Abstract:
The invention relates to a brush seal to seal a gap between two structural components, in particular between a rotor and a stator, having a bristle packet comprising bristles, with the bristles of the bristle packet being firmly attached to a bristle carrier via a fixation element. According to the invention, the bristle packet comprises several layers of bristles that are made of different materials.

Description:
BACKGROUND 
       [0001]    Gas turbines consist of several modules, for example of at least one compressor, at least one combustion chamber as well as at least one turbine. The compressor or each of the compressors as well as the turbine or each of the turbines are equipped with a rotor which rotates relative to a stationary stator. The stator involves in particular a stationary housing to which stationary guide vanes are allocated. Guide vanes are allocated to the rotor that rotate together with the rotor relative to the stationary guide vanes as well as to the stationary housing. 
         [0002]    Optimizing the efficiency of the gas turbines will require the minimizing of leakage flows. This applies, on the one hand, to leakage flows between components rotating relative to each other, and, on the other hand, to leakage flows between stationary components. Seal arrangements to seal a gap between components rotating relative to each other are also called dynamic seal arrangements. Seal arrangements to seal a gap between stationary components are also called static seal arrangements. 
         [0003]    For the sealing of so-called annular gaps between components rotating relative to each other, to with between a rotor and a stator, brush seals have proved to be of value. 
         [0004]    From EP 1 203 178 B1, a seal arrangement has been known in which a brush seal is positioned in a receptacle defined by a housing. The brush seal comprises a bristle packet of several bristles that are attached to a bristle carrier with the aid of fixation element, with the bristles of the bristle packet protruding from the receptacle defined by the housing and lying flat against the rotor. The housing forming the receptacle for the brush seal comprises a support element and a cover element. According to EP 1 203 178 B1, the bristles of the bristle packet of the brush seal are designed as synthetic fibers, for example Aramid fibers or, respectively, Kevlar fibers. 
       SUMMARY AND DESCRIPTION 
       [0005]    Therefore, an objective of the invention is to provide a novel brush seal. This problem is addressed by a brush seal as disclosed and claimed herein. 
         [0006]    According to one aspect of the invention, the bristle packet comprises several layers of bristles made of different materials. 
         [0007]    One embodiment of the invention is a brush seal whose bristles comprise bristles made of different materials. Therefore, the bristle packet of the brush seal according to this embodiment of the invention comprises several layers of bristles made of different materials. This makes it possible to create brush seals that, on the one hand, have a good sealing effect and that, on the other hand, are characterized by great mechanical resistance as well as by high temperature resistance. 
         [0008]    Preferably, the bristle packet of the brush seal according to another embodiment of the invention comprises an interior layer whose bristles are made of carbon fibers as well as an exterior layer whose bristles are designed as Aramid fibers or as wire fibers made of Haynes 25 wire. Such a brush seal with a bristle packet in a hybrid design distinguishes itself through particular advantageous temperature resistance as well as through mechanical resistance and therefore through longevity as well as through a particularly advantageous sealing effect. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Preferred further developments of the invention result from the subclaims and the subsequent description. Embodiments of the invention will be explained with the aid of the drawings without being limited thereto. Shown are: 
           [0010]      FIG. 1  shows a brush seal according to the invention per a first embodiment of the invention; 
           [0011]      FIG. 2  shows a brush seal according to the invention per a second embodiment of the invention; 
           [0012]      FIG. 3  shows a brush seal according to the invention per a third embodiment of the invention; and 
           [0013]      FIG. 4  shows a brush seal according to the invention per a fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1  shows a schematic representation of a brush seal  10  according to the invention per a first embodiment of the invention at hand here, with the brush seal  10  of  FIG. 1  comprising a bristle packet  11  of several bristles  12  and with the bristles  12  of the bristle packet  11  being firmly attached to a wire-like bristle carrier  13  by means of a fixation element  14  having a C-shaped cross section. 
