BRIEF DESCRIPTION OF THE DRAWINGS
Preferred exemplary embodiments of the invention are illustrated in the drawings and they are explained in more detail in the following description, the same reference symbols referring to identical or similar or functionally identical components.
In the drawings, in each case diagrammatically,
FIG. 1 shows an axial sectional illustration of a turbomachine in the region of a sealing device located between a stator and a rotor, and
FIGS. 2
a to 2e show different embodiments of the sealing device according to the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
According to FIG. 1, a turbomachine 1, in particular a gas turbine or a compressor, has a stator 2 and a rotor 3. The stator 2 may in this case be designed, for example, as a guide vane 4. A moving blade 5 may be arranged in the usual manner upstream of the guide vane 4 in the flow direction 7.
In order to keep the efficiency of the turbomachine 1 as high as possible and, on the other hand, minimize oxidation processes due to an eruption of hot gas, at least one sealing device 6 is arranged between the stator 2 and the rotor 3. The sealing device 6 in this case runs in the axial direction of the turbomachine 1. On the stator side, the sealing device 6 has a radially stepped sealing contour 8 of honeycomb-like design, with regions 9 and 10 projecting and retracting in the direction of the rotor 3 (cf. also FIG. 2). By contrast, on the rotor side, a plurality of sealing fins 11 projecting in the direction of the stator 2 are arranged, which engage in each case into adjacent retracting regions 10 of the stator-side sealing contour 8. According to some principles of the present invention, in this case, on the rotor side, at least one additional fin 12 projecting in the direction of the stator 2 is additionally provided, which is positioned between two adjacent sealing fins 11 arranged on the rotor side and which lies opposite a projecting region 9 of the stator-side sealing contour 8.
The sealing fins 11 give rise, together with the radially stepped sealing contour 8, to a labyrinth seal which at least hinders a penetration of hot gases. So that the labyrinth effect can be increased further, then, additional fins 12, as they are known, are additionally arranged, which bear against the projecting regions 9 of the sealing contour 8 or even dig into this. Both the sealing fins 11 and the additional fins 12 are in this case produced from a material which is more wear-resistant, as compared with the sealing contour 8, so that, in the event of contact between the fins 11, 12 and the sealing contour 8, a stripping of the sealing contour 8 occurs and the fins 11, 12 dig into the sealing contour 8, with the result that the sealing action of the sealing device 6 is additionally improved.
As one may gather from FIGS. 1 and 2, at least one additional fin 12 and/or one sealing fin 11 are/is arranged, inclined radially and axially, on the rotor 3 or on a heat shield 13 of the rotor 3. In this case, a degree of inclination of the at least one additional fin 12 or of the at least one sealing fin 11 amounts to approximately 25°-35° with respect to a radial perpendicular to the axis of the turbomachine 1. The inclination of the sealing fins 11 or of the additional fins 12 in this case takes place in the direction opposite to the main flow 7a, as a result of which, upstream and/or downstream of the respective fin 11, 12, a dam flow, as it is known, may be formed, which is also designated as a dead water zone and which additionally improves the sealing action of the sealing device 6. Reference symbol 7b in this case designates the leakage flow between the stator 2 and the rotor 3.
FIGS. 2
a to 2e show different embodiments of the sealing device 6, the sealing devices 6 according to FIGS. 2a to 2d having a uniform radial height over their entire axial extent, whereas a radial height of the sealing device 6 according to FIG. 2e varies in the axial direction of the turbomachine 1.
These sealing devices 6 are particularly suitable for instances in which the axial relative movement is greater than the radial relative movement. For this reason, all the sealing devices 6 according to FIGS. 1 and 2 have in this case in common the fact that the retracting regions 10 of the sealing contour 8 have a greater axial longitudinal extent than the projecting regions 9 of the sealing contour 8. Furthermore, an axial distance between two projecting or retracting stator-side regions 9 or 10 is approximately double a radial height of the sealing fin 11.
All the sealing devices 6 according to FIGS. 1 and 2 likewise have in common the fact that at least the sealing fins 11 have in each case a wedge-shaped cross-sectional profile in the circumferential direction and thereby, starting from their rotor-side tie-up, taper as far as a free end. This affords the advantage that a rotor-side tie-up region is designed to be stronger and therefore more load-bearing, while the free end of the sealing fin 11 is designed to be markedly lighter and therefore generates lower centrifugal forces.
Of course, a size both of the fins 11, 12 and of the projecting and retracting regions 9, 10 of the sealing contour 8 depends on structural requirements, the best sealing action being achieved when the various dimensions have specific geometric ratios. The stator-side retracting region 10 preferably has, in this case, an axial longitudinal extent of approximately twice to three times the height h, illustrated in longitudinal section, of the sealing fin 11, while a stator-side projecting region 9 has an axial longitudinal extent of approximately 1 to 2.5 times the height h, that is to say a width b, illustrated in longitudinal section, of 1 to 2.5 times h.
It may likewise be gathered from FIGS. 1 and 2 that a radial height of the sealing fin 11 is approximately 2 to 4 times greater than a radial height of the additional fin 12. In the same way as the axial longitudinal extents, mentioned in the previous paragraph, of the regions 9 and 10, in this case the radial height both of the additional fin 12 and of the sealing fin 11 is governed by structural requirements.
In FIGS. 2a to 2c and 2e, a last projecting region 9′ is designed to be markedly narrower, that is to say with a markedly smaller axial longitudinal extent, while, according to FIG. 2b, it is completely absent. Furthermore, all the sealing contours according to FIGS. 1 and 2 have in common the fact that the projecting and retracting regions 9 and 10 have a rectangular stepped cross-sectional configuration, the intention also being that differently stepped or wavy cross-sectional shapes are also optional. In general, combinations of sealing fins 11 and additional fins 12 which are optimized in terms of the sealing action may be used, and the sealing fins 1 and/or the additional fins may preferably be inclined opposite to the main flow direction 7a.
LIST OF REFERENCE SYMBOLS
1 Turbomachine
2 Stator
3 Rotor
4 Guide vane
5 Moving blade
6 Sealing device
7
a Main flow
7
b Leakage flow
8 Sealing contour
9 Projecting region
10 Retracting region
11 Sealing fin
12 Additional fin
13 Heat shield
- b Width, axial longitudinal extent
- h Height of the sealing fin 11
While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.
Patent Application
20080050233
