Gas turbine compressor casing flowpath rings

Abstract

A flowpath ring is securable in a machined groove of a gas turbine compressor stator casing. The ring includes a connector section engageable with and shaped corresponding to the machined groove. A flowpath section is disposed radially inward relative to the connector section and includes a clearance surface disposed facing a turbine rotor blade. The flowpath section defines a blade flowpath when secured in the turbine stator casing machined groove. The use of flowpath rings facilitates flowpath repair if rotor blade tip rubs occur. Additionally, the rings enable better matching of transient thermal responses between the compressor rotor and compressor casings.

1 . A flowpath ring securable in a machined groove of a compressor stator casing, the flowpath ring comprising: 
 a connector section engageable with the machined groove, the connector section being shaped corresponding to the machined groove; and    a flowpath section disposed radially inward relative to the connector section, the flowpath section including a clearance surface disposed facing a compressor rotor blade and defining a blade flowpath when secured in the compressor stator casing machined groove.    
   
   
       2 . A flowpath ring according to  claim 1 , wherein the flowpath ring comprises a plurality of segments.  
   
   
       3 . A flowpath ring according to  claim 1 , wherein the ring is attachable in the compressor stator casing machined groove between adjacent stator airfoils.  
   
   
       4 . A flowpath ring according to  claim 1 , further comprising an abradable coating on the clearance surface.  
   
   
       5 . A flowpath ring according to  claim 4 , further comprising a groove in the clearance surface, the abradable coating being disposed in the groove.  
   
   
       6 . A flowpath ring according to  claim 1 , further comprising at least one air gap insulator disposed on a casing side surface of the flowpath ring.  
   
   
       7 . A flowpath ring according to  claim 6 , wherein the air gap insulator comprises a groove formed in the casing side surface.  
   
   
       8 . A flowpath ring according to  claim 6 , wherein the air gap insulator further comprises a seal interposable between the casing side surface of the flowpath ring and the casing.  
   
   
       9 . A flowpath ring according to  claim 1 , comprising a substantially T-shaped cross-section, wherein the connector section defines a stem of the T-shape, and wherein the flowpath section defines a cross of the T-shape.  
   
   
       10 . A compressor comprising: 
 a stator casing having airfoil grooves each supporting a plurality of stator airfoils;    a rotor supporting a plurality of rotor blades for rotation relative to the stator casing; and    a plurality of flowpath rings secured in respective ring grooves in the stator casing, wherein each of the flowpath rings comprises: 
 a connector section engaged with the ring groove, the connector section being shaped corresponding to the ring groove, and  
 a flowpath section disposed radially inward relative to the connector section, the flowpath section including a clearance surface disposed facing the rotor blades and defining a blade flowpath.  
   
   
   
       11 . A compressor according to  claim 10 , wherein each of the flowpath rings comprises a plurality of segments.  
   
   
       12 . A compressor according to  claim 10 , wherein the ring grooves are formed between adjacent ones of the airfoil grooves.  
   
   
       13 . A compressor according to  claim 10 , wherein each of the flowpath rings further comprises an abradable coating on the clearance surface.  
   
   
       14 . A compressor according to  claim 10 , wherein each of the flowpath rings further comprises at least one air gap insulator disposed on a casing side surface thereof.  
   
   
       15 . A compressor according to  claim 14 , wherein the air gap insulator comprises a groove formed in the casing side surface.  
   
   
       16 . A compressor according to  claim 14 , wherein the air gap insulator further comprises a seal interposable between the casing side surface of the flowpath ring and the casing.  
   
   
       17 . A compressor according to  claim 10 , wherein each of the flowpath rings comprises a substantially T-shaped cross-section, wherein the connector section defines a stem of the T-shape, and wherein the flowpath section defines a cross of the T-shape.  
   
   
       18 . A compressor according to  claim 10 , wherein each of the flowpath rings is shaped to match transient thermal responses between the rotor and the stator casing.  
   
   
       19 . A method of assembling a stator casing, the method comprising: 
 machining a plurality of airfoil grooves each for supporting a plurality of stator airfoils;    machining a plurality of ring grooves interposed between adjacent ones of the airfoil grooves; and    securing a plurality of the flowpath rings of  claim 1  in respective ones of the ring grooves.    
   
   
       20 . A method of restoring original performance and compressor surge margin or modifying performance and compressor surge margin in the compressor of  claim 10 , the method comprising removing damaged ones of the flowpath rings, and inserting replacement rings.