         [0015]    In the sense of the invention at hand here, the bristle packet  11  of the brush seal  10  according to the invention comprises several layers of bristles, to with, in the embodiment shown, two layers  15  and  16  of bristles  17  and  18  that are wound in overlapping fashion around the bristle carrier  13  and firmly attached to the same so that the bristles  17  of layer  15  form an interior layer and the bristles  18  of layer  16 , an exterior layer. The exterior layer may also be designated as a cover layer. In the sense of the invention at hand here, the bristles  17 ,  18  of the layers  15 ,  16  differ with regard to their material composition. For example, the bristles  17  of the interior layer  15  of the bristle packet  11  are designed as carbon fibers. The bristles  18  of the exterior layer  16 , on the other hand, are designed as Aramid fibers or as wire fibers made of Haynes 25 wire. 
         [0016]    As has been known from EP 1 203 178 B1, the brush seal  10  represented in  FIG. 1  is preferably positioned in a housing so as to form a sealing arrangement that comprises a cover element and a support element, with the free ends  19 ,  20  of the bristles  17 ,  18  protruding from the housing and preferably lying flat against a rotor. Reference be made to EP 1 203 178 B1 with regard thereto. Consequently, in  FIG. 1 , a support element would adjoin the right side of the brush seal  10  shown there and a cover element of a housing, the left side. 
         [0017]    In the embodiment of  FIG. 1 , the bristles  17 ,  18  of the interior layer  15  and of the exterior layer  16  are designed in such a way that the free ends  19  or, respectively,  20  of the same define the same interior diameter. Thus, the free ends  19  of the bristles  17  of the interior layer  15  as well as the free ends  20  of the bristles  18  of the exterior layer  16  would lie flat against a rotor. 
         [0018]    In contrast,  FIG. 2  shows an example of an embodiment of a brush seal  10  according the invention in which the free ends  19  of the bristles  17  of the interior layer  15  define a larger interior diameter than the free ends  20  of the bristles  18  of the exterior layer  16 . Thus, in  FIG. 2 , the bristles  18  of the exterior layer  16  protrude at the interior diameter relative to the bristles  17  of the interior layer  15 . 
         [0019]    In contrast therewith it will also be possible, as shown in the example of an embodiment of  FIG. 3 , that the free ends  20  of the bristles  18  of the exterior layer  16  define a greater interior diameter than the free ends  19  of the bristles  17  of the interior layer  15 , in which case, in the example of the embodiment of  FIG. 3 , the bristles  15  of the interior layer  17  will protrude at the interior diameter relative to the bristles  18  of the exterior layer  16 . 
         [0020]    In the examples of embodiments of  FIGS. 1 ,  2  and  3 , the free ends  20  of the bristles  18  of the exterior layer  16  are each designed in such a way that they have the same length on the side of the support element and on the side of the cover element, i.e. that they define the same interior diameter on the side of the support element and on the side of the cover element. In contrast therewith, as can be seen in  FIG. 4 , it will also be possible that the bristles  18  of the exterior layer  16  will define differing interior diameters on the side of the support element and on the side of the cover element, with, in  FIG. 4 , the interior diameter of the ends  20  being smaller on the side of the support element than the diameter of the same on the side of the cover element. However, it will also be possible that the bristles  18  of the exterior layer  16  define with their free ends a greater interior diameter on the side of the support element than on the side of the cover element. 
         [0021]    All examples of embodiments shown in  FIGS. 1 through 4  have in common that the bristles  17  of the interior layer  15  of the bristle packet  11  are designed as carbon fibers and the bristles  18  of the exterior layer  16  or, respectively, the cover layer of the bristle packet  11  as Aramid fibers or wire fibers made of Haynes 25 wire. It is therefore in line with the invention to produce a bristle packet at least in a hybrid construction, with the bristles of an interior layer being made of a different material than the bristles of the exterior layer. 
         [0022]    The brush seal according to the invention distinguishes itself through high temperature resistance and high mechanical resistance. Moreover, it tends to generate only a minor amount of heat when brushing against a rotor. A good sealing effect can be realized together with a long service life.