Stator-rotor assemblies with features for enhanced containment of gas flow, and related processes

Abstract

A stator-rotor assembly is described, including at least one interface region and a gap between a surface of the stator and a surface of the rotor. The stator is a nozzle or vane that includes circumferential endwalls. Each endwall includes at least one leading edge and one trailing edge, relative to a hot gas flow path. A trailing edge of at least one of the endwalls includes a pattern of cavities that are capable of impeding the entry of hot gas into a wheelspace region that adjoins the gap between the stator and the rotor. The cavities can also be formed on various sections of the rotor. The stator-rotor assembly can be incorporated into various turbomachines, such as gas turbine engines. Related processes are also described.

1 . A stator-rotor assembly, comprising at least one circumferential endwall having a trailing edge that comprises a pattern of cavities. 
     
     
         2 . A stator-rotor assembly, comprising at least one interface region between a surface of the stator and a surface of the rotor, said surfaces being separated by a gap,
 wherein the stator is a nozzle or vane that comprises inner and outer circumferential endwalls; and each endwall includes at least one leading edge and one trailing edge, relative to a hot gas flow path; and   wherein a trailing edge of the inner circumferential endwall comprises a pattern of cavities that are capable of impeding the entry of hot gas into a wheelspace region that adjoins the gap between the stator and the rotor.   
     
     
         3 . The assembly of  claim 2 , wherein the cavities have a curved inner surface. 
     
     
         4 . The assembly of  claim 2 , wherein the cavities have a depth that is tapered along at least one dimension of the cavity. 
     
     
         5 . The assembly of  claim 2 , wherein the cavities are in the shape of a partial cone. 
     
     
         6 . The assembly of  claim 5 , wherein each partial cone has a base dimension, closest to the gap, that is wider than an opposite end of the cone that is farthest from the gap. 
     
     
         7 . The assembly of  claim 2 , wherein the pattern comprises an array of uniformly-spaced cavities. 
     
     
         8 . The assembly of  claim 2 , wherein the pattern comprises an array of non-uniformly-spaced cavities. 
     
     
         9 . The assembly of  claim 2 , wherein the cavities have an average depth in the range of about 10% to about 80% of the depth of the inner circumferential endwall. 
     
     
         10 . The assembly of  claim 2 , wherein the cavities are situated along the trailing edge, and are generally parallel to each other. 
     
     
         11 . The assembly of  claim 10 , wherein an edge of each cavity is in contact with an edge of an adjacent cavity. 
     
     
         12 . The assembly of  claim 10 , wherein each cavity is spaced from adjacent cavities. 
     
     
         13 . The assembly of  claim 2 , wherein the interface region between the stator and rotor surfaces is a flow-restriction region that limits the flow of gas from the hot flow path of the turbine engine, through the gap, to a wheel-space region of the stator-rotor assembly. 
     
     
         14 . A stator-rotor assembly, comprising at least one interface region between a surface of the stator and a surface of the rotor, said surfaces being separated by a gap,
 wherein the rotor is a bucket or blade that comprises inner and outer circumferential endwalls; and each endwall includes at least one leading edge and one trailing edge, relative to a hot gas flow path; and   wherein a trailing edge of the inner circumferential endwall comprises a pattern of cavities that are capable of impeding the entry of hot gas into a wheelspace region that adjoins the gap between the stator and the rotor.   
     
     
         15 . A gas turbine engine, comprising a stator-rotor assembly according to  claim 1 . 
     
     
         16 . A turbomachine, comprising at least one stator-rotor assembly, wherein the stator-rotor assembly comprises at least one interface region between a surface of the stator and a surface of the rotor, said surfaces being separated by at least one gap,
 wherein the stator is a nozzle or vane that comprises inner and outer circumferential endwalls; and each endwall includes at least one leading edge and one trailing edge, relative to a hot gas flow path; and   wherein a trailing edge of the inner circumferential endwall of each nozzle or vane comprises a pattern of cavities that are capable of impeding the entry of hot gas into a wheelspace region that adjoins the gap between the stator and the rotor.   
     
     
         17 . A method for restricting the flow of hot gas through a gap between a stator and a rotor in a turbomachine,
 wherein the stator is a nozzle or vane that comprises inner and outer circumferential endwalls; and each endwall includes at least one leading edge and one trailing edge, relative to a gas flow path; and   wherein the method comprises the step of forming a pattern of cavities on at least a portion of the trailing edge of the inner endwall of the stator component;   wherein the cavities have a shape and size sufficient to impede the entry of hot gas into a wheelspace area that adjoins the gap between the stator and rotor.   
     
     
         18 . The method of  claim 17 , wherein the cavities are formed by at least one technique selected from the group consisting of milling techniques, electro-discharge machining (EDM), electro-chemical machining (ECM), and casting.