Boundary Layer Blowing Using Steam Seal Leakage Flow

Abstract

A steam turbine includes a final turbine stage, a flow diffuser receiving a main flow from the final turbine stage, a diverging wall in the axial or radial flow diffuser that extends from a diffuser inlet to a diffuser exit, and a centerbody in the axial or radial flow diffuser. An opening is provided in the diverging wall and an opening is provided in the centerbody for fluidically actuating the main flow. The openings are located downstream from the diffuser inlet and upstream from a point where boundary layer separation would occur along the walls in a diffuser without the openings. A plurality of openings are provided in the diverging wall, and an end packing seal is positioned adjacent an end portion of the final turbine stage. An annular manifold collects fluid from leakage flow from the end packing seal and distributes the leakage flow to the openings.

1 . A steam turbine comprising:
 a final turbine stage;   an axial or radial flow diffuser receiving a main flow from the final turbine stage;   a diverging wall in the axial or radial flow diffuser, the diverging wall extending from a diffuser inlet to a diffuser exit;   a centerbody in the axial or radial flow diffuser;   an opening in the diverging wall and an opening in the centerbody for fluidically actuating the main flow, wherein the openings are located downstream from the diffuser inlet and upstream from a point where boundary layer separation would occur along the walls in a diffuser without the openings;   a plurality of openings in the diverging wall;   an end packing seal positioned adjacent an end portion of the final turbine stage; and   an annular manifold collecting fluid from leakage flow from the end packing seal and distributing the leakage flow to the openings.   
     
     
         2 . A steam turbine according to  claim 1 , wherein the annular manifold comprises a steam seal header. 
     
     
         3 . A steam turbine according to  claim 2 ,
 comprising multiple turbine stages and a corresponding multiple end packing seals, wherein the steam seal header collects fluid from leakage flow from the multiple end packing seals.   
     
     
         4 . A steam turbine according to  claim 3 , further comprising a steam guide in fluid communication with the steam seal header, the steam guide delivering the leakage flow from the steam seal header to the axial or radial flow diffuser to energize a boundary layer in the axial or radial flow diffuser. 
     
     
         5 . A steam turbine according to  claim 1 , further comprising tubes connecting the annular manifold to the openings. 
     
     
         6 . A steam turbine according to  claim 5 , wherein the tubes are curved convexly relative to the main flow. 
     
     
         7 . A steam turbine comprising:
 a final turbine stage;   an axial or radial flow diffuser receiving a main flow from the final turbine stage;   a diverging wall in the axial or radial flow diffuser, the diverging wall extending from a diffuser inlet to a diffuser exit;   a centerbody in the axial or radial flow diffuser;   an opening in the diverging wall and an opening in the centerbody for fluidically actuating the main flow; and   a steam seal header collecting fluid from leakage flow from at least the final turbine stage,   wherein the openings in the diverging wall and the centerbody are located downstream from the diffuser inlet and upstream from a point where boundary layer separation would occur along the walls in a diffuser without the openings, wherein steam is extracted from the steam seal header and directed into the openings in the diverging wall to energize the boundary layer.   
     
     
         8 . A steam turbine according to  claim 7 , further comprising multiple turbine stages and a corresponding multiple end packing seals disposed adjacent end portions of the respective turbine stages, wherein the steam seal header collects fluid from leakage flow from the multiple end packing seals. 
     
     
         9 . A steam turbine according to  claim 8 , further comprising a steam guide in fluid communication with the steam seal header, the steam guide delivering the leakage flow from the steam seal header to the axial or radial flow diffuser to energize a boundary layer in the axial or radial flow diffuser. 
     
     
         10 . A steam turbine according to  claim 7 , further comprising tubes connecting the steam seal header to the openings. 
     
     
         11 . A steam turbine according to  claim 10 , wherein the tubes are curved convexly relative to the main flow. 
     
     
         12 . A method of improving diffuser performance comprising:
 allowing a main flow to pass through the diffuser;   providing an opening in a diffuser wall;   utilizing a steam seal header as a fluid source;   injecting fluid from the steam seal header into the opening for preventing separation of the main flow from the diffuser wall; and   directing the fluid at an angle relative to the main flow and relative to the diffuser wall, wherein directing the fluid at an angle comprises sending the fluid through a curved passageway having a curvature which is convex relative to the main flow prior to injecting fluid into the opening.   
     
     
         13 . A method according to  claim 12 , further comprising positioning a centerbody within the diffuser and providing an opening in a wall of the centerbody. 
     
     
         14 . A method according to  claim 13 , further comprising injecting fluid from the steam seal header through the opening of the centerbody and into the diffuser.