 can still be used like a conventional (standard) sealing strip of the width S.
In the exemplary embodiment according to
Furthermore, it is conceivable according to
However, it is also conceivable, instead of the flat sealing strips 20 from
A further modification which is shown in
- 10 Guide blade segment
- 10a, b Guide blade segment
- 11 Airfoil
- 12 Outer shroud segment
- 13 Inner shroud segment
- 14 Outer shroud seal
- 15 Inner shroud seal
- 16, 17 Groove
- 16a, 17a Groove
- 16b, 17b Groove
- 16c, 17c Groove
- 16d, 17d Groove
- 18 Gap
- 19, 20 Sealing strip
- 20a, b Sealing strip
- 21 Lug
- 22, 23 Pocket
- 24, 25 End face
- 26 Longitudinal axis
- a Width (groove)
- b Thickness (sealing strip)
- S Basic width (sealing strip)
- S1, 2 Width (lugs)
- T Depth (groove)
- T1, 2 Depth (pockets)
- X Maximum width (gap)
- α, β Angle
Claims
1. A sealing arrangement, in particular for the blade segments of gas turbines, in which sealing arrangement two bodies with two end faces which extend along a longitudinal axis, adjoin one another while forming a gap, a width of which can vary between zero and a maximum width (X), and in which the gap is covered by a sealing strip which lies transversely to the gap, extends along the longitudinal axis and is mounted with clearance in two opposite grooves of a predetermined depth (T) which are incorporated transversely to the gap in the end faces of the bodies wherein the sealing strip has a basic width (S) transversely to the longitudinal axis, this basic width (S) being less than or equal to twice the depth of the grooves, and wherein the sealing strip has additional means which prevent the sealing strip from slipping out of the grooves if the sum of the maximum width (X) of the gap and the depth (T) of the grooves is greater than or equal to the basic width (S) of the sealing strip.
2. The sealing arrangement as claimed in claim 1, wherein the additional means comprise lugs which are arranged in a distributed manner on the longitudinal sides of the sealing strip, are defined in the direction of the longitudinal axis and locally increase the width of the sealing strip beyond the basic width (S) by a predetermined additional width (S1, S2).
3. The sealing arrangement as claimed in claim 2, wherein at least two lugs are arranged on a longitudinal side of the sealing strip in such a way as to be distributed over the longitudinal side.
4. The sealing arrangement as claimed in claim 3, wherein the at least two lugs are arranged on the ends of the longitudinal side.
5. The sealing arrangement as claimed in claim 4, wherein at least one additional lug is arranged in the center between the at least two lugs.
6. The sealing arrangement as claimed in claim 2 wherein the lugs are arranged in pairs opposite one another on the two longitudinal sides of the sealing strip.
7. The sealing arrangement as claimed in claim 2 wherein the lugs are integrally formed on the sealing strip and have the same width as the sealing strip.
8. The sealing arrangement as claimed in claim 2 wherein the lugs lie in the plane of the sealing strip in the initial state.
9. The sealing arrangement as claimed in claim 2 wherein the lugs are bent out of the plane of the sealing strip in the initial state.
10. The sealing arrangement as claimed in claim 2 wherein in order to accommodate the lugs, deeper pockets are formed at the corresponding locations of the grooves.
11. The sealing arrangement as claimed in claim 1 wherein the walls of the grooves are oriented perpendicularly to the gap.
12. The sealing arrangement as claimed in claim 1 wherein the walls of the grooves are oriented obliquely relative to the gap on one side or on both sides in such a way that the grooves have a V-shaped cross-sectional profile.
13. The sealing arrangement as claimed in claim 1 wherein the grooves and the sealing strip are of flat design.
14. The sealing arrangement as claimed in claim 1 wherein the grooves and the sealing strip are of bent design.
15. The sealing arrangement as claimed in claim 1 wherein the bodies are guide blade segments and/or moving blade segments of a gas turbine.
Type: Application
Filed: Aug 19, 2005
Publication Date: Aug 17, 2006
Applicant: ALSTOM Technology Ltd. (Baden)
Inventors: Richard London (Mellingen), Peter Marx (Baden)
Application Number: 11/206,824
International Classification: F04D 29/08 (20060101);