Compliant brush shroud assembly for gas turbine engine compressors

Abstract

A brush shroud assembly for reducing the tip clearance between a rotating blade and an engine casing is disclosed. The assembly includes a plurality of bristle packs supported within a housing such that the bristle distribution at the inner diameter of the bristle packs is substantially continuous. The continuous surface is created by mounting the bristles packs within a housing such that the packs are flared, i.e. width at the outer diameter of the bristle pack is smaller than that at the inner diameter. Various embodiments are disclosed for mounting the flared bristle packs to form a substantially continuous inner diameter. The bristle strips may be mounted in one or more annular rings, may be secured within one or more channels in the housing, the bristle packs may be formed into a tufted ring, or any of these may be utilized in combination with a backplate supporting an abradable seal, i.e. a hybrid design.

1 . A brush shroud assembly for use with a gas turbine engine, the brush shroud assembly-comprising: 
 at least one bristle strip including two or more bristle packs, each bristle pack being supported by at least on rail at a first end, the first end defining an outer diameter, the bristle strip further including a free second end opposite the first end defining an inner diameter, such that the width at the outer diameter is less than that at the inner diameter and the second end is flared relative to the first end;    a housing including a channel configured and dimensioned to support the bristle strip, at least one channel having an inner diameter sized to receive the at least one bristle strip therein and including an inner wall, wherein the at least one rail is supported within the at least one channel such that the bristle pack is spaced from the inner wall so that the housing is out of direct contact with the bristle pack, the flared second ends of the bristle packs extending from the housing such that the flared ends of adjacent bristle packs form a substantially continuous surface.    
   
   
       2 . The assembly of  claim 1 , wherein the number of channels corresponds to the number of bristle strips.  
   
   
       3 . The assembly of  claim 1 , wherein the at least one rail is a double rail.  
   
   
       4 . The assembly of  claim 1 , wherein the at least one rail extends from within the channel.  
   
   
       5 . The assembly of  claim 1 , wherein the channel has a stepped configuration.  
   
   
       6 . The assembly of  claim 1 , wherein the first end of the bristle strip is further supported within an annular ring such that an outer diameter of the at least one rail is disposed adjacent an inner diameter of the annular ring, the annular ring being sized to fit within the at least one channel.  
   
   
       7 . The assembly of  claim 1 , wherein the first end is constrained such that the constrained portion has a length of about 10% of the total length of the bristle pack.  
   
   
       8 . The assembly of  claim 1 , wherein the at least one bristle strip is supported within the channel at an angle of about 1 to 25 degrees with respect to a radial direction in the direction of blade rotation.  
   
   
       9 . A brush shroud assembly for use with a gas turbine engine, the brush shroud assembly comprising: 
 a housing;    at least one bristle strip including two or more bristle packs, each bristle pack being supported by at least on rail at a first end, the first end defining an outer diameter, the bristle strip further including a free second end opposite the first end defining an inner diameter, such that the width at the outer diameter is less than that at the inner diameter and the second end is flared relative to the first end;    at least one annular ring; and    wherein the at least one bristle strip is supported within a corresponding annular ring such that an outer diameter of the at least one rail is disposed adjacent an inner diameter of the corresponding annular ring, the annular ring being supported within the housing such that the flared second ends of adjacent bristle packs form a substantially continuous surface.    
   
   
       10 . The assembly of  claim 9 , wherein two or more bristle strips are supported within a single annular ring.  
   
   
       11 . The assembly of  claim 9 , wherein the annular ring is supported within a channel in the housing.  
   
   
       12 . The assembly of  claim 12 , wherein the channel has a stepped configuration.  
   
   
       13 . The assembly of  claim 12 , wherein the at least one rail extends from within the channel.  
   
   
       14 . The assembly of  claim 12 , wherein the number of channels corresponds to the number of bristle strips.  
   
   
       15 . The assembly of  claim 9 , wherein the first end is constrained such that the constrained portion has a length of about 10% of the total length of the bristle pack.  
   
   
       16 . The assembly of  claim 9 , wherein the at least one rail is a double rail.  
   
   
       17 . The assembly of  claim 9 , wherein the annular ring is generally L-shaped.  
   
   
       18 . The assembly of  claim 9 , wherein the at least one annular ring is generally U-shaped.