Turbomachine plasma seal system

Abstract

Various embodiments include a turbomachine with a plasma seal system. The turbomachine can include: a diaphragm section having: an axially facing diaphragm wall; and a discourager seal protruding axially from the axially facing diaphragm wall; a rotor section having: a bucket having an axially facing bucket wall opposing the axially facing diaphragm wall; and a seal member extending from the axially facing bucket wall, wherein the seal member axially overlaps a portion of the discourager seal of the diaphragm section leaving a radial gap between the seal member and the discourager seal; and a plasma generator coupled to the diaphragm section for generating a plasma which reduces the radial gap between the seal member and the discourager seal.

We claim: 
     
         1 . A turbomachine comprising:
 a diaphragm section having:
 an axially facing diaphragm wall; and 
 a discourager seal protruding axially from the axially facing diaphragm wall; 
   a rotor section having:
 a bucket having an axially facing bucket wall opposing the axially facing diaphragm wall; and 
 a seal member extending from the axially facing bucket wall, 
 wherein the seal member axially overlaps a portion of the discourager seal of the diaphragm section leaving a radial gap between the seal member and the discourager seal; and 
   a plasma generator coupled to the diaphragm section for generating a plasma which reduces the radial gap between the seal member and the discourager seal.   
     
     
         2 . The turbomachine of  claim 1 , wherein the seal member includes:
 an axially extending portion; and   a radially extending portion continuous with the axially extending portion.   
     
     
         3 . The turbomachine of  claim 2 , wherein the plasma reduces a radial gap between the radially extending portion and the discourager seal. 
     
     
         4 . The turbomachine of  claim 1 , wherein the discourager seal is substantially planar. 
     
     
         5 . The turbomachine of  claim 1 , wherein the bucket further includes a base section and a blade extending radially from the base section, wherein the base section includes the axially facing bucket wall. 
     
     
         6 . The turbomachine of  claim 1 , wherein the plasma generator is coupled to the discourager seal. 
     
     
         7 . The turbomachine of  claim 1 , wherein the plasma generator includes:
 a dielectric;   an embedded electrode within the dielectric;   an exposed electrode outside of the dielectric; and   a current supply for applying a current to the embedded electrode and the exposed electrode.   
     
     
         8 . The turbomachine of  claim 7 , wherein the dielectric is located on a radially inwardly facing surface of the discourager seal. 
     
     
         9 . The turbomachine of  claim 8 , wherein the plasma generator is configured to generate the plasma on a radially inwardly facing surface of the dielectric. 
     
     
         10 . The turbomachine of  claim 1 , wherein the discourager seal is located radially outward of the seal member. 
     
     
         11 . A turbomachine comprising:
 a diaphragm section having:
 an axially facing diaphragm wall; and 
 a discourager seal protruding axially from the axially facing diaphragm wall; 
   a rotor section having:
 a bucket having an axially facing bucket wall opposing the axially facing diaphragm wall; and 
 a seal member extending from the axially facing bucket wall, 
 wherein the seal member axially overlaps a portion of the discourager seal of the diaphragm section leaving a radial gap between the seal member and the discourager seal; 
   a fluid channel extending between the axially facing diaphragm wall and the axially facing bucket wall, the fluid channel intersecting with the radial gap; and   a plasma generator coupled to the diaphragm section for generating a plasma which reduces the radial gap between the seal member and the discourager seal.   
     
     
         12 . The turbomachine of  claim 11 , wherein the seal member includes:
 an axially extending portion; and   a radially extending portion continuous with the axially extending portion.   
     
     
         13 . The turbomachine of  claim 12 , wherein the plasma reduces a radial gap between the radially extending portion and the discourager seal. 
     
     
         14 . The turbomachine of  claim 11 , wherein the discourager seal is substantially planar. 
     
     
         15 . The turbomachine of  claim 11 , wherein the bucket further includes a base section and a blade extending radially from the base section, wherein the base section includes the axially facing bucket surface. 
     
     
         16 . The turbomachine of  claim 11 , wherein the plasma generator is coupled to the discourager seal. 
     
     
         17 . The turbomachine of  claim 11 , wherein the plasma generator includes:
 a dielectric;   an embedded electrode within the dielectric;   an exposed electrode outside of the dielectric; and   a current supply for applying a current to the embedded electrode and the exposed electrode.   
     
     
         18 . The turbomachine of  claim 17 , wherein the dielectric is located on a radially inwardly facing surface of the discourager seal, wherein the plasma generator is configured to generate the plasma on a radially inwardly facing surface of the dielectric. 
     
     
         19 . The turbomachine of  claim 18 , wherein the plasma interferes with fluid flow from the fluid channel through the radial gap. 
     
     
         20 . A method comprising:
 providing a turbomachine having:
 a diaphragm section having:
 an axially facing diaphragm wall; and 
 a discourager seal protruding axially from the axially facing diaphragm wall; 
 
 a rotor section having:
 a bucket having an axially facing bucket wall opposing the axially facing diaphragm wall; and 
 a seal member extending from the axially facing bucket wall, 
 wherein the seal member axially overlaps a portion of the discourager seal of the diaphragm section leaving a radial gap between the seal member and the discourager seal; and 
 
 a plasma generator coupled to the diaphragm section; and 
   actuating the plasma generator to generate a plasma which reduces the radial gap between the seal member and the discourager seal, wherein the plasma further reduces an axial gap between the discourager seal a radially extending portion of the seal member.